# 80mm long focal length refractor



## savarin

I came into possession of a matched pair of Jaeger 83mm dia lens of f15 focal length.
Although a focal length this long is somewhat against current practice I thought it might make a good project.
As this project is a long one I thought rather than just put the odd bit in the “what did you do in your shop today” I would do a complete build blog in case it might be of interest to others.

I started by making a 3d model with the full light cone to give me all the dimensions and hopefully how I could fit it all together.


Most amateur telescope makers start with the scope then go on to the mount.
I wanted to check out a few things so opted to start with the mount first.
So a quick render of how I wanted the feet.


And the following welded structure came about times 3


Todays job was drilling and tapping the end for the eye bolt.
The screw and knurled knob is to angle the leg downwards to adjust the central pier to sit perfectly vertical.


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## savarin

As conventional tripods have to be massive and heavy to stop flex and twist I went down a different route with a tall central pier with wide feet and using guy wires to tension the feet. I felt this would produce a solid base and such seems to be the case so far


The base is 3 angles from 25x10mm steel welded onto a 12mm thick steel disk turned to fit inside the central pier.
I cast and turned a chunk of aluminium to fit inside the pier as well. This is bolted to the base with a 14mm long bolt to provide a solid unit.
	

		
			
		

		
	



The three feet pivot in these.
and these pads pivot on the ends of the feet.





After I built the ball turner I made the brass ones for the adjusters, hollowed the bolt heads and rounded the other heads off.


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## savarin

The contoured aluminium spacers I made the same way as these brass ones.


The bit is set at the radius of the outer tube dia. Drilled, flycut then parted off, repeat again.


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## 12bolts

Nice work Charles,
Looks good. Does tensioning the guy wires happen after you have levelled the column/feet?
Will the guy wires run to the eye bolts on the ends of the feet?

cheers Phil


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## savarin

12bolts said:


> Nice work Charles,
> Looks good. Does tensioning the guy wires happen after you have levelled the column/feet?
> Will the guy wires run to the eye bolts on the ends of the feet?
> 
> cheers Phil


Thanks Phil,
as to tensioning order I am not sure what will be best, probably level then tension. They only need just over finger tight to work. I feel a knurled ring about 25mm dia fitted over the middle of the bottle screw will aid in this. (and maybe look cool)
I only finished installing the wires and eye bolts yesterday.
I would like to take this opportunity to thank Rob Herd from http://www.steel-fittings.com/miami_stainless/index.htm for all the help and patience in making up the wires and tensioners. Nothing was too much trouble. No affiliation to the company just a very satisfied customer.

I used hooks at both ends for ease at night with no tiny clips or parts to lose in the dark.

At the bottom




and at the top




Those little brass washers are the ones I was contouring above.
The black paint is only a quick spray to stop rust. All the black parts will eventually be powder coated.
The azimuth bearing at the top is a casting turned to fit a set of taper trailer bearings







A flat plate will be bolted to this with the altitude bearings on it.
I will replace the nuts with nylocs once Ive finished playing around.
The eagle eyed amongst you will notice the porosity in the castings.
I will be making this unit again with some "wheelium" and degassing tablets in the hope of getting a solid cast that can be polished.
I also screwed up the alignment of the three fixing bolts. All three are out just a tad so they dont lay flat on the contoured aluminium washer. (no photo)
Still, there is room to re-drill and tap them again.


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## savarin

As it stands so far.


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## 12bolts

Charles,
Do you think the tension on the guy wires will upset the levelling?

Aside,    on my recent handle castings I melted a fair amount of ally, and because it was a larger amount in the pot I doubled the amount of dry chlorine degas i usually use. It has given me a much better finished product. I did notice the "out of the mold surface" was a lot grayer and more textured than I have got in the past but I am thinking now I have just not been using enough to degas properly.
But if I melt half the qty of ally and use half the qty of CL then it doesnt degas properly? So maybe I need a specific volume of CL to get the required reaction?

Cheers Phil


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## savarin

12bolts said:


> Charles,
> Do you think the tension on the guy wires will upset the levelling?


Probably but the adjusting knobs on the feet have plenty of leverage to add more tension.



> Aside,    on my recent handle castings I melted a fair amount of ally, and because it was a larger amount in the pot I doubled the amount of dry chlorine degas i usually use. It has given me a much better finished product. I did notice the "out of the mold surface" was a lot grayer and more textured than I have got in the past but I am thinking now I have just not been using enough to degas properly.
> But if I melt half the qty of ally and use half the qty of CL then it doesnt degas properly? So maybe I need a specific volume of CL to get the required reaction?
> 
> Cheers Phil


what type of chlorine do you use for degassing?


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## 12bolts

Just dry chlorinator granules for pool use

Cheers Phil


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## savarin

Good day today.
Picked up the aluminium plate and the aluminium tube for the scope body.
Also re-drilled and tapped the three holes in the azimuth casting that I had buggered up before.
Now they are on the diameter and bolt up flat.
How? with a highly precise mark one eyecrometer.


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## Matthew Gregory

Excellent project - subscribed!


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## savarin

First job with the 10mm aluminium plate.
2 large flanges to make the clamps that hold the scope.
I opted to document all this for the thread on cutting aluminium plate and as I didnt want the hassle of cleaning up all the fine swarf from the table saw I elected to use the jig saw. Not as clean cuts but still pretty quick.
I've kept the dates and times on the photos so you can see how quick the cuts are.
Rough marked out on the 1500x160x10mm plate


first cut with the jig saw approx half way through


finished, 2mins


long side and 4 corners off, 14 mins including a blade change for the saw.


Using a hole saw on my p#$% weak drill


at last we're through. This is probably the longest part to do. I seems to take forever particularly when the drill stalls easily at it slowest speed but highest torque. Also incredibly messy.


Into the lathe and turn round, 2 flanges. Now I have to mount them to the face plate and bore them out to just over 80mm for the tube and some foam padding.


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## savarin

The two flanges bolted together with four 8mm stainless rods.
Now I have to bore the holes for the tension screws, mill the sides for the 8x40mm strips (cut on the table saw) that will bolt on and hold the bearing trunnions and then split them in half.
Thinking again about all this I have a feeling I should have drilled the plates for the clamp bolts then split them whilst they were still square, then turned and bored them.
If it doesnt work I will revisit and do it again that way.


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## savarin

Took a break from the stand etc and made a sun finder.
A quick dive into the scrap bin came up with 3 off cuts of 12mm     thick aluminium and a bit of thin tube.
    I wanted the sun end to fit into the tube with a 1.5mm dia hole but     how to hold the off cut.
    Centre popped the middle and held  it tightly  against the chuck     jaws with the rotating centre and some double sided tape.


Drilled with a 1.5mm dia for the sun to peep down and made it an interference fit into the tube.


The sun spot has to hit an opaque screen at the other end of the tube so the screen holder needed a threaded insert to hold it in place.


Made a small internal threading tool and cut a 0.7mm thread inside and on the outer clamp ring.


The screen is cut for a plastic milk bottle, scratched with dividers and inked.


Then I polished the lot.


It works a treat. now back to the stand.


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## 12bolts

Nice work Charles,
Did you use the double sided tape and centre because of the lack of a 4 jaw? And then hold the round to cut the centre out?
Thats a pretty high polish inside the "cup" Im impressed with the finish!

Cheers Phil


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## savarin

12bolts said:


> Nice work Charles,
> Did you use the double sided tape and centre because of the lack of a 4 jaw? And then hold the round to cut the centre out?


The off cuts were too small for the 4 jaw (original piece of crap) so I used the tape and centre. Then mounted the now round piece in the 3 jaw and used the bearing pusher to get it aligned flat, turned down the push fit part for the tube, reversed it to drill the small hole and bore out the taper.
The other two pieces for the screwed end were drilled first,  both mounted together on a long bolt trapped in the 3 jaw, turned to size then individually bored and the threads cut.


> Thats a pretty high polish inside the "cup" Im impressed with the finish!


Thanks, 600 wet and dry with wd40, then 1800 jewelers abrasive paper and wd40 then solvol autosol.
There are still some marks left so when I set the polishing wheels back up and use tripoli followed by rouge then all the marks and micro scratches should disappear.


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## savarin

Back to the stand and bits.
Milled the side slots out of the rings using a small end mill I had been given years ago and my vertical slide.


then drilled the chord for the clamp bolts once the rings are split.


Straight all the way through with no wander.


milled out the corners and enlarged the hole to 5mm


The finished rings before polishing with one 40mm wide side plate resting in the slot and a 5mm rod in the bolt hole.


Now I have to cut the rings in half.


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## savarin

I thought I had it nailed.

I need 8 stainless knurled nuts for the clamp rings.
The first was ok, the second and third were very nice.


The knurls are even and regular.
That's when I assumed I had solved all the variables. Bad assumption.
The fourth one started fine, the thread cut smoothly and all was going well until it came time to use the knurler.
It kept walking itself out of contact.
It just wouldn't stay at 90 degrees to the work piece and the tension on the central tightening bolt of the QCTP was as tight as I could get it.
Its a double or maybe a triple start, hardly any knurling in the centre.
The fifth one (still in the lathe ready to be parted off and thrown away) is what could only be politely called an abortion.


Its making me believe that a purpose built fixture that cannot swivel at all would be the way to go.
Anyone foresee a reason not to?


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## savarin

Split he scope clamp rings today.
I only had a hacksaw so to keep the blade straight I clamped two lengths of angle iron to them and sawed through the gap.



This kept the cut pretty clean for a by hand saw cut.



A quick rub on some wet and dry and a load of WD40 for approx 8 mins



And the ends are nice and smooth and clean.


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## Matthew Gregory

Nicely done! Great idea on the angle iron guides, too.


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## savarin

At last I can get back to scope work.
Now I have the 4 jaw chuck I can bore out the bearing shell.
There was just enough clearance between the end of the bracket and the lathe bed.
It was a hell of a job getting it centered, the slightest pressure on one jaw sent it way out of alignment 




Both brackets bored and the bearings turned up in delrin.
The 3x8 mm holes are for the cross pieces that the clamp bolts will fit once the slots for them are milled out.
Then they have to be split in half. I think I will use the two angle iron guides again for that.


These were shaped with a file and small flap disk.
I cant make up my mind whether to bore a large hole in each side plate or not. No function just for looks.


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## savarin

No holes at this time as I think I may need the sides of the supports for some future additions.
Milled out the slots for the clamp bolts.


The large round disk is the top clamp holding the bearing support onto the vertical milling attachment.
And then 4 holes drilled and tapped 5mm and split them with the trusty angle iron guides and hacksaw.


The clamp bolts are 5mm into 8mm stainless, the one with the double cross piece is so that when dismantled in the dark it wont drop and be lost.


Like so. The nuts will be similar to the 8 knurled stainless ones that hold the rings together.



and with the tube just for looks. You can just see where the bottom plate has a half circle cut out for the scope tube to recess into when pointing vertical.


I'm very pleasantly surprised at the smoothness of the bearings and how little pressure is required to change the friction/force required to move the scope. (so far)
I'm not looking forward to the huge amount of polishing to be done in the near future.


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## chips&more

Nicely done! And I especially like how you used the angle iron! That’s Yankee Ingenuity at its best!


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## savarin

chips&more said:


> Nicely done! And I especially like how you used the angle iron! That’s Yankee Ingenuity at its best!


Thanks for that, but I'm a Pom.
Thats an Englishman living in Australia.


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## rwm

That is looking sharp! What wall thickness is that tubing? I assume you are polishing that?
R


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## savarin

rwm said:


> That is looking sharp! What wall thickness is that tubing? I assume you are polishing that?
> R



Everything will be highly polished at the end, I'm not really looking forward to that job.
I also want to use some profile cutters on all the edges I can so it will look better than dead square sections.
The tube is only 3 mm thick.


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## Tony Wells

Going to do a reflector when you finish this project? I want to see how that's done.


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## savarin

Tony Wells said:


> Going to do a reflector when you finish this project? I want to see how that's done.


Hmmm Tony, then I guess you want to see how this one is going eh?


The truss tubes are 12mm square steel tube. They are made but I still have to weld the diagonals in.
I have the two lazy susan bearings for the top cages.
I have the glass for the two mirrors plus the grinding and polishing machine ready.
They will be two f6  12" mirrors where the back face will be ground to the same radius of curvature as the fronts.
They will be polished to a sphere then flexed to the parabolic shape required. I have made one 8" f3.7 spherical mirror flexed to a perfect mirror to check the process.
When I finish the refractor I will be starting on these again and will start a project blog.


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## rwm

Reflector binoculars?! Will you have the image inverted? 
R


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## savarin

rwm said:


> Reflector binoculars?! Will you have the image inverted?
> R


Yes but they are for astronomy so it doesnt matter although it helps if the finder scope produces the image the right way up and the correct left to right orientation but its not essential.


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## Tony Wells

Oh yeah! That's the ticket!


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## savarin

Fancied a change of pace so decided to make one of the finder mounts.
A quick play with the modeler to make something like this.
The two rings are 50mm dia.


Parted the rings then had to work out how to drill and tap them so I marked 6 radii off and used the square to set them vertical. Drilled then replaced the drill with the tap and started it, removed from DP and finished tapping in the vice them moved round to the next hole.


The two legs were cut with the angle iron guides and hacksaw and a heap of filing (I still cant believe how handy these are) then the curve for the rings to bolt onto was cut using the home made boring bar with a long bit. I first had to bore out the old tool holder to fit the 14mm qctp post.


The finished item all bolted up with the sun finder clamped in the rings. Only two more to make, one for the laser finder and one for the 2" optical finder (2" telescope) I used a short length of stainless 8mm shaft to ensure everything aligned ok. The grub screws will be swapped for brass knurled ones and the black screws will be stainless on my next order.


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## savarin

Managed a bit more. Made a lost foam pattern for the first part of the scope that the lens cell has to bolt to.
Buried in the loose sand and then filled to just under the edge of the tin. The straws are breathers.
Fired up the furnace and soon had a pot of metal.



Lifting it out with my new crucible tongs.



Starting the pour



Heaps of flames from the burning foam.



After a while its shaken out



Gee it looks ugly, still some plaster adhering.



After cutting the sprues off it looks a bit better



Turned the outer  dia to size to then took a skim from the tube so I could use the steady to bore the inner dia.



Once bored to size I removed the casting, turned up a mandrel to fit in the end, re-mounted and centred the casting to thin the tube and add some grooves just for show and cut the threads to screw into the joiner. (still to be cast in I hope brass)



Unfortunately there are too many porosity pin holes to be able to polish the casting so I will powder coat it black.


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## rwm

Nice work. (I hate lost foam)
R


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## randyc

Excellent design and work - I'm envious


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## savarin

rwm said:


> Nice work. (I hate lost foam)
> R


Thanks. This was my first go at lost foam and I think I will second that. The next foam pattern was a disk to make the joiner but was a total failure. It was interesting but I dont think I will do it again.
I've just finished a wooden pattern for the brass joiner and optical stop but have to replace the motor in my muller for a more powerful one which is why I went with the lost foam. 



randyc said:


> Excellent design and work - I'm envious



Thanks. I'm bucking the trend with this as virtually all scopes today are short focal lengths


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## savarin

Lens cell joined to the front barrel, undercoated only, I cant make up my mind as to gloss black or matt black, they both look good.
The flange is separated with an "O" ring to allow collimation of the lens via the three screws and three grub screws.



The six screws inside the cell that hold it to the front flange were drilled and tapped from the outside then plugged with aluminium plugs and turned down to size.
They are virtually invisible.


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## Matthew Gregory

Gloss black. No question. If the rest of it will be polished, the shiny contrast of gloss will be a great detail.

Excellent project!


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## rwm

That cast piece looks really good painted! I don't usually paint my castings. I would say the paint has to match the objective lens holder. Are you going to repaint that as well? How about Marks crinkle finish? Gloss would look great but you know it will get marred up.
What is the purpose of the threads on that piece? They look very clean for an un-treated casting. My castings machine poorly in general.
R


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## savarin

The thread is 1.25mm and the front lens cell will be painted the same colour as that cast section.
There will be a small section in brass (if all goes well) that has a smaller internal dia to act as the joiner to the main tube and as an optical stop.
I had to cast that section because the internal dia of that front part is 83mm dia at the front reducing down to 76 for the first stop, the 80mm tube has an internal dia of 74 which just fits the optical light cone where it will screw into the joiner.
In all, the focal length requires three optical stops to prevent grazing reflections from entering the eyepiece and I decided to machine them as joiners.
Most telescopes just push sheet metal ones down the tube but I thought that as the tube will be over a meter in length it would be nice to be able to dismantle it into shorter sections for traveling.


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## rwm

More complex than I imagined. I will have to read more about this:
"In all, the focal length requires three optical stops to prevent grazing reflections from entering the eyepiece and I decided to machine them as joiners."
R


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## savarin

The front cell is finished


all the lens edges have been blackened but I still have to blacken the screws inside.
The gloss black doesnt look as glossy in the photos.
You can just see the pusher grub screw that allows the cell to tilt for collimating.


Finished threading and polishing two of the tubes, (only one in the photo) how tedious is polishing. The original surface is the top tube.


Still some ultra fine scratches to remove so its back to 1500 grit then rouge.
I cant cast the brass joiners yet due to the changeable weather, sudden showers that I dont want to have molten metal around.


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## savarin

The first brass lump has been cast as a lost foam project for the joiner.


Man thats ugly, runners and sprue to remove.
Then a bit of machining and a thread cut we get this, its difficult to see but there is a 1.25mm thread there.


I dont know if it was required but decided that discretion being the better part of valor  I decided to make a threaded plug to fit the end so there was no chance of distorting the part when I clamped it in the chuck to part, turn and thread the other end.


Screwed on


Yep, thats a small inclusion hole you can see there, dang! but I'm not re-casting that (yet)
Its back in the 4 jaw and I've now parted it to length and hope to start on the thread today. (no pics of this bit yet)


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## savarin

And now its machined and threaded to size and successfully holds the two parts together as well as looking great (or so I think)


Only another two to cast and machine. At least I've finished polishing the tubes.


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## turnitupper

Looking great! , you're fooling yourself. That is magnificent work but I may be a little biased as I am an itinerant banana bender. Did you grind youy own lenses as I knew a painter friend in Rockhampton who ground his own but it was a PITA just watching him slave for hours over one facet.
John.


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## savarin

Thanks for the kind words.
The lens's came from surplus shed and were old Jaegers.
I forgot to mention I parted off a 3/4" section first before I turned the inner dia. It went very smoothly for such a large lump.


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## savarin

Had an awesome couple of days, so much done.
Cast the three joiners in brass in green sand.
Machined them to size, bored the baffle dia.
Then bored half way through to leave a thin section for the actual baffle and threaded the inside.




I then screwed a mandrel into the joiner, skimmed the bit thats protruding in the hope it would be more concentric when reversed to bore and thread the other side. This turned out to be the case but lets be honest, its not sub micron accuracy here.




Once the other side was finished it was impossible to remove it without marking the brass so I wrapped it in plastic tape and jury rigged a strap wrench from some steel banding




ID-10-T alert! The design was for 15mm of thread on the ends of the tubes and in the joiners.
Unfortunately after machining all the defects off the brass there was only sufficient material left for 10mm of thread so I had to either recast or shorten the tube threads. Yep, easier to shorten the threads.
I removed the bearings from my fixed steady and replaced them with oil soaked hard-wood shoes to keep the marring of the tubes to a minimum as I shortened the threaded ends




This worked really well and they all screwed up to make this. There is an "O" ring on each end of each joiner to seal the joints.




Tomorrow I'm off to get the 50mm tube for the focusser draw tube and then very little for the next 4-5 days as I have to go for an operation on my jaw. (Shameless plug for some sympathy)


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## Franko

Wow, Savarin. Outstanding work. I just found this thread, or I would have said it sooner.


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## savarin

Thank you kind sir for those words of encouragement.
This was meant to be a quick and simple project whilst I collected the bit for the giant bino.
I've got carried away.


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## savarin

Making the draw tube for the focusing unit was a bit of a pain.
The closest size tube I could obtain was a threads thickness too small so I had to bore and thread the inside of the tube then make an insert that was just that much thicker.


Just so the diagonal could screw on.


Still, it works and it all looks good.
Now I need a block of ally 70mm x 70mm x 50mm thick for the focusser body that will bolt to the brass end plate.
I've found a source for an 80x80x80 block for $26 but with postage I expect that will end up closer to $50.
Thats a lot of spondulics for what will be a lot of swarf. Maybe I will have to cast one.
Time to get some grain refiner and de-gassing tablets.


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## savarin

Still waiting for the block of ally so I started on the finder scope.
I'm using a doublet from an knackered binocular.


The right hand joiner was already made, one end of the tube was threaded, so today  I cut it to length and threaded it, also there is approx 30mm of taper on the inside with a fine thread for anti reflection once its painted matt black.
The centre joiner has three different dia threads, one for the tube, one for the lens cell and one for the lens hood.
I cut a fine thread inside the hood and have sprayed it matt black.
All assembled it looks like this


More polish needed on the hood and tube but the joiners will be gloss black.
You can just see the gaps left for the "O" ring sealing glands so moisture doesnt wick into the tube.


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## Matthew Gregory

Such a fantastic project... Love checking in to see your progress. 


How'd the jaw operation go?


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## savarin

Thanks Matthew, jaw doing fine, they had to go in from the side to remove an old bit of tooth root that kept getting infected.


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## savarin

Finder scope finished and looking very nice.
However, I now have a cemented 50mm japanese doublet that may be a better objective but it needs the central tube to be another 15mm longer and a different lens cell. Maybe after its all finished.



At last I can start on the focusser unit.
I couldnt find any 60mm plate but did find some 100mm round.
Now came the hard part, I dont have a mill but need to convert this cylinder to a block.
It wont fit securely in the chuck. 
I scribed the block size on the top of the cylinder, drilled the centre and mounted it on the compound in place of the tool post.
I used a rule to align the scribed line with the face of the chuck.


The only tool I could use that had sufficient off set happened to be the Eccentric Engineering diamond tool holder and this proved to be just right held at an angle in the 4 jaw.


about half way through here. as I got closer to the scribed line I just had to make a tiny re-alignment to bring it back to spot on.


Instead of doing the same thing to the other side I mounted it against the chuck jaws as there was just enough room and have started milling the other side. I'm hoping they will be parallel by doing it this way.
The first cuts seem to point this way.


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## Bill Gruby

And I thought I was bad, you really put that 9X20 through its comfort zone. Kudos.

 "Billy G"


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## savarin

Bill Gruby said:


> And I thought I was bad, you really put that 9X20 through its comfort zone. Kudos.
> 
> "Billy G"


Thanks Bill, what is it they say? A mans gotta do?
This old cook really needs a mill. (or should that be kook)


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## JimDawson

Very creative setup, I love it.  Nice work also.


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## brino

savarin said:


> I'm hoping they will be parallel by doing it this way.



It certainly should be. 

Savarin, 

You always amaze me with your out-of-the-box approach to problems. I know I have said it to you before but you manage more with a lathe than others with a shop full of tools.

I really enjoy your posts.
Thanks for sharing!

-brino


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## Franko

I agree with brino. I am very impressed.


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## savarin

Gee guys, at this rate my head wont fit through the door.
Many thanks.


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## savarin

It came out parallel ok which now let me mark it out for the next three sides so back onto the tool post to remove the waste.



I must have listened to you guys too much and thought I could do no wrong. I got a tad impatient and attempted to speed it up a bit.
ARGHHHHHHHHHHHHHHHHHHHHHHHH disaster


It started chattering and pulled the tool out of the chuck and I took a huge divot out before I could stop. I will have to place one on the other side and call it a feature.


I think that part of the problem was not just the extra speed but the tool bit wasnt quite right so I ground the back of a drill bit so I could turn the cutting edge to the correct orientation (as I saw it) to hopefully not do the same muck up again. This cut very smoothly.


Now all 5 sides are cut I can drill the holes for the bearings and bolts.
Clamped at 45', first holes at 3.3 mm then 10mm clearance for the 9mm dia bearings.

Then back onto the lathe to bore the 53mm dia hole for the focusser tube.


Once that was bored I could cut the apex of the triangle off


The design is not my idea its from this clever gentleman http://jimshomeplanet.com/CrayFocus/CrayFocus.html so credit where it is due.
Thats it for a couple of days as I have to lay a heap of pavers in the back yard.  (a large honey do)


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## prasad

Charles

I was looking at your bino-dobsonian project. I would suggest adding two controls for collimating the mirrors. one mirror moves around virtical axis and second moves on horizontal axis. The movement needed is very miute but without this adjustment your eyes will see different views which becomes confusing to the brain. I have viewed through similar bino and I have seen the problem. 

-Prasad



savarin said:


> Hmmm Tony, then I guess you want to see how this one is going eh?
> View attachment 97244
> 
> The truss tubes are 12mm square steel tube. They are made but I still have to weld the diagonals in.
> I have the two lazy susan bearings for the top cages.
> I have the glass for the two mirrors plus the grinding and polishing machine ready.
> They will be two f6  12" mirrors where the back face will be ground to the same radius of curvature as the fronts.
> They will be polished to a sphere then flexed to the parabolic shape required. I have made one 8" f3.7 spherical mirror flexed to a perfect mirror to check the process.
> When I finish the refractor I will be starting on these again and will start a project blog.


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## savarin

Its already in the plan but not on that drawing. However, when I was discussing this with the Bolton group who had a similar project they said they never had a problem with that and that the mirrors remained collimated. We will see. My thoughts are to ensure they can be co-collimated, better safe than sorry.
Also as they will be flexed then they wont slide around in the mirror cells so that may help.


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## savarin

Wow! time flies.
At last the focusser unit is finished.


Moving downwards:- main block, 4 bearings-screws-spacers, then plastic washers from milk bottle, brass plungers that hold the shaft, then bolts with pressure springs to hold the shaft against the focus tube, brass pusher with spring and adjustment knob for tension and locking, large knurled knob with smaller knob bolted to it, smaller knurled knob for other side.

I wound the springs on this mandrel but a lot shorter than the test in the photo.
The first two coils were wound with no travel, then the threading was engaged at 3mm pitch, then stopped to wind the last two coils with no travel.



The four bearings are held in the block and just protrude into the bore for the focus tube to ride upon. Yes, thats two spacers on that bolt, my drill wobbled a tad out of alignment and it needs a tad more clearance.
I still have to make the dust shield to cover the top 3 faces of the block. I cant decide upon ally or brass, guess it will be whatever I find first.



The shaft then bears against the other side of the tube, friction alone moves the tube in and out as the shaft is turned.

The small knobs are for coarse feed with the large knob for fine feed/focus.
The brass knob is an extra pressure point onto the centre of the shaft as a lock.




I am most pleased as it moves very smoothly with no grabbing or jerking. Just as a focusser should.
Its bolted to the brass ring that screws onto the last tube of the telescope.
Tomorrow is testing time to check how short the focus tube really needs to be (or longer if my calcs are way out)


----------



## Bill Gruby

Charles, fantastic work as always.

 "Billy G"


----------



## savarin

Bill Gruby said:


> Charles, fantastic work as always.
> 
> "Billy G"



Thanks Bill, much appreciated.


----------



## Matthew Gregory

The focusing assembly looks fantastic!!!


----------



## savarin

Thanks Matthew.
I just realised I never showed the bearing holes


Pretty ugly and 4 large holes for dirt etc to enter so I covered them with a thin plate


That funny twisted loop is actually a length of cotton reflected in the polished cover.


----------



## savarin

The scope is finished and assembled. It took long enough.


The end cap has a small brass loop for some stainless chain that will be bolted to the bottom of the flange so as not to loose the cap.
Its held in the cell via an "O" ring.
I wont collimate the lens until its in the cradle on the mount as it will be easier then.
Now started on polishing all the cradle parts.
I cant look through it yet as its too cumbersome to hold still and I dont want to scratch the tubes by resting it on the fence.


----------



## Bill Gruby

Very nice Savarin. You are a craftsman  at his best.

"Billy G"


----------



## savarin

Thanks Bill but I wish I worked faster.
I'm desperate to start on the binos.


----------



## Matthew Gregory

Gorgeous. How much does the assembly weigh?


----------



## Bill Gruby

Savarin:

Faster is not in the cards for a craftsman such as yourself. It's done when it's done.

 "Billy G"


----------



## Franko

What the world needs is more craftsmen such as yourself, Savarin, who take the time required to do a job worth doing.


----------



## savarin

Matthew Gregory said:


> Gorgeous. How much does the assembly weigh?


best guess (bathroom scales, notoriously inaccurate) is around 4Kg (8 lb) it feels around there as well.


Franko said:


> What the world needs is more craftsmen such as yourself, Savarin, who take the time required to do a job worth doing.


Thanks Franco much appreciated.


----------



## ch2co

Sir, your craftsmanship and attention to detail are above and beyond anything that I have ever seen.  You have a great little lens there, I have a mid '50's Jagers 4" f15 lens that I turned into a scope.  For planetary and double star work, this is my go to scope, harder to get around than my C8 cassegrain, but well with the extra effort. Long refractors rule.
What does the interior of your scope look like, baffles, type of antireflective interior tube coating etc?  

AMAZING work

CHuck the grumpy old guy


----------



## savarin

Thanks Chuck,
The first baffle is the internal edge of the tube where it screws into the first brass joiner.
This is why the front of the scope has that large black casting to bring the diameters down so the tubes would not cause any vignetting, the second baffle is a thin internal  edge in the middle of the second brass joiner, the third baffle is the internal edge of the focusser tube.
Everything inside is painted with a spray can matte black then top coated with thinned Artists carbon black acrylic.
I taped the ends of the tubes, poured the artists paint in and swirled it around to coat every surface, drained it and stood the tubes on end to drain fully and dry.
Of all the matte black paints I experimented with the "Atelier Artists Acrylic" Carbon Black was the flattest and blackest paint I could find.
The paint


Shots where the camera is just sitting pointing down the full length of the scope.
Unpainted inside



Spray can matte only



overcoated with the artists matte


Those two grey dots at 7 oclock were popped bubbles since been smoothed down and re-touched to remove them.
Simple test but looks "black hole" ish to me.


----------



## ch2co

I almost just sent you a series of 3 photos of my latest little refractor tube during blackening, and they look identical to yours. Thanks for the recommendation of the Atelier Artists Acrylic Carbon Black, never came across it before, but I'll have to get a bottle and try it out.  John Dobson, of Dobsonian telescope fame, used flat black paint that he mixed sawdust into to get a very black and rough non reflective finish, a real mess, but it works great! Keep up the great work. Let me know how it works when you get around to actually observing with it.

CHuck the grumpy old guy


----------



## savarin

My experiments were very interesting.
Some paints were very black when dead on but turned shiny grey at a glancing angle.
What was very surprising was the ones that looked a shiny grey dead on turned very black at glancing angles.
What paint did you use?


----------



## savarin

I had a re-think regarding the end cap, prising it off by inserting your fingernails into the gap just didnt seem right so I made a knob.





Hmm, large finger print. 
Easy to pop off now.
Now searching for some small stainless clips and chain so it wont get lost.


----------



## rwm

Really impressive work! Looks beautiful and very professional.
If you have the capability, I would love to see some planetary images. 
BTW stainless chain is super easy to make if you have any stiff wire or welding rod laying around.  Also a great source is chain from a toilet tank!
R


----------



## savarin

The only way I could take pictures is just by sticking my camera in the end of the tube and hoping I can reach focus. Ok for the moon but not for the planets.
I'm not really into astro photography, its seems a lot of time and angst for not much pleasure. (just my take on the subject)


----------



## savarin

After much soul searching and attempts I have at last got the clutch and slow motion drive working.
I cant believe how difficult this was to work out. This is all the parts.
The bottom casting could have been re made and the shaft screwed into it but by doing it this way I can alter the tension of the two taper rollers for a smooth but firm movement and set it with a lock nut (to be added later)



The curly keyway is where the bit flexed but as it works I didnt re-do it. The other one cut ok.
The lock screw stops the shaft from rotating when manually moving the aximuth plate (not shown)
The main part of the shaft is steel (old car drive shaft) and the top bit is stainless



The azimuth plate bolts on to the top of the unit via the 6 threaded holes.



The first ally spacer has a groove for an "O" ring to prevent dew and dirt from entering the bearing and seals against the hole in the azimuth plate (not shown)
plus a keyway and key that locks into the shaft preventing it from turning around the shaft.
There will be another "O" ring groove or I may use a thin gasket for the azimuth plate to seal against the top unit.
The next spacer is plastic and is machined to fit into the worm gear.



then comes the worm gear, another plastic spacer, the stainless spacer with the internal tongue so it cant rotate around the shaft then the knurled pressure knob.
Approx 1/4 turn from free to fully locked.
The large gap is where the 10mm thick azimuth plate will be bolted on. There is approx 0.3mm clearance between the azimuth plate and the first keyed spacer.



Now back to polishing.


----------



## brino

Complicated mechanism.....I am still trying to understand how it works.......

Great close-up pictures, thanks!
On the piece with the locking screw is that pitting from a home casting?

-brino


----------



## savarin

More like porosity from a home casting, there's also some tearing in the middle of the casting which is why I bored it out and locktighted a section from a real ally bar in there.
Ha ha, I feel better now knowing someone else has a problem with this. Its my fourth attempt to get it working.
The worm is bolted to the plate that's bolted to the top circular part.
The worm gear (above) is only held in place on the shaft by the plastic pressure shims/washers.
The bottom large spacer and the stainless washer with the tongue are fixed to the shaft with keys so they can move up and down a small amount depending upon the pressure of the large knurled knob.
When that knob is screwed down tight the worm gear is locked solidly to the shaft via friction and becomes a solid part of the peir and that bottom casting, so as the worm is turned it screws itself around the gear dragging the azimuth plate with it. The telescope is fixed to the azimuth plate.
It doesn't help that the plate and worm aren't in the picture yet so its difficult to visualise.
The previous version didnt have the keys and when the azimuth plate was moved manually it unscrewed the knurled knob releasing all the pressure.


----------



## ch2co

OK, I'm confused (which is really my normal state anyway), but are you currently building an equatorial mount for your 80mm scope? and is this just one axis of the mount?
or is this some sort of alt/azm mount??? or is this something completely different? 

CHuck the confused grumpy old guy


----------



## savarin

Hi Chuck,
Its an alt/az mount but not like a dob.
Have a look at the first pic on page one how it goes together.
The cast part sits into a vertical tube, the scope sits in the alt bearings at one end of the plate and the whole top unit with the plat spins round.
Near the top of page 2 has some pics of the test assembly showing how it should go together.
I used the table saw yesterday to cut down the azimuth plate from the large rectangle it was to something a little more streamlined.
No work today as its party time in 2 hours.


----------



## ch2co

So the worm gear if for hand control of the azimuth?  Are you planning to put a flexible control cable onto the worm gear?

CHuck the grumpy old guy


----------



## savarin

yes, already to use but I may end up adding a rod in a bearing as an extension because I cant find any flex couplings longer than those currently used on cheap dept store gems.
Theres also a slow motion control for the altitude bearings.
These are probably overkill but they add to the impressive look


----------



## savarin

Still have these to polish then lacquer.
Too much, I'm fed up with polishing, you start to get a bit ocd about removing every little micro scratch.
Most of these have gone through the tripoli but still have the polish to do, some still need a bit more sanding.


Argh!!!!!!!!!!!!!! when will it end.


----------



## brino

savarin said:


> Argh!!!!!!!!!!!!!! when will it end.



I think we all get that feeling when working on a large project.

I hope it helps to know that your build quality is remarkable.
You will end up with a beautiful and functional treasure when you're done!

-brino


----------



## savarin

Thanks Brino, The phenomenal amount I have learnt and the skills gained since starting this whole exercise have been absolutely priceless so really I shouldnt complain.


----------



## ch2co

The only reason that I really wanted a lathe (and minimill), was to repair, modify, rebuild and make from new, parts for my real hobby, astronomy.
I knew very little about machining before buying my tools. I know that a lathe could turn round stuff and thats about it. I was fortunate enough
to run into a good deal on a well maintained and upgraded G0602 lathe that came with tons of added tooling and including the G8689 mini mill, that  
I thought that I would probable just resell to someone.  Then after turning a little bit of aluminum, I tried out the mill and not knowing at all
what I was really doing I came up with a decent adjustable laser mount for my 4" f15 Jaegers scope. The learning curve was steep and only
motivated by what I wanted to actually make.  No regrets! Just as Savarin said, the whole exercise has been absolutely *priceless*. 
The Hobby-Machinist forum pulled me out of many dead ends that ended up as highly successful pieces of astronomical equipment.

CHuck the grumpy old guy


----------



## savarin

Hi Chuck, any chance of some pictures of what you have made for your scopes?


----------



## savarin

Change of pace today.
Made the pair of holding rings for the finder scope.
70mm dia, marked of and drilled each hole,


Then replaced the drill with the tap, started the thread,


removed it from the jig and finished it by hand.



now comes ---- you guessed it---polish them.


----------



## savarin

I had occasion to try out the shortie finder scope the other night, yuk! coma all around the outer quarter of the field.
I had another 50mm doublet handy of a longer focal length and as luck would have it it fit straight into the original cell.
All I had to do was make a longer tube.


Thats the shorter tube underneath so the new focal length is approx 15mm longer.
Now its a clean image across the field.
The gold tint is reflection from my shirt not brass tubes.


----------



## Tony Wells

You wear a gold shirt? I'm impressed..


Also impressed by your work. You've come a long way in a short time, Sav. Good on ya!


----------



## savarin

Thanks Tony thats really appreciated.
_(I thought I had already sent this but cant find it so have done it again)_
Made another brass screw today, only 11 more to go. I dislike repetitive jobs so am making them a few at a time.


Also made the clamps to hold the finder to the mounting rods.
They were somewhat roughly chopped out of some scrap and needed too much filing to get into shape so I attempted to remove as much as I could in the lathe.
Bolted together using the rear of the clamps as a register to the chuck body.


That then allowed me to reverse them using the new flat on the chuck body and bring the two to the same thickness.


Back to the other way to face as much as I could from the inside edge.


Now its just a little bit of filing. So after cleaning the remaining ends and face up with a file it was time to round the fat ends.


To get this, 


repeat again plus some extra filing for these.


Now to split them from the inside corner to the hole, drill and tap for a 4mm clamping bolt and then its more sanding and polishing again.


----------



## savarin

After splitting the clamps I bolted them to a chunk of ally plate,


I filed a groove for the 8mm shaft to sit in preventing the clamp from spinning round the bolt when I fly cut the profile in the end for the finder rings to sit.
Ask me how I knew that would happen.


both clamps profiled to fit the rings BUT........


Yep, when originally splitting the clamps into two I went too far with the saw and nicked the end.
Never mind, a quick design change and round these ones over. (no I'm not going back to do the others so they look the same)


And now for another design change, sorry, advanced feature.
The finder scope wont pass through the rings now the bolt is in place so I had to shave a little from the screw head, flatten the inside of the ring so the bolt head sat flat and lower and took a shaving from the offending lens cell of the finder.


Next stop powder coating the lens cell and hope I left enough clearance.


----------



## savarin

Have to wait for the powder coating till I get the spray booth finished so I decided to assemble it all and have a quick squiz at the universe.
Saw jupiters bands, 4 moons and it focussed nice and sharp but  Wide Angle 15mm was the smallest eye piece I had on hand.I still have to finish off the slow motion controls and add a brace under the support plate as I noticed it flexed a tiny amount.
Here it is with the sun finder, laser pointer and wide angle finder scope.






I rather pleased with its image results. And it looks cool.


----------



## turnitupper

savarin said:


> . And it looks cool.


You stole that from the TARDIS, I'm telling the Doctor!
Seriously, very nice work, I have been following this build and it is good to see the (almost) end result.
P.S., I noticed the neighbours coming over for a squiz,
John.


----------



## savarin

Thanks John. There are a couple of things have popped up that need something done.
The central support needs a join in the middle for easier transport.
The scope support cage needs a handle as the fully assembled scope is rather heavy. I will weigh it later.
I'm considering a counterweight for the front.
I think two right angle scrolls bolted to the centreline of the support plate and the top casting as a brace. 
A "Y" shaped yoke for the scope to sit into when at rest.
Hopefully that will be it.


----------



## savarin

And the gods of astronomy have reared their fickle heads again and produced thick clouds and rain (which we need) to bless the new telescope.


----------



## hman

savarin said:


> ... And it looks cool.


I disagree.  I think it looks ABSOLUTELY MAGNIFICENT!!!   ... and to think that you made the whole thing, _including the milling_, with just a 9x20 lathe and "some rusty files and a hammer."  ABSOLUTE WOWSERS!  Yours is an amazing accomplishment.


----------



## savarin

Thank you for that John much appreciated.
I suppose I should update the equipment list to add a drill press and welder
All I managed today was to make the patterns for those new bits


----------



## MozamPete

That is an amazing piece of art to be proud of - and a functional scope as well!  It will probably be in use for generations to come.

And the beauty of it is when you can combine two of your hobbies in one nothing seem like work  - it's all pure joy.  Well done mate.


----------



## savarin

Thanks Peter, 
I find it hard to believe the, dare I say, "astronomical" amount of knowledge I've gained in the two years its taken to get this far.
Its been well worth the journey.


----------



## hman

I recall from 'way back in history (when I was more into electronics), that a friend told me, "There's nothing more expensive than a free microprocessor."  I guess we can come up with a corollary - there's nothing more expensive than a free objective lens. 

... and, of course, Jon Miller is going through the same gyrations in his thread:  http://www.hobby-machinist.com/threads/free-is-never-free.47471/#post-401782


----------



## rwm

That looks so friggin' cool!
Robert


----------



## FOMOGO

turnitupper said:


> You stole that from the TARDIS, I'm telling the Doctor!
> Seriously, very nice work, I have been following this build and it is good to see the (almost) end result.
> P.S., I noticed the neighbours coming over for a squiz,
> John.



     I was thinking exactly the same thing when I saw it. The Darlic wouldn't stand a chance against that thing. Very nice work Savarin


----------



## savarin

Thanks heaps guys.
I'm working on the two gussets at the moment but its all hand filing due to the silly shape I wanted.
Then I will be able to contour the short edge where it will butt onto the large aluminium boss at the top of the pier.
I'm waiting on a length of 20mm aluminium rod for the handle that will fit between the two split flanges that clamp the scope into the cradle.
Still so much to do.


----------



## 12bolts

Charles, I must say i'm impressed with how far you've come with this during my absence. Its a little bit steampunk'ish. I really like the polished look. Have you considered keeping it like that rather than powdercoating?


----------



## savarin

Thanks Phil, I'm only powder coating odd bits that wont polish.


----------



## hoth2o

That is awesome!   Were can I find out more about making a telescope?


----------



## CraigB1960

Savarin, absolutely outstanding work there!  I have a passion for astronomy, used to have a C8, but sold it due to bad location.  Now that I'm in Tucson, AZ, which is very light friendly for astronomy, you have motivated me to look back into it.  Perhaps making my own.....

Thanks for a great thread!


----------



## savarin

hoth2o said:


> That is awesome!   Were can I find out more about making a telescope?


Hi hoth2o, 
do you want to build a refractor (what mine is) or a reflector?
Both have good and bad points
If a reflector do you want to buy the mirror or make one? Carl Zambuto makes what are considered to be the very best mirrors.
If a refractor then its easier to buy the objective lens and these two seem a good buy with a quick glance.
http://www.surplusshed.com/pages/item/l14233.html
http://www.surplusshed.com/pages/item/l3968.html

There are heaps of books available such as 
Amateur Telescope Making 2nd ed - S. Tonkin (Springer, 1999) 
Berry R. Build your own Telescope (1985)
MAKING YOUR OWN TELESCOPE by JJ PERSISTENT PUBLISHING INC
Texereau-HowToMakeATelescope (considered to be the classic)

atm_free@yahoogroups.com is worth while trolling through as well.


----------



## savarin

Thanks Craig, still making small bits to add on and a large casting to make a joiner for the central pier so it can be collapsed.


----------



## Tony Wells

Mighty fine work, Sav. Certainly shows that there is a lot of detail in a nice optical piece like that, and shows that it's not out of reach for some determined person.


----------



## savarin

Now I've built the vertical slide I can at last get back to this project.
set up to mill out the curve to fit around the 90mm dia boss at the top of the pier.



I found this interesting as this face is the as purchased plate.
Its swollen in the middle according to this first cut.
At least it follows the centre line




The third pass and its almost done.
Still a bit of blue left.



Final pass, no blue and smoother than it looks. The curve can just be seen.



This is where they will bolt on and hopefully prevent the azimuth plate from flexing.
They still need the final polish.


I still have to make a decision on how I will fix it to the boss, just pegs, or, a bolt from the edge of the large hole.
I will sleep on it.

(edit - changed fourth pass to third pass)


----------



## rwm

I'm pleasantly surprised that worked so well with that much tool hanging out on that bar.
 That looks like hours of polishing. What is your process? Do you sand first and then polish?
Robert


----------



## savarin

I took very fine cuts so as not to over stress the tool bit.
Sanding with differing grades of wet and dry soaked with WD40.
Down through the grits starting at 240, 800, 1200.
Then tripoli on a sisal or hard denim buff depending on how deep the remaining scratches are then white rouge/alluminium polish on a soft cloth buff.
It takes way too much time and I am totally over it the trouble is once you polish one item all the others have to be done else it looks terrible.


----------



## savarin

I have decided three bolts on the plate and one bolt and one peg on the boss.
Drilled and tapped one bracket and the plate so far.
I will make a short pointed peg to mark the boss for that hole and a 2mm point to mark for the bolt threaded hole.
It hurts when you want to get going but other things encroach on your time preventing you from ploughing ahead.


----------



## savarin

A small pointed rod to find the spot for the hole



replaced with a peg once the boss has been drilled


but look at all those scratches I now have to polish back out.


----------



## savarin

Brackets installed along with a forked front tube support.


First tests appear to have solved the flexure in the plate.
Next I wanted a pair of three hole brackets so I can fix a carry handle between the,
The first set I made from some 10mm scraps and rounded the ends in the lathe by bolting them to a long handle, pivoting off a 6mm  rod in the tool post so I could control the rounding process.
Its looks as dangerous as hell but its only aluminium and by only taking small cuts it was extremely controllable, way easier than I expected.


And produced this, nicely rounded off.


However the 10mm brackets looked so out of proportion I went back and redid them again in  6mm scrap.
Then I bolted the pair to the wonderfull vertical slide and milled out the sides to reduce the amount of filing required.


Not brilliant but way less filing required.


and ended up with these.


Being scrap they need a heap of sanding on the faces before ---- yep! you guessed it, more polishing.


----------



## rwm

Brilliant work with your new slide. That fixturing plate with holes is a great idea. I need to do that.
Robert


----------



## savarin

Got the handle brackets polished



Used a chunk of cast to make a screwed cap



To fit the finder scope


I did polish it but there are some shrink marks in the centre so I think its going to end up black.

Started on the handle by knurling the centre, this will bolt onto the two brackets above


Now I need to move the tail stock over to turn the two ends in a taper. I've never done this before so it will be a bit of a learning experience.


----------



## savarin

This went easier than I thought it would, a pleasant surprise.



Just have to drill some holes to fit it here.
.
	

		
			
		

		
	




This thing looks more complicated every day, I wonder if I will ever finish it?


----------



## brino

Stellar! (pun intended)

-brino


----------



## savarin

thanks


----------



## savarin

More bits.
I made a brass shield to go round the azimuth gear. It looked great.
BUT! I,D.10T moment, the telescope couldnt be removed from the support structure. 
Oh well, back to the drawing board and design one thats easily removable with captured screws so they wont be lost when dropped in the dark.
I came up with this, some 12mm plate with a section milled out (sorry, no pics) with one end rounded the same way I did the auxiliary holders. (A bit scary but doable)
Then mounted to a wooden backing plate bolted to the face plate.
The centre cut out then a flange cut.
A bit of filing to clean up and test fit.




looks ok, the brass sheet will be fixed to the rounded part reaching down to the milled out section.
Just looking at it now I think if the holes the two knurled screws go through were elongated vertically it would allow the shield to tilt away from the gear allowing the scope to clear the shield.
We will see.


----------



## savarin

Now working on the azimuth control.
I squared up a block of aluminium  to hold a shaft with two bearings for an extension rod that links the flexible knob/shaft to the azimuth worm drive.
I was just going to drill through its length and counterbore for the bearings but the first drill bit snapped when it was almost through.
Hmm, no more ally to start again so I had a re think and re designed the block as shown in the drawing below in the hope a wood working solid carbide router bit would cut through the embedded drill bit and I could drive it out the remaining bits.
Heres the new design with the block and embedded drill bit.



Lets start milling and see



and finally, Yay! it worked


The angle milled to the face that has the bolt holes is so the shaft can angle out a bit for more clearance between it and the altitude control.
Have to counter bore the ends for the two bearings.
And of course more sanding and polishing.


----------



## brino

savarin said:


> Yay! it worked



Hey Savarin,

Thanks for sharing even your little mistakes. Because this is not an uncommon occurrence in my shop, I wanted to take the opportunity to pick your brain about it.......

Was it a HSS drill bit?
If the drill was mostly thru, could you have started from the other end of the part and drilled thru and punched out the broken drill bit?
How did the milling cut go when you made it as far as the imbedded drill bit?
Did you mill clean thru the broken bit, or just open up a space to pull it out partially intact?
Also, why choose this method over EDM? was it strictly about the small diameter broken bit and access thru the recess?

Thanks!
-brino


----------



## savarin

brino said:


> Hey Savarin,
> 
> Thanks for sharing even your little mistakes. Because this is not an uncommon occurrence in my shop, I wanted to take the opportunity to pick your brain about it.......
> 
> Was it a HSS drill bit?


yes



> If the drill was mostly thru, could you have started from the other end of the part and drilled thru and punched out the broken drill bit?


Hmm, never thought of that, what a dick. It was approx 1.5" in and I was unsure if it had wandered



> How did the milling cut go when you made it as far as the imbedded drill bit?


I went clean through in the vertical direction, it made a fair bit of screeching as I went through but didnt seem to be a problem.
Then I milled along the the bit from the top not quite touching it then milled horizontally into it not quite touching it. This allowed me to pick it out and l drove the remaining bit into the gap.
Then some cleaning up but no dro fitted (dont have one so not perfect.)



> Also, why choose this method over EDM? was it strictly about the small diameter broken bit and access thru the recess?


It was too thin and too deep so would have taken days I reackon.



> Thanks!
> -brino


no worries mate.


----------



## Bill Gruby

Charles, I have never seen anyone put the 9X20 lathe to work like you do. You are an inspiration to all. Kudos my friend.

 "Billy G"


----------



## savarin

Thats very nice of you Bill, thank you.
Continuing with the azimuth bearing block.
I had a bit of a hard time deciding how to clamp this for boring it out for the stainless roller bearings.
After a couple of attempts to mount it on the face plate and being unable to get it centered to my satisfaction I had another idea.
I turned a mandrel to the inner dia 7mm to a tight slip fit in the holes and mounted it between centres in the 4 jaw chuck.
To get sufficient clearance I had to use a 3 to 2 mt adapter and a 2mt centre, gently tightening the jaws in the hope it would stay centred.
Then removed the mandrel and tail stock out the way and bored the hole for the bearing.




And it fits. I flipped it around and did the same for the other end.


Now I just have to hope they are parallel and the 6mm shaft will fit in them smoothly.
I have a bit of a problem with the altitude control cover plate as shown above.
When tightening the friction knob your knuckles now hit the two knurled screws removing a bit of skin. Answer - make a longer friction knob, that means another bit of brass casting.


----------



## savarin

The bearings work and the shaft fits nicely.
I had to use two universal joints to transfer the motion from the knob to the worm wheel.


but it rotates very smoothly. The new shield around the altitude gear is now aluminium as I had no brass wide enough.
Heres an overview of the how the controls hang.



I've made a new stainless washer to reduce the backlash in the azimuth clutch and that seems to be a lot better.
Now waiting for a short length of 100mm dia aluminium tube to make the dew shield.
Unlike a standard GEM mount the controls stay in the one place and never foul each other.


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## savarin

Whilst waiting for the 100mm dia tube I thought I may as well start on the fitting.
I turned a bit of 12mm plate to approx size and bored out the middle.
Bored this to the loose slip fit to the lens cell, then ground a grooving cutter and cut two "O" ring grooves, I did this with the lathe in reverse so it was easier to see paying a lot of attention to the screw on chuck to ensure it didnt un screw.



They fit just right with only a tiny bit proud



This is now a fairly tight push fit to the front of the lens cell


Now this ring has to be turned down to fit the inside dia of the 100mm tube, when ever that arrives.


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## savarin

turned the ring to a tight fit inside the tube and used high strength bearing lock to hold it in place.
Centered in the 4 jaw and cut a thread inside to act as  an antireflection surface once coated in matt black.
Centering was a long job, every tiny adjustment of a jaw flexed it and sent the other three out of wack, it took forever but I got there.
Yes, thats a huge overhang and I was unsure if it would actually work but it did with no problems.
I really must make a carriage stop but the clamp worked perfectly.



I then turned down two mandrels for each end so I could clean them up and sand and polish the tube.
This shot is after using 800 grit followed by 1200 grit



Then it was of course polished.



Mounted in place


Very rigid, no chance of falling off or being knocked off. 
Six more jobs left:-
1 make a solar filter holder (easy)
2 make a new end cap to fit in the dew shield (easy)
3 cut the central pier into two for ease of transport (easy)
4 cast a joiner for them (bit harder)
5 dismantle and re clean/polish everything (arghhhh)
6 powder coat all the black parts. (not my problem)
That should be the lot, I hope.


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## ch2co

Savarin
As usual good lookin' stuff. How do you plan to keep the polished finished polished and avoid scratches, oxidation etc?
I have always had most of my tubes powder coated with the exception of smaller stuff like finders, laser mounts etc.
The last two tubes that I made were a lens shade for my 105mm f15 and a main tube for a little 80mm f9.5. both those
tubes like most of my tubes are cheap welded irrigation tubing that always has a main seam that isn't very round.
I ground the seam mostly flat conforming to the rounded surface of the tube, then I turned
both these tubes on my lathe just like you did, but had a lot more oxidation. One tube was too long for my little lathe
and I had to improvise a bearing that pressed against the fully retracted and almost falling off the end of the lathe tail stock.
I tried to put a brushed finish on them, but it came out looking all wrong. Then I had the idea to use my angle grinder with a Scotch bright disk while the tubes were turning
slowly on the lathe for a finish that hides all the old scratches not already removed as well as the unevenness of the area around
the ground down weld. I am very pleased with the results and have gotten a lot of good comments on this finish from fellow
astronuts. So far after almost a year, this finish doesn't show scratches or oxidation that I have run into in the past.
Here's a couple of shots of it.


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## savarin

ch2co said:


> Savarin
> As usual good lookin' stuff. How do you plan to keep the polished finished polished and avoid scratches, oxidation etc?


I've used an ultra clear lacquer for all the brass bits but am not worrying about the aluminium. I think the lacquer will get scratched eventually and have to be redone.
I'm hoping the dulling will occur slowly and I wont notice it until it really needs a clean up

Nice scopes, is the gem mount tracking? It looks a good one.


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## ch2co

The mount started out life as non goto, but with tracking.  I totally tore it down and cleaned and rebuilt it with new bearings and proper new grease, quite unlike
the black tar that the chinese decided it should have.  I added to stepper motors and an off the shelf computer control board that turned it into a goto.
I can control it from my iPhone or computer over a wireless interface.  Very convenient. I'm still working on the tripod to make it more stable and easier to set up.
All my polished aluminum tends to get dull in a very splotchy sort of way. I'm always getting my hands covered with various foods during long nights under the stars 
and going gulp my scopes. My next telescope attempt will be a 10"  f4.5 Surrier-truss tube reflector that can be used either in a Dobsonian 
base or attached to the mount mentioned above. 
Do you guys have astronomical gatherings down under?  You're welcome to come join us at the next big one close to home. 

CHuck the grumpy old guy


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## savarin

Most cities have a club, I'm in our local astronomy group but the only idiot who builds scopes.
It seems to be a lost art in most places. Quite a few do it down south, say 5 or 6, there must be more because we have a large supplier catering to the market.
I've just found out that Skeye for my samsung tablet has the ability to align and turn the scope to a push to with planetarium.
I cant wait to try that out.
Very cloudy at night these days so that must mean the scope is ready to test.


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## ch2co

Even down under? I thought that you guys were different somehow.
I belong to the Denver Astronomical Society. We are a group about 400+ strong and do a LOT of astronomical outreach at schools, civic groups, libraries, etc.
We are almost 118 years old (although I'm a bit younger) and have a home base at the University of Denver Historic 1894 Chamberlin Observatory.  We 
offer two public nights with lectures tours and views through "our" little 20" 1894 Alvin Clark / Saegmuler telescope each week and one Open House with
the observatory open to the public and members set up 20 -60+ personal telescopes on the south lawn all looking up through  Denver's light polluted skies.
We have many amateur telescope makers some of whom are vastly superior to anything I can turn out.
Here's a peek of our scope.


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## savarin

This time of the year up here is supposed to be the wet season so its usually cloudless days but rainy nights.
We are getting the clouds at night but no rain.
Now that is a think of beauty.
We are a small club and before we became an official real club with all the resulting rules and regs we did a lot of schools outreach.
I presented a lot of them and it was all no charge.
Now we are official the club charges for those sessions which I dislike immensely so am no longer involved and we dont do very many now.
we still do public viewing on our light polluted beach front once a week and only ask for a gold coin donation. Its very popular but the objects are few, a couple of planets, the moon and thats about it.
Our dark site is approx 20 mins out of town and is very good with just a hint of orange glow behind the hills.


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## savarin

Now the larger dew shield is on it needs a larger cap.
The resistance of the "O" ring is sufficient to hold it in place firmly.


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## 12bolts

Looking good Charles, I must pick a good night to come down for a visit.

Cheers Phil


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## savarin

sounds a winner, wait till its powder coated as its in bits at the moment.


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## 12bolts

Are you coming to Tyto this weekend Charles? And will this be centre stage if you do


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## savarin

12bolts said:


> Are you coming to Tyto this weekend Charles? And will this be centre stage if you do


Whats Tyto?
I guess the answer is no as I'm not going anywhere this weekend.


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## 12bolts

It was in our local rag today. Townsville astronomy club is coming to Ingham to show all us country hicks how to look at the cheese in the moon and stuff  Sorry cant find the link for that online
Tyto is the local information centre and wetlands. https://www.tyto.com.au/


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## savarin

news to me, we just did one at the museum here on sunday, about 80 people.


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## savarin

Saturday night was first light for the scope.
A few things became apparent as the evening progressed.
This is not a scope for beginners.
The field of view is somewhat narrow meaning objects pass through the field rather faster than expected.
Being a manual telescope the slow motion controls are very important.
The clutch on the azimuth control is very good but the altitude left a bit to be desired as it slipped no matter how tight I screwed up the adjuster so I replaced the two plastic plates with aluminium.
This is most of the parts involved. The top plastic disk is replaced with the aluminium next to it and sits in the gear wheel, its then sandwiched between that disk and the bottom disk.










Then the tabbed stainless washer is slid on.




Then the assembly is squeezed up with the brass nut and fancy cast pressure plate with all its inclusions.




Now it works, slack and the scope can be manually moved, tighten with the brass nut and the slo-mo control works.


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## ch2co

Savarin

Long refractors are great scopes but.....   They are long and have a narrow field of view which makes them great for planet and double star observations. 
But just a tiny amount of movement makes the field of view move around a lot. 
I remember the first time I set up my home brew 105mm f15 Jaegers scope (over 5.5 feet long) I was astonished at how careful I had to be to balance it
on its mount. At the time I had it mounted in a wooden box structure about a foot long that I could loosen up and slide back and forth on the scope which made it
easy to balance out on the mount. After finding the sweet point I tightened the box up and it rode easily in either a altitude-azimuth  mount that had
very little friction. Balance was paramount or the scope would slowly try to move down on whichever end was heavier. Late I built a pair of aluminum
mounting saddles tied together on the bottom with a dovetail bar. I already had found a good balance point so it behaved easily on a small equatorial
mount that I had rescued and rebuilt. The first star party I went to was out in the middle of nowhere and my little scope handled wonderfully until
the wind began to blow and it became unusable due to it bouncing around to much. The mount wasn't sturdy enough to really handle a long scope like that. 
Next swap meet I picked up a used MUCH heavier mount that I had to completely rebuild. The innards reminded me of a small automotive transmission.
 The scope become a wonder to use, until I added a lens shade to the top end. Suddenly even the much beefier mount just 
didn't track worth a darn. Balance was once again rearing its ugly head. After moving the scope back a little in the saddle all was well again.
I have finally installed a sliding weight bar along the rear section of the main tube which made it simple to rebalance the scope whenever
I add or take off an accessory piece like a large finder or tracking scope with camera attached, just by sliding the weight forward or backward
on the balance bar. Just a little front to back out of balance can make a huge difference in the operation of the clutches and drive train, and the
viewing.
Beautiful work you are doing. Far more artistic than any of my.

Chuck the grumpy old guy who is going to view the total eclipse of the Sun from along its centerline in about 3-1/2 days. (Clouds willing)


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## hman

savarin said:


> Saturday night was first light for the scope.


CONGRATULATIONS on your achievement!!!! 

It's been absolutely wonderful reading your build description.  You're a true artist in metal.


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## savarin

Thank you John that really is appreciated.
Its been a bit of a struggle at times and I still have to powdercoat the pier and feet.


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## savarin

I like the idea of the sliding weight Chuck I may just copy that.


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## ch2co

I saw that on a  4" f15 Unitron scope


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## savarin

It is finished, no more to do, nada.
Awesome views of the moon but I couldnt blow up Saturn to a large size but it still looked good and the manual controls kept it in the eyepiece.
Well pleased with the whole thing.



Now to start the binoculars
No rest for the wicked.


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## brino

savarin said:


> Well pleased with the whole thing.



You should be very proud.
It looks great! (and stable).

-brino


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## savarin

Thanks Brino I must say I am.
Probably the best project I've ever done.


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## Downunder Bob

G'day Charles, as always I'm constantly amazed by your inventiveness when it comes to makeing a workaround, not only do you make it work, it looks good as well.

Bob


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## rwm

That is very sharp looking! Any chance you could post a pic or two to demonstrate the image quality? Can you take a cell phone pic thru a telescope?
Robert


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## savarin

Thanks Bob and Robert.
I will attempt to get a shot through the scope but they have never been very good in the past.
At present its cloudy nights most nights so I dont know when.
Its mainly a lunar and planetary scope as its focal length is rather long.


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## ch2co

savarin said:


> Thanks Bob and Robert.
> Its mainly a lunar and planetary scope as its focal length is rather long.



Hey, Savarin, don’t forget that these long refractors are great for double star observing, some of my favorite objects. With a long focal length eyepieces (my longest is 60mm) they are very good for a lot of deep sky objects. Besides show stoppers like Saturn and Jupiter and their myriads of constantly changing moons, the Orion Nebula is gorgeous and a real jaw dropper especially good for showing to the general public.  Four of my favorite telescopes are long refractors. 

CHuck the grumpy old guy

PS I just had a fight with the spell checker on my phone substituting “Savings” and then “Savage” when I typed your name.


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## Downunder Bob

savarin said:


> Finder scope finished and looking very nice.
> However, I now have a cemented 50mm japanese doublet that may be a better objective but it needs the central tube to be another 15mm longer and a different lens cell. Maybe after its all finished.
> View attachment 111494
> 
> 
> At last I can start on the focusser unit.
> I couldnt find any 60mm plate but did find some 100mm round.
> Now came the hard part, I dont have a mill but need to convert this cylinder to a block.
> It wont fit securely in the chuck.
> I scribed the block size on the top of the cylinder, drilled the centre and mounted it on the compound in place of the tool post.
> I used a rule to align the scribed line with the face of the chuck.
> View attachment 111492
> 
> The only tool I could use that had sufficient off set happened to be the Eccentric Engineering diamond tool holder and this proved to be just right held at an angle in the 4 jaw.
> View attachment 111490
> 
> about half way through here. as I got closer to the scribed line I just had to make a tiny re-alignment to bring it back to spot on.
> View attachment 111491
> 
> Instead of doing the same thing to the other side I mounted it against the chuck jaws as there was just enough room and have started milling the other side. I'm hoping they will be parallel by doing it this way.
> The first cuts seem to point this way.
> View attachment 111493



G'day Charles, Brilliant6 work and as usual an amazing way of doing things. I see you're putting a Diamond tangential tool holder thru its paces. I've been wondering if they are worth it. but it looks like they are.
Bob.


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## savarin

I think the Diamond tangential tool holders are well worth while I really like mine. Very simple to sharpen.


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## Arnoldskynet

Great work!


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