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The Giant Binocular

savarin

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#1
Its time to re-visit the binocular.
This is roughly what I want.
binoscope1.jpg
I started these over 5 years ago but got side tracked building recumbent bicycles.
Now I've almost finished the refractor I've started back on these.
This is being built entirely from scratch including grinding and polishing the two 12" mirrors.
I will purchase the secondary and tertiary mirrors but that should be about it.
I got as far as building the mirror grinding machine,
machine from end.jpg machine from lhs.jpg

the pendulum grinder, this bolts to the grinding machine and hogs out the mirrors to the required radius of curvature. The motor drives a diamond disk to grind the glass and a standard grinding disk for steel for some of the tools.
overviewL.jpg

the jigs for the hexagons
hex jig.jpg

and a jig for the vertical struts.
verticals jig.jpg
I will show how these work as we go along.

I managed to make a start on the four trusses and one top cage before I put it away so thats where this project re starts.

trusses.jpg
The top cage was rusty so with a generous application of a wire cup brush on an angle grinder (do not do this at home kiddies) I removed all the rust and gave a quick spray of primer.
By the time I finished the cup brush was shedding wires and a large number of them embedded themselves in my wrist and arm.:bawling:
I had purchased all the square tube and as its just been sitting there it also rusted so I cut all the bits for the second top cage and started the derusting process on them.

pickling.jpg

You will notice there is one diagonal brace in the bottom truss, now I need to add 35 more and de rust them.
I'm thinking some plastic drain pipe with an end cap as a long holder for the derust and all the sections.

The two top cages will rotate using the large lazy susan bearings.
In the mean time I went through the older mig welder and checked it out, gas wont turn off when the trigger is released so I have to fix that but otherwise its all good.
There is a lot to do so this will not be a fast project and I expect other things will pop up to prevent me from working on it but the fingers are well and truly crossed.
 

T Bredehoft

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#2
If when you get them (it) done, I may have to consider a trip to Queensland. If we're both still around. That is one awesome project. I had a friend who 'walked the stump' on an eight inch Newtonian, years ago. It seemed to take him forever.
 

savarin

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#3
Hand grinding and polishing is time consuming.
I can get both mirrors hogged to the correct radius of curvature in about 2 hours.
Then I cast the tool into the hollow using steel dumps (punched centres from washers) and spin grind through the grits then spin polish to a very smooth sphere.
I will not be figuring them but flexing them into the parabola.
There are many giant binoculars in the states if you google them but this group gave me the impetus to go for it.
http://www.deep-sky.co.uk/telescopemaking.htm
They also gave me the ideas for the refractor mount.
 

savarin

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#4
A quick scrub with a bit of scotch bright and they are like new.
But, they started rusting as soon as I dried them so I dunked them in the vinegar again, scrubbed them, wiped them, dunked into water and soda to neutralise the vinegar, then soahed in a jar of WD40 till ready to weld.
That worked.
They started as the rusty top one.
top-cage-1.jpg

set into the hex jig for welding,
top-cage-2.jpg

Then transfered to the vertical jig to weld the uprights in.
top-cage-3.jpg

Then flip to weld the two hexagons together and add the last two verticals,
top-cage-4.jpg

A quick touch up with the sander then a coat of primer in the hope it wont rust again
top-cage-5.jpg

Now to start cutting the 35 diagonals.
 

brino

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#5
Charles thanks for sharing another of your amazing projects with us.
You certainly do dream big, but you're always able to pull it off.
I am looking forward to another great project!

popcorn.gif

-brino
 

FOMOGO

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#6
Very nice Charles, but you're going to need a pretty good sized lanyard to hang those binoculars around your neck. :) Cheers, Mike
 

savarin

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#9
Purchased the steel for the base today.
I have decided to make the feet from 25x50mm 2.5mm wall thickness rectangular steel, 12mm thick plate 150mm dia to fit inside a 150mm tube (except its 152 mm dia. when I measured it)
I have decided to make the base similar to the refractor albeit larger to account for the width of these beauties.
footplan.jpg
The two steel disks (blue) are welded to the 6 red vertical 25x12mm bars as separators, the green legs/feet hinge down for transport.
I am unsure if the deep blue sections will be required for rigidity so they may or may not be welded on.
 

savarin

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#10
The steel for the disks is only 150mm wide so I cut two sections 160mm long and built up the 150mm width with weld to 160mm wide.
Wacked off the corners with the angle grinder, mounted it on a 10mm bolt with another off set to act as drive dog on one of the jaws.
bottom-disk.jpg

I used a braised carbide tool that stood up to the interrupted cut with no problems.
Here its just so you can see the weld being cut.
This was a very noisy operation as the disk rang like a bell on every interruption.
Most of the chips came of blue but quite a few came off glowing red hot and burning.
I think I may be pushing this lathe outside its comfort zone.
bottom-disk-2.jpg

Once it was turned down to 154mm dia I placed it in the 4 jaw to face it.
bottom-disk-3.jpg

This whole task to this point from cutting the steel to getting the first face cut took most of the afternoon to do.
 

Bill Gruby

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#11
Glad to see I'm not alone when it comes to pushing the 9X20 to its limit.

"Billy G"
 

Silverbullet

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#12
What power are you shooting for ? You better get a selfpropelled tripod to haul them around. Nice leather case sure gonna be expensive.
 

savarin

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#14
What power are you shooting for ?
Planning on f6, may go to f5.6 depending upon other constraints.
The mirrors will be flexed and f6 should be easier than a faster mirror.
Grinding and polishing on my machine should produce a superb sphere that will take very little flexing to form an excellent f6 parabolic surface. (he states rather hopefully)
 

savarin

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#15
Not much to show for this afternoons work but I flipped the disk to face it and turn down to fit inside the main central tube.
The welding of the two sides to get the width required left some horrendously hard tough spots that just ripped the edge off the HSS tool bits as soon as look at them irrespective of the speeds and feeds.
I had to resort to an old carbide insert that I ground to a sharp edge and wacked the speed up really high and gave it some wellie. That did the job.
bottom-disk-4.jpg

Thankfully the next disk will be turned down to a metric smidgen under 150mm to fit totally inside the tube so it wont require any welding.
 

savarin

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#16
I thought I was supposed to be building a binocular not a stern wheeler paddle boat
stand-internals.jpg
This will fit inside the main support tube.
The tube will be bolted to the 6 verticals with 5mm stainless screws.
I need to find time to visit a friends lathe as it wont fit on mine now.
I want to take a mere skin off the top disk and just kiss the verticals for a slightly looser fit.
 

savarin

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#17
That worked very well.
The assembly now slides easily into the tube.
Next job was making 9 identical lengths of 12mm x 25mm x 90mm for various brackets.
Rather than filing my angle grinder rough cuts to size I decided to try and face them.
I clamped 3 lengths together with the "G" clamp then set them up in the 4 jaw and faced the ends.
The top 4 have already been done in this pic and these three have been faced at one end.

equal-lengths-1.jpg

Held with the clamp then set in the 4 jaw very firmly.
The middle piece is the length to face down to.
Yes, I know that a lot of hanging out but I took it gently with slow feed and shallow cuts and it all worked fine.
Even after the event I find it unbelievable the two outside lengths didnt shift out of position.
You wont know till you try.

equal-lengths-2.jpg
 
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savarin

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#18
After getting them to the same length I turned down the corners to round them off.
This is where I thought they may be sent sideways if the tool dug in so I superglued them together and used my toolmakers clamp in an aid to help prevent this.
Re thinking this I should have just cut two small spacers to span the three pieces at the jaws but this worked well.

curving-stop.jpg

These were then welded to the end of the foot
The three feet were made from 25x50mm tube with a triangular section cut out then re welded.

foot-1.jpg

foot-all-3.jpg

The remaining 6 lengths have to be drilled 10mm and welded to the base of the paddle wheel.
This all makes a substantial and heavy base that I hope will be stable.
 

terrywerm

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#19
That is looking great so far, as usual with your projects.
 

savarin

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#21
I rounded the ends at 500rpm with the 12mm end mill. Thanks to Bob Korves for suggesting the speed.
Virtually a hot knife through butter.

end-rounding-3.jpg

all 6 done with the handle I used as an aid.

end-rounding-4.jpg

To weld them to the base I clamped a length of steel to the legs as guide to keep the angles correct according to the mark 1 eyecrometer.
then clamped the foot to the upright with a large worm drive clamp.

welding-base.jpg

Checking the opposite side with the two strips to ensure they were centred they were tacked in place then the foot removed so they could be welded in place.

welding-base-2.jpg

The main tube now slides onto the feet and will eventually be bolted to the verticals.

base-tube.jpg

So far its a very stable base.
And here is a teaser.

teaser.jpg

Somewhere between the two ends of the second level is where it hopefully will pivot so approximately a quarter of that tube will be cut off.
 

Bob Korves

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#22
I rounded the ends at 500rpm with the 12mm end mill. Thanks to Bob Korves for suggesting the speed.
An easy way to do surface speeds in your head is to use the surface speed you want times 4, divided by the cutter diameter. 70-100 SFPM for mild steel, 1/2" cutter. I used 80 SFPM, times 4 equals 320, divided by 1/2 equals 640, rounded down to 500 to start with, or whatever the closest machine speed is. It is that easy, no calculator or even a pencil needed. This is not rocket science...
 

savarin

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#25
I've now screwed the pier tube to the welded base and I think I may have gone a teensie weensie bit over the top with 15 x 5mm screws holding it on.
Mind you, there aint no way no how its gunna come loose:laughing:
screwed-pier.jpg
Unfortunately that is instant rust. We've just had 80+ % humidity for the last 2 weeks.
(The rain was very very welcome though)
 

savarin

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#27
Almost finished welding in the diagonals for the first truss when just as I was going to start the last cross brace the wire ran out.:cussing:
Typical for a sunday and I was on a roll it was going so well.
first-truss-welded.jpg

That left a fair bit of time before the day ended so I marked out 40 third circles in 3mm strip and drilled all 40x6mm holes.
These will be cut along the diagonal line to produce 40 segments that will end up as brackets welded into the corners of the hexagons to use as fixing/locating brackets. 40of these is nearly 1.5 meters long which is why the photo only shows 10.:grin:
truss-brackets.jpg
I will bolt 6 (or more) together aligned as best as possible along one flat edge then drill a pilot hole roughly in the middle (already centre popped)
use the 6mm bolt to clamp in the chuck with a smaller bolt as a dog to prevent them spinning and turn the outside curve.
I then hope to be able to clamp them to my vertical slide and mill off each straight edge to to even them up opening the 6mm hole so it will clear the weld in the corner of the hexagons. At least thats the plan.
I have a sneaky suspicion that if I had really thought of mow many repiticious parts to make there would be I may have changed the design to solid tubes instead.
 

savarin

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#28
One side truss with all the diagonals welded in. Now has to have the welds sanded smooth then the third circle brackets welded into all the corners.
truss-full-1.jpg

After I cut 12 of the patterns out for the third circle brackets I bolted them together set them up to turn smooth
third-circles-1.jpg

It was a bit scary due to the off centre mass but worked well to my surprise.
third-circles-2.jpg

then I set them up in the vertical slide to face the two straight edges
third-circles-3.jpg

Rather pleased with the result as I was really not sure if it would work.
I love it when a plan comes together.
third-circles-4.jpg

I've started welding the diagonals into the second set of trusses.
Slow but sure I hope.
 
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