80mm long focal length refractor

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
 
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)
 
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)
clutch-parts-1.jpg

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
clutch-parts-2.jpg

The azimuth plate bolts on to the top of the unit via the 6 threaded holes.
clutch-parts-3.jpg

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.
clutch-parts-4.jpg

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.
clutch-parts-5.jpg

Now back to polishing.
 
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
 
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.
 
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
 
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.
 
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
 
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 :grin:
 
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.
polishing-bits.jpg
Argh!!!!!!!!!!!!!! when will it end.
 
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