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Cave Astrola Mount Restoration & Upgrade

DIY Equipment Mount Refractor Classic
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#1 gazpachosoup

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Posted 30 August 2022 - 05:09 PM

I'm creating this post for a couple of reasons. The primary intent is to catalogue the restoration of this specific mount. Although there is quite an extensive resource base for restorations for Cave-Astrola mounts and scopes, each one is unique to the equipment. Some are minimal and others are complete teardown and rebuilds. In some cases the restorations are purist, back-to-factory state, while in other cases I've seen nice upgrades to make the equipment more functional than when new. So I'll get that out of the way right up front and hopefully not lose anyone. I will be using any original parts that came with the mount and restoring them as best I can. Some parts are clearly missing and I will require solutions as I go forward. This is intended to solicit ideas and in return I promise some voyeuristic eye candy of the telescopic kind. Half the fun in my opinion is looking at the pictures and trying to figure out what's going on. I'll try to be as descriptive as possible. If I get my terminology wrong please feel free to correct me as I am relatively new to the hobby, but yes, I'm jumping in with a resto. I'm a big believer in DIY!

 

The other reason I'm doing this is that I've found posting in a progressive manner, when working on a project, is motivating to keep me going and very useful in thinking through steps. I've also received great feedback along the way - many eyes see many things. And let's face it, any DIY project deserves a little boasting. 

 

Alright let's jump in with an overview of what we're dealing with. This will be over a few posts as I can only upload 4 or 5 pictures at a time and the point is to do as complete an analysis, before diving into the "doing" part. Of course the doing is the most fun, and in the past I've typically jumped into projects without thinking them through. I always figure them out but sometimes that adds unnecessary time as I try to figure my way through suboptimal choices. With this project I will try to deviate from that practice and be as methodical as I can be. Feel free to keep me honest if I veer from that. After all, this is a long haul project...  

 

Astrolamount1.JPG

 

Here she is in all her glory. Off the top, the mounting cradle is a gigantic piece of aluminum with no fewer than 22, unevenly positioned holes (in addition to the 4 hex bolts attaching it to the Dec shaft). No chamfering or fine finish work (I'm not a machinist but I can appreciate nice work). This ain't it! Some of the holes are chewed at the edges so I'm going to have to decide whether this is a keep or a replace. I do know that the original mounting cradle had more of a skeleton shape - in that it was a frame, rather than a solid hunk of metal. I may decide to use a Losmandy mount, but that's remains a distant consideration once it comes time to decide what scope will go on top of this.  

 

Cradlemount1.JPG

 

Cradlemount2.JPG

 

I'm out of picture space so I'll continue in the next post and will continue until I've covered the whole scope. Comments welcome. 

 


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#2 gazpachosoup

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Posted 30 August 2022 - 05:23 PM

Analysis Part 2:

 

From the top, let's take a trip to the bottom and look at the legs. The caster are double wheeled and in pretty good shape other than some grease build up. A good cleaning will take care of that. The pier braces have holes at the very ends for levelling screws and I'll be devising something to make use of this feature, but I will have to engineer something as it appears the holes are quite close to the wheel bearings.  

 

Wheel3.JPG

 

The casting line is visible on all three braces - and while, cleaning them up requires a bit of effort and doing so doesn't add any extra functionality, I prefer to have something that looks like care was taken with every component. I'll do my best to clean the casting marks up.

 

Pierlegs2.JPG

 

Overall - a new coat of paint is needed on just about everything. 


Edited by gazpachosoup, 30 August 2022 - 05:23 PM.

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#3 Frank Otsuka

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Posted 30 August 2022 - 05:38 PM

From a CloudyNight member down in Tucson AZ (38 pages)

 

https://www.cloudyni...-in-field-astrola-cave-12-12-f6-i-think/


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#4 gazpachosoup

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Posted 30 August 2022 - 06:16 PM

Analysis Part 3:

 

But first we break for some light entertainment... 

 

This passed week, I was at Starfest in Ayton, ON https://www.nyaa.ca/.../sf22/sf.home22 and my vehicle was absolutely packed on the way there. When someone offered the subject of this restoration, without even thinking whether I had space, I naturally jumped at the opportunity to bring home this fine piece of equipment. Astronomers are problem solvers and resourceful by nature so I knew I get it in there.

 

Car1.JPG Car2.JPG

 

That said, naturally I had to disassemble the pier and pier cap, to get it to fit in the car. Luckily, or unluckily, there was only one original bolt, which you'll see in the photos, I've replaced with a zinc plated hex head (I'll call it a fender bolt). It has a built in star washer pattern stamped into the underside of the head. I don't know what it's called but you get the idea. The bolts are not completely tightened down since there will be disassembly sometime in it's near future, and they will each get a nylon washer. What I found interesting was that the holes were not drilled precisely spaced and so I had to play around with the rotation of the top flange plate. You can also see two hex set screws on each side of the flange plate (beside the RA bolt) - in various states of screwing / connection. I've read that these are designed to provide a little extra clamping power, since the original locking nut typically experienced slippage. I have not tired to loosen the RA nut, but I have, preemptively sprayed WD40 on it, in anticipation of eventually unscrewing it. I will likely replace the bolt with something nicer (perhaps stainless).

Attached Thumbnails

  • Piertop2.JPG
  • Piertop3.JPG

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#5 gazpachosoup

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Posted 30 August 2022 - 06:20 PM

From a CloudyNight member down in Tucson AZ (38 pages)

 

https://www.cloudyni...-in-field-astrola-cave-12-12-f6-i-think/

I had brief look, but will read through once i'm done posting the analysis on this bad boy. Thanks for sending it along. I love reading other peoples restoration journeys. 



#6 gazpachosoup

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Posted 30 August 2022 - 06:40 PM

Analysis Part 4:

 

For this post I'm going to tackle something with only a few photos because, really the next thing is the RA drive motor, and there are a ton of pictures for that, because it's going to require the most complex (for me) work. So let's focus on the Dec motor plate. All I have to say is Swiss Cheese. Now I like Swiss Cheese, I even like it when looking at a scope, I mean the moon is made of the stuff, but I don't necessarily like it as part of the scope itself. I think over the years and (I assume) multiple owners, multiple solutions were needed as motors failed due to poor design. 

 

DECdriveplate1.JPG  DECdriveplate2.JPG

 

I don't really want to get into fixing something that was likely not a great solution in the first place so I'm eventually going to come up with something different here. I've seen motors mounted at the top of the DEC shaft but this model doesn't seem to be designed that way... I'm open to suggestions and pictures or links.

 

DECshaft.JPG

 

The shaft itself will need some elbow grease to remove rust, but I sort of find that activity somewhat relaxing.

 

Wormgear5.JPG

 

The equipment did come with a large gear, but it's unlike anything I've seen in my research. Will I be able to match a worm gear to it or do I have to start with something new? It's made of aluminum and has a leather clutch - although I'm not sure why, because the two parts are screwed together so there shouldn't be any motion between them. It almost looks like there was some other mechanism at work in a previous iteration of this setup. I'll add another picture in the next post to show what's going on, but the large gear had a central plate that is beveled - seems to me to be some sort of friction plate. In that case I case I can see why the clutch may have been useful. Now that it's fixed it doesn't make immediate sense to me. 

 

There is a central collar, also made of aluminum. Nice milling all around except one surface is a big chewed with what look like grind marks (next post). 


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#7 gazpachosoup

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Posted 30 August 2022 - 06:54 PM

Analysis Part 5: (DEC Drive Con't)

 

Continuing from the previous post here you'll see the state of the DEC gear. Surfaces are a bit rough but nothing a little polishing can't fix. The teeth seem nice and deep and aren't chewed up so I'd like to save it if I can. That is providing I can figure out what the original configuration might have been.

 

Wormgear6.JPG  

 

Here you can see the central collar and imaging the next ring is bevelled where it meets the outer gear 

 

Wormgear7.JPG

 

You can see the collar looks mostly good with the exception of one surface, which, again, some polishing will remedy.   

 

Alright, I have to run out to Princess Auto before it closes, but when I return I'll post on the drive unit. Grab some popcorn, it may be a few posts.  


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#8 apfever

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Posted 30 August 2022 - 08:15 PM

To allow easier breathing for some, I'm not going to launch into fixing this or anything else nor go into pet peeves.

 

As per OP request: These are not the Right Ascension (RA) bolts. They are the altitude bolts or some might accurately call them latitude bolts. They adjust the altitude of the mount for changes in latitude position on Earth. It is a common design among many makers of the same era and size. They all stink because the small contact area is insufficient for the massive head load. 

post-370990-0-91156700-1661899628.jpg

 

 

 

 

The two mutually exclusive holes in the end of the legs may or may not be original. Two of my Caves have casters and no extra hole for a leveling screw. Telescopics used the same legs and those do have the second leveler holes on mine. All my legs here have smaller caster bearings that will clear a leveler bolt but the wheels wouldn't turn without hitting the bolt. The wheel body has to be rotated out of the way to lower the level bolts. This is also common across many makes and models of the era. 

P1010010.JPG


Edited by apfever, 30 August 2022 - 08:27 PM.

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#9 gazpachosoup

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Posted 30 August 2022 - 08:27 PM

To allow easier breathing for some, I'm not going to launch into fixing this or anything else nor go into pet peeves.

 

As per OP request: These are not the Right Ascension (RA) bolts. They are the altitude bolts or some might accurately call them latitude bolts. They adjust the altitude of the mount for changes in latitude position on Earth. It is a common design among many makers of the same era and size. They all stink because the small contact area is insufficient for the massive head load. 

attachicon.gifpost-370990-0-91156700-1661899628.jpg

 

 

The two mutually exclusive holes in the end of the legs may or may not be original. Two of my Caves have casters and no extra hole for a leveling screw. Telescopics used the same legs and those do have the second leveler holes on mine. All my legs here have smaller caster bearings that will clear a leveler bolt but the wheels wouldn't turn without hitting the bolt. The wheel body has to be rotated out of the way to lower the level bolts. This is also common across many makes and models of the era. 

Thank you for the nomenclature correction - I am always looking to the collective wisdom and expertise of this forum and I am grateful. You are more than welcome to launch into a fix, although by your description I assume the fix may have something to do with larger washers to increase surface area... And if this is meant to be locked for latitude then I would imagine the only way to accurately set that is with a bubble level somewhere on the pier cap. I've seen that mod, but again, let me know if I'm off base. As for the two set screws on either side - what is the purpose of those? Are they like cat claws hanging on for dear life?

 

Thanks again for the feedback. 


Edited by gazpachosoup, 30 August 2022 - 08:33 PM.


#10 apfever

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Posted 30 August 2022 - 08:48 PM

Don't worry about fixing the altitude bolt thing yet. You'll get to it and by that time you'll have seen many things people have done. Larger washers don't work, the system is flawed. Fixes are thinking outside the box, literally outside that red circle. 

 

The pictures of your saddle and especially the DEC motor plate had me ROTFLMAO.

 

Ohhh, about your DEC clutch....You'll probably find the three bolts only go through the outer clutch faces. The gear will spin on a larger diameter machining outside the bolts similar to this clutch shown. 

Attached Thumbnails

  • P1010015 - Copy.JPG

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#11 gazpachosoup

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Posted 30 August 2022 - 08:55 PM

Analysis Part 6:

 

I think I'm going to leave the drive motor analysis for another day as there are several things that need to be addressed and multiple pictures. I'll keep this post brief because it's getting late and I'm need of some hot tub time. 

 

I find it funny that there are clearly major parts missing like the RA setting circle and motor housings, but something oddball, like the DEC wormscrew, is there. I admit I forgot about this part in my previous posts, because the previous owner messaged post pickup to let me know that there were additional parts. Always a good thing and I'm happy that there's less to attempt to fix. 

 

DECplus.jpeg

 

The rig also came with the drive corrector and control unit, which to me, is really oddball. Again - totally happy it's there!

 

Drivecontrol1.JPG Drivecontrol2.JPG

 

The front of it is in great shape and looks really good after a quick cleanup. Once I pop it open I will likely be able to determine how it works (aka what monstrous cable plugs into the input terminal). I am also going to go out on a limb and say that the unit is basically an old-school PWM. Purists, now is when you'll want to close your eyes and ears...

 

So maybe I can integrate something smaller in each of the drive cases instead of this giant thing. Open to suggestions or a push in the right direction. If you've come across anyone that's done this please post a link.

 

The rear of the device is not in as great shape for paint (image in next post).


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#12 gazpachosoup

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Posted 30 August 2022 - 09:03 PM

Analysis Part 7: (Drive Controller Con't)

 

This one is quick - promise. 

 

Here's the back of the drive controller - with 5 terminals, 3 of which still have some of the paint denoting their function. While the 2 on the far right the writing has peeled off..

 

 

 

Drivecontrol4.JPG  Drivecontrol5.JPG

 

And am I correct in assuming this is lead paint? 

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  • Drivecontrol3.JPG

Edited by gazpachosoup, 30 August 2022 - 09:04 PM.

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#13 Geo31

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Posted 31 August 2022 - 10:27 AM

Interesting timing.

What size scope goes on this?

I say interesting timing because I finally was able to begin taking apart the mount for the "Field Cave" in my signature.  I was originally going to restore it (yeah, I'm a sucker for basket cases - see the RV-C6N restoration thread).  Anyhow, I have a number of components that could help you restore this depending upon what your goal is.  BTW, that drive is not original, nor the mounting for the Dec drive.  I'm pretty certain your RA drive is from Schmidt & Associates in Wisconsin.  They were a cheaper alternative to the Byers drives in the 70s, and probably better than the factory Cave drive.

 

[edit]  Oh, and the scope mounting plate is definitely not factory correct.


Edited by Geo31, 31 August 2022 - 10:29 AM.

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#14 Frank Otsuka

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Posted 31 August 2022 - 10:36 AM

Yikes!!!

The frequency control goes from 1 to 11 - shades of SpinalTap.


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#15 gazpachosoup

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Posted 31 August 2022 - 01:31 PM

Interesting timing.

What size scope goes on this?

I say interesting timing because I finally was able to begin taking apart the mount for the "Field Cave" in my signature.  I was originally going to restore it (yeah, I'm a sucker for basket cases - see the RV-C6N restoration thread).  Anyhow, I have a number of components that could help you restore this depending upon what your goal is.  BTW, that drive is not original, nor the mounting for the Dec drive.  I'm pretty certain your RA drive is from Schmidt & Associates in Wisconsin.  They were a cheaper alternative to the Byers drives in the 70s, and probably better than the factory Cave drive.

 

[edit]  Oh, and the scope mounting plate is definitely not factory correct.

Thanks for info on the RA drive, I'll be looking that up later. As for the DEC drive - I was reasonably certain it was a home made jobby, and I appreciate the confirm. It's always amusing seeing this kind of stuff. Whomever machined the original piece did a decent job

 

DECdriveplate1.JPG

 

the centre bore fits nice and snug around the DEC shaft bearing housing. There are three really nicely threaded holes around the back to clamp the plate. Some of the holes look alright. And then someone came along and mounted things over and over and over again. 

 

The  cradle is the best part of the hole thing (see what I did there?). It's a beautiful, heavy chunk of aluminum and then they had to go mess it up by drilling all willy nilly. Not only that, you can tell that it was cut from a larger piece and no care was taken to straighten any of the edges. I know sometimes I build stuff to be "good enough" and promise I'll go back to finish it up once whatever it is, is functional. Of course I rarely do - so benefit of doubt - maybe that's what happened here...  

 

JonMilesAstrolaCradle.jpeg  

Image Credit: http://www.cave-astr...ge18/index.html

 

I know this is what the original cradle looked like and I haven't decided if I want to clean up the one that I have or if I'll go with a modern one - like a Losmandy... Another consideration I'm contemplating is taking my 10" Meade (Newt turned Dob) and turning back into a Newt (long story). Well not really - drive stopped working for previous owner of the Meade and he turned it into a Dob. It's currently on a Zumhell base, which I've finally dialled in but it took a long time. I'd say it's at 92%, which is what's making me think the Meade would be happier on the Astrola pier mount instead. It's not the only option just one of a few. Either way, I'll cross that bridge as I get closer to fixing everything - this mount has a lot going on - or not...

 

I wouldn't mind a housing for the RA drive if you have one, beyond that let me know what else you think might be useful. I'm also not sure if the previous owner will continue to dig things out, so more things may turn up...  


Edited by gazpachosoup, 31 August 2022 - 01:38 PM.

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#16 gazpachosoup

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Posted 01 September 2022 - 10:38 AM

Analysis Part 8: (RA Drive)

 

My initial sense is that the clock drive is likely going to need the most amount of work (don't know what gave me that impression). Apart from missing the cover, and multiple unnecessary holes on the outer plate, the power indicator light has been cut from the circuit - not a huge problem - it will have to be resoldered with new leads. The resistor will need a quick test as will the bulb. The motor does turn on however it very quickly runs out of alignment on the large gear that moves the worm gear. Not sure if the wormgear or shaft are seized, but since I'll be taking the whole thing apart and giving it a good cleaning, I'll take a closer look then anyway. I suspect it's just grease buildup. In the first picture you can also see the locking knob for the RA shaft. This happens to be missing on the other side so I'll either fabricate a new one or just replace both of them. 

 

Not sure why someone began cutting through the collar - luckily they didn't get all the way around so I can take a template and have a new piece made. I wonder if as some point, someone tried to remove it and realized it was seized, and then proceeded to brute (er barbaric) force it? Either way - totally unnecessary. As my Father taught me, "Right tool for the right job!" And if you want to use the wrong tool - no problem - just be prepared to take longer and likely redo the job.

 

In the next post I'll show the gearing.

 

 

 

 

 

Attached Thumbnails

  • Drive1.JPG
  • Drive5.JPG
  • Collar1.JPG
  • Drive9.JPG

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#17 gazpachosoup

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Posted 01 September 2022 - 11:05 AM

Analysis Part 9: (RA Drive Con't)

 

Two pictures showing the motor gear in and out of alignment. The next picture is the RA gear and you can see that the tops of the teeth all have cracks in them. Since it's like that all the way around, I suspect that it came this way from the factory. I don't thing it will affect performance, but once I take it all apart, I'll take a look under a magnifying glass to see if anything looks off. Will check the clutch too. Leather seems ok but I know these were originally cork, and I believe after time, leather will develop a patina that stops providing friction and just creates more slippage. 

 

I'm sure I'll find more things along the way, but that's about it for the analysis. Next step is to determine a plan of attack. Should I start with the most complex parts (the drives), to get them out of the way? Or should I start with the mechanical restoration? Part of me wants to start with the restoration (ie. cleaning, stripping, grinding, polishing, painting, fabricating, etc...) because it will have immediate results, whereas the drives can't be used until the rest is done. On the other hand, if I get the drives done, they'll be ready to reinstall once the rest of the work catches up. As a sidebar, I also have the RV-6 which needs drive work. If I do one then maybe that will give me the confidence to repeat the effort. 

 

I think that was a lame attempt to convince myself to start with the drives. So it looks like I'll start on some of the mechanical stuff and see how the spirit moves me. 

 

 

Attached Thumbnails

  • Drivegear2.JPG
  • Drivegear1.JPG
  • Wormgear1.JPG

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#18 gazpachosoup

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Posted 01 September 2022 - 11:11 AM

Yikes!!!

The frequency control goes from 1 to 11 - shades of SpinalTap.

SpinalTap11.jpeg

 

More numbers - more better!


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#19 bjkaras

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Posted 01 September 2022 - 11:22 AM

To allow easier breathing for some, I'm not going to launch into fixing this or anything else nor go into pet peeves.

 

As per OP request: These are not the Right Ascension (RA) bolts. They are the altitude bolts or some might accurately call them latitude bolts. They adjust the altitude of the mount for changes in latitude position on Earth. It is a common design among many makers of the same era and size. They all stink because the small contact area is insufficient for the massive head load. 

attachicon.gifpost-370990-0-91156700-1661899628.jpg

 

 

 

 

The two mutually exclusive holes in the end of the legs may or may not be original. Two of my Caves have casters and no extra hole for a leveling screw. Telescopics used the same legs and those do have the second leveler holes on mine. All my legs here have smaller caster bearings that will clear a leveler bolt but the wheels wouldn't turn without hitting the bolt. The wheel body has to be rotated out of the way to lower the level bolts. This is also common across many makes and models of the era. 

attachicon.gifP1010010.JPG

Those altitude bolts have been giving me nightmares too. There has to be a better way of locking down the RA shaft without putting so much strain on those tiny bolts. What has anyone else done about that?



#20 dhferguson

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Posted 01 September 2022 - 11:45 AM

Cheers,

 

There are a number of threads online that deal with various aspects of Astrola mount restorations. Here's a thread I started a few years ago about modifying just such a mount that was in better shape than yours: "Cave GEM mods, including Byers drives." Try searching "Astrola" for much more. Also, there is www.cave-astrola.com that contains good info on really nice restorations including the OEM drives.

 

Best,

 

Don


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#21 Geo31

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Posted 01 September 2022 - 06:24 PM

Hey, my bad!  Your RA drive is original.  The DEC drive is the Schmidt & Associates drive.  Sorry to create confusion.

My drive cover is definitely a different size.  I've seen people make others, including out of plastic.  I think I'd consider bending polycarbonate and make a new bottom and rear out of aluminum.  If you really wanted to be fancy, you could leave the PC clear.


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#22 Geo31

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Posted 01 September 2022 - 06:30 PM

Those altitude bolts have been giving me nightmares too. There has to be a better way of locking down the RA shaft without putting so much strain on those tiny bolts. What has anyone else done about that?

Some folks have installed turnbuckles or you could get threaded rod ends (one RH and the other LH) and thread a hollow rod and machine flats in the rod.  That would not only allow for fine adjustment, but would make adjustment easier.  That presumes you are not changing the azimuth much.


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#23 Geo31

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Posted 01 September 2022 - 06:36 PM

Analysis Part 9: (RA Drive Con't)

 

Two pictures showing the motor gear in and out of alignment. The next picture is the RA gear and you can see that the tops of the teeth all have cracks in them. Since it's like that all the way around, I suspect that it came this way from the factory. I don't thing it will affect performance, but once I take it all apart, I'll take a look under a magnifying glass to see if anything looks off. Will check the clutch too. Leather seems ok but I know these were originally cork, and I believe after time, leather will develop a patina that stops providing friction and just creates more slippage. 

 

I'm sure I'll find more things along the way, but that's about it for the analysis. Next step is to determine a plan of attack. Should I start with the most complex parts (the drives), to get them out of the way? Or should I start with the mechanical restoration? Part of me wants to start with the restoration (ie. cleaning, stripping, grinding, polishing, painting, fabricating, etc...) because it will have immediate results, whereas the drives can't be used until the rest is done. On the other hand, if I get the drives done, they'll be ready to reinstall once the rest of the work catches up. As a sidebar, I also have the RV-6 which needs drive work. If I do one then maybe that will give me the confidence to repeat the effort. 

 

I think that was a lame attempt to convince myself to start with the drives. So it looks like I'll start on some of the mechanical stuff and see how the spirit moves me. 

You could substitute nylon for the cork.  Losmandy apparently uses nylon and that's what I used for me RVC-6N (you can see it in my thread).  That's another project I have to finish.  Waiting on one part that a friend was going to make for me, but a major life change had him scrambling to redo his entire art (he's a Native American artist who uses modern processes, including a CNC mill).  That put my work WAY back on the shelf, so I'm trying to find another source that isn't God-awful expensive.


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#24 Starsareus

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Posted 01 September 2022 - 06:52 PM

RE: Part 7

 

I think those are "Pots" with locking nuts to hold their setting, not "terminals."  BTW, Pots are variable Resistors. You have two options, restore that old controller (?) or just buy a newer version that can provide the Voltage/Wattage the little motor wants.

 

 

Naturally, a newer/working one is fastest way to go, unless you like a challenge and have the skillset/time.


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#25 gazpachosoup

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Posted 01 September 2022 - 10:51 PM

Cheers,

 

There are a number of threads online that deal with various aspects of Astrola mount restorations. Here's a thread I started a few years ago about modifying just such a mount that was in better shape than yours: "Cave GEM mods, including Byers drives." Try searching "Astrola" for much more. Also, there is www.cave-astrola.com that contains good info on really nice restorations including the OEM drives.

 

Best,

 

Don

In between posting what's already in this thread I've been researching what's out there. Luckily this is not an obscure mount and restorations are well documented so I hear you when you say I'm in good company. Sure feels that way and it makes tackling some of the bits less intimidating. I particularly like the restos that leave the metal in a highly polished state. There's something 1960's futuristic about that look. I picture sci-fi and ray guns. 

 

Thanks for the redirect to your post - for anyone that wants to check it out, here's the link: https://www.cloudyni... byers drives




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