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Restoring a '59 Cave 10" f/7.1

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#76 KentTolley

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Posted 18 December 2018 - 10:04 AM

The key to using a power polisher is to use a variable speed sander/polisher. This is what auto detailers use.   I polished my Parks f/g tube at a LOW SPEED.  If you can polish a car with it you should be able to do the same on an unpainted fiberglass tube.  Utube should have videos of techniques in using a power polisher.  Look for f/g boat restorations.  

 

Your mirror is #1363.  Be sure to register it with PiSigma.

 

Show us pics from all angles of the focusser.   Does it have any marks on it?  What did Cave use before the Rukes focusser?    


Edited by KentTolley, 18 December 2018 - 11:08 AM.


#77 Guy Earle

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Posted 18 December 2018 - 11:31 AM

The polisher I have only has one setting, and I'm quite alright doing it by hand. There's a great satisfaction wiping away the years of grime. I figure one more round of restorer, then I work my way up to the final wax. I absolutely love the feel of the fiberglass. All this Florida dew will just slide right on off. 

 

I would like to use focuser to maintain the original quality of it, of course, but it is not complete. The gear that interacts with the drawtube has lost all its teeth, so you can spin the focuser knob and nothing happens. In addition, the inner compression sleeve isn't attached in any way and there is an upper ring missing (where the set screw would be). You can see the shadow on the compression tube where it should be. Unless there are any aftermarket parts, I can't use it.

 

Guy

 

 

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#78 Guy Earle

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Posted 18 December 2018 - 11:33 AM

The key to using a power polisher is to use a variable speed sander/polisher. This is what auto detailers use.   I polished my Parks f/g tube at a LOW SPEED.  If you can polish a car with it you should be able to do the same on an unpainted fiberglass tube.  Utube should have videos of techniques in using a power polisher.  Look for f/g boat restorations.  

 

Your mirror is #1363.  Be sure to register it with PiSigma.

 

Show us pics from all angles of the focusser.   Does it have any marks on it?  What did Cave use before the Rukes focusser?    

Yep, I already posted in the thread with the information about the mirror's information. I'll take more pictures later today. 



#79 Geo31

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Posted 18 December 2018 - 11:42 AM

The key to using a power polisher is to use a variable speed sander/polisher. This is what auto detailers use.   I polished my Parks f/g tube at a LOW SPEED.  If you can polish a car with it you should be able to do the same on an unpainted fiberglass tube.  Utube should have videos of techniques in using a power polisher.  Look for f/g boat restorations.  

 

Your mirror is #1363.  Be sure to register it with PiSigma.

 

Show us pics from all angles of the focusser.   Does it have any marks on it?  What did Cave use before the Rukes focusser?    

Actually, more important than the variable speed is the random orbit action.  I use a Porter Cable 7336 (current model 7424XP) on the fastest setting.  It's the rotary polishers you have to watch out for as they can quickly burn through the paint.  I used this and the multi-step polishes, along with a paint sealer on the tube of my RVC-6N.  It turned out amazing.


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#80 TOM KIEHL

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Posted 18 December 2018 - 01:08 PM

 

I would like to use focuser to maintain the original quality of it, of course, but it is not complete. The gear that interacts with the drawtube has lost all its teeth, so you can spin the focuser knob and nothing happens. In addition, the inner compression sleeve isn't attached in any way and there is an upper ring missing (where the set screw would be).

 

Guy

Guy , are you sure the set screws in the knobs are tight on the pinion shafting ? If I'm  not mistaken the " Compression sleeve " is solely a interference fit and so are the EP's that go into it ......Old School for sure !


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#81 Guy Earle

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Posted 18 December 2018 - 06:16 PM

Guy , are you sure the set screws in the knobs are tight on the pinion shafting ? If I'm  not mistaken the " Compression sleeve " is solely a interference fit and so are the EP's that go into it ......Old School for sure !

Yes, that was one of the first things I checked. The gear does not catch the focuser tube, so there's no way to rack it in and out. And you can see where there was one something at the top of the compression tube. I put in an eyepiece and it just falls out if I turn it sideways. It's like I'm missing two key parts, unfortunately. Do you have an idea what model is this old focuser?



#82 TOM KIEHL

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Posted 18 December 2018 - 07:30 PM

Yes, that was one of the first things I checked. The gear does not catch the focuser tube, so there's no way to rack it in and out. And you can see where there was one something at the top of the compression tube. I put in an eyepiece and it just falls out if I turn it sideways. It's like I'm missing two key parts, unfortunately. Do you have an idea what model is this old focuser?

Looks like a RUKES ........The bushings that the pinion shaft go thru are eccentric to allow adjustable  mesh of the rack and pinion . Get that pinion out so we can see it better . Could just be out of adjustment .


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#83 chuck52

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Posted 18 December 2018 - 07:42 PM

Looks like a RUKES ........The bushings that the pinion shaft go thru are eccentric to allow adjustable  mesh of the rack and pinion . Get that pinion out so we can see it better . Could just be out of adjustment .

I was thinking it was a Rukes too.Isnt it usual to have the Rukes name on the underside of the focuser? Also, I remember reading a post somewhere here on Cloudy nights about making a new shaft using pinion wire of the right pitch.They turned the ends down for the knobs and left the pinion gear in the middle.Remember because I have an old cave focuser with the same issue.


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#84 TOM KIEHL

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Posted 18 December 2018 - 09:42 PM

I could be wrong ...... ( First time this year lol.gif ) But it might be a Garth Focuser also . They look similar and you are  right , RUKES would be cast into the underside . GARTH Not cast into the underside , no ID.

 

Total disassembly and inspection is suggested .coolnod.gif 

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Edited by TOM KIEHL, 18 December 2018 - 10:05 PM.

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#85 Guy Earle

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Posted 18 December 2018 - 10:33 PM

I was thinking it was a Rukes too.Isnt it usual to have the Rukes name on the underside of the focuser? Also, I remember reading a post somewhere here on Cloudy nights about making a new shaft using pinion wire of the right pitch.They turned the ends down for the knobs and left the pinion gear in the middle.Remember because I have an old cave focuser with the same issue.

There is no marking underneath as to what brand. I did, however, find the same focuser on a 1958 Cave restoration page, and you can see that there is a set ring missing at the top of the focuser which matches the shading I saw on the barrel. Here are the pics:

 

Edit: I see that the two brass bushings (?) do not have a concentric opening for the focuser knob shaft, and that the idea is to rotate them forward so the focuser knob shaft and gear then presses up against the the focuser tube, but despite all my attempts it sticks too tough and never engages, even when the two brass bearings match on either side.

 

Guy

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Edited by Guy Earle, 18 December 2018 - 10:51 PM.

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#86 Guy Earle

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Posted 18 December 2018 - 11:00 PM

I could be wrong ...... ( First time this year lol.gif ) But it might be a Garth Focuser also . They look similar and you are  right , RUKES would be cast into the underside . GARTH Not cast into the underside , no ID.

 

Total disassembly and inspection is suggested .coolnod.gif

Tom, you are right. It matches the Garth completely. Funny that it's Springfield, Mass, as that is where my mom was born. I found an old ad that has it too. There just isn't enough compression to hold an eyepiece in though, and I can't get it to engage. I think the gear is just worn down after all these years. I'm going to clean all the parts tomorrow and see how it all fits back together and tackle it with a fresh start.

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Edited by Guy Earle, 18 December 2018 - 11:04 PM.

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#87 clamchip

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Posted 19 December 2018 - 12:10 AM

My 1957 8 inch f/7 deluxe has what looks like the same focuser.

I looked and I looked for the ruby red shoes to fit my prince, all I had to go by was the footprint on

the tube, and I eventually found them:

 

post-50896-0-26488400-1531522339.jpg

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Edited by clamchip, 19 December 2018 - 11:00 AM.

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#88 TOM KIEHL

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Posted 19 December 2018 - 07:30 AM

There is no marking underneath as to what brand. I did, however, find the same focuser on a 1958 Cave restoration page, and you can see that there is a set ring missing at the top of the focuser which matches the shading I saw on the barrel. Here are the pics:

 

Edit: I see that the two brass bushings (?) do not have a concentric opening for the focuser knob shaft, and that the idea is to rotate them forward so the focuser knob shaft and gear then presses up against the the focuser tube, but despite all my attempts it sticks too tough and never engages, even when the two brass bearings match on either side.

 

Guy

Guy I see NO remnants of a pinion gear what so ever in your images ??????confused1.gif  Pinion stock can be purchased if size is known .


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#89 KentTolley

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Posted 19 December 2018 - 09:31 AM

Guy

I agree with Tom's observation above.  No pinion gear.   What is that small black round thingamajig?  Looks like it would thread on the shaft where a pinion gear would go.  Looks like a rubber grommet.  Unless the grommet thingy is actually what's left of a worn- down non-metal pinion gear.

 

My 1963 Rukes focuser works the same as your Garth.  The 2 bushings are eccentric.  I had to try different ways of inserting them until the shaft turned smoothly.  Then the 2 screws over the bushings adjust the tension to focussing.

 

I didn't understand what you said about the missing set ring at the top of the focuser.  From the ad you posted there is a main tube to which the rack is attached and an inner tube which slides up snd down the rack tube and acts like a bushing between the rack tube and your 1.25" eyepiece.  It looks like you have both tubes.  No set screw holds the ep in.  It's held by the tight fit between the inner tube and the ep.  You may have to reshape (tighten or loosen) the tube to fit your ep.  The scar you see is not sign of a missing part.  The inner tube was pushed inside the rack tube except for the last 1/4" which, exposed to the elements, corroded slightly.


Edited by KentTolley, 19 December 2018 - 10:03 AM.

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#90 Guy Earle

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Posted 19 December 2018 - 09:53 AM

The "pinion gear" is the little black circle that I'm holding in my palm, and is also in another pic with the two brass bushings and the bar that connects the knobs. That black gear has very little teeth left on it, so it has nothing to grab on the drawtube. That piece isn't a rubber grommet, as it is hard and has the remnants of gearing. Without that piece, you could turn the knobs all you want but nothing would catch the gearing on the drawtube.

 

I was thinking, when I believed it was a Rukes, that there should be some way of closing the tension where the eyepiece is inserted. Because as it is the eyepiece won't stay. The Garth does not have that piece, but there is still a shading difference on my drawtube where I thought there must have been another part at some time. 


Edited by Guy Earle, 19 December 2018 - 09:54 AM.


#91 KentTolley

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Posted 19 December 2018 - 10:00 AM

I get it.   I thought all pinion gears were brass.  Yours is, as you say, worn down snd will no longer engage the teeth of the rack.  But see my last post about how the 2 tubes work.  See clamchip's photo.  His focusser is complete.   Somebody here must know how to tell from your rack, which pinion gear you need. 


Edited by KentTolley, 19 December 2018 - 10:11 AM.


#92 Guy Earle

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Posted 19 December 2018 - 10:11 AM

I'm looking for it as well. Something brass rather than plastic would be better. Shapeways may even have something or can be printed.

What do you have in yours? What I'm wondering is if the two non-concentric brass bushings are to push the gear into place, then what keeps the gear from simply spinning on the bar? Being sandwiched between the two bushings?

#93 TOM KIEHL

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Posted 19 December 2018 - 10:13 AM

The Garth does not have that piece, but there is still a shading difference on my drawtube where I thought there must have been another part at some time. 

The " shading difference " is the oxidized portion of the drawtube that is exposed above the rack gear drawtube at correct fL. You can tweak that tube in upon it self to achieve a snugger fit on your EP .


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#94 KentTolley

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Posted 19 December 2018 - 10:19 AM

Pinion in my early Rukes is brass and welded to the shaft.  Yes the eccentricity of the two bushings allows the pinion/shaft to move toward or away from the rack.  Sounds like someone got the shaft/pinion kittywampis to the rack and racked it in and out until the teeth wore off.   You could easily do this by positioning the two bushings such that the shaft/pinion is not perpendicular to the rack.   I had to play with  different orientations of these bushings to get it right.  The bushings may also be left and right so try that too.  


Edited by KentTolley, 19 December 2018 - 10:27 AM.


#95 TOM KIEHL

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Posted 19 December 2018 - 10:22 AM

. Something brass rather than plastic would be better.

What do you have in yours?

Mine has a brass spur / pinion gear press fit to the shaft . Plastic ? at one time someone may have replaced it . With age the shaft fit has loosened . 



#96 Compressorguy

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Posted 19 December 2018 - 10:25 AM

Ok I’ll throw in an o’”pinion”, pun intended. When I first saw a pic of the focuser I thought that it was a neat design as it had a “hard rubber” or “phenolic” smooth face pinion gear. This gear was pressed upon the draw tube rack by the eccentric pinion bearings. I’m not convinced the “pinion gear” originally had teeth but the impression was made upon it from the rack teeth. I would also imagine if it was any sort of rubber that it has turned very hard by now! Also looking at the focuser rack teeth does not look like usual geared teeth. They look closely spaced and very shallow. Obviously not helical either, not that is a tell tale sign. The only thing I can’t figure is what held the pinion gear on the pinion shaft to keep it from spinning on the shaft. Was it glued on or a tight press fit originally. This design would had made for a very smooth focuser, with no gear lash and very precise control. Didn’t Edmund have a similar design at some time. Anyway, just spitballing here! 

 

Two questions:

Does the pinion gear spin freely on the pinion shaft?

 

Will the eccentric bearings still push the pinion gear up against the focuser rack? If the gear was/is rubber and is hard it would have shrank over the last 60 years and could be causing the gear not to contact the rack. 

 

Seems another pinion gear, if it’s just a pressed, smooth face gear, would be easy to make or at least try it.


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#97 clamchip

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Posted 19 December 2018 - 10:30 AM

My complete focuser shown above has a metal pinion, it may be nickle plated brass.

You can see my rack is much coarser and yours has fine teeth.

Your focuser could very well have originally had a rubber pinion, and actually it could

be rather nice and smooth if the right material is selected for the job.

Something that is a tight fit on the shaft, and the right diameter to be a friction fit with

the rack, with the available adjustment from the eccentric bushings.

 

Robert 


Edited by clamchip, 19 December 2018 - 10:53 AM.

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#98 KentTolley

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Posted 19 December 2018 - 10:33 AM

Yes to compressorguy above.  If you can adjust the eccentric bushings such that the toothless pinion engages the rack it could work this way.  Is there a tiny set screw on the pinion to lock it down on the shaft.  It will not work until shaft and pinion turn as one piece. Play with it and it will become clear how it works.


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#99 clamchip

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Posted 19 December 2018 - 10:37 AM

I don't have time to look now but I remember Coast Treckerscope? advertised their focuser as fluid drive?

or hydromatic or something along those lines implying something other than gears, possibly.

Robert 

laugh.gif Here it is, Hydro-Glide:

http://www.philharri...net/trecker.jpg


Edited by clamchip, 19 December 2018 - 11:01 AM.

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#100 KentTolley

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Posted 19 December 2018 - 11:47 AM

Precursor to the Crayford focusser.  It might even have been the inspiration for Mr Crayford.

Off-topic but now I wonder if Sky Micro is not the same principle since it focusses so smoothly.  And the Sky Micro rack tube has a helical thread and not your normal rack.


Edited by KentTolley, 19 December 2018 - 11:54 AM.



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