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Help with refurbishing Edscorp Motor Drive

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#26 bartine

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Posted 28 March 2009 - 01:50 PM

And finally - the drive disk pushed up to engage the worm gear.

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#27 clamchip

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Posted 28 March 2009 - 07:16 PM

Hi Ben. You answered my question with your pictures.

I was wondering how the shaft lock plate and the fine adjust casting were held together. It looks like there is two allen head screws holding them together. This is what makes it work on the larger mount.

The ball bearing is strange, it must just be used as a spacer.

Is your drive working OK now?

Clutch should be adjusted up pretty snug, but still able to push the OTA around without damaging the drive.
OTA balance is important also, do this before you have the drag of the installed drive.

The gap at your teflon thrust bearing (near the setting circle) should not be there, the two castings should sandwich that teflon washer with no gap. Check the teflon sleeve bearings on the shaft, they sit in grooves cut for them on the shaft and could be hanging things up.

My mount has a Pacific Instruments drive so I'm not much help.

The Edmund "Super Duper" mount is simply fantastic, when you start using it you will see why. The mass and cast iron absorbs vibration like nothing else.
The short distance from saddle to polar shaft makes it very solid and stable platform for the OTA.
I use mine for my D&G 6" refractor with a pier extension and my largest reflectors, 10"f6 being heavyist.

You won't need a motorized focuser with this mount. Keep your body in good shape if you need to move it around much so you don't pop your back out.

Robert

#28 bartine

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Posted 29 March 2009 - 12:28 PM

No luck so far.

I need to get an allen wrench that fits the weight collars, then I can adjust the balance a bit.

I removed the slow motion control lever, and I could turn the entire scope with the gear.

Put back the slow motion control lever, set the mount and marked the gear.

The gear turns, but the scope doesn't move.

#29 DAVIDG

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Posted 29 March 2009 - 01:50 PM

Maybe this will be of some help. These images came out of Sam Brown's All About Telescopes that Edmund published. While not exactly your drive, it have a number of the same components.

- Dave

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#30 DAVIDG

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Posted 29 March 2009 - 01:54 PM

Here is another.

- Dave

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#31 jimarshall

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Posted 29 March 2009 - 06:56 PM

Ben,
I don't understand this at all, your drive is just like mine except for the odd end cap and ball bearing.

"I removed the slow motion control lever, and I could turn the entire scope with the gear."

That sounds like your leather clutch is gripping correctly. Here is the way mine works:

If I move the slow motion control lever up out of the way and tighten the clutch thumb screws, I can move the polar shaft by turning the large brass gear by hand. (the motor assembly and gear moves with the shaft). If the slow motion is engaged, I can't move anything by hand. With the thumb screws loose and slow motion disengaged, the whole motor and gear assembly rotates freely around the inner drum which is attached to the polar shaft with two recessed allen screws (the shaft and drum does not move). If your scope is properly balanced, the clutch tension screws tight and with the large brass gear turning, I don't see any reason for it not to work.

Jim

#32 clamchip

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Posted 29 March 2009 - 07:16 PM

Make sure the worm gear is not slipping on the motor shaft. Mark the motor shaft and worm gear with a felt pen and watch the movement. Brass gear movement is hard to detect visually.

Also worm gear should be directly under the brass gear with teeth fully engaged.

If you can turn the scope with the brass gear clutch sounds OK.

Robert

#33 Telescopeman54

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Posted 29 March 2009 - 10:50 PM

First of all, the ball bearing goes under the spring clip on the corrector. There is a small groove under there that is cut into the shaft. It rides in there.

See Picture

Steve

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#34 Telescopeman54

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Posted 29 March 2009 - 10:56 PM

Next, you are missing parts! There are two flat disks that should be where that one black piece of hollow stock is placed. You have no clutch! No wonder it doesn't work!

Here is how it SHOULD look.

Steve

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  • 3013133-CN-ED-RA.jpg


#35 Telescopeman54

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Posted 29 March 2009 - 11:00 PM

I just looked at an earlier picture. You DO have all of the parts. The black thing has no purpose. All you need is a Nylock nut and you should be in business.

Steve

#36 Telescopeman54

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Posted 29 March 2009 - 11:06 PM

By the way, this is a later mount. Sometime from the mid to late 70's. This one has Nylon sleeve bearings on the axles. The earlier ones had Oilite bronze bushings and were much more accurate and lasted forever. The Nylon crushes and deforms over time. It was a cost cutting measure that was implemented near the end of the product life. The bushings are still made. If I owned the mount I'd have the castings bored out and have the bushings installed and honed true. If you think these are good with the Nylon, you should try one of the old ones with the bronze bushings!

CS

Steve

#37 bartine

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Posted 30 March 2009 - 04:00 PM

I have the mount tracking now. I may tinker with it a bit to get a tiny bit of slack out of the movement, but it tested out well, and should track fine.

Thanks to everyone for all the assistance.

What I did:

There was a huge amount of play in the mount, due to my incorrect assembly of the slow motion adapter. I took the ball bearing and placed in as directed by Steve (I swear I got that bearing out of an upper assembly!) The slow motion adapter actually had an eraser in the hole - which worked, but the bearing fit the hole perfectly.

I also determined I hand't fully pushed the slow motion adapter shaft down in between the two little pins / shafts from the motor housing. I actually had to tap it to get it to slide all the way down.

And as Dave said, I needed to adjust to the two circular sleeves that the slow motion shaft fit in between to remove most of the slack. I removed all the slack once, but the adapter was so stiff you couldn't use it at all.

Rob was correct about the motor binding. Once I got rid of the gap at the top of the assembly, the inner shaft would protrude just a tiny bit beyond the end of the motor mount, which allowed the motor housing to be free from the shaft.

I also did need that thin locking nut (got it at Ace Hardware). Thanks Mike.

I tried assembly with the leather washer above and below the gear. Eventually, I determined there was too much up and down play in the motor assembly when the washer was above the gear. So - I cut a thin plastic washer to go between the gear and motor housing, and used the leather washer at the bottom between the gear and clutch pieces.

The last adjustment was to tighten down the worm gear to stop it from moving up and down when the scope moved and the clutch engaged. There is a small hex nut on top of the gear bearing.

Heartfelt thanks to everyone.

#38 bartine

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Posted 30 March 2009 - 04:55 PM

By the way, I got an extra 1/15 rpm motor from Sheldon on the classifieds section- very inexpensive! Just search for "Edmund motor". He also has new gears - you could actually put together a geared drive for the other mount axis (no - no more projects! )

The plastic bushing only covers the very top 2" of the shaft, and there is a slight indentation where the plastic fits. The rest of the shaft fits exactly. Where would you get the Oilite brass sleeves Steve?

Motions are pretty smooth with the plastic bearing. I'm not sure when the mount was made, but most of it seems to be nicely machined with very close tolerances. The OTA has the mirror with an etching on the back of the cell, and the erector set spider / diagonal holder.

I have other pieces that came with this to play with now:

If I add a heavier finder, I could move the tube much lower in the rings, making it possible to use the scope without a ladder. Right now, the tube is very bottom heavy.

This came with one of the Herschel Wedges that replaces the diagonal. Would need one additional filter, then this would make a cool solar scope.

The tube needs end rings - and I need to make some minor repairs to the end of the tube, then re-paint it.

Center dot the mirror, possibly put together a Dob mount for quick viewing, and???



Ben

#39 Telescopeman54

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Posted 30 March 2009 - 05:38 PM

Check with any industrial supply house for the Oilite bronze stock. Anyone that handles bearings should have it.

Steve

#40 mikey cee

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Posted 30 March 2009 - 09:12 PM

That black ring is for mounting the RA circle onto. :smirk:Mike

#41 clamchip

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Posted 31 March 2009 - 12:01 AM

Ben,
your drive motor should have a date stamped on it.

That mount and scope was introduced around 1961-62.
The "Improved" mounts started mid 60's with the Teflon bearings and also the drives with the fine adjust lever.

You said something about the mirror is etched on the back?

Robert

#42 clamchip

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Posted 31 March 2009 - 12:10 AM

I forgot to say that you could find the stock finder, I see them for sale quite often.

It is the Edmund "Deluxe Finder" 50mm X6. The inerds are WWII surplus optics in brass so they weigh a TON and they have a wonderful wide field and optics are superb.

Robert

#43 Telescopeman54

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Posted 31 March 2009 - 12:11 AM

Oh yeah! Most of the Edmunds had the setting circle up at the front of the housing. I'm a little rusty on the 8" mount. I need to go through the old catalogs again to refresh my memory.

Thanks,

Steve

#44 clamchip

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Posted 31 March 2009 - 12:41 AM

Your mount has the "Optional Super Setting Circles" they are in the catalog, It's the first time I have seen these.

I'm putting them on my list for Santa and also the optional Dec axis fine adjust.

Years ago I replaced the Teflon bearings with impregnated sintered bronze bearings on a Edmund 1" mount and it did tighten things up and made it work better. Infact I wish I still had that scope!

Robert


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