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8" Edmunds Restoration - New

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#1 Ron500E

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Posted 17 March 2013 - 12:11 AM

Spurred on by the recent "History of Edmunds" I decided to commit my restoration to writing.
Last summer I picked up an Edmond 8" Reflector OTA, probably paid too much for it but if that's the worst I can say so be it. It came with the "promise" that the mount, which was at their country home, and some paperwork would come later. I waited and waited when, just after the first of the year, I received a call saying they have it in their van and could deliver it but I would need a few people to help move it.
Pressed sons into service and we (they) dutifully carried it up to the 6th floor.
The scope and mount were remarkably original with no modifications whatsoever or extra holes drilled here and there.
I decided to restore it to original condition rather than "make improvements," If I wanted an improved modern scope I would have bought a 50" RCOS (in theory I would have bought it, not in actual spending).
After photographing and inspecting it I started disassembly. Since the mount was stored indoors and covered it presented no problem. Restoration was relatively straight forward. After masking off the machined surfaces I had the cast iron parts blasted down to the bare metal with walnut shells.
Next I cleaned everything with lacquer thinner and applied a few coats of primer with a drying time of 48 hours between each coat. Since I was painting on cast iron fine sanding the primer was not necessary. I only sanded down to 220 grit for proper next coat adhesion. The final coat of primer got sanded down to 400 grit.
I then cleaned/polished up the shafts to their proper finish.
Then I applied the top coats with the same drying time.
I painted the bolt heads by making a hole in a piece of metal and screwing them in before painting. This ensured that only the visible parts of the fasteners were painted, not the threads.
A call to McMaster-Carr produced the needed hardware (while saving the originals of course) along with 2 roller thrust bearings and four washers for the Dec and RA shafts. Surprisingly the bearings were "Made in the USA."
All the threads were cleaned up using a cleaning tap/die. A cleaning tap and/or die is not your regular hardware store item, it is cut undersized to just remove rust and or imperfections. A regular one removes metal which over time will enlarge the hole and loosen the clamping power.
Most items were held in place by set screws, I soaked them overnight in lacquer thinner before using a toothbrush for the final cleaning. Then used a small wire brush on a Foredom flexible shaft machine to clean up the thread even further. Loctite Anti-Seize was applied to the threads.
Once everything was cleaned and painted reassembly started. I used an "acid brush" to smear Loctite anti-seize on the threads and all other bare metal to bare metal surfaces. If you do this your grandchildren will thank you when it comes time to disassemble it.
The bearings come in 3 pieces, the cage, which contains the rollers and two washers which the cage "rides" on. I prepared them by placing low temp grease in a baggie and placing the cage inside. Some finger work pressed the grease into every nook and crannie (also known as the roller cage). The washers were prepared by putting grease on the roller surface and anti-seize on the surfaces that contacts the mount head.
Assembly of the legs and pier was straight forward requiring a liberal dose of pain killers while sitting on the living room floor trying to move everything. Darn thing weighs a little less than a Bentley it seems. Shipping weight, according to an old Edmunds catalogue, was 210 lbs. They were not exaggerating in the least.
The OTA restoration was straight forward as no addition holes have ever been drilled. In fact it seemed that this scope has seen little use over the years, such that the "restoration" only required a clean up. The tube was sanded starting with 1200 and 1600 grit paper to ensure proper adhesion for the paint. After spraying the tube was rubbed down using various Meguiar's products, finishing up with Plastic -X, used for cleaning up Plexiglas on old cars (yet another hobby of mine that takes a large amount of space and money).
The finder scope, satellite scope's lens, the one with the cross hairs, has come loose from it's ring. That's the next thing to tackle once I figure out how to remove it.
Other than that, the brackets were painted in the proper black wrinkle and hardware was prepared as noted above.
The mirror did not require re-coating and still retains it's original UPCO sticker. Everything in the cell looks fine so I decided to leave well enough alone.
The focuser only required cleaning and lubrication.
A trip to Home Deport produced a few flooring samples, an excellent way to prevent indentations on the carpet. They also have carpet samples, another excellent way to prevent tripod spikes from damaging the floor for us indoor scope users.
I try to use American made products because the scope was made in America, I have a bunch of German cars and try to use German made products on those, etc.
I would like to thank those who "have come before me" in doing restorations. To mention them would be a disservice to those of whom my failing memory has forgotten. That said... Caveman and Roland Chavez have set the standard of which I can only hope to aspire to after years of work. Albert DeCandia also put up with a bunch of novice questions and answered them promptly. He also sold me my wonderful Dynascope but has not fulfilled the promise of 365 clear viewing nights here in Chicago....
Also, I should have paid more attention to Brother John's English 101 class so I wouldn't end sentences in a preposition but that's another story.
The sad part is that in my Condo I have only east facing views, towards the center of Chicago. But it sure looks nice in the living room. Oh well.
Pics to come as soon as I figure out how to post them.
Kind Regards,

Ron

Sources:
Ace Sandblasting for paint removal.
McMaster-Carr for bearings.
Rockford Products for fasteners.
Rustoleum for paint.
Meguiar's for paint finishing products.
Loctite for Nickel based Anti-Seize.
Mercedes-Benz for low temp grease, had some laying around for sunroof lubrication.
3M for Emery wet/dry paper.
Starrett for proper taps and dies.
Home Deport for wood flooring and carpet samples.
American Science center for generic acid and miscellaneous brushes.

#2 proteus5

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Posted 17 March 2013 - 09:29 AM

Can't wait for pics. Nice write up!!

#3 Masvingo

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Posted 17 March 2013 - 11:54 AM

+1, looking forward to the pics.

James

#4 bremms

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Posted 17 March 2013 - 12:38 PM

That is really a nice scope. The mount for the 8" is superb.
I remember using one many years ago. Looking forward to the pictures.

#5 Ron500E

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Posted 18 March 2013 - 04:11 AM

The OTA had not been painted yet.

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#6 Ron500E

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Posted 18 March 2013 - 04:13 AM

EQ Head.

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#7 Ron500E

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Posted 18 March 2013 - 04:14 AM

Roller Thrust Bearings.

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#8 Ron500E

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Posted 18 March 2013 - 04:14 AM

Saddle.

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#9 Ron500E

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Posted 18 March 2013 - 04:16 AM

More.

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#10 Ron500E

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Posted 18 March 2013 - 04:19 AM

Before Restoration.

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#11 apfever

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Posted 18 March 2013 - 09:55 AM

Roller Thrust Bearings.


?? Mine is strictly teflon thrust washers and bearing collars.

Ron, where was the thrust washer? I would think on the RA shaft between the RA housing and DEC housing. Any specs on that bearing? Here's a picture of mine. I also raised the DEC housing on the counter weight shaft and the bearing between that and the saddle is also Teflon. Both of the Teflon washers are full diameter flush to the edge of the housings so they look good and help keep contamination from catching.

Does anybody else have any experience with finding a thrust bearing on the Edmund 8"?

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#12 bremms

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Posted 18 March 2013 - 11:19 AM

You could just get some sheet Teflon and use a gasket cutter.

#13 mgwhittle

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Posted 18 March 2013 - 02:28 PM

Great job on the restoration! That is a wonderful example of a classic telescope. You should be very proud to own that. Looking forward to an observing report when you get a chance.

#14 Ron500E

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Posted 18 March 2013 - 04:51 PM

Roller Thrust Bearings.


?? Mine is strictly teflon thrust washers and bearing collars.

Ron, where was the thrust washer? I would think on the RA shaft between the RA housing and DEC housing. Any specs on that bearing? Here's a picture of mine. I also raised the DEC housing on the counter weight shaft and the bearing between that and the saddle is also Teflon. Both of the Teflon washers are full diameter flush to the edge of the housings so they look good and help keep contamination from catching.
Does anybody else have any experience with finding a thrust bearing on the Edmund 8"?


Hello Apt,
The washer is under the roller cage. The bearing assembly comes in 3 parts. One roller cage and two washers. There are several choices in the McMaster-Carr catalog, I chose these over the Teflon. The following are McMaster-Carr's info from their invoice. All were found on page 1122 of Catalog 114. "Needle and Thrust Bearing" section and are Made in the USA by INA. I THINK the universal bearing number is "TC2435-HLA/05E", the number "006093493" also appears on the box along with "VAR: 4062"
5909K41 - Cage assembly for 1 1/2 id shaft 2 /3/16 od. Steel Thrust Needle Roller Bearing. Price $4.19 each. Quantity of 2 needed.
5909K54 - .032 Thick Washer for 1 1/2 id. Steel Thrust Needle Roller Bearing. Price 1.88 each, quantity of 4 needed.
I did not take any pics of the bearing before installation but imagine a cage of rollers sandwiched between two washers and you'll get an idea as to what it looks like. I found nothing in their catalog that has an ID of 1 1/2 AND an OD of 2 11/16 inches with a nominal thickness. I'm not sure contamination would be a problem, not sure it wouldn't though. A rubber bicycle inner tube, cut to around 4" in length and placed around the bearing area would be an acceptable dust shield solution IMHO, after all it's not like it's spinning in circles all the time.
I considered Teflon but I was concerned about "looks," Didn't want to buy a circle cutter and my ability to cut a neat looking circle is pretty much non existent. I have trouble putting food in my mouth without leaving evidence on my tie it seems. I have had good luck in the past using Berry Bearing but didn't want to spend 3 days looking for bearings if you know what I mean. The McMaster-Carr catalog was at hand. As an FYI..... PTFE (Teflon - DuPont) would have been more expensive ($15.39 each), and not as effective, than the steel cage assembly. I'm pretty sure a ridge would have been worn in short order. All things considered the range of movement on a regular basis is no more than 100 degrees. Again, on a regular basis. Other choices were Nylon, UHMW, Delrin, Rulon 641 and Rulon LR. If you look at the shaft and were the load is and forces are I think what I got was the best choice, but I am not an engineer, nor do I play one on the Internet.
Kind Regards

Ron

#15 apfever

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Posted 18 March 2013 - 06:46 PM

Ron,

I had the same problem with eating, so I quit wearing a tie.

I thought your bearing assembly might have been original. The Teflon in mine is in good shape so I'll keep it. However, I might be tempted to get one of those thrust bearings just to check it out. I'd be interested in knowing how crazy fluid smooth that movement is compared to the buffering given by Teflon washers.

We have slightly different RA shafts. Mine has a motor drive so the shaft has extra grooves and stubs machined into it. One groove, close to the saddle, has the Teflon bushing. There might be another teflon bushing on the other end of the RA shaft towards the drive, which would be missing in my case. The shaft is grooved where it would contact the housing, but that groove may just be for clearance (or a bushing). I'll have to research that.

The setting circles are on their way.

#16 kansas skies

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Posted 18 March 2013 - 07:51 PM

Very nice restoration. Your attention to the small details is nothing short of exemplary.

Bill

#17 amicus sidera

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Posted 18 March 2013 - 08:01 PM

Looks like a brand-new old telescope to me! Excellent work!

#18 Edward E

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Posted 19 March 2013 - 11:12 AM

That is a beautiful restoration job; congratulations! Like others said, it looks like a brand new "classic" scope. I see that you have the "Deluxe" Edmond finder scope, excellent. That finder, IMHO, is the best finder ever made. I have one that I use on my 6" refactor and it does double duty on my 20" Dob at the dark sky site.

#19 Ron500E

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Posted 19 March 2013 - 07:12 PM

Thanks for all the nice comments people. It was my first scope restoration and, although I've done some of my cars before, it's great encouragement to hear such nice comments from the pro's.
There's immense joy in bringing something back to life. But without reading this forum, and stories of what and how others have done, it would not have been possible. Thank you all.
I'm inclined to offer the back story of the restoration... like when I was painting the finder bracket. One can still see the outline on the carpet where the overspray occurred while "someone" was in Poland. And the earth shattering discovery that lacquer thinner, that was used in cleaning up said overspray, dissolves nylon, as in nylon carpet. Also, do not use kitchen basting brushes to dislodge loose dirt and crud. Sad thing is that if I were found murdered I wouldn't be listed in the "obituary" section, I would be listed under "Civic Improvements." And there's not a jury in the world that would convict her.
Kind Regards,

Ron, whose purpose in life is to test the patience of Saints.






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