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spudrick
28-05-2006, 11:51 AM
I have a 10" F5 setup which is in a very sorry state :(
I now have started to get it back to its former glory and the first stage will be to have the mirrors recoated then purchase new focuser, spotting scope rings. The tube will have to be stripped a bit of panel beating then powder coated. Finally i will have to tackle the mount, it seems to be in reasonable condition so i will strip down check the bearings and see if the motor is OK.
Hopefully this will not take too long but i have bought the GSO 12" Dob to keep me company :)
If anyone has suggestions on anything about the rebuild please feel free to tell me as i am a complete novice.
Also as i am in Melbourne any suggestion as to where i can have the mirrors recoated.

leon
28-05-2006, 12:43 PM
Hey Terry, looks like you have some work ahead of you, but enjoyable work.

I recently had my mirror re aluminised, and had to send it to Sydney.

To Astro Optical
P.O. Box 568
Crows Nest 2065
Sydney N.S.W.

It cost about 10.00 dollars packed in it's proper wooden container to post.
The service is reasonably quick and is courier shipped back to you very well packaged.

My eight inch cost about 154.00, including postage costs.
I don't know, if they do diaganols, but presume they do.

Leon

stringscope
28-05-2006, 07:39 PM
Hi Terry,

Yep, looks loke quite a bit of work there. What is the history of the scope? Is it a commercial scope or ATM?

Looking forward to watching the progress.

Cheers,

spudrick
28-05-2006, 08:27 PM
Thanks Leon i will contact them and get the easy part started.
I am actually looking forward to do something to get it back to working condition, and having another scope to use will mean i wont have to rush.
Hi Ian when i got it secondhand it had an all timber fork mount and was quite obvious ATM. I bought the mount about 2 years ago with the intention of fixing it but work etc.. time passed you know the rest. Now with some inspiration from some of the projects i see here i want to get on with it :D

iceman
29-05-2006, 05:05 AM
Nice mount! You could always send it to me if you get bored with it!?? :whistle:

stringscope
29-05-2006, 04:15 PM
Hi Terry,

Just a suggestion for the tube. I recently refurbished a small steel tubed scope. The tube was somewhat battered and while a was able to clean the dents up it would never have looked good even with a fresh paint job.

What I did was find some suitable patterned cloth (quilting material), glued it onto the tube and then coated it with 5 coats of estapol. Repainted the endcaps gloss black and it looks great for very little $.

Some of the quilting material patterns avialable would look quite good on a scope tube.

Just a thought :).

Cheers,

stringscope
29-05-2006, 04:17 PM
Image of the cloth covered scope tube.

leon
29-05-2006, 06:14 PM
Now Ian, thats a hell of an idea, never come across that before, and it sure comes up well, love your scope. :thumbsup:

spudrick
29-05-2006, 07:19 PM
Thanks Ian that is quite a good tip on making the tube look great, you even had a similar colour to what i wanted :).
The tube looks pretty uneven and maybe this will be a good alternative to Paint/Powdercoat.
lol Iceman if the rest of the scope is in bad condition the mount is still pretty good so I will keep it at the moment but you are at the top of the list should i ever want to get rid of it :D

netwolf
30-05-2006, 09:14 PM
Terry, put me as number 2 on that list.. incase Iceman gets an EQ6 or G11 or better.

Ian, hats off on that Dob and base. Did you make that base yourself?

regards

stringscope
30-05-2006, 09:51 PM
Yep, the little dob was just put together from what I had in the scrap bin. The only things I purchased were the PVC end caps from Reece Plumbing and the cloth from Lincraft. I had the lazy susan bearing in the shed and plenty of scrap timber and paint. It will be great to see Terry's scope progress.

Hey Terry, I have just had a thought, why don't you refurbish the tube first followed by fabricating a dob base, then the GEM. If you use a clamping tube cradle for the dob mount you would be able to swap the OTA between the 2 mounts. This might get you up and running a little quicker if you wanted.

Cheers,

netwolf
30-05-2006, 10:00 PM
Hey Ian you rekcon you could make on of those for me??? My 10" GSO dob base is ok but no good for motorisation as it is. The Cradle and bearings on your seem more suitable for a drop in bearings and motors solution. A similar approch to this one http://4dw.net/svdgoto/custom.htm.

Regards

spudrick
01-06-2006, 06:35 PM
Thanks for the good ideas Ian, I now have the 12" Dob and so do not have to speed up the work on the Newt. Although i will have to decide on the ring system eventually. I was planning on a set of rotating rings.
Your idea of making a clamp type taking advantage of interchangable mounts is food for thought.
I have already dismantled the Mount and have begun to take of the layers of paint. Aside from buying new bolts, nuts etc, the next step will be to get the parts powder-coated.

stringscope
02-06-2006, 05:11 AM
Congratulations on the 12" GSO Terry :thumbsup: . Please keep the progress reports and pic's coming :) .

Cheers,

stringscope
02-06-2006, 05:27 AM
Hey Netwolf,

To avoid diverting Terry's thread I have sent you a PM.

Cheers,

Roger Davis
02-06-2006, 07:34 AM
Terry, Looks like an old Samson mount from Astro Optical. Designed by Alex Stern back in the late 60's. Aluminising: you have a variety of options
The ASV has it's own aluminising plant which is run through our Instrument Making Section (you have to be a member though to utilize it) we can do up to 12" I think? Then there is Chi Qin Co (that's pronounced Chi Chin) in Campsie NSW (they can do an overcoat for you too). Also Astro Optical offer aluminising.
I would look at modifying your secondary cell. There is too much obstruction by the cell itself and this should be minimised. You would have to make a smaller cell so that the actual mirror edge makes the obstruction. (See MAKE YOUR OWN TELESCOPE by Richard Berry.) Also look at replacing the old focuser as well for a more readily operatable one!

Satchmo
02-06-2006, 09:11 AM
Just a note to add there, Astro Optical coatings are not overcoated.

Mark

spudrick
02-06-2006, 07:52 PM
Thanks for the info Roger yes you are correct i have found it is a Sampson Mount. The secondary is as you describe a lot of obstruction, I compared it to the new 12" dob. The focuser is destined for the recycle bin it is totally non-operational. I will invest in a Crayford style (10:1 fine focusing).
I do not have the Richard Berry book but i have the "How to make a Telescope" by Texereau which although published in 1957 still has some good ideas for ATM`s. I will check for the Berry Book.
Now when you come to Aluminising I am a little confused, the mirror needs recoating (aluminising) then the overcoating is a protective layer?
So from your description these are 2 different steps and from Marks input (thanks Mark) it seems that Astro Optical are not the preffered supplier.
Appreciate the helpful comments and suggestions

spudrick
17-06-2006, 12:55 PM
Well i have made some progress on the scope. a bit of Spit `n polish the mount is now up to speed. Charcoal Grey :D
Next i will get the motor in good order then make a cover for it.
After that next on the list is the tube cradle and working from Ian`s idea i am designing it to also mount to a Dob base.

stringscope
17-06-2006, 03:19 PM
Fantastic Terry :thumbsup: . A really professional job, looks brand new. Keep the pics coming.

Cheers,

Roger Davis
22-06-2006, 08:17 AM
Just a quick after-note; see if you can get some large grip diameter RA & DEC lock knobs it makes for easier use.

spudrick
22-06-2006, 05:57 PM
Thanks for the tip Roger i have been trying to get them already. I cant believe how difficult it is! I tried 2 local Fastener specialist`s in Geelong and neither had anything, then tried the biggest Bunning store also nothing. I am on holidays soon i`ll pick them up in Melbourne.
I now have re-attached the Drive to the mount and want to make a sheet-metal cover, i have also started on the scope mount and rings.

spudrick
12-07-2006, 06:15 PM
About time for an update on the scope, i have changed direction because of the fantastic idea from Ken on using Gas cylinder rings. So i have bought a pair and decided to follow suit and put the 12" up on the mount and proceed with the 10" as a DOB mount. As the Sampson mount is capable of carrying the scope i thought it was the only way to go.
The 10" is progressing in the photo the tube is almost back to bare metal, i have a new secondary mirror, 8x50 finder and new focuser for it already. Next job is to send the primary mirror away for re-coating while i finish the tube.
I will make a new DOB mount soon.
:D

ballaratdragons
12-07-2006, 07:31 PM
Another EQ restoration Project done well.

Excellent Terry. Feels good doesn't it! I'm glad you gave the LPG gas bottle rings a go! Shows that my posting of the idea was worth it :thumbsup:

spudrick
13-07-2006, 05:56 PM
Well i have soldiered on and put the Scope up on the mount, i painted the rings in the matching Hammertone finish of the mount and i used the carpet on the inside of the rings. The job is not finished it needs to be all balanced and stuff and I stll need to get a few extra weights,hand knobs for the ring bolts etc but it is looking like a serious machine now:D
Thanks Ken for your ring project

Satchmo
13-07-2006, 06:37 PM
A smooth stable 12" Dob tube lumbered on top a shaky German equatorial mount built for an 8" tube at best ??????:eyepop:

Makes me think of a bird tethered to a kite string :rolleyes:

Mark

spudrick
13-07-2006, 08:49 PM
Hello Mark
Dont know why you say the mount is not capable of holding the 12", It held my 10" for many years without problems. I only decided to put the 12" on it after seeing Paul Mayo setup (see photo)
http://www.skylab.com.au/pmsa/equip.html
Exactly same mount as mine.

ballaratdragons
13-07-2006, 09:01 PM
Looks fine to me too Terry.

spudrick
07-08-2006, 06:33 PM
Just added the extra weights and lifted up the 12" today. Just shows how not so portable this is. So i have left the bearings on the tube and will keep the Dob base so it is a versatile scope. I have recently picked up a much more portable scope a Celestron SCT Ultima 8" which i plan to make my main scope and hopefully buy a modded Toucam soon :)

IanW
08-08-2006, 12:48 AM
Bringer of bad news here, you've assembled the DEC housing upside down, the long section is supposed to be at the counterweight shaft end with a Sampson Mount and there's very little clearance between the saddle plate and RA gear. :)

asimov
08-08-2006, 01:47 AM
Correct:)

IanW
08-08-2006, 06:43 AM
Pic of my Sampson Mount taken the day my first 8" saw first light as a complete scope, August 14 1975. No RA drive at the time though as AOS had no stock.

spudrick
08-08-2006, 08:07 AM
Thanks for your help Ian, Will get it fixed this weekend.:)

IanW
08-08-2006, 02:17 PM
No worries Terry, glad to be of help.

The Sampson mount as a standard unit was okay for visual use, but horrible to align as the mount was really a knock off design based on a mixture of the old Cave, Edmund Scientific and Fullerscopes Broadhurst and Clarkeson (UK) mount designs of the late 50s and early 60s.

I extensively modified my mount from '75 to '84 to get it not only operating well but to make it far easier to setup, some of the mods I made were:

RA and DEC locks:
If you remove an existing lock you can have the thread identified at any industrial fastner specialist.

From memory they use a BSW thread. I dissassembled my unit, pulled the locks and retapped the thread to accept a standard tri-nut unit as used in stage lighting (Par 56/64 cans). These tri-nuts are available from any stage lighting supplier for a couple of bucks each.

Leg levellers:
I drilled and tapped the end of each leg to take a stainless steel capscrew to act as a leg leveller. On my legset there were threaded holes on the underside of the round tip of each leg. Why capscrews? Though needing an Allen key to use, they are lower profile and less likely to be walked in to at night and far less tempting for people to want to play with.

The Pier:
Before modifying the pier make sure the top of the pier tube is squared off accurately. I ran my pier tube through a lathe to make sure it was accurate to 1/1000th of an inch. This step really isn't needed though as there's so much slop in the RA mount cap anyway.

After squaring the pier tube I plugged the bottom of the pier, just above the leg mounting bolts with a bit of chipboard and gaffa taped the gaps then filled the pier with concrete. It not only reduced vibration but also made the mount far more stable. A lighter weight version would be to fill the pier with expanding foam as used in small boat floatation cells

The mount (RA) Cap:
A horrific bit of design work this! Slop laden, with a single fastening screw it's truly a nightmare.

If you have access to a lathe and milling machine I can supply you with a couple of suggested ways of sorting out the cap, otherwise the best you can do is shim the cap to reduce slop and add 2 extra locking screws at 120° intervals around the cap. I highly recommend replacing the existing tightening bolt (flat screwdriver head) with capscrews.

Other fun:
There's a couple of other nightmares with the Sampson mount, the biggest of which is actually getting the swine polar aligned accurately. As there's no provision in the standard mount for fine adjustments you can either build some (late, mill needed) or use the knockometer method for azimuth adjustment and a variety of methods involving car jacks, lumps of wood etc for the RA polar axis altitude adjustment.

Cheers,
Ian

spudrick
08-08-2006, 04:26 PM
Thats what i love about this place there is an endless supply of knowledge and you guys are so helpful. I really appreciate the help.
I took the mount back apart and fixed the housing to point the correct way, and there is min 25mm clearance for the drive gear.
Ian all of the suggestions you have made are great the most important being the polar alignment, it is truly difficult and to rely on just a single bolt is just not right. It should have some type of locking pin or similar.
Well i do not have a lathe but would like to modify/fix some of the faults with the mount to make it more enjoyable to use

asimov
08-08-2006, 05:30 PM
My mounts the same principle, so I added a big turn buckle to the setup to give me some fine adjustment which go's between the pier and the end of the RA housing.

IanW
08-08-2006, 05:30 PM
Hi Terry,

Glad to be of help. I'll post some methods for aligning the beastie later tonight as I need to knock up some drawings to illustrate the method.

Do you have access to any of the following: Plunge Router, Drill press as well as a good quality builders level and square?

spudrick
08-08-2006, 07:54 PM
Thanks Ian i have the Router, level and square you can send me the drill press:)
I do have access to a drill press.

IanW
09-08-2006, 12:24 AM
Here you go Terry, Ian's azimuth fine tuner (wood version). The original was made out of aluminum and didn't go all the way around the pier cap and pier as it was held in place with some strategically placed tapped holes in the pier and cap.

It can be made out of 25mm ply scraps and I've not dimensioned the unit as I no longer have my Sampson mount and am working largely from memories that are 12 years old while roughing out the unit design so view the design as nothing more than a guide to a method that works well.

Construction wise the only difficult bit is making the unit fit tightly on the pier and cap, as you need a good level of clench on the pier and cap to overcome the friction induced by the metal to metal contact between pier and cap, adding some grease to the inside of the cap where it meets the top of the pier will help.

Asimov's turnbuckle suggestion for RA altitude adjustment is pretty much what I did, though I made up a custom slip ring for the back of the RA shaft as there wasn't much room to fit it. If I remember rightly (now stretching my mind back to mid 76) the back of the RA drive has a collet that just butts up against the RA drive. If this is correct you could simply tap a hole in to it and put in a heavy threaded eyelet and hook the turnbukle to another eyelet mounted on the pier. Needless to say you'll have to remove the turnbuckle when rotating the RA axis.

Cheers,
Ian