BCB
Undercover Saboteur
Reged: 11/24/03
Posts: 5197
Loc: Look over your shoulder
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can you take some vid of the play you speak of ?
If I understand you right, the hole is larger then the OD of the bearing your putting back in..
Let me ask you this.. Compare the bearings that came out to the new ones.. Are they an EXACT match in o.d. and width ?? if the new ones don't match, that COULD be the source of your problems. Wish you were closer. I could help you solve this better in person..
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Mark
Lost in thought. Please send search party!!!
Astro-Tech 111EDT
Orion 8" F5 Newt w/Moonlight CR-2 focuser
SVP mount w/Meade 497 Autostar GOTO mod
Treeline Observatory
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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The original bearings had the horizontal play too. It's the hole inthe housing that is too big.
Anyway the black circular caps sort of hold that bearing in place and there is little play now. The other housing and worm was fine without having to put the cap in.
The while worm moved axially because the bearings wouldn't stay in the housing like they do on the video. But hopefully it will be ok and I will resume tomorrow and figure out what spacers I need.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Is the LED for the reticle suppose to be held in by a piece of sctoch tape? What about scotch tape with a finger print on it?
There is a metal looking loop that looks like the LED fits in there but maybe that is just the field of view of the polar alignment scope?
Yes watching the video again it is just taped in place. However the previous owner when doing the GOTO upgrade left most of the tape in the field of view of the polar scope. I will retape it when done so that the tape is out of the way.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Ok I am finally ready to put back together, as soon as I get the proper spacers (the orginal ones broke on me trying to get the axes out!)
Jeff please check your PM box! 
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Well jeff has ignored his PM box so I bought some spacers from another cloudynights member. now I am fighting trying to get the mesh just right, which is not easy since there is horizontal play in the worm. I'll try retightening the lock nut but the problem remains that the holes for the two worm gear bearings (the little skate wheel ones) are too big and the bearings slide axially, taking the worm with it.
Also I wish to replace the tapered bearings as sitting out for a while with no grease has caused one to rust. I am looking for Strgazr27's post which was recently quoted telling us which bearings to buy can anyone help find it?
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Charlie Hein
Postmaster
Reged: 11/02/03
Posts: 7968
Loc: 26.06.08N, +80.23.08W
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Quote:
I wish to replace the tapered bearings as sitting out for a while with no grease has caused one to rust. I am looking for Strgazr27's post which was recently quoted telling us which bearings to buy can anyone help find it?
Ask and you shall receive...
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"He's dead, Jim - I'll get his wallet, you get his tricorder." - Leonard "Bones" McCoy
Weston CSC:
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Thanks. SKF-USA bearings (made in Germany) arrived tonight. Will hopefully grease em up and install tomorrow and be back in business this weekend.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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this is the worst mount i have ever worked on.
someone help, I cannot get the stupid declination assembly back together. the bronze gear is supposed to just "sliiiiide right in" to the housing that holds the dovetail according to the video and after hammering it to death it only went half way.Can't even get it back out since if I hammer the other way the worm is going to get damaged.
Not to speak for atlas mounts in general but the tolerances on this particular one have REALLY ticked me off.................................................................................................
I feel like Happy Gilmore, Bob Barker: "Just taaaaap it in Happy. Nice and easy!!"
Nice and easy my left foot......
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Edited by Charlie Hein (11/21/09 07:16 AM)
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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If I squirt WD40 in there it will be in there forever. The gear wont budge. I had a devil of a time getting it apart too but I slid the worm out the hole first. Now that I put the worm back together decently (bad tolerances on those bearing holes and all) I would prefer not to mess with it again but I guess I might have to now.
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Edited by Charlie Hein (11/21/09 07:17 AM)
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Nobody is really answering my questions in this thread!
If it is necessary should I put the dec assembly in the freezer or heat it up? Does the brass gear expand/contract more than the aluminum housing or less?
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tturtle
journeyman
Reged: 03/03/09
Posts: 9
Loc: Florida
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I have attached a pdf that shows the thermal expansion coefficient of different metals. It appears to show that aluminum has a higher coefficient than brass although not a lot higher meaning that the aluminum expands and contracts more than the brass with change in temperature. This would imply that if the brass gear is tight now in the aluminum housing that cooling it would not help as the aluminum would contract more and make the fit even tighter. Following this logic, heating the pieces up (or even just trying to heat the aluminum part) should cause the aluminum to expand more than the brass which would allow the pieces to fit together.
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-tom
CGEM 925
Baader Hyperion Zoom 8-24
6mm TV Radian
G3 Astro Aimer
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Charlie Hein
Postmaster
Reged: 11/02/03
Posts: 7968
Loc: 26.06.08N, +80.23.08W
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Sorry I didn't see this sooner, Joe! Heating up the chassis sounds like a good idea to me. It certainly can't damage anything to try.
Something I noticed when I was working on my mount is that if you don't have things really squared up well as you assemble them then they will jam, sometimes very badly. Instead of trying to tap the assembly in or out to drive it into the hole, give it a good look and try tapping sideways instead in order to square the assembly to the chassis. If you get it right then it should just drop right in.
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"He's dead, Jim - I'll get his wallet, you get his tricorder." - Leonard "Bones" McCoy
Weston CSC:
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Thanks will give those ideas a try.
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DanB
scholastic sledgehammer
Reged: 12/05/07
Posts: 835
Loc: Pacific Northwest
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I've just torn my mount down as well. I bought the Hypertune kit which is on its way now so I'll be keeping an eye on this thread.
I have lots of experience with similar auto bearings and such, I'm hoping it goes ok. Taking it apart was'nt exactly a joy but it was'nt too bad either. Tolerances are tight with that brass gear lol, I did notice that and was thinking it may be a pain going back in.. Now I know:-)
I'd definatel try a little heat and, this brass gear is not going to tolerate being even a little bit cockeyed going in.. You might think about taking it too the local machine shop and let them press it in. I dont know if they can but they can do other very similar things with auto's, I dont see why not.
Good luck, I need to hear good news from you so I can feel good about all of this now lol:-)
Dan
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AT8RC astrograph
AT80ED refractor (guidescope)
10" Meade f4.5 reflector
8" Meade f6 reflector
EQ6 Skywatcher/Synscan
Meade DSI (Guide camera)
CCD Labs Q453 (Main imager)
Nebulosity 2
PHD guiding
"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual".
- Galileo Galile -
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jimguy08
member
Reged: 07/17/08
Posts: 33
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I just finished my rebuild this evening...it's straight forward, especially with a video. Take your time...it's not rocket science.
I re-packed all the bearings (including all the new ones) with a lithium grease rated to -40 degrees F for midwest winter use.
On some of the large bearings, you really have to wack to get them to seat (used a block of wood and a hammer).
Keep all the parts in a tub, I used several small tupperware-type tubs to keep the sub-assemblies seperated.
After it's done, it is so much smoother! Well worth the effort.
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Celestron C102F Flourite w/Moonlite focuser
Orion 80ED w/Moonlite focuser
Astro-Tech AT66 Guidescope
Atlas EQ-G Bluetooth enabled
Orion SSAG
QHY8
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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I got the SKF tapered bearings for 38 shipped and they are made in germany not china. Can't wait tp put em in!
i am now trying to whack the brass gear the other way, I might have to take apart the worm bearing which would be a shame since I got that one seated well. I think I had trouble getting this gear off as well. Should I put it in the oven on lowest temperature? and for how long?? I already put superlube on the brass worm gear teeth, will that stink up the whole house if you heat it? I ask since the wife is having people over tomorrow 
Oh and Jim I am a rocket scientist by day (well helicopter engineer that's almost as complicated!), I know it's not rocket science. I did get all 6 "big" bearings seated (the tech term is 6008 I think) with wood block and many many hits with a hammer. The problem is after I got the mesh set very well with the RA gear, I tried to get the brass Dec gear back into its housing - really the top part of the mount that takes the saddle on its other sie - and that is where I am stuck... pun intended! I am 90% done just have to get the darn thing back where it belongs so I can adjust its mesh and finally put the mount back together at long last. I will upload some pics to show you where I am stuck.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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thats as far as I can bang it in. trouble is that's as far as I can bang it out too! darned thing won't budge.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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Quote:
can you take some vid of the play you speak of ?
If I understand you right, the hole is larger then the OD of the bearing your putting back in..
Let me ask you this.. Compare the bearings that came out to the new ones.. Are they an EXACT match in o.d. and width ?? if the new ones don't match, that COULD be the source of your problems. Wish you were closer. I could help you solve this better in person..
I put an original bearing back in to illustrate the problem, now that I removed the worm to more safely whack on the ring gear (really a worm gear but people confuse the *worm* that fits through the bearing hole shown here with the *worm gear* which is the big brass gear that's stuck!). I can slide this in and out either side of the hole in the casting way too easily. It "press-fits" okay at first but then I realize it is cockeyed as when you put the bearing over the worm, which aligns the bearing to the hole, then it pushes in and out if you slide the worm along its axis. The ONLY way to get it good like the video was to use the screw on black cover which was not reattached yet in the video to get good worm installation. The spanner nut only tightens one side not both of the worm gear in its housing. In the video they were press fit in pretty good, much like my stuck Dec brass gear is right now.
This hole is too big, the other housing is too small. Poor tolerances on my mount I hope you guys have less trouble than I am having.
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Joseph Gillman
Carpal Tunnel
Reged: 12/06/05
Posts: 2784
Loc: Aston, PA
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THe only reason I started the rebuild was I bought this on Shop and Swap locally, from a well rated seller, and it worked okay but there was about 5 degrees of slop in the right ascension axis. I probably only needed to tighten the spanner nut or just adjusted the mesh-changing setscrews and could have avoided all this. Once I got started though, I got a video from another CN friend, which of course made it look really easy so I figured get the tar-like grease out and relube and things will be even better.
I didn't really understand how the mesh setting setscrews worked until I tore into it and saw what was inside. That's the kind of engineer I am- you can explain something to me step by step but I have to see it for myself to understand it sometimes.
The RA slop was not disclosed by the seller I guess that explains the good price I got. That and the fact tht I had to air it out for 2 weeks before I could use it since it reeked of cigars. 
Please advise with more specific recommendations vis a vis the heating process.... temperature, duration, etc.
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jimguy08
member
Reged: 07/17/08
Posts: 33
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By the way, I'm an engineer too and I teach at a university.
I simply wasn't plagued with the tolerence problems you seem to have in your sample.
If you have absolutely stuck parts with no hope, best to take the offending parts to a machine shop...they will no doubt be able to rig a puller. Even a reasonably well-equipped automotive repair shop will have the common hydraulic H-frame press to press the parts back together.
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Celestron C102F Flourite w/Moonlite focuser
Orion 80ED w/Moonlite focuser
Astro-Tech AT66 Guidescope
Atlas EQ-G Bluetooth enabled
Orion SSAG
QHY8
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