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sabir
professor emeritus
Reged: 06/23/07
Posts: 698
Loc: Pune (India)
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Thanks Guys for the replys!
It looks like the 'Do it best' bearing fits the bill quite nicely.
Jim,
the 'Aluminium Lazy Suzan Bearing' look really nice, but I'm afraid, it would increase the spacing a bit too much for the azimuth encoder to work. The spacing required is about 6.25-6.5mm. The Aluminium bearing has a thickness of 12.7mm whereas the 'do it best' bearing has a thickness of 7.9mm, so I guess it fits the bill better.
Any body else with any suggestions/feed back??
Sabir
-------------------- No one can attain good livelihood-even if he is so lucky - without passing through misfortunes. Days will usurp the opportunities of those who waste today's opportunity due to their expectation of tomorrow's opportunities. Day's custom is the usurpation of opportunities and the habit of time is wasting them.
Imam Ali (a.s)
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epee
professor emeritus
Reged: 11/30/06
Posts: 696
Loc: Suh-van-nuh, Jaw-juh
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Once you have the bearing in your single biggest issue will be adding stiction or a brake to stop the OTA from spinning at the slightest amout of force. That's a problem I'm still battling and the COL encoder complicates things considerably. I don't understand calan's solution; my center bearing protrudes above the rocker base. Perhaps I'm being to fussy and a simple block of carpet or foam would do the trick but adding stiction is definately something you're going to have to deal with.
-------------------- Jim Girardeau
Orion XT12 Intelliscope
Celestron 11X80mm binoculars
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UKJim
member
Reged: 11/27/07
Posts: 35
Loc: Grantham, Lincs, UK
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Sabir,
I have created a page on my site regarding the Azimuth Bearing problem:
Jims Orion XT10 site - Azimuth Bearing friction/stiction and mods
I too have added a lazy susan and have detailed the part number and my intention is to create a page detailing the mod. Sorry its not done yet (its on my todo list!).
With regards potential damage to the sensor, the brass bush is designed to ensure the correct critical gap is maintained between magnetic disc and sensor surface for the IntelliScope to operate properly. Problems only occur if poor assembly results in the two base parts becoming skewed off axis, i.e. perhaps the central nut is not done up tight enough which allows too much wobble of the two base sections to each other. If anything a lazy susan makes this less likely to happen since it provides a wider diameter for support of the top base onto the bottom.
Other notes are in agreement with other posters, i.e. the scope now rotates incredibly freely, and I need to implement a braking mechanism (such as carpet!), otherwise even the wind will blow it round, and/or my movement near the scope has to be careful.
The bearings do have a notching effect sometimes, i.e. you move the scope but the bearings want to roll it back or fore slightly before it rests. This might be due to me making a silly mistake when installing the lazy susan. I drilled mounting screw pilot holes, with the bearing in place, and blew the resulting sawdust away, but some got into the ball bearings! Ooops.
So something to be careful of for would-be modders.
This could account for the idea of "flat spots" mentioned by you, meaning they are NOT flat spots, but more likely to be dirt or particles which have got into the bearings. I think the low cost of the lazy susan might warrant a 2-yearly renewal?
I do sometimes feel that the Teflon pads and stiction approach, if maintained well, offers better control for wide viewing. Its just the high magnification that requires the smoothness of a ball bearing.
I'm sure Dobsonian designers have considered ball bearings but felt that Teflon was a better approach. I don't think Teflon is particularly a cheaper method, unless high quality lazy susan were used.
Generally I much prefer the smoothness of the lazy susan, but it can sometimes be annoying having to move so gingerly around the scope if I have aligned it on something, and want to change the eyepiece for example (must sort out that brake).
The LS I used raises the top baseplate above the teflon pads by about 1.5mm so the pads are no longer in contact. This also means the mod is non-destructive - I can remove the LS and have it working in the normal Teflon way quite easily.
Some additional notes and pics on this page might be of use also:-
Orion XT10 - Azimuth Bearing Assembly
Jim
-------------------- Orion XT10 Intelliscope with COL.
Low-Profile Crayford+AccuFocus
Orion 25mm, 10mm Plossl EP's
Baader Hyperion 13mm 68deg with 14 & 28mm FTR's
Adler Optik Skarp 38mm(32x)2" 5 EL SWA 70*FOV
Orion Shorty-Plus 3 El. 2xBarlow
Baader Laser Collimator. 13% Moon filter.
Binos: Super Zenith 10x50 7deg FOV, Adler Jupiter 20x80ZCF and Fumoto 10x25
Laptop+Stellarium, Starry Night, ECU.
My site dedicated to the www.Orion-XT10.com
Edited by UKJim (05/28/08 10:00 PM)
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UKJim
member
Reged: 11/27/07
Posts: 35
Loc: Grantham, Lincs, UK
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At last I have finished my detailed page on the Lazy Susan bearing mod, which I have added to my Skyquest XT Mods page in my web site......
XT Mods - Addition of a Lazy Susan turntable bearing on Orion Skyquest XT telescopes
My page provides lots of photos, and detailed explanation of the procedure, and discusses some of the concerns raised on this thread.
Hope some folk find it useful! 
Best wishes Jim
-------------------- Orion XT10 Intelliscope with COL.
Low-Profile Crayford+AccuFocus
Orion 25mm, 10mm Plossl EP's
Baader Hyperion 13mm 68deg with 14 & 28mm FTR's
Adler Optik Skarp 38mm(32x)2" 5 EL SWA 70*FOV
Orion Shorty-Plus 3 El. 2xBarlow
Baader Laser Collimator. 13% Moon filter.
Binos: Super Zenith 10x50 7deg FOV, Adler Jupiter 20x80ZCF and Fumoto 10x25
Laptop+Stellarium, Starry Night, ECU.
My site dedicated to the www.Orion-XT10.com
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sabir
professor emeritus
Reged: 06/23/07
Posts: 698
Loc: Pune (India)
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Hi Jim 
Thats a great site you've got there!! In fact I had found it to be a great help even before you updated it with your lazy-susan Az mod. 
I'm sure a lot of people like me will find it to be very useful 
Sabir
-------------------- No one can attain good livelihood-even if he is so lucky - without passing through misfortunes. Days will usurp the opportunities of those who waste today's opportunity due to their expectation of tomorrow's opportunities. Day's custom is the usurpation of opportunities and the habit of time is wasting them.
Imam Ali (a.s)
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epee
professor emeritus
Reged: 11/30/06
Posts: 696
Loc: Suh-van-nuh, Jaw-juh
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Very nice work there Jim.
-------------------- Jim Girardeau
Orion XT12 Intelliscope
Celestron 11X80mm binoculars
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Bob W6PU
Carpal Tunnel
   
Reged: 12/23/04
Posts: 2200
Loc: Springer-N.E.NM
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Enjoyed your nifty site Jim!
Just wondering, how many encoder boards did you have to replace due to ruined sensors before you got it right, as I did, By Trial And Error?...LOL! I went through three of them! ....Very Stressful!
There is absolutely no warning, and the sensors are wiped right off of the board by the pressure of the magnetic strip digging into them, as soon as you start to rotate the base! You can't see it or measure it, and it happens faster than a 1000Amp. short!
The first clue is that you no longer have any changing Az readings on you COL, and the COL function no longer works. This is very tricky business Jim, and I don't recommend it unless some sort of protection is provided to the magnetic sensors, such as a raised barrier as I mention in this post.
I wrote a suggestion to Orion Tech, services suggesting that a small hard plastic raised barrier be placed either side of each sensor to make this destruction impossible. It would only have to be a fraction higher than the sensors themselves. The worst that would happen was that you dug into the magnetic strip, when it slammed into the protective raised barrier, which wouldn't do the strip any harm, just gouge it which wouldn't effect its operation unless you really peeled it off!
Cheers!
Bob
Edited by Bob W6PU (09/03/08 05:48 PM)
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Bob W6PU
Carpal Tunnel
   
Reged: 12/23/04
Posts: 2200
Loc: Springer-N.E.NM
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The more that I read this thread, the more that I feel that Orion really needs to have their own "technical" website....let's see now, they could call it..."The Doctor Is In"
Their Intelliscope series really brings this home, in that they sell a line of Dobs with superior optics, and an amazingly accurate COL, but one that uses a flawed base, and has undersized altitude bearings.
Oh sure, we amateurs can experiment and correct this Azimuth flaw, but, IMO, instead of ignoring this issue as Orion seems to have done, they should address this problem and offer their own solutions perhaps in a news letter or a technical bulletin sent out to all registered owners!
The Lazy Susan solution is a fine one, if it is done correctly,( and we have to experiment to find how without destroying Az senors) and again,in my opinion, Orion should be right on top of this! I'm sure that they must be sending out these Az sensor boards like pop corn!...LOL!
Another accident waiting to happen are the magnetic senors on the azimuth board. It would be so simple, and inexpensive to protect them, and yet, they have done nothing about this situation except to provide you with a new Az sensor board.
I realize that Orion does not manufacture these, but couldn't they at least pass this on to those that do?
I am a great fan of Orion, and have passed along technical suggestions, which seem to be ignored.
Apparently in their new XX model, they have improved the base Az problem as well as added larger diameter Alt bearing for smoother altitude operation, so perhaps they don't ignore all suggestions!
I have moved away from the lazy susan approach, removing same, and instead using the Scope Stuff Formica ring and new "Virgin Teflon" sliders.
The Lazy Susan bearings were constantly getting "gunked up" in this windy NM high desert environment, and required constant degreasing/cleaning, and relubing of the bearings!
Another must is to attach the magnetic disc. to the base with a few dabs of quality contact cement. This solves once and for all the problem of azimuth encoder slippage with the resultant need to constantly be re tightening the main center bolt...LOL!
Cheers!
Bob
12" F/4.9 Intelliscope with COL
10" F/5.0 Coast Instrument Treckerscope,circa 1956
Stratus 35mm. Naglers 22T4, 17T4, and 12T4. BO/TMB 7mm and 5mm. TeleVue Paracorr
Barlows: GSO 2"ED 2x, Orion Shorty Plus 2.2x, TeleVue 2.5x and 3x.
Edited by Bob W6PU (09/04/08 01:24 AM)
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Bob W6PU
Carpal Tunnel
   
Reged: 12/23/04
Posts: 2200
Loc: Springer-N.E.NM
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Hey folks, I hadn't realized that this was an old thread until I got off page 2 and saw my previous comments on page 1 Oh well, it can't hurt to repeat good advice.LOL!
Bob
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John Carruthers
Skiprat
   
Reged: 02/02/07
Posts: 2258
Loc: Kent, UK
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Have you tried the wide flat bearing from a disabled swivel cushion? the sort sold to make entry/egress from cars easier? mine has stainless balls in a plastic spider, 5mm thick, 12" diameter. I believe there's a 10" version too.
-------------------- Jc
ATM 10" F6.1, 1/25th wave spec (max wavefront error +/- 1/12.6 in zone 4 of 6, sodium light )
6" F7 spec
127mm F9.4 Refractor
10 x 50 bin
ETX80 (finder)
Canon 20D
PST
DSI 1
and a curious mind
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UKJim
member
Reged: 11/27/07
Posts: 35
Loc: Grantham, Lincs, UK
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Hi All,
Thanks for your kind comments about my page.
For those of you who read it you will realise I was trying to address the concerns of several people, sparked not only by this thread, but also my own research over the last few months from various other sites I had found. It made sense to try and consolidate this Lazy Susan "knowledge" when I wrote up my page.
Bob you said: Quote:
Just wondering, how many encoder boards did you have to replace due to ruined sensors before you got it right, as I did, By Trial And Error?...LOL! I went through three of them! ....Very Stressful!
There is absolutely no warning, and the sensors are wiped right off of the board by the pressure of the magnetic strip digging into them, as soon as you start to rotate the base! You can't see it or measure it, and it happens faster than a 1000Amp. short!
The first clue is that you no longer have any changing Az readings on you COL, and the COL function no longer works. This is very tricky business Jim, and I don't recommend it unless some sort of protection is provided to the magnetic sensors, such as a raised barrier as I mention in this post.
Well, I've had NO trouble, no damage, and I'm still on the original encoder boards, despite dismantling and re-assembling for maintenance many times, cleaning, Teflon lubrication improvements, and finally the Lazy Susan mods! Sorry! 
While I agree that not only you, but several others have complained about the apparent ease with which the sensor chips can be "wiped out", I don't understand how this is possible given that the brass bush is designed to keep the magnetic disc AWAY from the chips .
In the interests of science and helping others can you recall how you might have done the damage?
I gave my thoughts on my page as to why I think folk could cause the damage, but since I've not actually killed them myself I don't "get" what actually does it.
Bent encoder disc? Tightening too much? Adding washers where you shouldn't have? Did you remove the original Teflon pads? Was your Lazy Susan a very slimline style? Did the magnetic disc slip off the brass bush and get skewed when you were re-assembling the base? Did you remove the brass bush altogether!!?
I totally agree with you that Orion should try and protect the chips - your idea of a raised barrier seems a good one. It would be interesting to know exactly what improvements they have made to the Az bearing for the new XX12.
Has anybody else screwed their sensor chips when trying to make mods to the azimuth bearing? If so what went wrong?
Anyway, I hope my page provides sufficient warning and information to help people understand how they might accidentally damage the sensors, so as to prevent them doing so.
Jim
-------------------- Orion XT10 Intelliscope with COL.
Low-Profile Crayford+AccuFocus
Orion 25mm, 10mm Plossl EP's
Baader Hyperion 13mm 68deg with 14 & 28mm FTR's
Adler Optik Skarp 38mm(32x)2" 5 EL SWA 70*FOV
Orion Shorty-Plus 3 El. 2xBarlow
Baader Laser Collimator. 13% Moon filter.
Binos: Super Zenith 10x50 7deg FOV, Adler Jupiter 20x80ZCF and Fumoto 10x25
Laptop+Stellarium, Starry Night, ECU.
My site dedicated to the www.Orion-XT10.com
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epee
professor emeritus
Reged: 11/30/06
Posts: 696
Loc: Suh-van-nuh, Jaw-juh
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I did! I did! Early on in my experimenting with the azimuth motion I tried the old CD-ROM as a bearing trick. It seemed perfect in that the center hole of a CD-ROM is just big enough for the brass bearing to slip into. I'm still not sure how the encoder was damaged because the entire disc/bearing/encoder board assembly SHOULD have been shimmed upward the thickness of the CD. All I can imagine is that the CD allowed the brass bearing to wobble enough to scrub the encoder sensors.
The CD-ROM bearing mad should not be used by Intelliscope owners.
-------------------- Jim Girardeau
Orion XT12 Intelliscope
Celestron 11X80mm binoculars
Edited by epee (09/16/08 06:22 PM)
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