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G11 stiction fix
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Bill Faatz
Howdy
I just joined this group. I have a G11 mount. One of the annoyances I initially had was stiction, especially in the dec axis, when the mount was moved manually to use the analog setting circles or sweeping the field without using the axis motion paddle. The dec axis is especially prone to this stiction because the weight of the saddle and load is supported by the nylon washer in the clutch assmbly rather then the roller bearings as is the case on the RA axis. It gets noticeably worse as the temperature drops. THE SOLUTION: I replaced both axis nylon washers with teflon washers fabbed out of 0.030in sheet. This has completely solved the stiction problem and made the motions buttery smooth. Also I found the green grease used to lube bicycle bearings to work well for lubing the rollar bearings. A little goes a long way. Bill Faatz |
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Elton J. Chambers, Jr.
Bill;
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I did the same thing (I think it was you on sct-user I first heard about such a solution). However, I could not find 0.030 Teflon but instead I found a sheet of 0.039 at McMaster & Carr for about $12 USD, and it also worked. I have no "striction" problems now. Thanks and others with this problem, give it a try. That and re-lubing solves the problem. Elton Chambers Bill Faatz wrote:
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Steve Nightingale
--- In Losmandy_users@..., "Elton J. Chambers, Jr."
<cabinets@l...> wrote: about such a solution). However, I could not find 0.030 Teflon butUSD, Hey Folks, I just checked out the site. They also have 1/32 inch (.031") which is actually closer to the supplied .03" nylon washer. Steve
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Elton J. Chambers, Jr.
Steve;
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You are correct...but they were out of stock when I ordered. I just wanted it known that the 0.039 worked also. Elton Steve Nightingale wrote:
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I remember reading a recent post about this solution somewhere and it
was suggested that Teflon will flow under pressure. So therefore the solution should be "rechecked" every little while, I presume meaning disassembling and replacing the teflon, and also the clutches should not be left engaged to reduce the pressure. Is this correct? And what about the comment Scott made earlier about the clutches not able to do their job properly? Is that a really big problem, and does that mean another $100+ must be spent for the other clutches are needed? I'm not a Losmandy owner yet, but am looking at getting the GM-8, so please excuse any obvious ignorance in my questions as I don't have a mount to examine, but just your descriptions. I'm confused about this whole issue of nylon as the load bearing element on the Dec axis and not on the RA axis. According to the specs on Losmandy's page, all axes use bearings. I thought this nylon issue was only a problem with older Celestron versions of the GM-8. --- In Losmandy_users@..., "Steve Nightingale" <snightingale40@h...> wrote: --- In Losmandy_users@..., "Elton J. Chambers, Jr."but instead I found a sheet of 0.039 at McMaster & Carr for about $12USD, |
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Bill Faatz
I hope this clears up some of these questions...Bill
--- In Losmandy_users@..., "GC GC" <gcert1@i...> wrote I remember reading a recent post about this solution somewhere andit was suggested that Teflon will flow under pressure. So thereforethe solution should be "rechecked" every little while, I presumeclutches should not be left engaged to reduce the pressure.I have been using the "fix" for 6 months and have noticed no problem. And what about the comment Scott made earlier about the clutchesnot able to do their job properly? Is that a really big problem, anddoes that mean another $100+ must be spent for the other clutches are The clutches will not "lock up" but provide plenty of resistance for visual use. Also, I think you are confusing the clutch assmby for the optional clutch tightening knobs with handles. I recommend using these as it allows you to apply more force when tightening. I'm not a Losmandy owner yet, but am looking at getting the GM-8,nylon issue was only a problem with older Celestron versions of the GM-8. The Dec axis has needle bearings just like the RA axis, but, as I said in my earlier post, The weight of the saddle and load is supported on the nylon washer rather then the bearings. This is why stiction is more noticable in this axis; the RA load IS suported on the needle bearing set. |
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Donald J. D'Egidio
Bill,
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If you are talking about the G11 both the DEC and RA are functionally identical as far as supporting the weight. Both axes are supported by the large thrust needle roller bearing below the worm gear and both axes use the same nylon washer in the clutch. Don ----- Original Message -----
From: "Bill Faatz" <faatz1@...> To: <Losmandy_users@...> Sent: Wednesday, August 02, 2000 17:53 Subject: [Losmandy_users] Re: G11 stiction fix I hope this clears up some of these questions...Bill |
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Bill Faatz
--- In Losmandy_users@..., "Donald J. D'Egidio" <djd52@b...>
wrote: Bill,functionally identical as far as supporting the weight. Both axes are supported by the large thrust needleroller bearing below the worm gear and both axes use the same nylon washer in the clutch.If you think of the weight distribution of the load on the mount, the load is essentially being applied axially through the Dec axis (except for the small horizontal vector as a result of not being perpendicular), but at right angles or radially to the RA axis. In one case, the load is borne by the clutch surfaces (the Dec axis), in the other case, the load is supported by the needle bearings. In any case, the bearings can only support the load radially, not axially. Am I missing something?? Clear skies....Bill |
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Stephen M. Linscott
On Wed, 2 Aug 2000, Bill Faatz wrote:
Yes, you are. In addition to the needle bearings in which the shaft rides, there are thrust bearings under each worm gear. Think about it - when the clutch is locked tight, and you move the DEC with the motor, the clutch disk is moving with the worm gear and provides no bearing action at all. In one sense the clutch is acting as a bearing when you are moving the DEC or RA manually, but the load is actually being carried by the thrust bearings. The high quality thrust bearings allow a smooth, precise motion in RA and DEC when under electric control, and don't depend on Nylon or Teflon. Scott, if I've done a poor job of explaining this, please correct me. - Steve - * * Steve Linscott Information Technology Division * * linscot@... Rice University Houston, Texas * * |
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Bill Faatz
--- In Losmandy_users@..., "Stephen M. Linscott"
<linscot@r...> wrote: On Wed, 2 Aug 2000, Bill Faatz wrote:the theload is essentially being applied axially through the Dec axis Iother case, the load is supported by the needle bearings. In any it -missing something??Yes, you are. In addition to the needle bearings in which the shaft when the clutch is locked tight, and you move the DEC with themotor, the clutch disk is moving with the worm gear and provides no bearingaction at all. In one sense the clutch is acting as a bearing when you aremoving the DEC or RA manually, but the load is actually being carried bythe thrust bearings. The high quality thrust bearings allow a smooth,precise motion in RA and DEC when under electric control, and don't dependon Nylon or Teflon.me. Steve Good point, I stand corrected on this issue. However, the force applied to the clutches is different...in the case of the Dec axis, the weight of the load, plus the tension of the clutch combine to make the stiction load greater then the RA axis, which sees only the clutch tension. The difference in the breakaway stiction force necessary between the two axis is very noticeable. Thanks for correcting my analysis. I am beginning to enjoy this group. Bill |
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Stephen M. Linscott
On Wed, 2 Aug 2000, Bill Faatz wrote:
SteveBill, you're absolutely right - the DEC setting is a balance between easy to move, and having to hold the scope when you take out that heavy eyepiece! It's not so bad on the MCT, but the large refractor is a challenge. I guess the solution is to install Scott's GoTo, and do electric slewing! :-) - Steve - * * Steve Linscott Information Technology Division * * linscot@... Rice University Houston, Texas * * |
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Donald J. D'Egidio
Bill,
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I agree with you that the DEC axis will require more clutch force to hold the scope than does the RA axis because of it's orientation. I'm glad we now have this group to discuss our ideas instead of wading through all the other posts on SAA. Don ----- Original Message -----
From: "Bill Faatz" <faatz1@...> To: <Losmandy_users@...> Sent: Wednesday, August 02, 2000 19:56 Subject: [Losmandy_users] Re: G11 stiction fix --- In Losmandy_users@..., "Stephen M. Linscott" |
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Bill Faatz
--- In Losmandy_users@..., "Stephen M. Linscott"
<linscot@r...> wrote: On Wed, 2 Aug 2000, Bill Faatz wrote:clutchSteve between easytension. The difference in the breakaway stiction force necessaryBill, you're absolutely right - the DEC setting is a balance to move, and having to hold the scope when you take out that heavy Steve, my point is that the teflon clutch washer IS a solution that works very well to solve this problem. There is plenty of resistance to hold the telescope in position when taking out Negler EPs. You actually have to apply some force to move the scope, but the breakaway force is constant and repeatable, qualities that are necessary for using the manual setting circles and moving fractions of a hash mark.I don't want the added complications of GoTo when I can locate objects very well with the manual setting circles. I like to keep equipment as simple as possible in the field. Bill |
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Stephen M. Linscott
On Thu, 3 Aug 2000, Bill Faatz wrote:
Bill, I agree - my answer was an attempt at humor, hence the smiley. - Steve - * * Steve Linscott Information Technology Division * * linscot@... Rice University Houston, Texas * * |
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Milton Esquinaldo
Does anyone know the exact size of the supplied nylon washer? I
guess I can find out by taking the head apart, but would rather see if anyone knows. Thanks, Milton --- In Losmandy_users@..., "Steve Nightingale" <snightingale40@h...> wrote: --- In Losmandy_users@..., "Elton J. Chambers, Jr."but instead I found a sheet of 0.039 at McMaster & Carr for about $12USD, |
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Donald J. D'Egidio
Milton,
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I think it's 3.5" OD by 1.25" ID and .031 thick. Not quite sure about OD but it did measure it and that's what I remember. Don ----- Original Message -----
From: "Milton Esquinaldo" <milton10@...> To: <Losmandy_users@...> Sent: Saturday, August 05, 2000 3:49 Subject: [Losmandy_users] Re: G11 stiction fix Does anyone know the exact size of the supplied nylon washer? I |
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