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Losmandy GM811... removing motors to adjust OPW

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14 replies to this topic

#1 willykros

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Posted 20 March 2018 - 06:24 PM

Folks,

 

The Nov 15, 2017 YouTube Losmandy video "OPW Adjustment" seems to show how easy it is to adjust the One Piece Worm (OPW).

 

I'm tempted to try it sometime, when/if it needs adjustment, and just to better understand my mount.

 

The video begins with the motor removed, but the video doesn't show how to remove the motor assembly.

 

How difficult is removing the motors?  Is it as simple?  Are there things to watch out for?  Any gotcha's or hints/tips for removing the motor.

 

Thanks...

 

... Bill

 



#2 Real14

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Posted 20 March 2018 - 06:44 PM

Folks,

 

The Nov 15, 2017 YouTube Losmandy video "OPW Adjustment" seems to show how easy it is to adjust the One Piece Worm (OPW).

 

I'm tempted to try it sometime, when/if it needs adjustment, and just to better understand my mount.

 

The video begins with the motor removed, but the video doesn't show how to remove the motor assembly.

 

How difficult is removing the motors?  Is it as simple?  Are there things to watch out for?  Any gotcha's or hints/tips for removing the motor.

 

Thanks...

 

... Bill

Hi,

 

Why would you remove the motors for adjusting the backlash ? In order to get a good adjustment in both axis you need to move the axis and test if there is some binding or not ...

 

If nothing has changed the bore holding the left ball bearing has nearly no play and the bore on the right has enough play to get the worm onto the wormgear in a good position.

 

If you have the Gemini 1 or 2 system then it will tell you when it is binding as you will get a stall message.

 

Removing the motors and then attaching them again makes the whole process far to complicated ...

 

You have to slew the RA axis in 180 degrees to find any binding and the DEC axis more or less nearly 350 degrees.

 

If you do not that you will never find the best adjustment. 

 

Rainer



#3 otisw

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Posted 21 March 2018 - 01:20 AM

It is easy.  You need to remove the motors if they're the newer tucked in design because they're in the way of the worm adjustment hex bolts.  There are two hex bolts on the motor you need to remove and they come right out.  No worries about getting them back in.  

 

As far as the adjustment itself, just follow what he does in the video. 


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#4 EFT

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Posted 21 March 2018 - 02:34 AM

Yes, if it is an old-version mount then there is no reason to remove the motors and in fact you want to leave the in place so that you can easily test during or after you make it.  The adjustment itself is easy (although one could wish for a better adjustment mechanism).

 

otisw has a good point though.  If the video is from November 2017 then it is like about making the adjustment on a mount with the new tucked in motors which could be a problem.  From photos of the G11 it looks like there is still access to the cap screws that hold the worm mounting in place (although more difficult than before).  It is not clear that there is much access on the DEC axis of the G811G.  It not, that is problematic since it leaves you having to adjust the worm spacing manually by hand and then putting things back together to test it with the motor to see if you got it right.  It is definitely possible to do this since that is exactly how I begin the process of making the adjustment with the two-piece worm blocks, but it is not ideal, especially if it is not something you are used to doing in the first place.



#5 Real14

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Posted 21 March 2018 - 08:48 AM

It is easy.  You need to remove the motors if they're the newer tucked in design because they're in the way of the worm adjustment hex bolts.  There are two hex bolts on the motor you need to remove and they come right out.  No worries about getting them back in.  

 

As far as the adjustment itself, just follow what he does in the video. 

 

Hi and,

 

OH, I see. As I have the very old ones, with the motors on the outside, I did not think about that. Thanks for clarifying waytogo.gif



#6 rmollise

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Posted 21 March 2018 - 09:25 AM

Folks,

 

The Nov 15, 2017 YouTube Losmandy video "OPW Adjustment" seems to show how easy it is to adjust the One Piece Worm (OPW).

 

I'm tempted to try it sometime, when/if it needs adjustment, and just to better understand my mount.

 

The video begins with the motor removed, but the video doesn't show how to remove the motor assembly.

 

How difficult is removing the motors?  Is it as simple?  Are there things to watch out for?  Any gotcha's or hints/tips for removing the motor.

 

Thanks...

 

... Bill

 

 

 Removing the (tucked) motors is the hardest part of the procedure. The problem is the placement of the screws is kind of a pain. Losmandy does have a video showing motor removal.

 

After I had 'em off, adjusting my declination axis was a 2-minute job. wink.gif


Edited by rmollise, 21 March 2018 - 09:26 AM.

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#7 elinchrom

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Posted 21 March 2018 - 11:19 AM

The trick to remove those two motor mounting screws is to using a good screw driver type of the hex key with ball head. 

 

It is kind of hard to remove the screw in dark in the filed with a small L shape hex key.


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#8 gdd

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Posted 21 March 2018 - 05:49 PM

A minor modification can make it easy to make worm adjustments without removing the motor. But you do have to remove the motor to make the modification. Remove the left cap screw that was blocked by the motor, insert a quarter inch long compression spring and reinstall the cap screw. Tighten the cap screw until it stops turning, then back off a bit. This is the pivot screw in the adjustment video. It is now sufficiently tight to hold the OPWB to the mounting plate but loose enough to allow a pivoting motion. Replace the motor. Loosen the cap screw near the adjustment screw and do your adjustment by pushing the OPWB all the way in and then pushing it way by turning the adjust screw clockwise about 1/16 of a turn. Retighten the cap screw and test by running the motor and checking for stall messages.

 

Whether this works with the tucked in motors depends on how much clearance there is between the left cap screw and the motor. Also if there is slop in the  bore hole accepting the left worm block you will need to add a 1/8" thick spacer 3/8" diameter with a #10 hole to prevent any motion of the OPWB other than the pivot motion. If you are worried the screw will back out use some low strength purple locktite to prevent that.

 

 

Gale


Edited by gdd, 21 March 2018 - 06:08 PM.


#9 Wildetelescope

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Posted 21 March 2018 - 10:57 PM

The trick to remove those two motor mounting screws is to using a good screw driver type of the hex key with ball head. 

 

It is kind of hard to remove the screw in dark in the filed with a small L shape hex key.

Lol. This became apparent to me tonight, as I decided remesh my RA on my g11gt during our 4th nor'easter in 2weeks.  Other than that, the whole process is very straight forward.  These mounts are designed to facilitate maintenance, and I find them to be put together in a fairly intuitive way.  And I am not overly mechanically inclined.  First stop once we get plowed out is Loews to pick up a set of screwdriver style hex keys!  :-) 

 

cheers ! 

 

Jmd


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#10 Charlie B

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Posted 22 March 2018 - 04:12 PM

Lol. This became apparent to me tonight, as I decided remesh my RA on my g11gt during our 4th nor'easter in 2weeks.  Other than that, the whole process is very straight forward.  These mounts are designed to facilitate maintenance, and I find them to be put together in a fairly intuitive way.  And I am not overly mechanically inclined.  First stop once we get plowed out is Loews to pick up a set of screwdriver style hex keys!  :-) 

 

cheers ! 

 

Jmd

I got this for Christmas to keep from losing my other hex keys.   https://www.amazon.c...t/dp/B0064S0XWM

 

I've even adjusted in the dark.

 

Regards,

 

Charlie B


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#11 willykros

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Posted 23 March 2018 - 05:30 PM

Thanks guys, much appreciated for the comments.

 

Uncle Rod... looked for the Losmandy video but couldn't find it.  Do you have a link?

 

And I know the mount got shipped with a back of L-shaped hex key wrenches, that I've managed to misplace.  I may pick up a set of the screwdriver type.  I'm assuming, since USA-made, that all the hex keys are SAE sizes?

 

... Bill



#12 gdd

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Posted 23 March 2018 - 05:39 PM

g11g/gm811

 

https://www.youtube....h?v=IiQlTMaUXkg

 

 

g11gt/titan

 

https://www.youtube....h?v=FrMuLJTi0Fs


Edited by gdd, 23 March 2018 - 05:45 PM.


#13 willykros

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Posted 23 March 2018 - 05:44 PM

GDD...

 

Yeah that's the video AFTER the motors have been removed.  I thought there was a video on removing the motors as well.

 

... Bill



#14 gdd

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Posted 23 March 2018 - 05:56 PM

GDD...

 

Yeah that's the video AFTER the motors have been removed.  I thought there was a video on removing the motors as well.

 

... Bill

 

Maybe you saw this one for adjusting the motors for noise:

 

https://www.youtube....h?v=Vqqjz40qAu4

 

The screws he is talking about are the same ones that attach the motor to the gearbox.

 

 

Gale


Edited by gdd, 23 March 2018 - 06:19 PM.

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#15 seitanfingers

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Posted 05 April 2018 - 02:01 PM

Hi folks- I've got the new GM811 and wondering a bit about adjusting OPW as well. My dec seems to have a fair amount of backlash and this is what I would do to correct that, right? He moves through everything pretty quick (ie. moves smooth when it breaks free, pushing inward, a little unclear on these).

 

https://www.youtube....h?v=IiQlTMaUXkg




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