Crayford focuser, aligning the focus tube, not the tension!!

[Rustang]

The tube of the my Crayford Focuser (fitted to a SW 72ED DS PRO) that runs on the rollers inside the scope, doesnt run square. The gap either side is not the same, i know you can adjust the tension of the tube but is there anything to straight up the running in and out of the tube if that makes sense!? The roller plate is held in by two screws but these don't appear to have any kind of adjustment!? Can anyone confirm if this is actually an issue for my image train being aligned properly!?

Edited August 28, 2020 by Rustang

[Rustang]

I guess its something that's miss aligned with mine then?

[Robindonne]

I remember having this issue with a crayford on my newton.    Its very easy to do.   When the tube is removed you see the part that has to be adjusted.   Of course you dont Always have to remove the tube, but thats the only way to see what parts need adjustment. 
 

oh i see its on a refractor. Maybe its a bit more work, i’m not sure.   But the parts that needed adjustment on my focuser were the rail on the bottom of the tube, and if i remember correct, the “shell” that has bearings on it.  
 

i think for the rail on the bottom, the whole tube has to come out.   But mine focusser was really far out of alignment so perhaps only that shell with the bearings would work for you.   

Edited August 27, 2020 by Robindonne

[Rustang]

It's the silver tube that's a little out, it's sitting slightly over to one side so not central to the outer metal surround of the scope. There appears to be no adjustment for this unless I'm missing something. It runs on a plate with 4 rollers/bearings, that plate is screwed to the shell of the scope but there appears to be no adjustment on that plate, that plate and its positioning appears to be what determinds where the focus tube sits. I mainly want to know if this will effect my image train and also if it could have come out the factory like that and it's not necessarily an issue. 

Edited August 28, 2020 by Rustang

[DDH]

I see this post is 1 year almost old,  But I have the same problem with my newtonian.  The draw tube does not extend inline with the housing.  I have had this MN190 scope for 3 years but only started using it in October 2020. I found it impossible to collimate  due to this problem. Each time the focus is moved the collimation goes out so it is not possible to get good astro images.  I agree with Rustang that it would seem there is no way to adjust the carrier with the 4 rollers on it.  Maybe the only possible ways would be to shim the block that carries the rollers or to re engineer it.  The only alternate is to throw the focuser in the bin and buy new, unless someone out there has another idea.  See my two photos of the focuser on a mirror with the laser collimator.   See the gap in the image with the focus closed between the draw tube and body.  Also when I hang my DSLR on it the situation gets much worse.   By the way I am only a frustrated novice. 

Edited July 23, 2021 by DDH

[wimvb]

The MN190 has a low profile focuser, and in order to achieve focus in visual mode, Skywatcher decided to put an extension tube inside the draw tube. This extension is the part that usually causes problems. You can shim it to make it more rigid. I put a small strip of aluminium tape along the tube and then pushed it back in. This fixed the extension tube inside the draw tube.