Focuser issue

[jeffwjz]

Hi everyone, I recently acquired a TAL 100RS, the optics are in great condition, however there is one issue - the focuser doesn't work. Basically when I rotate the focuser knob the focuser tube is not moving at all, and if I loosen the focuser locking screws I can just spin the knobs freely. I pulled out the tube, and I think the focuser is missing a part but I'm not sure which and not sure how to repair it. Can anyone advise? Thanks in advance. 

[Stargazer33]

Do the two screws behind the lock knob not tension the adjuster against the tube?

[MarkAR]

I think Bryan is right. Re-assemble and try tightening them up gently a little at a time.

If that doesn't work it might be the little round plastic bit in the middle is worn.

[Robindonne]

26 minutes ago, Stargazer33 said:

Do the two screws behind the lock knob not tension the adjuster against the tube?

Yes when you look closer on that first picture, that tension knob is a bit visible.  A bit hidden behind the lock knob

[wookie1965]

8 hours ago, Stargazer33 said:

Do the two screws behind the lock knob not tension the adjuster against the tube?

Yes they do I have adjusted mine on my Tal 100rs,  as I have put a 2" diagonal in which was heavier.

[jeffwjz]

Hi all thanks for all the replies. As I played around it, I found that the top silver screw in first pic is for tension and bottom is for locking. I had to tighten the tension screw really really hard to the focuser knobs can drive the tube. I disamble the focuser and found the mechanism opposite to the knobs has a ball bearing missing. I suppose this is the issue so I ordered some replacement bearings. 

[jeffwjz]

[wookie1965]

I give mine a good clean and used a tiny bit of grease on those runners, I found if you adjust both knobs together you dont have to tighten the top one that hard and still have a smooth action.

 

A friend on here made this bigger knob brilliant for fine focusing maybe something to think about for the future. 

Edited August 22, 2020 by wookie1965

[DaveL59]

reading this thread makes me wonder if the 100RS came with 2 focuser options?

The one I have has a R&P focuser that looks very different to the one pictured.

Edited August 22, 2020 by DaveL59

[RobertI]

31 minutes ago, DaveL59 said:

reading this thread makes me wonder if the 100RS came with 2 focuser options?

The one I have has a R&P focuser that looks very different to the one pictured.

I read a long thread from quite a while back where the different focuser options are discussed - I think the conclusion in the end were that there were three or four different versions over time!

[wookie1965]

Very strange totally different, I wanted to fit a dual focuser but I could not find anything about doing it. 

Only one person had changed the focuser and by what he said it was a nightmare. 

[John]

9 hours ago, RobertI said:

I read a long thread from quite a while back where the different focuser options are discussed - I think the conclusion in the end were that there were three or four different versions over time!

Yep - I've got the OVL brochures somewhere that show them changing over time.

I think the crayford focuser that this thread started out on is the latest focuser type used on this scope.

Astrobaby reviewed here 2008 model and that had the crayford fitted, rather to her surprise:

http://www.astro-baby.com/reviews/TAL 100RS/TAL 100RS Review.htm

The TAL Apolar 125 that I reviewed back in 2011 used a revised version of the crayford focuser as well: