Roughness felt while focusing refracting telescope

[S.A.M]

I recently had a slight accident with my 80 mm refracting telescope, dropped it on the ground while still in carrying case (silly person me!) I have noticed some roughness when I move the focusing knobs in and out (should be smooth in operation)? I guess there is a slight problem with the focusing movement, can I repair it or does somebody know where I can get a breakdown plan of the focusing unit before I go and try to fix it? Any help would be most grateful.

Peter

[ronin]

I assume it is the WO ZS80 (?)

The focuser should be (at last I think it was) a crayford so should be easy to "dismantle" and check and rebuild. Concern is I was going to say a bit of dirt but you say it was in the case so that seems improbable.

This relates to the GSO Crayford, but they appear to follow along similar lines, use it as a bit of a guide: http://polluxchung.com/gso_crayford_fix/index.html

If you search for "WO Crayford rebuild" I suspect that you will find a number of articals, WO focusers had a poor name at one time and I guess quite a few had ideas on making them better. So would expect posts all over the place. I half think they were no worse then the majority of the others but people complained.

As they operate basically by friction - rubber on the focuser plate - the problem could be at the actual bit that turns and that likely means the 10:1 arrangement. Most likely you just need to take it apart, clean and reassemble it. There is a plate on the base that has tightening screws and access (I assume access) that may be easier to look at first.

One aspect is that I am not sure how much more complex the DDG aspect is.

If you are a member of Swindon Club ask if anyone has any experience.

[Stu]

If it is a Crayford then it's quite likely that you have bent the focuser shaft, easily done, I did it myself the other day ?

Fixing is usually relatively straight forward. There are normally grub screws holding the focus knobs to the shaft, once out, you can measure the shaft and get a replacement of the same diameter from eBay, 318 stainless steel is best I believe. The only challenge is creating a flat or dent for the grub screw to grip.

Here is mine with bent shaft!

[rwilkey]

Hi Peter, sorry to hear about your misfortune, hope you get it fixed!

[Putaendo Patrick]

Don't know if these pdf drawings will help?

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi-6PDIkdLMAhUBkZAKHQUvDPkQjhwIAw&url=http%3A%2F%2Fwww.williamoptics.com%2Fsupport%2Fdownload%2FF3.0-DDG.PDF&psig=AFQjCNHwspmQ6tdFL5mHPBzHm15fiKRmbA&ust=1463059770327978

Good luck!

[S.A.M]

Thank you Putaendo, the pictures are what I need, hopefully one of them will sort my problem out?

Peter