Crayford focuser

[Vapouriser]

I have recently bought a 6" refractor with a crayford focuser. How nice after 4 years of clunking rack and pinion! Unfortunately it s not quite that easy. At any angle steeper than about 30• the focuser slides down and the only way I can adjust it is by hand pushing. Haven't had the courage to take it apart without some much needed advice please!

[Zakalwe]

There's lots of guides on the Web for tweaking Crayfords. Before you go ripping it apart make sure that you have adjusted the tension screw.

http://polluxchung.com/gso_crayford_fix/index.html

[Vapouriser]

The only screw I know is the one which locks it up solid! Trouble with buying secondhand you dont always get the instructions. I m looking up the site right now. Thank you lots.

[Vapouriser]

Mine hant an adjuster. Blow it I m going to take it apart! There s something in favour of rack and pinions- they move up and down !

[Peter Drew]

If all else fails try the rubber band "trick". Attach one end to a moving part, eyepiece or diagonal, and the other end to a fixed part on the OTA. With the right tension or number of bands the focuser will hold better and will be smoother.  

[coulthamst]

Crayford adjustment can often be made by a small allen grub screw directly beneath the centre of the focuser drive axle. Hope this is understandable, it's not easy to describe!

[Vapouriser]

Thanks Peter. That will be useful.

[Vapouriser]

There is an Allen key but its so tight I haven't been able to move it. Probably not an adjuster! I m taking apart. Ha ha ha! Doesn't look complicated really. Thanks fellas.

[Zakalwe]

There is an Allen key but its so tight I haven't been able to move it. Probably not an adjuster! I m taking apart. Ha ha ha! Doesn't look complicated really. Thanks fellas.

Take care. Its easy to completely loose the "feel" of a crayford. Sometimes there's small O-rings under some screws- lose these or over-tighten the screws and the focuser goes horribly rough.

Maybe post a picture of the focuser first? Someone here might have an idea before you start ripping it apart.

[Steve Ward]

http://www.teleskop-austria.at/information/serv-just-hu/pdf/Adjusting_Crayford_focuser.pdf

[Peter Drew]

So that's where Sir PM's typwriter ended up. 

[Vapouriser]

Aha. Got it. It is a tesioning screw , with a counter screw it could be that tight. Cant send photos unfortunately. Only have iphone which isnt compatable with much!