Making a Crayford silky smooth - suggestions ?

[topdude]

Hi, i have a basic 2" Crayford focuser "purchased second hand" attached to my SW 130 and need suggestions on how to make it operate nice and smooth without slipping.

I have dismantled it and it all seems unworn but when in use it is either jerky or slipping depending on the tension of the adjuster.

Any suggestions on a lubricant for the shaft / bushing which will make it smooth without slipping ?

Thanks.

[Astro_Baby]

How to make a CRayford smooth ? Throw it in the bin and buy a Moonlite

Seriously its probably down to the flat on the focus drawtube. If this isnt perfectly flat it will play up in the way you describe. The other possible reason is a slightly bent spindle (the bit that the focuser knob is attached to).

It may just be that its engineering isn't very good - do you know who made it originally ? Can you put a pic up ?

[SiriusB]

I second the idea it may be the drawtube flat bearing surface is not flat enough.

Heres a useful link if you fancy a spot of DIY?

Andy's Shot Glass - tweaking your 100ED drawtube

Best grease i've found for slippery smoothness generally is Finishline bike grease with teflon-It's a bit expensive unless you have other stuff to grease up though

I take it you know where grease can go & where it can't on a Crayford?

[topdude]

Thanks for that link, the flat on my drawtube is higher at the edges so will have a go at stoning it flat.

[beamish]

I had very similar probs with a GSO SCT crayford and believe me it is worth honing it flat and may I add, once done polish the flat and then rub a little good quality beeswax, making sure any XS is removed. Also worth considering is replacing the shaft with a better quality SS shaft

HTH