Re: [ATM] Crayford focuser pinion problem

[Daniel Fundo <fundo@bellsouth.net>]

<<  My pinion for moving the drawtube up and down will
be a 6mm (OD) aluminium tube but I need to coat it 
in something to give it some friction against the drawtube.
I've thought about wrapping a rubber band around it but was 
worried that it might make the motion feel 'spongey'
Does anyone have any better suggestions.  >>

Marco,  I agree, to some extent, with Bob May.  I use music wire or
drill rod for the pinions on bare aluminum for my focusers and have no
problem with friction.  But 1/4 inch thick aluminum tube is a lot of
extra weight, IMHO.  I have never used any aluminum tubing over 0.065
inch in wall thickness, and have not had a tube collapse on me.  I
generally use 0.125 or 0.0937 inch ( 1/8" or 3/32") music wire,
although, I did make one using 0.0625 inch.  

I have simplified plans for my Crayford.  I have sent out about 20
copies to members on the list.  If you want a diagram and instructions,
just send me your snail mail coordinates.  It can be, and I have made
one, with nothing but hand tools.  I can even supply some of the
materials.  OoTD, I'll get some digital photos of my design and send
them off to S&T.  (The ATMJ went defunct before I could send them to
Bill Cook....to my shame and regret.)

*****-----
Dan F.
Secretary/MAS
Memphis, TN
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