[ATM] Comment on Crayford construction

[Dave Smith <smithersscope@yahoo.com>]

Hi,
I had my 16" tridob out last night after building an
adjustable jig to support a digital camera at the
eyepiece for afocal imaging. (on a side note, I have
never seen the atmosphere as stable as it was last
night. Incredible. But then the dew set in. argh.)
And thus my comment about my Crayford focuser... Some
time back I converted the two Teflon cylinders that
maintain tension between the focusing shaft and the
draw tube into a single unit of wood. Much more
effective design, but the substrate if very important.
Wood and dew don't mix. The friction and slippage were
insufferable. Under dry conditions it works
beautifully, but last night after the dew set in, I
was basically unable to control the focuser.
Anyone following my lead on that part of the focuser
design should be aware that you'll see issues with
moisture and wood on steel. No big surprise, just FYI.

Thanks,
Dave


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