Re: encoding free leadscrew end?

You might try a flexible coupling since the torque is just about zero. Even better, two flex couplings with a rigid extension
between them.

You could even lower the encoder and let it be driven at a slight angle and it would give you the top clearance you need.
Bertho Boman
=======================================

> stratton@... wrote:
>
> Now that I have a linear encoder strip up on the Z axis of
> my lathe, I'm thinking of putting a salvaged 500 cpr rotary
> encoder on the crossfeed screw.
>
> On the South Bend and similar lathes, the back end of the screw is
> unsuported, so the slide can in fact simply be cranked off the back of
> the machine. I'd like to put the encoder back there so as to not
> interfere with the handwheel end.
>
> The main thing I need to figure out is how to make a removeable
> attachment to the end of the screw. There is a center hole that I was
> able to get a drill into, and could probably tap - but runout would
> I'm sure be excessive. Another idea would be to turn a brass sleeve
> that would fit over the end of the screw, then reduce to go through a
> small bearing and then the necessary thin shaft for the encoder wheel.
> Thought about just gluing that on. Even if I do get it attached, I'm
> not sure if there will be any issues with constraining the back end of
> a screw that has been running free for 30 years and might well be
> slighly bent. Any ideas?
>
> Also, the rear cover/extension of the cross slide has to pass over the
> top of all this, and the stock encoder housing is just barely too big.
> Guess I'll have to make another with thinner walls.
>
> Chris
>
> --
> Christopher C. Stratton, stratton@...
> Engineer, Instrument Maker & Horn Player
> (978)538-5179 work, (617)492-3358 home
> 30 Griswold Street Cambridge, MA 02138
> http://www.mdc.net/~stratton