Hi Ray,

I'm Thinking of have a go at building one of these for my TM20VL mill. The only bit I don't like is the pneumatics to lower the Stepper.  I want to get rid of the air supply.

Did you look at other means of lowering the Stepper, such as another smaller stepper?

Cheers,

Peter

Peter,

A stepper seems to me like severely over-complicating things.  Perhaps a small AC or DC gear-motor driving a screw.  However, keep in mind, the drawbar needs to generate about 300# of down-force to pop the collet free.  Also, depending on how you couple the drawbar to the PDB, either the drawbar or PDB dhaft needs to turn some to get aligned, before the PDB will come all the way down.  A pneumatic cylinder can easily accommodate the coupling mis-alignment, but a leadscrew would require some kind of heavy spring mechanism to deal with it.  Pneumatic really is the simplest, cheapest solution.

Regards,
Ray L.

Hi Ray,

Thanks for that. I looked around for solenoids that could do the trick but could not find anything suitable.

I still need to sort the brake out, but It looks like I'll end up using pneumatics liker you.

Cheers,

Peter

Peter,

If my machine didn't already have a spindle brake, I would've just adapted a bicycle disc brake.

Regards,
Ray L.