Friday, November 8, 2013

Fixed the Mill

Last week I was ecstatic to set up my shiny new (old) Spectralight CNC mill.  Unfortunately the Y-Axis had a backlash problem.  About an inch of backlash.  I had to go out of town and just got back in the shop today.

That doesn't look right... 
The Leadscrew is supposed to be connected to the stepper.


I had guestimated the problem to be that the Cap screw that held the leadscrew to the motor coupler had come off.  That was incorrect.  The Spectralight mill differs from the stock Sherline 5400 mill.  Instead of having a hard mount for the steppers to the lead screw it uses a coupling that permits small amounts of misalignment.

The motor coupler.. (Half of it.)
The fix was pretty easy.  I had to clean the end of the leadscrew (it was oily), move the rubber sleeve out of the way, put the thrust bearing/washer/and coupler back on, take out as much play as possible, and tighten up the cap screw on the coupler.  Easy peasy.

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