Sherline 2000 - Uneven Z-axis Lead Screw Resistance

Mikey, I have steppers. they are installed between the wheels and the ends of the lead screw shafts. the stepper shafts are connected to the leadscrews with couplings which have a lot of slots intended to accommodate some misalignment in the two shafts. I would be dollars to doughnuts that my saddle nuts is a tad (technical term) out of alignment and that I can improve it and then use the backlash adjustment to get the backlash down to something reasonable like what you have.

Thanks again,

john

Heh, forgot about the fact that your machine is CNC - sorry about that. I'm sure you'll get it to a reasonable point, John.
 
Hi Bob,
I think you have the process down cold. You're right about the backlash adjuster acting like a jam nut. this is how the other two leadscrews are de-backlashed, but with very clever starwheel nuts which permit very slight adjustments.
best,

john
 
I got into it and discovered that one of the two set screws was loose. The lock screws wasn't too tight either. The effect of this was to put some anti-alignment pressure on the saddle nut. Apparently this was aggravated by leaning on it with the jam-nut (backlash adjuster). As Bob suggested, I ran the saddle all the way up to the top where the control wheel is and adjusted the set-screws and lock screw until I got no resistance. Seems to work.

I got the backlash down to a bit under .003. I continue to think that once the machine has run in a little more I should be able to do better. When I start cutting complex surfaces, it will get a lot more exercise than it has so far, although only over a limited part of the lead screws unless i back it off more than necessary between cuts.
 
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