Sherline Mill setup and adjustment

[Yotamkasam]

Following mill CNC upgrade using Sherline's kit and Sure Step motors I have
difficulties setting up the machine.

The X and Y movement is stiff and smooth, however, backlash seem to be huge and uneven so jogging CW shows different backlash value than CCW.

I have taken the mill apart, cleaned, greased and tighten all screws, made sure everything it stiff but moves without too much force. The only problem I had was removing the axis nut for visual inspection so I can't tell what its condition.

Sherline support suggested not touching the gibs but apart from that game me no specific information on what to do in such case.

Should I make an effort to remove the stacked axis nut?

Where else to look?

Btw, I am using Abro #2 lithium grease and was wondering if that can cause any problem. Is there such a thing as too much grease?

Thanks for your help.
Yotam

[awerby]

That's usually predictable - it happens when you change directions, and doesn't accumulate or occur randomly. I'd suspect the "Sure-step" motors you used instead. What you're probably experiencing is step loss, which can cause problems like you're noticing. Even if the holding torque on the motors is sufficient, they may want more power than they're being given by the Sherline CNC system, or they may have too high an induction factor to respond swiftly enough. If you've tried lowering velocity and accelleration without finding values that give predictable results, then you might look for motors that are better matched to the controller, or a controller that's more compatible with your motors.

Oil is usually better to use on these machines than grease, which tends to collect dust and form a clay-like substance that gums up the works, but I doubt that's your problem at this point.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Yotamkasam]

Thanks Andrew.
I will look into the motor issue as well.
As for the grease, I got rid of it and it moves much better now.
Yotam