Hi M,
That info helps...
BindingLet me respond first on the binding issue as it's important. On the "grinding noise" -- let me explain what I believe this noise is (I could be wrong, but can't really be sure without being there). When a stepper motor misses steps (this is also described as losing sync with it's step signal), the rotor just spins, but it spins across a series of little magnetic fields or notches that give it a fast stuttering or grinding sound and vibration. You will hear it if you drive the axis into the end-stop with the Keypad -- and then keep going. This "grinding" does not hurt the motor (assuming you don't keep drilling it into the wall for hours). But importantly, it is not the
cause of the motor missing steps and the axis losing location; it is a telltale result. In fact, if you hear it, you've likely lost your location to at least some degree.
The grinding happens when the axis binds (resists motion) or is held. Usually on a Handibot, this happens if the motor, screw, and nut get out of alignment. BUT, the bearing blocks on which the car rides might also bind. They may have gotten crud in them; there might be a flaw in the bearings or bearing cage.
So with respect to the diagnostics that the Support team suggested -- After moving the X axis to the far right and removing the two bolts marked in the figure. The X-Z car is now disconnected from drive nut. You should be able to push the car freely up and down the X axis because the screw and motor are not engaged and the car is just sliding on its bearings. The bearings will be firm, but it should only require pressure from a finger or two to move the car up and down the axis in either direction. If the car has been correctly disconnected from the motor and screw, then needing "two hands" of force is not right -- and certainly the issue.
As Mark suggests, you can further refine the diagnostic by removing the 4 bolts in each bearings, one bearing at a time, and push the bearing out from under the car to test it individually. This might allow you to figure out which bearing(s) is hanging up ... and if you were really brave, you could remove the motor so that you could take the bad bearing(s) off to inspect and clean. But I think that at this point we should swap out your tool for a new one so that we can have a look and see what the bearing issue is. It is not something we've had much experience with ...
Per Mark's comment on Jog Speed. I did not mean to suggest running files while Jogging at 5ips, only using 5ips as a diagnostic test for alignment/binding because it will quickly reveal where there is serious binding on a tool. I also like 3ips as a good default Jog speed for the Handibots.
Tool PathPer the discussion earlier on tool-pathing your carving files, I was suggesting skipping the 1/4" roughing pass in the case where you have a rastering finish path in a "dished" carving, or, where you program the first line of cutting so that it works it's way down to depth. In both cases the raster nature of the machining means that the cutter is only removing a small amount of material on each pass. In most cases it is not necessary to first clear the area out with a roughing pass. And this way, at least for the carving component, you don't have to worry about registration after swapping out a roughing bit.
Ted Hall, ShopBot Tools