Y axis stalling

[richie00boy]

Not used the machine for some time until the other week when I did a couple of PCBs. Noticed that it was losing position a bit when drilling the holes as they were not quite central on the pads - I put up a thread about this.

After trying to reface my spoilboard it was stalling like mad on the Y axis again and I think actually this is what caused the PCB holes to be misaligned - the machine is just moving so slow that I can't hear or notice it then.

I turned off the controller and tried turning the stepper by hand using the knob on it, it was pretty stiff. So I decided to take it apart a bit and try Jazz's suggestions.

Well it moves freely on the rails when I unscrew the leadscrew mount. With the leadscrew mount loose I did rapid Y movement (shift and up/down arrow on Mach3) and it runs nice until the mount hits the lip of the gantry and then starts dragging the gantry along. I can see the mount bobbing up and down slightly sometimes. So I'm wondering if the leadscrew is a bit bent? I guess if it is this could be the cause of the problem?

If I do need a new leadscrew where can I get one and is there an upgraded type worth fitting?