@naPS OK on the pulleys - I guess that your Y pulley shaft must have been threaded rod or something then ?
@Gav - had already checked grub screws and all clamping were tight (as a duck's ar$e
) but rechecked again anyway. thanks.
OK, I completely replaced my alloy 12mm Y shafts with 10mm steel - turned to 6mm at the ends to suit the pulleys (all my pulleys are aluminium and are all the same). I replaced the single mount plates with dual mount plates and dual bearings. I realigned everything this morning - the belts are as tight as I can get them - not as tight as top E on my guitar, but close to bottom E/A ! (bear in mind I didn't have this problem before).
Sadly, the problem is EXACTLY
I pulled out my old dial gauge and set it up on the stage and locked in position. Set the stage to go off in Y at 100mm and back again - did this tens of times and it returns to within 10 microns each time (0.010mm). I did this with the stage going positive and negative, measuring it from the back and front reference bars. This is definitely not backlash, or it would show on the gauge. I repeated the snake test using the dial gauge this time - in both directions (I reversed the system Y direction just in case) - again, it returned within 10 microns of it's start position.
Looking at the pulleys, I checked the runout on the shafts, pulleys and even did it with the belt surfaces - all within about 10-15 microns.
I even checked everything again using a vernier gauge just in case
I've attached a pic of the actual snake test - you can see both start and finish are accurately aligned, but the individual segments are not. Again, the total length should be 60mm, but they are exactly 59.0mm - the X is exactly 60.0mm and uses the same pulleys. I even gauged the OD of the pulleys just in case - as expected, all the same.
So, for me, it is still pointing toward software/firmware contrary to Bill's results.
@Bill/@artofmystate, are you all using the latest and greatest versions of firmware and software ?
For reference, here's my setup again ...
Main board 7.12.04.01
It would be interesting to see if artofmystate gets the same results from the backlash snake file.
I'm not sure I have any mileage left from a hardware standpoint - any smart ideas gratefully accepted - I'm stumped.
PS, Just remembered, I swapped the stepper drivers too - exactly the same results