Bill, many thanks for trying that for me - it is really a great help !
If I can believe your software (and I've no reason to disbelieve it
), then it would indeed indicate that it is definitely backlash I have.
To that end, I stripped out the complete Y axis assemblage this morning. My front pulley mounts are dual bearings in each doubled up 6mm acetal mount plate. The shafts for the pulleys (regular toothed pulleys BTW - not smooth) are 'shoulder screws' - accurately ground 6mm M6 screws - pretty much industry standard for this type of job. They feel as bullet proof as when I put them in. However, the long shaft at the back with the axial stepper is a slightly different matter. My shaft (all 1500mm of it
) is 12mm alloy tube with turned aluminium ferrules on each end. The ferrules fit into either a standard shaft coupler (grubscrew type rather than clamp type as that was all I had) or they fit through a single version of the same front mount plate. This single version may be an issue as it is not quite so rigid as the front units (even though held at both ends).
I've CNC cut another pair of plates and will double up the bearings to suit along with replacing the alloy shafting with some 10mm steel shaft which I'll turn down to suit the pulleys. If that doesn't cure it, I have some petrol in the garage that I'll put in a bowl and let the laser fire down on it
@naPs, thanks for the info, I tried the belts as a matter of course - no change - still not sure what advantage the smooth pulleys offer - perhaps you or someone can explain - I'll turn some up and swap them in if warranted.
@Tim, strangely, when trying to get to the bottom of the problem, I swapped leading to trailing edge of the pulse to see if it made a difference - it didn't.
I even swapped steps, changing from 1/16 to 1/10 (remember my system isn't a 2.x) - again, no change.
As you accurately say in your sig Tim - "The answer is usually easy and obvious once you know what it is."
If only we could find out the answer prior to the problem, we'd be on a winner
I'll find out if any of the changes have fixed the issue and report back - if nothing else, the Y axis rear should be as bullet proof as the front.