one corner of rectangles bad/ splayed out

[austinmmm]

Cant seem to cut perfect squares... its always the 4th corner near the end point of the cut - cut splays out or in.
motors are tightened and offset bearings are tight - no movement from xy car on the gantry.
overall i get slight jiggle on all axes but I think this is normal?
thought it was something to do with the de-acceleration tried cutting using several methods to avoid that with no luck..
happens on first pass, so this rules out slipping parts or tabs problems.

IMG_20200221_144512611_2.jpgIMG_20200221_163535_01.jpg

[EricSchimel]

overall i get slight jiggle on all axes

I think that's your answer.

How much play are we talking about? Have you measured it with a dial indicator?

Also, what machine are you running?

[austinmmm]

running a prs standard. it appears after tightening the motors in place the gantry can move almost .01 according to the dial indicator..

[EricSchimel]

.01" is high. If you figure that your gantry has one motor at each end you've got a combined .02" of slop, and that's after you tightened things up. I'd check for worn pinions first as they're a wear item, then I'd look at your gearboxes. As those get older they get backlash in them as well.

[evan]

Don't forget that these pinion gears often have two set-screws in each threaded hole, one on top of the other.

[pro70z28]

If that cut was made with a 1/4" bit, that's a lot more movement than just a few .01".

[bill.young]

Do your parts turn out correct other than the bumps on the corners? The correct size, corners square, etc? If so then trying some changes to optimize the toolpath like lead-ins or lead-outs or ramping into the cut seems like the sensible and easy first shot at fixing the problem.

Bill