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z height moves up when changing directions on xy plane

Posted: Mon Nov 16, 2020 11:40 pm
by brand_in
SOMEONE PLEASE HELP

When I do travel moves in a single direction the z is perfect, but as soon as I change to the opposite direction the nozzle lifts up about .2mm on a 10mm move

This phenomenon is more pronounced the further the nozzle is from the center

as you can guess when i do large prints the i get great adhesion going in one direction, and then when it switches direction it raises up and no squish

this is not z hop, it is when im just jogging the machine manually

Re: z height moves up when changing directions on xy plane

Posted: Tue Nov 17, 2020 8:13 am
by geneb
It sounds like your bed has a slight tilt to it.

g.

Re: z height moves up when changing directions on xy plane

Posted: Tue Nov 17, 2020 5:46 pm
by brand_in
negative, my bed is perfectly flat, when I change direction (xy) and tell the nozzle to go backwards 10mm to the spot it was just at, the nozzle is .2mm higher (z) than when it was at that same exact position the first time ( and as I continue going back to the center it gradually slopes back down to zero.

it essentially is a reputability issue, I tell the machine to go to the same spot but when coming from the opposite direction there is a z difference of .2mm to 0mm depending on how far away i am from the center

Re: z height moves up when changing directions on xy plane

Posted: Wed Nov 18, 2020 8:42 am
by geneb
Then it's a mechanical issue of some kind. If the drive gears are plastic with a metal core, check to see if one has a crack. If they're all metal, make sure the grub screws aren't loose and allowing movement.

You also want to make sure that all three belts are in good shape and have an equal tension.

g.