cant seam to get a circle to cut right need help

[umoribawar]

i could really use some help,
so quick run down i have a mini mill i converted to cnc long ago, took a while to learn nd set everything up but i had it working perfectly.
the controller went out this year. i upgraded it to the controller and motors i was gonna use for my new cnc mill, which im happy with, they are a lot stronger then my old set up, i got it all dialed in so x and y cuts perfectly and precisely better then my old ones ever did, and adjusting the jibs became a lot simpler.

the problem comes when im cutting circles, but only at the top and the bottom, and i can figure out why, i researched the issue myself and have tryed a bunch of things but without luck.

this never happened with the old motors and controller, and i find it odd its only happing at the top and bottom. attaching a picture,
marked the top with the axis directions, and the lines represent where the problems are

if anyone has any ideas i appreciate the help and will try everything even if i already tryed it just so we can rule it out.

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[CNCMAN172]

i could really use some help,
so quick run down i have a mini mill i converted to cnc long ago, took a while to learn nd set everything up but i had it working perfectly.
the controller went out this year. i upgraded it to the controller and motors i was gonna use for my new cnc mill, which im happy with, they are a lot stronger then my old set up, i got it all dialed in so x and y cuts perfectly and precisely better then my old ones ever did, and adjusting the jibs became a lot simpler.

the problem comes when im cutting circles, but only at the top and the bottom, and i can figure out why, i researched the issue myself and have tryed a bunch of things but without luck.

this never happened with the old motors and controller, and i find it odd its only happing at the top and bottom. attaching a picture,
marked the top with the axis directions, and the lines represent where the problems are

if anyone has any ideas i appreciate the help and will try everything even if i already tryed it just so we can rule it out.

Verify your steps per unit are accurate on the Y axis. Also check couplers and everything on the Y axis and you will find your issue

[umoribawar]

thanks for your reply, i was actually just doing that right now and discovered something new,
so the latest things i tryed was switching the axis, the flat spot was still at the top and bottom just on the opposite side,
which lead me to believe the problem is not in mach 3,

so redid all gibs and ball nut holding screws, still the same problem, but lead me to notice something else
on x i can move .01 and feel the movie, on y i cant fill it to .03, i converted this mill about 20 years ago, using a cnc fusion kit, im thinking the y axis ball screws need replaced, which i needed a longer y axis screw anyways, so its not a bad thing to do, how ever cnc fusion site has long since been closed, so just have to do the leg work to find what i need now. but im believing that may be the problem now

[fc60]

Greetings,

Check the configuration of your software looking for a "backlash compensation" field.

My mill has play in the ball screws and once I typed in the actual backlash value into the controller things a working well now.

Bear in mind that my machine is the old Stepper method, not the newer Servo approach.

Cheers,

Dave

[umoribawar]

Greetings,

Check the configuration of your software looking for a "backlash compensation" field.

My mill has play in the ball screws and once I typed in the actual backlash value into the controller things a working well now.

Bear in mind that my machine is the old Stepper method, not the newer Servo approach.

Cheers,

Dave

thanks for your suggestion, i have not played much with backlash compensation, but was able to get the gist of it though trial and error, while im still not sure exactly what im doing there, i was able to get the circle dialed in a lot more, there's still a wired jolt when it compensates im gonna assume that's normal? i was able to get it to be less of a jolt, and get a pretty decent circle. that if i have a project comming up where i need to ill be able to, till i get the longer y xis bar screw and new nu.

so thanks for the suggestion.