Circles problem

[Flanker]

Hi I'm Leonardo.
I ahve a proble when I mill circle.
The circles are not fine, are lightly elliptical and the edge are not smooth.

Tanks a lot.

Leo.

[Bubba]

Flanker,
As you are in the TCNC group, I have to assume you are using TCNC? If so, which version are you running? If <4.01, you definately need to get the latest as there were problems in V3.x.
Secondly, does your machine have backlash? If so, this could be the problem.

Need more info to give you difinative answers!

[Flanker]

Bubba, thanks for answer!
Yes I'm working with Turbocnc 4.0.
My Stepper working at 200 step/revolution (full step).
I've notice that for cutting large hole (example 40mm diameter o moore) I've not a problem,
but when I try to cut small circle (example 20mm diameter o less) the problem there is.
The circle appear slightly flatten and with small stair on edge.
With backlash correction Turbocnc make a stair at end of every quadrant, and this is wrong.
Thanks for your help.
Best regards.
Leo.

[ger21]

Backlash compensation is really not going to fully correct for bqacklash in your machine. Tha'ts probably what's causing the rough edges, too. Could you post the g-code you're using for smaller circles?

[Flanker]

Hi.
the G-code is:
G00 Z0.1000
G00 X30.7000 Y15.0000
G01 Z-1.0000
G03 X30.7000 Y15.0000 I-10.7000 J0.0000
G01 X30.7000 Y15.0000 Z-2.0000
G02 X30.7000 Y15.0000 I-10.7000 J0.0000
G00 Z0.1000

thanks a lots.
Leo.

[Flanker]

Somebody can help me?
Yesterday I'tried with driving the stepper in full step, half step and 1/4 of step.
It seem that in half-step there are strange noise (as interferences?) and it is seem also that there is lost steps (but only in half-step). I believe that the problem on cut circle originate from this. Furthermore the Turbocnc management of backslash on circular interpolation is, in my opinion, harmful because Turbocnc correct the problem at the end of any quadrant. So at the end of any quadrant there is always a stair.
I do not understand.

Best regards.

[Flanker]

perhaps I understand now...
...my circles are ellipticals.
...perhaps the problem is in the "bit and byte"?
...and perhaps there are many, too much, professors.