Question Specific move causing step loss on D-420 when cutting nothing but air.

Hi,

I have generated a pocketing operation using Fusion 360 and GCode using WinPC-NC post processor.
When I run the GCode through WinPC-NC cutting nothing but air I consistently get step loss always at the same spot. (seemingly on X and Y axis)
I have tried slowing down transition feed rate and it does not seem to make any difference. When the step loss occurs I do hear a rather unpleasant noise. The way I test this is to Home the machine, send it to origin, run the GCode, stop after the noise and send it back to the origin at which point I observe that it does not go to the correct origin!! After homing the machine the origin is correct again.

I was wondering if anyone has some thoughts on this ?

I have attached the GCode, from what I can tell it happens at or just after Line 193.

Thanks,
Serge

hello,
I asume you use WinPC-NC as your controller program?
Did you encounter earlier problems with your code or is this the first step in milling?
And by the way your G-code is not attached in your message.

Can't give you any suggestions on present info.

Hi.

Yes sorry thats with a WinPC-NC controller + App.
What I have discovered is that despite the Specs. for the D420 Generation 3 quoting a max speed of 99mm/s the machine cant do this without loosing steps, it cant even do 70mm/s! This is simple repositioning moves without cutting anything. I have had to drop the Max speed in WinPC-NC to 50mm/s to get something stable.

It seems that the X axis is worse than than the Y and normally I see the step loss on a diagonal move. In this case a link move for the next cut.

The reason I saw this now is that there was a mismatch in the units being used by the WinPC-NC post processor in Fusion360. So the speeds in GCode where much to fast but WinPC-NC was limiting the max speed to 70mm/s based on the parameter settings. For now I have dropped this to 50mm/s.


So now I am wondering why I can achieve anything close to the max diagonal speed quoted on the website ?

Thanks,
Serge