Wandering Y Axis.....

[Lester]

Hi Guys,

Looking for some help with my home converted Amat30lv. Have made a few parts with success however I am struggling to to keep the Y axis from drifting whilst using adaptive tool paths. The picture show my issue, the pocket was started in the centre using a helix before moving to the thin right side and then back to the left. You can see the jump in the part where the mill returns to the centre to machine the fatter left side, but the y axis has drifted (this is obvous as well if i ask the machine to return to x0,y0)



Am running:
DM860N drivers
4Nm Nema stepper motors (wired in bipolar parallel)
ST-V2 breakout board
UC300ETH
UCCNC
Have tried running with a 48v and 60v power supply.
16mm ballscrews on X and Y and a 20mm on Z. All 5mm pitch.



Was worried I was loosing steps because I was trying to run too quickly approx 2500mm/min rapids (with a 1000mm/min cuttuing speed and a small DOC), so lowered the rapids to 1300mm/min (at 400mm/min with a bigger DOC). The drift seemed to get smaller, but I'm guessing this could be due to the larger DOC, less direction changes?

Am thinking it could possibly be due to my gib adjustment. After watching John Sauders' video on his Tormach and having a play I managed to get the Y axis 'lost motion' to be minimal and think there is about 0.001" of rocking when measuring the saddle from the chip guard. I did however struggle to get the X axis twist (measured from the table to the head to be less than 0.004" without tightening the gib so much that the motion is less consistent and jumpy.

Is this gib adjustment something I should be looking into more or is there anything else I should be looking into?

Also interested what kind of speeds and accelerations people are managing to achieve with similar setups.

Thanks,
Lester