HBS57 and oval circle issues.

Hi,

I recently purchased a closed loop stepper kit (HBS57 driver + 57HSE2.2N-D24-3M motor) to replace one of my broken open loop stepper drivers. Currently my X and Z axis are open loop steppers (DQ542MA drivers) and the Y axis has the closed loop stepper. Everything seems to be running well, the servo does exactly what I tell it to do.

The only problem is that all the circles that I mill comes out oval shaped. 
I have checked to make sure I have no bakclash, and that I am not losing any steps - even after running a 2 hour long job no steps have been lost.

I am using a generic 5-axis BOB from china with linux cnc through a parrallel port.

The machine has been working great for years - the only change I made was the closed loop stepper, so I am fairly certain that it is not a mechanical issue on the machine, rather a issue with the software of either the driver or linuxcnc.

Might there be some sort of timing issues between the closed loop driver and linuxcnc?
Should I rather use another board with these drivers?

Any suggestions would be greatly appreciated.

I Checked all dip switches and they are all fully up or down - no change.
I have only ever used the setup wizard and have never changed anything in the .ini files.

I also tried the following:

Changing the micro stepping from 1/8 to 1/4 (ofc adjusting the software steps per mm)
Decreasing the maximum velocities and accelerations for the motor.
Running the program at different feed rates.
None of these made a change.

I did notice one stange thing, attached is a image of two circles cut side by side - the one on the left has been cut with climb milling and the one on the right with convetional (otherwise the toolpaths are identical). the circles are both screwed the same ammount but in opposide directions.

It seems that the problems has to be with the software and not mechanical. Could it be the contoller board and stepper driver combination?


This is the Fusion 360 g-code to cut one circle:
%
(1001)
(T41  D=6. CR=0. - ZMIN=-11. - FLAT END MILL)
N10 G90 G94 G17 G91.1
N15 G21
N20 G53 G0 Z0.
(2D POCKET2)
N25 T41 M6
N30 S16000 M3
N35 G54
N40 M8
N45 G0 X-25.758 Y30.387
N50 G43 Z15. H41
N55 G0 Z5.
N60 G1 Z2.5 F3600.
N65 G2 X-23.542 Y25.135 Z0.101 I1.108 J-2.626 F1800.
N70 X-25.758 Y30.387 Z-2.298 I-1.108 J2.626
N75 X-23.542 Y25.135 Z-4.697 I1.108 J-2.626
N80 X-25.758 Y30.387 Z-7.096 I-1.108 J2.626
N85 X-23.542 Y25.135 Z-9.495 I1.108 J-2.626
N90 X-27.5 Y27.761 Z-11. I-1.108 J2.626
N95 X-24.5 I1.5 J0. F3600.
N100 X-30.5 I-3. J0.
N105 X-21.5 I4.5 J0.
N110 X-33.5 I-6. J0.
N115 X-18.5 I7.5 J0.
N120 X-36.5 I-9. J0.
N125 X-15.5 I10.5 J0.
N130 X-39.5 I-12. J0.
N135 X-15.5 I12. J0.
N140 G0 Z15.
N145 M9
N150 G53 Z0.
N155 M30
%
 

If it only happens with the closed loop step motor drives.
I would suspect issues with the closed loop tuning of the
drives

I changed the drive from closed loop to standalone (no closed loop feedback) and the issue was still there.

I changed out the drive to my old DQ542ma driver and ran the same g-code. This worked perfectly.

Is it possilbe that there is a step or direction timing issue between linuxCNC and the controller?

 

Hi,

The circle is supposed to have a diameter of 30mm.
The largest measurement is 30mm and the smallest is 27mm (see attached picture).

Pulleys are in both cases the same? Is it only on circles or also at rectangles?

My machine uses ballscrews with direct couplings so there are no pulleys or gearing ratios.

Rectangles have the correct dimensions but the corner radius of the rectangles are not correct (see attached picture) - Opposing corners have the same radius but are not the same to the other two opposing corners.