G540 + EMC2 = missing steps

I have seen two cases of step loss when using simultaneous motion over multiple axes:

- Case 1: the problem was the switch mode power supply. Although it was a hefty 48V/10Amp supply, it was not capable of running 3 motors at the same time. Switch mode power supplies are not good motor supplies unless grossly overdimensioned; they have problems coping with regenerative energy. Solution: I had the guy add a second power supply and power one of the axes from that one.

- Case 2: The problem was some deformation in the machine frame. When the X axis was moving the Y axis was binding and vice versa. Alignment and stiffening solved the problems.

Not sure if this is the problem here, but checking it doesn't hurt.

Arceye,

Sorry, I forgot to mention the controller is by Xylotex. See attached emc2 code.

Thanks

Hi

The code is typical generated, no spacing, unnecessary repeats etc but no use of cutter compensation, so that is out.

The points by DaBit are good ones, his first point was my next gambit.

The overcuts correspond exactly with the entry plunges at the start of the cut (and the retraction). The entry is preceeded by a 3 axis move to co-ordinates and the exit is a XY moving into Z



I have amended the code as per below.

I have introduced G61 to force exact path mode, broken the 3 axis moves with included spindle startup into a S18000 M3, then XY followed by a Z,
reduced the seemingly suicidal F508 feed for the Z plunge to F100 (this is used thereafter for cutting for now)
and spaced the code so you can read it!

Give it a try and see if it cuts properly.

If so you can add things back until it errors and you will get a good idea what is causing problems.

regards

Sorry, just got in. Thank you very for the excellent support that I am getting.

I will try this new code but I am a rookie on this. Where can I edit this code to add this statements?


Thanks

I will try this new code but I am a rookie on this. Where can I edit this code to add this statements?

The code has already been changed as I outlined.
Just cut and paste the code in the yellow code box, paste it in gedit and save as say test.ngc

Then run Linuxcnc and load test.ngc and try it.

regards

Arceye,

Thank you very much. Perfect outcome on circles and square. Now that you have solved the problem, how do I do this if I have 3000 lines of code ?

Regards

Hi

The gcode takes the strain off the PSU by only having a max of two axes at once operating.

The answer is not to change your gcode but to beef up your power supply.

As an experiment I ran my big mill with a 24v 350W PSU covering all 3 axes, the results were diabolical, could hardly move without losing steps.
My normal setup is a 76v 14A PSU for X and Y and 56v toroidal 8A PSU for Z

Difference, next to impossible to lose steps with the latter

regards

would it be okay if I change my power supply to 350 watt from 125. ( I am using xylotex (3) 269 oz stepper @ 2.8amp each.