[cooperman435]

Hi all. Im new to CNC so my apologies now for any noob mistakes but this one has me stumped now.

Ive recently purchased a converted Denford (believed) micro mill, it was allegedly working fine when used by the last owner but I'm doubtful!

Ive rewired it all and neatened up the snakes nest of a wiring loom it had to isolate the issue but it is exactly the same as before so it would appear that was not the issue.

I have an after market control board (which I'm currently waiting for details on) rated at 12-36v
24v power supply
PK266 E2.0A motors (standard from the original machine)
running MACH3 (allegedly licensed but will only run 500 lines of code)

I'm reasonably tech savvy but cannot fix this issue so am finding out if anyone can even suggest an avenue for me to investigate please.


When using the jog function as full speed I now have the motors / axis running smoothly, no jerkiness or sticking. BUT when running a program as the axis move at much reduced speeds it appears to be loosing its 0 positions.

If i reduce the jog rate to 5 or 10% and then index along them there is an audible "jog" in the normal smooth running of the motor and the carriage stalls for a fraction of a second loosing position.

Ive tested this by doing three things.

1: Zeroing the machine to a point and then jogging it round for ages at full speed, when told to return to zero it instantly goes back to the exact point it is supposed to. Success!

2: doing the same at 5% or 10% jog speed which results in it returning close but definitely not perfectly to the position it should be going to. each time its results are different

3: running a program and then running it again, this results in the second cut being slightly off from the first and if I do it again the result is a third set of cuts differing from the first two.

All axis seem to be loosing settings at slow speeds but especially the vertical z axis which usually gets shallower and shallower the longer a program runs.

Any comments are very much appreciated but please excuse my ignorance of terminology right this moment I'm learning as fast as I can :-)

[Flateric]

I've had this problem myself on two different occasions and had two different solutions.

Like you I went through all the wiring and cleaned it all up but found it did not change anything other than possible future issues related to the messy wiring.

On both occasions I did the exact same tests with jogging and moving around at full speeds, then sending the return to home which worked perfectly. With the same result when slowing the jog speeds that you are seeing.

The solution the first time around was for me to fit chokes to my wiring as described on the gecko drive page....

RF Interference - Step Drives - Application Notes - Support

This cleaned up the signal and my lost steps or added steps went away completely.

The second time around it was my power source which was plenty up to the task of moving 1 axis or 2 axis at a time while testing, but when running a program and all axis were being called on at once only occasionally would it fault and things went bad. The only happened after the program was a fair bit into it's run after say 15 or 20 minutes.

Not sure if these are your issue but hopefully you can get it figured out. Frustrating as all hell I know when you are in that situation.

[cooperman435]

Thanks very much, I rewired with 4 core and fastened the shielding to earth already, not five core admittedly but if the problem manifests still Ill try that too.

I doubt it can be the power supply as the problem happens during single axis jog even alone

In the end I found another post that suggested switching to 1/2, 1/4, 1/8 or 1/16 steps and by using 1/16 the problem SEEMS to have stopped, but I assume that if it was still there that errors would now be 1/16th of the size?

Ill try the chokes anyway to try n help in either case!

[Flateric]

I wish you good luck man, it is very frustrating fighting with issues like this. Intermittent issues are my most hated problems to solve.