[JoshNZ]

Hi guys,

We have a little 600x900 hobby CNC machine, have run it several hundred hours no troubles over past 4 years. It has probably not been used a year but I have blown the dust off it and gone to run a small job today and the X axis is moving at 1/5th the distance it is being commanded to.

Jogging is 1/5th the speed, 1/5th the distance (readout says 500mm for a 100mm physical movement), jobs are cutting scaled 1/5th their correct width. They are open loop steppers but never missed a beat before.

I have actually fixed the problem by changing the steps per mm in configuration to 1000 instead of 200 as they should be, and were, and what the Y axis is set to - which is still working correctly.

Bit of a strange one, is there anything else I've overlooked? I don't think Mach3mill will have been opened since the last job the router ever did, nevermind settings changed. Scaling beside axis are all set to 1.

Thanks in advanced of course!
Josh

[joeavaerage]

Hi,
have you got a G51 Gcode scale active?.

Craig

[JoshNZ]

Hi Craig,

I wouldn't even know how to set that up so unless I've done it by accident, no.

The machine is producing this problem without any G code loaded in mach.

I.e. If I zero X, Y, and Z axis, then set X axis to 500, then hit Goto zero, the spindle will shift 100mm.

The Y axis will move correctly.

With the X axis setup to 1000steps per mm however it does so this correctly, so somewhere 4 out of 5 step signals are dissapearing.

[joeavaerage]

Hi,

that sounds like you have a G51 active. Read up on G51. G51 scales one or more axes while a G50 cancels all scaling.

With the X axis setup to 1000steps per mm however it does so this correctly, so somewhere 4 out of 5 step signals are dissapearing.

No, I disagree. Aside from anything else why does it just happen on the X axis, a fault like your describing would occur on other axes as well.

Craig

[joeavaerage]

Hi,
another possibility is that one of the microstepping switches has changed or failed, so the stepper now requires 1000 steps rather than the 200 you had originally programmed it.

Craig

[JoshNZ]

I tried adding G50 to the init string in Mach3 which produced no change. I haven't been able to find anywhere else I'd be adding a G51 code, as I said I have no Gcode loaded and I can't find anywhere else it would be implemented so to speak.

I don't know anything about the microstepping switches I don't think I've ever opened the control box. Is there firmware beyond mach3/usb cable with a bit register that could have become corrupt or something?

Before I dig any deeper I'll run it from another computer, we have two PCs setup to run it and one is away for the week, I'm wondering if it could be USB driver nonsense also. Will report back..!

[joeavaerage]

Hi,
I'm guessing from your name that you are in NZ? I am in Christchurch.

Craig

[JoshNZ]

Yep Tauranga here.

I tried our second machine today and same story, hasn't been opened in a year or so and no settings changed, and X axis is slow.

Must mean there is something wrong with the motion card or onwards? Where are the microsteoper switches you mentioned are they hardware?

[JoshNZ]

I ended up swapping X and Y drivers and the problem followed to the Y axis. I swapped back and cycled all of the dip switches on the X axis and the problem has dissapeared. Thanks for your help!