[routercnc]

Hi there,

First post at this forum because I'm having a problem with glitching on the stepper motors. I've lived with this for a year on my first cnc machine, but now I'm building a better one I want to get it sorted.

When traversing the stepper motors run smoothly, then periodically glitch or hesitate. I have carried out alot of tests, including sending the driver board (system3 all in one) for repair and being sent back a completely new board. This also glitched.

I then borrowed an oscilloscope from work, and the signal from the parallel port also has glitches, so it must coming from the computer, not the bits attached to it.

For example, my steps / mm is 320, traverse speed is 1500mm/min. This works out at 8000Hz or steps of 125 microseconds. The glitching varies but an example would be 3 steps at 125 microseconds, then a gap of 187 microseconds, followed by a few more at 125 microseconds. 187 = 125 + (125/2) so there is something odd going on.

So far I have:
Played with the pulse width, step width, traverse speed in Mach3
Disabled as many startup items on my PC as possible
Disabled parts of the computer not directly involved in machining (e.g. network card)
Uninstalled AVG virus program, and removed the internet cable
Made sure I have the latest video drivers
Ran the DriverTest program and all was well
Reformatted the hard disc and installed windows XP fresh, then Mach3

All tests show the same random glitching on the parallel port. Some people I've talked to have suggested going to Linux and EMC2, but I would like to stick with Windows and Mach3 if at all possible.

I can only think it must be a fault with the parallel port.

My PC spec is:
AMD Athlon XP 2600
1.5Gb RAM
128Mb GeForce FX5200 graphics card
MB Asus A7N8X Deluxe
160Gb HDD

Should be good enough for machining. Is there anything left to try?

Thanks
Barry

[Claude Boudreau]

When I first set up my cnc homemade router I almost gave up as I was loosing control of my motor current due to ground loop it seem.
The final solution was to isolate the computer ground and my control box ground. This can easily done with a piece of insulating material (acrylic) to mount the parralel port connector*to the control box.

hoping this might help you.