This is my first posted question here!
I have built myself a router/plasma gantry using Mach 3, Gecko stepper drives, Bob Campbell's breakout board and size 34 steppers.  The problem that I am having is that Mach 3 is loosing the location of zero or I am missing steps.  This seams to happen on rapid moves only. It doesn't matter if I am using the router or plasma or pen tool, when the tool is under load or not.  So when I am using the router and doing a rough pocket opereration, the step-downs "shift" in usually one direction and my offset zero is altered on the X or the Y.  This will happen during an operation.  This also happens when I am using a pen tool or plasma torch and closed shapes that are nested together are shifted apart.  The shapes are the right size just not the right distance apart. Is this happening because I am using an older and slow computer? I have nothing else running on this computer so I know that it is not another app.  Has this happened to anyone?
Thanks,
Eirwin

Hey Erwin,
     It sounds like you are loosing steps.  Have you tried slowing things down in motor tuning to see if it helps?

Brett

I have the motors set to about half way on the setting.  I set the motors so that they sounded good when jogging.  If I set them lower, It might be real slow but I will try that. 
If I get a faster computer, will that effect this problem if in deed my motor tuning needs adjustment?

EIrwin

Eirwin, I have sent you a personal message.

Nope, if your motors are trying to go faster than they can or have a tool load that is too great, it will miss steps no matter how fast your pc is. What are the specs on your PC? What are your steps per set at? If you will post your xml, we will try and look at it.

 
Brett

I responded to your personal message but I don't think that it went through the first time. 
I am using an older Dell with a Pentium 3 in it.  I have got my steps set to 2546.5376/inch and my velocity set to 300.  My stepper is driving a shaft and on that shaft are a set of timing belt pulleys for each side,If you are interested, I can upload a picture of it.

EIrwin

A pic of your setup would be good, also any other details such as pitch of the screw, any reduction you have in the timing pulleys, motor size.
Hood

also try making the step pulse longer... I have seen that fix problems like this