oh man ...
Hood thank you anyway for trying to help me.

.....

Something which you can try is to put a dwell every so often in the code.
Maybe every 100 lines just add a G4 P5 ( the 5 in P will cause the axis to stop for 5 seconds).
The intent would be to find some code or spot which is causing the burp when machining. Radom stuff can be hard to track down and
this just may narrow it down to a combination of code which can be repeated and thus give you a hint on were or what to look for.

It would be nice if you had a digital display such that you could compare that display to what Mach DRO is showing.
That would show if it is somewhat progressive leading up to a something.

It possible it would be interesting to try swapping the axis around ie; Since it skips on only the x or Y ....let the Z move in place of the X & Y and see what happens.
Another way ,which is may not be an option, would be to run the code on a different machine using the same controller and see if there is any problem.

You are using backlash compensation....correct?

RICH

OK let's step back and start again.

IS this a laptop computer?

HOW are you determining that the XY are loosing steps?

(;-) TP

BR549,
Normaly you know if the steppers have skipped as your can hear it and know you have lost position or steps.
Sometimes the axis will go off on it's owne, but, what i have found here is that when doing small numerous moves that you can loose steps and not hear it
or know about it ( which really supprised me). Mill here never missed a beat in years until i tried doing 3D contouring with it. I think i have figured out my
mills problem but will not muddy up this thread with it. There have been about 3 posts from folks with similar problems in the last six months when they are
contouring something.
RICH

OK let's step back and start again.

IS this a laptop computer?

HOW are you determining that the XY are loosing steps?

(;-) TP

I'm using PC with pentium 4, 2Gb RAM.
if you check my prev. there is a photo of how I find out loosing step. it's a radial cutting with Z depth.
it's a radial cuttingl for half sphere shape.

Something which you can try is to put a dwell every so often in the code.
Maybe every 100 lines just add a G4 P5 ( the 5 in P will cause the axis to stop for 5 seconds).
The intent would be to find some code or spot which is causing the burp when machining. Radom stuff can be hard to track down and
this just may narrow it down to a combination of code which can be repeated and thus give you a hint on were or what to look for.

It would be nice if you had a digital display such that you could compare that display to what Mach DRO is showing.
That would show if it is somewhat progressive leading up to a something.

It possible it would be interesting to try swapping the axis around ie; Since it skips on only the x or Y ....let the Z move in place of the X & Y and see what happens.
Another way ,which is may not be an option, would be to run the code on a different machine using the same controller and see if there is any problem.

You are using backlash compensation....correct?

RICH

adding G4 and P5 ... that's a lotta adding on my 30.000 lines.
but for sure it's loosing when cutting radial (XY) with Z depth for "half sphere" cut.

Yes it would be nice to have a digital display.

I don't think a good idea swapping the x to z axis, since it's different lead on my ballscrew, course I can change that...
but I just don;t want to.

I would like to try to do it on the other machine, but I don't have anyone I know who has this kind of machine.
I know commecrially and I'm sure they will laugh at me.

no I don't use backlash compt.

do you guys know how long I built this CNC Router with my own hand ?
14 months, I built from scratch, welding, soldering, etc. done on weekends.
it's about 1 meter square travel on XY and about 40 Cm Z travel.

thank you

Rich,
you said there are 3 people having the same counturing problem.
did they solve the problem ? or they just like me now  ... ?

I wonder when Mach4 upgrade release ?

The problems "seem" similar from my recollection.....and don't remember some specific resolution of the problem.

RICH

I'm with Terry here when he says:

HOW are you determining that the XY are loosing steps?

I've just read the whole thread again and there is abosultely nothing here that SHOWS us that it's X/Y that is losing steps. You MAY be right, but the way I read this it looks more likely to me that it's Z.

BTW - did you change the step pulses for Y and Z to active low?

Ian

I'm with Terry here when he says:

Quote from: BR549 on January 12, 2011, 10:28:54 PM

HOW are you determining that the XY are loosing steps?

I've just read the whole thread again and there is abosultely nothing here that SHOWS us that it's X/Y that is losing steps. You MAY be right, but the way I read this it looks more likely to me that it's Z.

BTW - did you change the step pulses for Y and Z to active low?

Ian

when I see the result of cutting sphere, the Z depth cut is exactly in the right measurement.

yes I did change Y and Z to active low.

when I see the result of cutting sphere, the Z depth cut is exactly in the right measurement.

I'm not sure what you mean by this. If when you've finished you have a "ding" in the surface of the sphere, how do you know whether it was X/Y or Z?
i.e. if you start at the pole and XY takes you radially to the equator as Z descends. THEN if X/Y miss steps then "correct" Z movement will cause the ding. BUT if X/Y move normally and Z erroneously drops you'll get that same ding.

I'd suggest you arrange a datum somewhere off model for XY and Z, do your job and return to datum. Try this both for real and in air with spindle off.

Ian