Help!!!

[Dodad]

Need some help with a problem. My Taig, Xylotex controller, Mach 2 software fed by Rhino and Rhino Cam, shorts the travel by about 1/16 inch per 6 inches. I've run 1 inch squares that turn out perfect, but when the X travels to the other end of a 6 inch piece I loose about 1/16 of an inch.

I'm kind of lost on this one. Any help would be appreciated.

Dodad

[Smertrios]

I can think of only a few things...

Can you move the table about 1/16" just with your hand?? If so I think you need to adjust the backlash and/or tighten the nut on the end of the screw a bit if the assembly is loose (was for the z-axis on my mill).

What speed is the table moving at? There will be resonance during rapid moves with Xylotex step motor driver which can be a MAJOR source of either huge numbers of lost steps during 1 move or a huge accumulative error that occurs as your cutting a series of parts either way its always bad. I am not even using my mill I got fed up with this open-loop system. I'm going to either get a servo system or geckdrive stepper system which has resonance dampening.

You have the steps per inch set to 32,000?

[Dodad]

Thanks for the reply.

I've checked everything it's all snug. I don't believe it's mechanical. It's set at 31000. This is the second computer I've put it on. The first ran at 32000 and didn't have any problem with size. This computer is slower and runs without lost steps. The resonance factor sounds interesting. The jog rate is currently 50% of max. I take you found no cure for the resonance disturbing problem?

Dodad

[Smertrios]

Set it to 32,000 at 31,000 it will cause the x,y,z axis to all be short by .015625 per inch.

[Dodad]

Thanks, I'll try it at 32000 again. But it ran large at it before. I'll let you know how it ends up.

[Smertrios]

Are you using the same tool as you used on the other machine? Maybe the diameters are different. Same toolpath? On the coordinate display there are scaling factors next to the X,Y,Z numbers that could be effecting the machine as well if they are not all set to 1.0

edit Any chance your path is using cutter compensation G codes? If so that could be another source of error.

[Dodad]

Yes it is using cutter compensation G-codes. It is the same tool. The scales are all set at +1.0 and the tool path is exactly the same.
I did reset to 32000 but have no information about it because my Y motor decided to take a trip on its' own.

It appears I may have more issues than I thought.

Again thanks for your help..

[philbur]

I don't understand how changing the computer would require a change in the steps per inch. Steps per inch is dictated by the leadscrew, steppper motor and driver and whether you have any gearing between the motor shaft and the lead screw shaft.

You need to calculate this then set it and then leave it alone.

Regards
Phil

Thanks for the reply.

I've checked everything it's all snug. I don't believe it's mechanical. It's set at 31000. This is the second computer I've put it on. The first ran at 32000 and didn't have any problem with size. This computer is slower and runs without lost steps. The resonance factor sounds interesting. The jog rate is currently 50% of max. I take you found no cure for the resonance disturbing problem?

Dodad