The X axis would need to be geared to the Spindle to try doing something like this at all.

Dan

Set the machine for the CORRECT calculated steps there is NO way around that part. The error you saw after that was probably servo error due to poor tuning.

Servos HAVE to be properly tuned  or else you suffer servo following error.  You may want to find a CNC repair service in your area and have him tune the servos. It has to be done ON the machine and you  should have a small load on the table when tuning. Once it is tuned correctly write down the PID numbers for reference.

I believe that screw mapping is the least of your problems at this point.


Just a thought, (;-) TP

My maximum occurred error after tuning each axis for a whole days was 5 encoder counts.  Z is more like 15, but my parts come out to like about +/-.010 with about 80% of the parts being within .001".  Far from what a machine with NSK ball screws barely used ways and good spindle bearing is capable of.   

It is NOT about encoder counts as much as it about precise control of the servo. A loose tune and the servo will never move up to the precise position and a overshoot condition will drive the servo PAST the position then back it up. Are you tuning with a scope? perhaps with a ball Bar tester?

Mach3 is far more precise than most machines can deliver.

Just a thought, (;-) TP

I don't have a scope attached, but I am using teh servo config software that came with eth dugongs.  Like I am saying, it can barely be over shooting if  my maximum occured error is 5 encoder counts.  Wish I could tune with a linear encoder.  I have yet to remount all my components in teh cabinet to separate 130 VDC signals from control signals.  I also have to ground my input /signal cables and have my servos reconditioned.  Then I will retune and see what I get. 

Tuning without a scope to SEE what you are doing can be a nightmare. Some can do it by ear(after doing many hundreds of them) most cannot.

Also the tuning is done ON the machine with a light load on the table. You cannot properly TUNE a servo sitting on the bench.

The ball bar test verfies the actual movements of the machine. IF this is a large machine it would be money well spend to get a CNC tech to TUNE them for you. AND you watch the process 1 time.

(;-) TP

You familiar with teh servo config program for teh Dugong drivers?  It gives you a chart that shows how much overshoot, settling time and what your trailing error is for your move.  Its better than tuning by ear.  I can not seem to find a CNC tech anywhere in my area.  Orlando FL. 

Hell that's Terry 

He told me he doesn't do that anymore.  He doesn't even have his equipment. 

Try searching for CNC machine repair , Orlando Florida. I found several in the area.

(;-) TP