Problem- Calibration problem

[Bell 430]

Hello fellow chip makers
I just setup my Shopmaster Eldorado bridge mill after installing ball screws from shopmaster. there were a few problems, but there fixed now.
I'm running a liscensed version of Mach 3(Backlash not activated), I have Jenix DRO's installed and calibrated using two dial indicators
Heres the problem
If I give the command: g01 y-1 the table will move 1 inch +-.001
If I give the command G01 Y0 it goes to "0" within .001. I can get it to repeat this doing 25 cycles, BUT If I give the command G01 y-.5 the table comes up .008 short. If i command g01 y-.6 it comes up .004 short, if I command go1 y-.9 it is .001 short.
The machine does this no matter if it to the plus or minus side.
Any Ideas would be appreciated.
Thanks
Brian

[dgapilot]

Try running larger distances and see what it does. Then overtravel in one direction, then bring it back to the desired location and see what the delta is. Report back and we'll see if we can help.

[Bell 430]

dgapilot
Thanks it would keep increasing past the setting, eg 2 inches would become 2.034 and so forth, BUT I got it fixed. I E-mailed Dan Mauch at camtronincs. He said to set the steppers at 20000, then use the backlash feature of Mach 3, after doing this and adjusting the "Shuttle speed" it works PERFECTLY so as of right now, my 2007 shop master eldorado bridge mill now has .001 accuracy in the "X" and .002 in the "Y" and .001 in the "Z" with repeatability
of .001 after 15 cycles.
Thanks for the suggestion!
Brian

[wilsonrj22]

I'm a greenhorn just setting up my machine and wondered which menu in Mach3 you used to adjust Shuttle and what were the numbers for x, y & z. Thank you.

[Bell 430]

Hello
The screen is where you adjust the motor tuning, under "General config" at the top of the screen

Okay I fixed my problem, something I never thought of.
1 I put a computer UPS on the stepper motors
2. I shielded all the stepper motor wires in steel braiding
3 I grounded all the steppers together and to one central ground one the case.
Problem fixed!
I now have .001 on "X" .0015 on "Y" and .0001 on "Z" these have been repeated 25 repetitions!

Have a great day!

[Bell 430]

Okay after several more gray hairs, I started to do things which were way outside the box! I started by putting a UPS on the CNC side of the machine, low and behold, the "wondering" got better. Second I put a "Line Conditioner" on the plug coming from the UPS to the CNC, placed steel sleeving over all the CNC wires, and I grounded all the stepper motors to the steel shield and to the frame of the machine. I've been running like this for about three weeks, and so far things look great! I can give the command g01 x5, the result is x5.001, then if I command to x0 it comes back to 0+-.0002
If I give any "X" command it will come up within .0015. I can repeat this for 25 cycles, the "Y" and the "Z" are just as accurate. been a lot of work , but right now I'm HAPPY with my Shopmaster Eldorado bridge mill!