Need calibration help

[JasonCcnc]

Alright I have been working on my table for over a year now. It is finished and the cutting has begun. Now I have a new problem. Calibrating. The table is roughly 4 ft x 4 ft. All three axis were driven with a ball and screw system. My y axis was way too shaky because it was driven by one central leadscrew which didn't drive the gantry evenly. I scrapped the y axis and went with a rack and pinion drive system. Now, I can't tune my stepper properly because it needs to run slower than optimum speed and no matter how I try I cannot get the y axis to hold a decent tolerance. It is off nearly 1/4in over 9 inches.

On top of that my x axis I thought was calibrated pretty well but it is out 1/16in over 6 inches.

I am thinking I need to upgrade the linear bearing systems and possibly scrap the y axis again and change it to a dual lead screw system.

Where do you guys think I should look first to tighten this machine up?

[atwooddon]

Jason, would it be possible for you to post a few pictures of your machine and some close up views of your problem areas? That would help the gurus generate possible solutions for you.

thanks
Don

[zool]

Take a look at these videos. The combined knowledge in them will get you spot on!

‪Calibration of Linear Motion Systems Driven by a Stepping Motors‬‏ - YouTube
‪Mach3 CNC Axis Calibration Tutorial -- Neo7CNC.Com‬‏ - YouTube
‪Mach3 X axis calibration over 12" travel‬‏ - YouTube
‪Improved Mach 3 Axis Calibration‬‏ - YouTube