Y axis problems

[ranchak]

I have a series I ridgid ram that appears to either be loosing steps or has excessive backlash. I'm not too sure where to start. I am machining multiples of the same part, but the inconsistencies vary. One part will be off on the "top" of the part the other on the "bottom". I attached some pics to show the problem. It's hard to see, but in the first picture the bottom is smaller than the top and in the second the opposite, the top is smaller than the bottom.

[ranchak]

Here's some further information. I removed the drive belt and installed a dial indicator on the y axis. I then moved the axis and compared the dial indicator reading to the DRO in Mach, typically I had about a .0003 - .0006 difference. But the difference didn't compound, meaning it didn't keep adding up, the axis was always within this difference. Of course I wasn't able to see what happens when the table moves a few inches. I am wondering now if maybe my motors are loosing steps?

[machintek]

I would think that most issues with losing steps is during rapid. This because of the acceleration demands. I would check the DC fuse for any corrosion/resistance. I would make sure that the static current is set to 8 amps. These motors are old. They get weaker with age and heat.

George