It's the same PC that I was using when I had my 3' x 4' screw drive system and never had any problems, Accuracy was perfect. Basically, I'm using the same PC, motors, drivers, power supplies as I was on my smaller system so the problem should be mechanical I would think. I'm thinking it must be the motors, drivers, or psu's. I've already checked for slippage, backlash and freedom of movement and all those check out ok.
Again, even though I may be under powered, I have not seen or heard any stalling, even running at 400ipm - something is happening on a much smaller scale. I'm still getting measurements that are .01 to .02 off when cutting parallel lines but the errors are smaller at much slower speeds.
Any other thoughts? Thanks,
Jon