Quote Originally Posted by handles View Post
Thanks Jazz, that is very helpful.

I retrammed and recalibrated the X and Y/A axes, and could find no discernible backlash. It is basically an Avid replica with their Rack and Pinion drives. Perhaps my measuring tools are just not accurate enough, but I managed to get an acceptable result by adding 0.15 mm backlash compensation to the X with a compensatory acceleration of 20% extra (600mm/s/s/).
I set the max Velocity at 5000mm/m and Acceleration at 500mm/s/s on a small item profile.

The maximum before lost steps is actually 21000mm/m at 1000mm/s/s acceleration, but I would have to bolt the table to the floor to run at anything like those speeds with a gantry of around 80 or 90kg total. Seriously powerful motors those Lichuan Nema 23/24s. Thanks for the recommend on those btw.
Well first off 600mm/s/s is low, I'd at least double it, this will help straight away with reducing ovals if it's an IJK issue. However, R&P can be a pain in the arse regards getting the gantry square if the linearity of the racks isn't spot on, esp on a wide machine like an 8 x 4. So are you sure the gantry is spot on square.?