So now I'm more edumacated on steppers and drives, it's obvious that there will be resonance somewhere in the speed range unless using tunable digital drives. At 3x the cost of an analogue drive, I'm not so convinced that the digitals are worth the extra cost at the moment. No doubt they will become more reasonably priced when more people adopt them.

Since my last post, I have refitted the Y-axis motor and pulleys, belts and X table (with a 25Kg lump on top) so that I'm testing the motor under normal conditions. I then created a g-code file to test all feed rates from 0 to maximum velocity, increasing in 5% steps. This helped me isolate the speeds/frequencies at which resonance was most noticeable. Starting at 2 microsteps (1/2 stepping), I ran the test file for each setting up to 64 microsteps. The resonance band was tightest and least noticeable at 8 microsteps, so that appears to be the optimal setting for my machine. I also gave the machine a good hammering with randomly generated G0 codes (thanks Jonathon) at full speed and acceleration of 2000. The machine danced around a little due to the high inertia changes but the main thing is that it didn't lose any positional steps. I've now put the acceleration to a more sensible 250 to prolong machine life.

Now I need to stop farting about and get on with finishing the Y-axis before contemplating the X and Z...