Yes 250mm/s^2 is low but as i was having so much trouble getting it to move smoothly at all i figured its best to start low and work my way up. it seems to tolerate 1000mm/s^2 quite well as i ran it through some of my 3D
tool paths yesterday without the spindle attached at 5000mm/min and it didnt seem to have any problems (the test will be in a week or so if it can actually cut at these speeds)
the 40 tooth test gear i bought was made of alluminium so the weight was well dowm but when i went to order them i found that they were not available in ally in HTD.
i have cut the boss off the back of them to suit the lenght of the Translock mini locking bushes im using to hold them to the shaft. (iv marked them up to see if they slip but they shouldent as they are rated at 39Nm wich is over 4 times the torque the motor can give out)
The 75v power supply is at the top of my "to buy asap list" and has been for a while (since i ran the numbers through the motorcalc spreadsheet.
Thanks for the link to the random G-code spreadsheet that helped no end to see just where some tight sopts were.

one of these days im going to get out of my shed and into the sunshine!!!