Hi All...

Have been testing my new cnc router under full speed in all 3 axis, individually and all together.. Runs sweet and goes round and round to stop bang on where it starts.. My dial clock cant measure any slop at all..

2 x nema 34 on x axis (5.5Nm) (800 microsteps)
Nema 23 3Nm y axis (800 microsteps)
Nema 23 3nm z axis (800 microsteps)
System 3 board using onboard drivers for the z and y
PM752 drivers for the x axis, wired step and dir together into the 4th axis off the board.
Separate power supply for the board (24v from Roy, Diycnc), and one for the nema 34's (from Jonathan (nice one)).

So ran a small v carving code on it and ow..! Lotta noise from my motors which are juddering and losing steps.. The slower I run it, the worse it gets.. Spin it up to full speed and it runs very smooth with no loss of steps, dial the jog (Mach3) down to 5% and the z and y judder and lose steps big time.. Seems to halt for a moment every 1/4 turn.. The nema 34's seem to rum fine at any speed..

Have spent the day changing the Mach settings around to alter speed and acceleration, kernal speed, and everything I could think of but nothing makes any difference.. I have read quite a few posts relating to similar problems but cant find anything that I either haven't tried, or applies to this..

Anyone had anything similar happen? Just read a post about psu's so am going to see if I can dial down the power a little for the system 3 board (which powers the z and y).. Will welcome any and all suggestions as have little hair left to pull out now..

Thanks
Steve..