Leadshine AM822 drivers purchased!

[Agathon]

Thanks for all the advice from members of this forum. Finally bought 3 AM822s - http://www.ebay.co.uk/itm/330782929553 - worked out at about £62 each including UPS shipping (one week) and VAT etc.

Very pleased with these except that they're not driving the direct coupled Astrosyn Nema 34 4.8Nm (8 wire series connected) motors above about 500mm/min terribly well. Plenty of torque at low speeds but losing steps at anything over 500mm/min on the X-axis. This is a very high quality Swiss made mill-drill with 4mm pitch ball-screws and coated cast iron dovetail slides - the coordinate table weighs in at around 100kg. The machine specs state that the maximum rapid traverse was 4000 mm/min. The original motors were massive Superior Electric 11A 2.1Nm jobs, so the Astrorsyns should be up to the job.

The motors have a nameplate current of 2.8A. The best match to that on the driver is 2.57A. They do perform better at the next setting (3.29A), but they get too hot to touch (just warm at the lower setting).

I've got the micro-steps set to 32/6400 and Mach3 set to 1600 steps/rev which seems to give reasonable smoothness.

I'm using a 36v 9.6A switch mode power supply to power all three drivers. I suspect that this is the weak point and that 60 or 72v supply would improve higher speed performance.

Any observations welcome.