Are the Zapp 3NM steppers good with their PM-752 drivers?

[irving2008]

Those 3Nm motors you sell Gary will do fine for this application at 60 - 65v with no meaningful loss of torque as even at 60v the corner speed is 850rpm so he'll still be in the flat region... in fact it would still just be ok at 48v but I wouldnt go any lower than that..

[Jonathan]

Those 3Nm motors you sell Gary will do fine for this application at 60 - 65v with no meaningful loss of torque as even at 60v the corner speed is 850rpm so he'll still be in the flat region... in fact it would still just be ok at 48v but I wouldnt go any lower than that..

Didn't see this before I posted. I'll probably use 65V then. If I use the microwave transformer it shouldn't be hard too wind it accordingly...

[Gary]

The PM752 is running low, but have about 15 in stock and another 100 cominig in in about 2 weeks.

[Jonathan]

I've been waiting for money to transfer to my bank account from paypal. I didn't pay with paypal directly as I don't think it's fair to make a website pay paypal fees when I can pay using a debit card. Now I've just found that the stepper drivers have gone up from £44 to £50 today :( Now I've not got enough pocket money...

How much difference will getting the PM542 and running the lower voltage make?

[Gary]

The price has gone up because of the exchange rate, out of my control im affraid.
have a look at the torque curve in the datasheet, and this will give you an indication of the difference in power.

[Jonathan]

My mum lent me £20 so I was able to buy them on Friday :).
Order was dispatched on Monday and arrived yesterday - excellent service, thanks!

Been doing some testing...
I've not got round to making pulleys for a 1:1 ratio, so for the moment the closest I can get is 22T on motor, and 42T on screw.
The motor stalls above 1250rpm (no load), yet it still has enough torque to drive the X-axis at 25mm/s (1150rpm). Trying higher feed-rates than this gets a bit dicey.
I think this means that if I put a 1:1 ratio, then above 25mm/s is almost certainly attainable since the motor will only have to run at 600rpm to get the 25mm/s. Having said this the current speed is pretty scary! I had to put a lot of tension in on the belt to stop it slipping.

Currently I'm using 1/4 microstepping. I've tried 1/8 but it doesn't seem to make much difference. What do you recommend I use? The computer I'm using is only 1.4ghz, this might be a limiting factor? I'm using Mach3 at the moment, I intend to change to EMC.
Also, I've set the port frequency setting in Mach3 to 25Khz. I tried 35Khz but it seemed worse, should one be better than the other? I've set the pulse width to 5us, is there any reason to change this? I guess not unless I start using 10000pulse/rev...

Thanks for all the advice so far.

[Jonathan]

Oh one thing I forgot to mention...I measured the current into one driver (using both an ammeter and a shunt resistor) and when idle it's about 0.3 amps. It goes up a bit when the motors running, but either way that seems a bit low to me? I've got the driver set to 4.09A peak, I take it this is correct for these motors in bipolar parallel? The motor is only a little warm, nowhere near 80°C.

I'm currently using a 225VA toroid for just the one motor. There's no perceivable temperature rise on it so maybe I can run more than one motor from this transformer?