Help - Current For Stepper Motor Driver AM882 - ProTuner

[PaulP]

OK lots of food for thought given here, thanks in advance for this help...

"Almost too hot to touch" is about right for steppers! Particularly if you also use the "half current when stationary" setting, I wouldn't worry too much.
Current sounds low - I think I run my 3Nm steppers at about 3.something amps on the "crank it up until you can't rest your hand on them then wind it back a bit" basis.

Originally they were set to 4A in ProTuner but I could have fried eggs on them as they were almost too hot to touch. I started to worry a bit which is why I reduced the PeakCur to 2A. At 2A they don't get hot which I thought was better but I now think that might be wrong.

Bit worried that you say you are using a series configuration. For best torque, parallel wiring is advised. As long as your PSU can take it (can supply enough current) parallel beats series hands down.

I've been debating whether or not to switch to parallel as it seems to be what everyone is doing with their routers. I got lazy doing the electronics as I started to get fed up so ended up setting each motor in series. I was mistaken at the time because for some reason I imagined all 8 wires on the motor had to go all the way back to the driver, ie using an 8 core 1.5mm2 cy cable. Each of my motors has a plug with 4 connections going to their respective A+A-/B+B- socket coming from the driver. To go parallel I assume I solder the respective 'spare' wires together on the motor plug. Is that correct?

As for the PSU it's a Leadshine 68v 500W linear PSU from Zapp. Since my machine has 4 motors in total if I changed the wiring to parallel would I need another PSU as I thought 500w/68v = 7.35A and if 2 motors in parallel are set to 3.5A each then my single PSU stated above would only be supplying enough for 2 motors. I'll get another 68v 500w PSU if needs be but wanted to check before shelling out again.

And if you are generating that much drag with the dust shoe, you need to do something about it! I've made mine adjustable by using a series of 1/2" or so plywood plates with small magnets glued in so I can easily adjust height to suit cutter length, etc. I managed to rip the bristle strip off mine recently due to a little accident and as a quick fix staple-gunned overlapping strips of plastic from an old milk bottle round the edge. Crude but effective! Strips are probably around 1.5" long to give flexibility when going over edges of work and so on.

I like that milk bottle idea for skirting it defo beats the tedium of gluing bristles into a channel. I did see that video on youtube of some german chap making one but he used a small metal tube squashed at one end to help with the fiddlyness of the bristles. Similarly to the milk bottle idea I was thinking of drawing up and printing some strips on the 3d printer. Maybe 2 layers of 0.2mm with a rim with holes for securing it.

Like Neal has said if they are 8 wire steppers then I would use them in a parallel configuration as you will get more torque.
I run AM882 drive on my router at 3. something A with twin screws and 68V PS. Steppers are happy at 60'C and above.

Would you recommend another 68v 500w supply for this setup?

Ok, this bit is a little confusing.? Are you saying the motors only have 4 wires or it's got 8 wires and your only using 4 of them.?

The motors have 8 wires but only 4 are in use, the other wires are soldered together in their respective pairs. I'll include a sketch but i think the A+A-/B+B- polarities in the sketch might be different as I can't see the motors at the minute.

If it's an 8 wire motor then you have it wired wrong which would explain all your problems, in fact, if I'm correct then I'm surprised it even works.

They do work but when I fire up their linear power supply you can hear a very slight whistling sound, it's high pitch and really annoying to be honest, when they drivers get the ENA high signal they switch off and go quiet. These motors were bought from zapp some years ago but I can't find them on zapp now so am unable to confirm the drawing is defo for this motor. The motors are labelled as SYS80STH86 - 3008BF. Do you hear any sounds from your AM882 powered motors when they are idle?

Here's the motor pic and what I think is the closest match to the spec sheet for them, the colours are in Hungarian but i translated them manually and they were the same colours. You can see in the pic that the white/coloured wires are paired together to get what you see in the sketch of the wiring.

Like Neale says the best way to wire the coils for a router is in parallel. then you would set the current to 4.2a in protune. When setting current always use the peak value.

So does the PeakCur box in ProTuner refer to the total amperage the driver supplies to each coil or to the motor? If a spec sheet says 2.5A or 4.0A per phase do I double that figure in ProTuner's PeakCur box? This is what I find hard to understand, If Leadshine stated that the figure was for each phase or if it was for each motor in total it would make it much less confusing.

What voltage are you running and what velocity and Acc do you have them tuned at.?

I'm running 4x AM882 drivers with a 68v/500W PSU (Leadshine) to 4x SYS80STH86 - 3008BF currently wired in series. As for vel/acc I'm running OK at 6000mm/min with 1200mm/s2 without stalling.


Thanks again chaps, I can see my soldering station coming out again soon but before I do that will I need another 68v linear power supply to deal with the extra amps required for parallel? I read many posts from those that went from series to parallel and have had better results but it was either laziness or amperage concerns that pointed me to wire them in series.