stepper motors build up heat

A couple of my 5 stepper motors seem to build up a lot of heat, even when the machine is idle.

Is this normal or have wired up something wrong.

Any thoughts

Thanks

Arnnie

Edited 1 time(s). Last edit at 12/07/2011 07:16PM by Arnold Lane.

HI Arnold,

Stepper motors do get pretty warm. Even hot to the touch under a lot of use and load. But you can calm things down a bit by backing off of the current to them. If you have the pololu stepper boards, there is a pot on the board that allows you to adjust the current to the steppers.

Rule of thumb, if you can put your hand on the motor but have to remove it, it's hot but not too hot. If you can't touch it without being burned... probably a bit too hot, back off on the current. If you can keep your hand on it... you're fine.

Regards,

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

If the motors are enabled they will still get hot even when not moving. Mostly the Z axis is the only one that is disabled between moves, and the others are enabled all the time unless you specifically disable them. Depends a bit on firmware and electronics. If you can turn the motors easily they are disabled, if not they will heat up. Not a big deal unless they overheat, and the drivers should be set to prevent that.

Thanks very much, that explains a few things nicely.

I've wondered how necessary it is to lock the x and y motors? If microstepping them requires it or if the drag of the belts would keep them locked enough?

Microstepping requires it to hold position, otherwise the motor snaps to its detent position. Also vibration and nozzle pressure would move one axis while the other was moving.

I keep all my motors energised throughout the build. I think disabling Z is a bad idea. I disable X &Y at the end of the build to allow me to move the axes by hand.

---

[www.hydraraptor.blogspot.com]

Rule of thumb... never rely on friction for anything except rug burns. Microstepping is an in-between step. If you are between steps and turned off the motor, it would cog back to it's closest step. Designers of stepper control boards often build in current reduction when steppers are stationary. This accomplishes exactly what you are referring to without undue heating. I do not know if this is designed in to these small stepper controllers that we use... it might be. Anybody?

Steppers by design give zero positional feedback. Once they loose position, they stay lost until the controller sends them all "home" again. (You can buy encoders that attach to steppers that give positional feedback... but the steppers themselves have none.)

If like most of us, you want your printer to print the best that it can, keep the motors turned on when idle. Never let them loose grip on their position. You'll be the happier for it.

Best regards!

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

OK theoretically yes, but practically would it really make a difference to let Z lose or gain a half step per layer? (everybody's doing it I currently have my Z axis set to half stepping and I need 283 steps (half steps) per mm. So to lose one half step will kill the accuracy of my layer height by +/- 1/283 of a mm or .0035 mm. That's about 1% error for a 0.4 mm layer height and 2% for 0.2 mm height. Are you really going to see a noticeable difference in prints? (Think of the trees and puppies and kittens and snails and such that are being ground up and burned for power right now because of your profligate waste. I can see the other axes needing to be locked all the time, but Z seems like one you could disable when not in use unless you are doing .01 mm layers like some of the bleeding edgers out there.

@Ross: Stepper drivers are mostly based on Pololu/Stepstick drivers that have only one enable signal. Motor is either energized or not. There is not a position holding state different than the enable state.

Heat builds up proportional to the current through the motor coils. Steppers should be operated with the lowest current possible (that does not compromise its task). This way you will get as low heat as possible.

On the other hand, some slicers (I know Slic3r does this) will send a "disable motors" command at the end of the print, and this will let motors to cool down when you are not printing.


misan

Thanks Misan... I suspected as much. And I agree Brian, it's probably not much error to worry about. Still... I think homing before print and staying energized through print to keep track of steps would be my preference. Turning off after print sound fine.

Regards,

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

The toshiba driver aka47 is using has torque control. It uses two control lines per driver to set 20, 50, 75, or 100% torque. For Z you might just use one pin to control both lines and get either 20 or 100% torque. I'm not sure how useful it would be for other axes though since they're almost always moving.

Thankyou!!!

I've been struggling to get things sorted on my machine with inconsistent results which really throws you when your adjusting one param at a time and yet nothing seems to be fixing it. Read this thread and remembered I'd set my motors to power off at idle. Set them on again and things are much much better.

I had an issue with my x axis stepper motor heating up while idle with the motors on and I tuned the amps down to under half and still no change... the one thing I kept wondering is if the polarity of the motor wires would make a difference even though some of the videos on steppers says polarity doesn't matter HOWEVER I switched one pair of wires and the heat buildup went away. I will keep my eye on it and if anything changes I'll post the results

Oh one thing I didn't mention is that my one issue now is that there is a wobble effect in my X axis from what i can tell. My circles are not quite round and smooth. I did have the X axis off of the 90 degrees from the Y. I straightened that by eye for now as I have a few parts to print to make some modifications. This is a home built printer running marlin on a ramps 1.4 board being driven by Pront...

Miles of Smiles
Pete

I don't know what you did, and I don't know where you saw that polarity doesn't matter, but it is extremely important. The polarity of the two windings relative to each other determines whether the motor will turn at all, and the polarity relative to the driver determines which direction it will turn. How many wires are coming out of your motor?

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Yeah I found that out 5 minutes after I posted that. The motor heated up once more.. then another print it wasn't hot at all.. I'm a little confused as to what's going on. I guess it might be the motor as I switched the X and Y wires and the same motor heated up but now on the Y axis. As long as it doesn't catch fire I'm good =)

I have the 6 wire Nema 17's, but only 4 are used. All the wiring is correct except for maybe polarity I guess.