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Author Topic: Motor Sound and Motor Temperature  (Read 2633 times)

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Motor Sound and Motor Temperature
« on: February 20, 2018, 12:19:23 AM »
Greetings!  I'm new here and eager to learn.  I have a router I bought ten years ago, never mastered g-code, gave it to my grandson, then retrieved it recently.  I'm doing Fusion360 for a 3D printer and think I can generate g-code for the router.

My router has kl23h276-30-8b motors and I'm getting it to run well, I think.  However when doing a lot of stepping the motors get hot, about 175F 80C.  Is that normal?

Also, when the router stops the motors sometimes are still making a noise, pretty low, but I have to turn the breakout board off to get them to stop, or step them manually to a different location.  Do I have a configuration problem?

Thanks in advance for any help.
Re: Motor Sound and Motor Temperature
« Reply #1 on: February 20, 2018, 01:11:36 AM »
yes it is quite common for steppers to get hot, 80 degrees C is on the hot side. Many drivers have the option to set the output current.
Its never advised to set for more current than the motors rating but you can set less. To reduce the current to about two-thirds or maybe
three-quarters of rated can markedly improve the cooling situation without unduly affecting torque.

Another common feature with stepper drivers is the ability for the driver to automatically reduce current if the motor is idle. The holding torque is such that at
idle there is ample torque to keep the motor in location. it is possible to reduce the current, usually to a half and reduce the heating.

Even at idle there is current in the motor and any variation of that current can produce noise. At full step or half step at idle I wouldn't expect any noise.
With microstepping there could be a small fluctuation and noise as a result. I still would expect no more than low hum, louder than that may indicate a problem.

My wife left with my best friend...
     and I miss him!
Re: Motor Sound and Motor Temperature
« Reply #2 on: February 20, 2018, 08:57:17 PM »
I am always surprised about reports of motors running hot.  My steppers barely get warm and they are running from a 68 volt power supply.  However I have Leadshine digital drivers so maybe they do a better job of controlling the motor current.  I do have them set for half current when idle but sometimes a program runs continuously for several hours and the motors never get at all hot.
Re: Motor Sound and Motor Temperature
« Reply #3 on: February 21, 2018, 12:42:06 AM »
I run 23 size Vexta 5 phase steppers through low lash 10:1 planetary gearboxes. The gear reduction means I get great thrust and torque but fairly slow, and to make
up I run the steppers as fast as I can without losing steps.

The Vexta stepper drivers are powered direct from the 230V mains but the DC link voltage, that is the peak output voltage, is just over 150V and consequently
I can get them to run nicely at 2400 rpm. The rated current is 1.4A, but remember there are five phases as opposed to the more regular two phase steppers, so
is probably equivalent to about 2.5A in a two phase stepper.

I've found that at 1.4A the motors get uncomfortably warm when in active (highly active) service. I've reduced the current to 1A and found that even when working
flat stick for hours at a time they run about 60 degrees C. I've stuck a couple of aluminum heatsinks on each motor and have reduced the running temperature to about
45 degrees C.

I can only assume garylucas has very generously sized steppers that he can run without any heat build up.

A high voltage driver pays real dividends when trying to get a stepper to go fast without losing steps but is not responsible for heating. That is all about current.
Peak current determines peak torque, clearly any reduction in current reduces torque as well...not desirable but the heat build up is proportional to the
square of the current so even a modest reduction in current can help in the heat stakes.

My wife left with my best friend...
     and I miss him!
Re: Motor Sound and Motor Temperature
« Reply #4 on: February 21, 2018, 01:52:08 PM »

I tried to find my motor current but couldn't figure it out.  Is that Mach3 function or in the breakout box?

I did make a five minute engraving run and the motors were barely warm so the hot temperature may have been sitting idling and I'd like to reduce the amperage.
Re: Motor Sound and Motor Temperature
« Reply #5 on: February 21, 2018, 04:58:12 PM »
My motors are 980 in/oz nema 34 size and also low inductance. However steppers are constant power motors, they use the same amount of power whether loaded or not. So I wonder if the low inductance means less of the energy lost as heat.
Re: Motor Sound and Motor Temperature
« Reply #6 on: February 22, 2018, 01:22:34 AM »
Hi garylucas,
according to physics inductance does not dissipate energy. Low inductance means a low number of turns in a winding and with a low number of turns you have a
lesser length of wire to complete the turns and can use wire of bigger diameter. Low inductance tends to go hand in hand with low resistance.
According to physics resistance is the only circuit element that dissipates energy. Your low inductance motors are probably low resistance types and consequently
run cool.

To OP, no, motor current is a rating determined by the manufacturer of the motor which is in turn determined by the physical properties of the motor.
Some manufacturers will tolerate running their motors hot in order to maximize the current and therefore torque to appeal to the market. Others favour
a more conservative rating which will see their motors run cooler but probably with a little less torque.


My wife left with my best friend...
     and I miss him!