Group: DynoMotion	Message: 12856	From: semperfikurt	Date: 2/25/2016
Subject: Stepper Heating and Eventual Stalling/Skipping

Attachments :

I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?

The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.

Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Thanks!

@@attachment@@

Group: DynoMotion	Message: 12858	From: Tom Kerekes	Date: 2/25/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping [1 Attachment]

Hi,

Looks like the current should be 2.1A. About 8Watts of heat due to resistance. What current are you driving them with? What type of drives? Steppers normally run hot whether they are moving or not. I think up to about 70C is normally ok. High drive voltage causes higher current ripple which also adds significant heat. Do you have any heat sinking?

Over current and over temperature may have damaged your motors by demagnetizing the magnets.

Regards
TK

On 2/25/2016 4:41 AM, semperfikurt@... [DynoMotion] wrote:

I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?

The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.

Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Thanks!

Group: DynoMotion	Message: 12859	From: kurt huizenga	Date: 2/25/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

I am running them with a 48V power supply through a KSTEP, with the jumpers for 1.88 Amps. At first I had them set at 2.5 but noticed I had it wrong and changed it however, the problem persisted afterwards. I could feel the steppers with my hand and they were pretty hot, but not too hot to touch. I could always tell when they were about to miss a step, they would have a hissing whiny sort of noise first then "clunk-clunk."

I had thought about adding heat sinks, right now I am not using any. I have read some articles online about adding heat sinks to steppers but have seen drastically differing remarks as to the actual heat removal/effect on performance, what is the real story here? I know they will certainly remove some of the heat but would they affect performance in this regard? and is there a ballpark of what size sink I am going to need to think about adding to each stepper to make it work?

thanks again for all the help!

On Thursday, February 25, 2016 12:49 PM, "Tom Kerekes tk@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 2/25/2016 4:41 AM, semperfikurt@... [DynoMotion] wrote:

I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?

The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.

Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Thanks!

Group: DynoMotion	Message: 12860	From: carlcnc	Date: 2/25/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Kurt
your voltage should not be greater than
the sq rt of the motors inductancex32
I have had size 34 motors that maxed at 35 volts,
and size 23 that could handle 90 volts
over voltage will cause more heat faster than over current

do you have the spec sheet on your motors?
it will give you inductance for series or parallel connected
Carl

Group: DynoMotion	Message: 12861	From: TKSOFT	Date: 2/25/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Hi Kurt,

Strange. It doesn't sound like they were severely overheated or
severely over current.

Is your motor wiring excessively long and thin gauge?

You might try wired parallel with a 24V supply.

Regards
TK

On 2016-02-25 10:22, kurt huizenga semperfikurt@... [DynoMotion]
wrote:

> I am running them with a 48V power supply through a KSTEP, with the
> jumpers for 1.88 Amps. At first I had them set at 2.5 but noticed I
> had it wrong and changed it however, the problem persisted afterwards.
> I could feel the steppers with my hand and they were pretty hot, but
> not too hot to touch. I could always tell when they were about to miss
> a step, they would have a hissing whiny sort of noise first then
> "clunk-clunk."
>
> I had thought about adding heat sinks, right now I am not using any. I
> have read some articles online about adding heat sinks to steppers but
> have seen drastically differing remarks as to the actual heat
> removal/effect on performance, what is the real story here? I know
> they will certainly remove some of the heat but would they affect
> performance in this regard? and is there a ballpark of what size sink
> I am going to need to think about adding to each stepper to make it
> work?
>
> thanks again for all the help!
>
> On Thursday, February 25, 2016 12:49 PM, "Tom Kerekes
> tk@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:
>
> Hi,
>
> Looks like the current should be 2.1A. About 8Watts of heat due to
> resistance. What current are you driving them with? What type of
> drives? Steppers normally run hot whether they are moving or not. I
> think up to about 70C is normally ok. High drive voltage causes higher
> current ripple which also adds significant heat. Do you have any heat
> sinking?
>
> Over current and over temperature may have damaged your motors by
> demagnetizing the magnets.
>
> Regards
> TK
>
> On 2/25/2016 4:41 AM, semperfikurt@... [DynoMotion] wrote:
>
>> I am working on a drawing project with my cnc, and after about 45
>> minutes to an hour of machine time the steppers start sounding a
>> little strange, and then they stall for a couple of steps. They also
>> start getting pretty hot at this point. Is this normal?
>>
>> The toolpath consists of a lot of very small zigzag type actions in
>> the Z axis which results in a lot of very small back and forth
>> actions for the motors. also attached is the spec sheet for my
>> steppers, they are wired in bipolar series. Originally I had the
>> current too high which I thought was the problem but after fixing
>> that it remains.
>>
>> Is this an indicator of a problem or have I pretty much just found
>> the performance limits of the whole steppers-based machine thing?
>>
>> Thanks!
>
>

Group: DynoMotion	Message: 12862	From: kurt huizenga	Date: 2/25/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Hey Carl,

Yeah the spec sheet is attached to my original message in this thread. I did the math though and with the way I have my steppers wired I have 8.8 mH of inductance/phase which comes out to about 95Volts. right now I am running 48.

On Thursday, February 25, 2016 2:07 PM, "carlcnc@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Group: DynoMotion	Message: 12867	From: Steve Blackmore	Date: 2/26/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping [1 Attachment]

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
--

Group: DynoMotion	Message: 12870	From: kurt huizenga	Date: 2/26/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

So I rewired the steppers in Parallel and swapped the 48V Power for 24V. Everything seems fine until about fifteen minutes in, the Y axis has a squeaking sound and starts skipping steps. The change in voltage definitely made a difference in the running heat though, they feel nearly room temperature however, the skipping is happening much sooner now. As far as the cables go how does length affect stepper performance? I think the longest I have now, going through all the cable chains and whatnot is about 12 feet or so (24awg.)

On Friday, February 26, 2016 3:56 AM, "Steve Blackmore steve@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
--

Group: DynoMotion	Message: 12872	From: Moray Cuthill	Date: 2/26/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Provided the wiring is rated for the current, that length should not make much difference.

Is the problem affecting all axes/motors?

Did you fit a different power supply when you moved from 48 to 24V?

Given the time frame involved, it sounds like something failing/jamming once it gets warmed up. If it's only one axis, have you checked that axis for any mechanical problems?

If it's all, the change of sound from the steppers could be something like the power supply failing, but if you've swapped to a completely different supply, that should of ruled that out.

As a start, I'd be monitoring the power supply voltage to see if it changes when the fault occurs.

I'd also be trying to spin the steppers/screws by hand with everything cool/powered down, and then spinning them again after powering down once the fault happens to see if there's any noticeable difference.

It may also be worth removing the steppers, checking the couplers are ok (if you have slotted alu style couplers, they are bad for splitting and giving strange faults), and spinning each axis by hand to feel for any binding/roughness.

It's always worth spending a bit time covering the basics, before digging too deep for faults.

Moray

On Fri, Feb 26, 2016 at 9:45 PM, kurt huizenga semperfikurt@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

So I rewired the steppers in Parallel and swapped the 48V Power for 24V. Everything seems fine until about fifteen minutes in, the Y axis has a squeaking sound and starts skipping steps. The change in voltage definitely made a difference in the running heat though, they feel nearly room temperature however, the skipping is happening much sooner now. As far as the cables go how does length affect stepper performance? I think the longest I have now, going through all the cable chains and whatnot is about 12 feet or so (24awg.)

On Friday, February 26, 2016 3:56 AM, "Steve Blackmore steve@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
--

Group: DynoMotion	Message: 12873	From: kurt huizenga	Date: 2/26/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

I think it is just the Y axis, but I am still in the process of working that out for sure. I also am fairly sure that it is happening while decelerating in transfer from rapid feed rate, so I am going to try cranking down the acceleration and see if that changes something. I did use a new power supply when I did the changeover.

I appreciate the help! I will have a look at this stuff here in a bit.

On Friday, February 26, 2016 5:01 PM, "Moray Cuthill moray.cuthill@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Provided the wiring is rated for the current, that length should not make much difference.

Is the problem affecting all axes/motors?

Did you fit a different power supply when you moved from 48 to 24V?

Given the time frame involved, it sounds like something failing/jamming once it gets warmed up. If it's only one axis, have you checked that axis for any mechanical problems?

If it's all, the change of sound from the steppers could be something like the power supply failing, but if you've swapped to a completely different supply, that should of ruled that out.

As a start, I'd be monitoring the power supply voltage to see if it changes when the fault occurs.

It's always worth spending a bit time covering the basics, before digging too deep for faults.

Moray

On Fri, Feb 26, 2016 at 9:45 PM, kurt huizenga semperfikurt@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

So I rewired the steppers in Parallel and swapped the 48V Power for 24V. Everything seems fine until about fifteen minutes in, the Y axis has a squeaking sound and starts skipping steps. The change in voltage definitely made a difference in the running heat though, they feel nearly room temperature however, the skipping is happening much sooner now. As far as the cables go how does length affect stepper performance? I think the longest I have now, going through all the cable chains and whatnot is about 12 feet or so (24awg.)

On Friday, February 26, 2016 3:56 AM, "Steve Blackmore steve@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
--

Group: DynoMotion	Message: 12875	From: Tom Kerekes	Date: 2/26/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Hi Kurt,

A long shot but do you have the KStep Voltage Clamping set at 25V? Decelerating a big mass will push energy back into the supply which causes some supplies to fault. The Voltage Clamping is for preventing that.

Maybe a bad cable with an intermittent internal break? Do they flex through a rolling loop? That current is pretty high for 24AWG wire. With 24ft round trip I estimate 0.6 ohms which is more than your motor. This means you're putting more heat into the cable than the motors (well from I2R losses anyway).

Regards
TK

On 2/26/2016 2:09 PM, kurt huizenga semperfikurt@... [DynoMotion] wrote:

I think it is just the Y axis, but I am still in the process of working that out for sure. I also am fairly sure that it is happening while decelerating in transfer from rapid feed rate, so I am going to try cranking down the acceleration and see if that changes something. I did use a new power supply when I did the changeover.

I appreciate the help! I will have a look at this stuff here in a bit.

On Friday, February 26, 2016 5:01 PM, "Moray Cuthill moray.cuthill@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Provided the wiring is rated for the current, that length should not make much difference.

Is the problem affecting all axes/motors?

Did you fit a different power supply when you moved from 48 to 24V?

Given the time frame involved, it sounds like something failing/jamming once it gets warmed up. If it's only one axis, have you checked that axis for any mechanical problems?

If it's all, the change of sound from the steppers could be something like the power supply failing, but if you've swapped to a completely different supply, that should of ruled that out.

As a start, I'd be monitoring the power supply voltage to see if it changes when the fault occurs.

I'd also be trying to spin the steppers/screws by hand with everything cool/powered down, and then spinning them again after powering down once the fault happens to see if there's any noticeable difference.

It may also be worth removing the steppers, checking the couplers are ok (if you have slotted alu style couplers, they are bad for splitting and giving strange faults), and spinning each axis by hand to feel for any binding/roughness.

It's always worth spending a bit time covering the basics, before digging too deep for faults.

Moray

On Fri, Feb 26, 2016 at 9:45 PM, kurt huizenga semperfikurt@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

So I rewired the steppers in Parallel and swapped the 48V Power for 24V. Everything seems fine until about fifteen minutes in, the Y axis has a squeaking sound and starts skipping steps. The change in voltage definitely made a difference in the running heat though, they feel nearly room temperature however, the skipping is happening much sooner now. As far as the cables go how does length affect stepper performance? I think the longest I have now, going through all the cable chains and whatnot is about 12 feet or so (24awg.)

On Friday, February 26, 2016 3:56 AM, "Steve Blackmore steve@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
--

Group: DynoMotion	Message: 12888	From: kurt huizenga	Date: 2/27/2016
Subject: Re: Stepper Heating and Eventual Stalling/Skipping

Attachments :

toolpath image capture-12888.PNG

Test 2-12888.JPG

Test 1-12888.JPG

Hey Tom,

I got an error message when I sent this so I'm not sure if it went through. Here is the message again in case.

I did set the voltage clamping at 25V. The change in supply voltage totally solved the heating problem, the steppers are now just slightly warmer than room temp, so in that regard everything is running perfectly. Nice.

I did a couple of tests yesterday with the acceleration and found that as I lowered it, the machine would run for longer periods of time before the missed steps started. Right now I have it at 4 in/sec^2 (Test 2 Image) and it will run for about 45 minutes before things start going crazy, compared to about fifteen minutes when the acceleration was 8 in/sec^2 (Test 1 Image.)

I also narrowed the problem down to specifically the Y axis which runs two steppers, if you look at the test images, the two hatched toolpaths are aligned horizontally, but top and bottom are all wonky. I haven't been able to pin down exactly the failure mode, sometimes they would just skip steps, and sometimes the two steppers would actually be fighting each other running in opposing directions. I would leave it and things would be okay for a couple minutes, and then something would happen again. Also I found the skipped steps only happened while retracting vertically from a tool path, or immediately afterwards while accelerating into the traverse to the next start position.

At first the heating seemed to be the low hanging fruit in regard to the problems, but now that that is resolved, and it has come down to only one of the axes, it kind of starts the discussion over again. This is a screen capture of the RhinoCAM tool path.

Thanks!

On Friday, February 26, 2016 10:43 PM, "Tom Kerekes tk@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 2/26/2016 2:09 PM, kurt huizenga semperfikurt@... [DynoMotion] wrote:

I think it is just the Y axis, but I am still in the process of working that out for sure. I also am fairly sure that it is happening while decelerating in transfer from rapid feed rate, so I am going to try cranking down the acceleration and see if that changes something. I did use a new power supply when I did the changeover.

I appreciate the help! I will have a look at this stuff here in a bit.

On Friday, February 26, 2016 5:01 PM, "Moray Cuthill moray.cuthill@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Provided the wiring is rated for the current, that length should not make much difference.

Is the problem affecting all axes/motors?

Did you fit a different power supply when you moved from 48 to 24V?

Given the time frame involved, it sounds like something failing/jamming once it gets warmed up. If it's only one axis, have you checked that axis for any mechanical problems?

If it's all, the change of sound from the steppers could be something like the power supply failing, but if you've swapped to a completely different supply, that should of ruled that out.

As a start, I'd be monitoring the power supply voltage to see if it changes when the fault occurs.

I'd also be trying to spin the steppers/screws by hand with everything cool/powered down, and then spinning them again after powering down once the fault happens to see if there's any noticeable difference.

It may also be worth removing the steppers, checking the couplers are ok (if you have slotted alu style couplers, they are bad for splitting and giving strange faults), and spinning each axis by hand to feel for any binding/roughness.

It's always worth spending a bit time covering the basics, before digging too deep for faults.

Moray

On Fri, Feb 26, 2016 at 9:45 PM, kurt huizenga semperfikurt@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

So I rewired the steppers in Parallel and swapped the 48V Power for 24V. Everything seems fine until about fifteen minutes in, the Y axis has a squeaking sound and starts skipping steps. The change in voltage definitely made a difference in the running heat though, they feel nearly room temperature however, the skipping is happening much sooner now. As far as the cables go how does length affect stepper performance? I think the longest I have now, going through all the cable chains and whatnot is about 12 feet or so (24awg.)

On Friday, February 26, 2016 3:56 AM, "Steve Blackmore steve@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

On 25 Feb 2016 04:41:15 -0800, you wrote:

>I am working on a drawing project with my cnc, and after about 45 minutes to an hour of machine time the steppers start sounding a little strange, and then they stall for a couple of steps. They also start getting pretty hot at this point. Is this normal?
>
>
> The toolpath consists of a lot of very small zigzag type actions in the Z axis which results in a lot of very small back and forth actions for the motors. also attached is the spec sheet for my steppers, they are wired in bipolar series. Originally I had the current too high which I thought was the problem but after fixing that it remains.
>
>
> Is this an indicator of a problem or have I pretty much just found the performance limits of the whole steppers-based machine thing?

Those generic Chinese steppers look fine to be wired parallel at 60-
70Vdc & 2.5 to 3.5A.

But, I don't take too much stock from data sheets unless they come from
a reputable known manufacturer.

Steppers do run hot, they are designed to. Insulation breakdown is
usually 120-150 deg C - normal running can be considered as anything up
to 75 C. You will not demagnetize them permanently by running hot -
modern hybrid motors do not use ferrite magnets - but power does drop
with increased temperature.

Nice article here that explains it for the non scientist <G>

http://www.duramag.com/techtalk/tech-briefs/how-heat-affects-a-magnets-holding-power-and-how-to-use-temperature-coefficients/

Too high supply voltage is usually what causes overheating. Check your
wiring. I'd suspect the drives or power supply overheating rather than
the steppers unless you are undersized to begin with.

Steve Blackmore
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