Help Requested: Constant High Pitch Sound From Only One Stepper Motor

TannerFrisby · Aug 31, 2020

Hello all, I hope this is the correct subforum to ask this:

I am outfitting a machine with closed-loop stepper motors. Three of the motors (of different size and different brands) are working as well as I could ask, but I have one NEMA 34 hybrid stepper motor and driver from Longs Motor that isn't. The motor makes a constant "alarm" style noise when it is energized. It functions correctly but it is very loud and incessant! When I start the machine, it sounds off, stops briefly, and then continues as long as the driver is powered. Please help me troubleshoot this dang motor/driver.

TeachMePlease · Sep 1, 2020

Tanner, you appear to be younger (from the youtube profile picture), so I'm gonna be more gentle than I normally am, and more than other members probably will be.

This forum is intended for professional machinists using professional machines (y'know, VMCs that weigh 10 tons) and equipment. Most here don't mess with stepper motors and retrofits. That said, lots of people here do have experience, and you MAY get someone who stops by and helps you... But in general, a lot of people on this forum are either going to ignore a post having to do with stepper motors, or they're going to stop by just to be rude and tell you that we don't deal with hobby machines on this forum. And while they may be rude, they're also correct.

Not saying you can't ask for help here, just saying you probably won't get as much help as you'd like.

There is a forum at CnC Zone dot com that is more open to hobbyists and stepper motors, and many of the knowledgeable people here also contribute there.

I'd encourage you to post a thread there, as you'll likely get more help than you will here.

That said, stick around here, read and learn all you can, and you can ask any machining related questions you may have, just don't mention things like "Sherline", "Grizzly", or "Jet" and you should be fine.

Hardplates · Sep 1, 2020

TeachMePlease said:
Tanner, you appear to be younger (from the youtube profile picture), so I'm gonna be more gentle than I normally am, and more than other members probably will be.

This forum is intended for professional machinists using professional machines (y'know, VMCs that weigh 10 tons) and equipment. Most here don't mess with stepper motors and retrofits. That said, lots of people here do have experience, and you MAY get someone who stops by and helps you... But in general, a lot of people on this forum are either going to ignore a post having to do with stepper motors, or they're going to stop by just to be rude and tell you that we don't deal with hobby machines on this forum. And while they may be rude, they're also correct.

Not saying you can't ask for help here, just saying you probably won't get as much help as you'd like.

There is a forum at CnC Zone dot com that is more open to hobbyists and stepper motors, and many of the knowledgeable people here also contribute there.

I'd encourage you to post a thread there, as you'll likely get more help than you will here.

That said, stick around here, read and learn all you can, and you can ask any machining related questions you may have, just don't mention things like "Sherline", "Grizzly", or "Jet" and you should be fine.

You're getting soft :codger:

ChipSplitter · Sep 1, 2020

Hardplates said:
You're getting soft

Naw, civil.

Like we all should.

Hardplates · Sep 1, 2020

ChipSplitter said:
Naw, civil.

Like we all should.

I've spent years perfecting the grumpy old machinist attitude that you very much :angry:

TeachMePlease · Sep 1, 2020

Hardplates said:
You're getting soft

Only been in the trade for 8 years, and my girlfriend hasn't left me because I work too much OT yet, so I'm not as bitte... Uh... Hardened... as some

TannerFrisby · Sep 1, 2020

@TeachMePlease
Thank you for the advice. I'd say I'm at least 10yrs out from having the money and space for a "real" machine. Until then, I'm trying to spruce up second-hand imports (yes, I can't even afford new China machines). Or is "import" another no-no word?

I'll update and close this thread when I figure out my issue.

ChipSplitter · Sep 1, 2020

TeachMePlease said:
Only been in the trade for 8 years, and my girlfriend hasn't left me because I work too much OT yet, so I'm not as bitte... Uh... Hardened... as some

Someone here (Oldwrench?) has speculated that post count indicates the density of said poster's skull. (More posts = more stubborn to prove his point).

I better run!

3t3d · Sep 1, 2020

What if the encoder and the stepper were "out of phase"
Stepper is commanded to position 001 but is where the encoder thinks is position 000.
The driver tries to back up and overshoots where the encoder now wants to be....
Back and forth they never agree....

Try removing and remounting the encoder.
Or turn off the encoder feedback option.

Or this could be complete bullshit. I'm not sure.

plastikdreams · Sep 1, 2020

Hardplates said:
I've spent years perfecting the grumpy old machinist attitude that you very much

That = thank...mmmhmm

TannerFrisby · Sep 3, 2020

3t3d said:
What if the encoder and the stepper were "out of phase"
Stepper is commanded to position 001 but is where the encoder thinks is position 000.
The driver tries to back up and overshoots where the encoder now wants to be....
Back and forth they never agree....

Thanks for the input. This was a real issue on some of my other drives as I didn't receive paperwork when I bought them. The schematics were posted on the eBay listing, but I didn't feel a rush to print them. Life got in the way and the listings had been pulled by the time I got back to them. I found comparables for sale, but they didn't agree on wire-colors, etc. I probed impedances to take my best guess but still had to shuffle wires until they worked.

My driver (and it is my understanding that all closed-loop stepper drivers have this property) treat your scenario as one of the "alarm" conditions. There is a way to program the maximum position error before alarming out. The other typical alarm conditions are over-voltage, under-voltage, and over-current. Most drivers report their alarms through LED blinking rates, through an alarm pin, and through a serial connection.

I wasn't able to find the "root" cause, but I dug deep enough to resolve my immediate problems. The noise follows the driver, not the motor. I had a spare comparable driver and swapped it in. Now I'm on to the next gremlin.

Thank you all for the input.
-Tanner Frisby

ss_user · Sep 3, 2020

For future reference try linuxcnc and machinekit; both are heavily into steppers. A few of the linuxcnc guys get into machines weighing tons and reasonable travel like a couple of meters. :-)

TannerFrisby · Sep 3, 2020

I'll remember machinekit for next time. Linux CNC forum was very helpful.

Parallel threads:
CNC Zone
Linux CNC

Milland · Sep 3, 2020

I may a grumpy old fogey, but I'm going to request that Tanner sticks around. I was impressed that he took a spectral analysis of the noise, that's a "step" (hah, is joke) that most don't do, and points to a level of sophistication that should fit in and grow here.

And maybe show the "Pro's" a thing or two...

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Help Requested: Constant High Pitch Sound From Only One Stepper Motor

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TeachMePlease

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ChipSplitter

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TeachMePlease

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TannerFrisby

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ChipSplitter

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3t3d

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TannerFrisby

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Milland

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