X axis stepper motor hissssss

I completed the assembly of my cross fire this weekend! (WaHoo!) After following the alignment and set up in Mach 3 - i did a few jogs to get the X and Y axis set. I noticed that the X-axis stepper motor made a noticeable “HISS” sound but moved smoothly in the jog settings. I ran the break in program and all went very smoothly.

I set the break in program to run a second time at at about 2/3 of the way through, the X axis motor stopped and made a LOUD rattle sound. I stopped immediately, reset and clicked go to zero and everything moved fine back to my 0,0 point.

I ran the break in program again for about 30 seconds without any drama, but the X-axis motor is still hissing…

Any Help?

Hi @brettkeath,

Break loose the two screws that secure the X axis lead nut mounting tab to the torch carriage. Then re-tighten both. Based on your description it sounds like it may be a little out of square. Beyond that, its always a good idea to have lubricant on the lead nuts if you don’t already.

Thanks! I had already checked (loosened and reset) both the lead nut mount bolts as well as verifying square on the lead screw mount. Lubricant recommendation?

Grease works the best, really any that you have on the shelf will be sufficient.

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Thanks! Love the Machine!

My motors hiss anytime the table is not moving. Is that what you’re talking about?

@langmuir-daniel - I went back and reviewed some of the others posts on the x axis. My X axis lead nut was very tight and hard to install. I’ll try greasing it up tonight. I think that may be it.

@bricklef - My Y axis motor vibrates lightly but does not “HISS” The X-axis is much noisier but seems to vibrate similarly to the Y motor. Vibration is normal - didn’t think the Hissing was, though.

Also make sure the white part of the nut is pulled back behind the raised ridge on the black “fingers” on the lead nut. If it runs up over the ridge it will be tight and if it goes far enough forward it won’t turn by hand at all.

(Don’t ask me how I know :grin:)

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I also am wondering what the baseline for noise is for this machine.

When operating it sounds like StarTrek and i am fine with that :sunglasses:.

When sitting idle the motors seem to be pretty noisy, not to be confused with the fan sound of the power supply. The motors do not seem to be heating up at all and run smoothly. Just Noisy a loud humm or hiss. Especially at certain positions on the table if it stops there.

First CNC, just wondering what “Normal” is.

Exactly the information I’ve been googling for. Thanks!

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going to bring this back up…mybe my shop is too quiet…but my x motor when not in use sounds like it has an air leak…at first I thought it was an air leak…but my compressor is not in the same room…there is no compressed air lines in the new shop…and the noise stops when I turn the power off to the table.
it is not the PC fan…if you listen each motor hisses…but the x one is pretty loud.

Just read your post on the hissing sound coming from your stepper motors. I just got my table assembled and noticed the same sound. Did you ever get a clear answer on what causes it and if it is an issue that I need to be concerned with?


The drivers for stepper motors use a high speed switching technology to control the current in a power efficient way. Depending on the switching frequency, subharmonics can be in the audible region. The drivers LS uses in their controllers will do this. Other drivers don’t. In any case it is not a problem and working as designed.


Perfect. Thanks

When stopped, my motors sometimes hiss, sometimes they don’t. If they are I find a quick bump of the axis in either directions stops the hiss. I did not consider it to be a problem as I have heard other stepper motors do the same when “between” steps. Is it a problem?

For lube: By “lead nuts” I assume you mean the polymer nuts the lead screw fees through.
I generally use this on my ShopBot rack/pinions (for 15 years now)
Boeshield T9 https://boeshield.com/why-boeshield-2/
I find grease “collects bits of stuff” while T9 ends up being not sticky and everything falls off of it.
I was planning on use the same on the lead screws (thus lead nuts) as well.

Anyone see an issue with that lubricant on the leadscrews?

a hiss is normal…not to worry…mine hiss all the time.
as for lubrication…Langmuir has often suggested a fine machine oil is all that is required…I use a sewing machine oil…clear and super fine…plus I clean my rails frequesntly.


Same issue here each stepper motor sounds like an air leak durning idle.

it is normal for them to hiss a bit…