Right Y Axis weird sounds Shapeoko Pro

Hi all,

I’ve noticed some weird sounds coming from the right Y Axis. Should I be concerned about this? I don’t really see anything interfering. I haven’t properly checked the tension of my belts (ie per the ebook) but the right and left ones seem pretty close and I don’t believe they are over tight. I did see some small metal shavings which makes me concerned because I’ve only been cutting wood, but otherwise there’s no debris I can detect. It’s most noticeable when doing rapids. The left y axis sounds fine.

Please power down and remove both Y-axis belts, then put a bit of tape on the pulleys so that you can more easily see their rotation, then power up and connect and initialize — the machine will zero Z, then begin moving X and Y — do the Y-axis motors turn evenly and rotate in synch?

Let us know what you find out at support@carbide3d.com and we’ll do our best to assist.

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Thanks for the tip. I tried what you mentioned and they do appear to move in sync and I don’t hear any weird noises when the belt isn’t attached.

I put the belts back on and retensioned. It appears the belt did stretch a bit after the first time I tensioned it, and the noise is a little less now but still present.

It’s mostly noticeable when homing and rapid positioning

Most likely this is some sort of resonance issue from the Y-axis belts not being evenly tensioned — it may help to move the machine all the way forward and adjust the belt tension from the front, then repeating the reverse to get the others.

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Thanks, I will give that a shot. I am trying out the method of measuring frequency using the Gates app to properly tension both sides.

Following this: Measuring belt tension, squaring and calibration

I notice the Shapeoko Pro has 15mm belts. Is there any chance you could do me a favor and provide the linear density of the new 15mm belts, in kg / m / cm? My understanding is this is calculated by dividing the weight of the belt by its surface area (i.e. weight / (15cm x length)) I am building a spreadsheet and just want to ensure I have the right value. That way in the future, others can reference this spreadsheet in setting the tension of their Shapeoko Pro properly :slight_smile:

Thanks in advance!

So far, 56 Hz seems like a decent frequency, but I am using the linear density of the gates Gt3 9mm belts:

And then this diagram:

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Is this based on the spreadsheet “Belt Tension Examples” from that post?

If so the b field (with the unit cm) is indeed the width and the general view from Gates and some other data sheets I read through was that for the same type of belt the linear density would be the same. So fiberglass and kevlar cored belt would have the same density, I found that even the steel cored belt was not substantially denser on the samples I had at the time.

I have used this to calculate tensions and frequencies on my 3GT 15mm belt system, just using a higher linear density for the thicker belts and it seems to have worked out, so far as I can measure.

If you can weigh a sample of your belt then all the better.

The stepper motors have a breakaway torque which equates to around 18lbs force (assuming the Pro has the same motors?) which converts to about 80N. This is realistically the upper limit of useful belt tension, any more than this and you’re just wearing out the belts and motors early. In reality, whilst moving and seeing cutting forces this torque drops off quite quickly so there’s really nothing to gain by going to higher tensions.

So, yes, I think you’re in the ballpark at 55-60Hz for 81-97N belt tension over the 500mm span.

Remember the tensions only need to be enough to not go slack on either side as the machine operates, what’s important is to get them set evenly across the machine and not too tight.


edit - note that the Lambda at the top of the sheet will also be different for the 15mm belts but the only output that affects in frequency measurement is the calculation of static extension.


I’m new here with a Pro XXL so take this is my 01 cent. lol
I am wondering if it could be a dry bearing cage with bearing rattle.
Sounds like metal rattling to metal.

Just what I would check.




I’ve just listened to the videos properly and I’ve had very similar sounds on my SO3 XXL. I’ve also spent a long time checking every bolt was tight etc.

I found that it was actually a few loose items which were rattling and resonating when the steppers cause the machine frame and bench to vibrate. One was the handle of a small G clamp, some others were M6 bolts and washers in my clamping parts tray.

Have a good look around for anything outside the machine that might rattle.

I’d still make sure my linear bearings were properly oiled and my belt tensions were good, both those things ought to be true anyway, but check for loose change around the machine too.


Yes. I couldn’t actually find the spreadsheet so I just made my own based on the images. Happy to link it here if that is helpful.

Thanks, this is super helpful. Unfortunately I wasn’t able to weight the belt or find a proper spec online (I did look), but 56Hz seemed to be a pretty good frequency to go for.

Will was 100% correct here. I set the gantry to Y0 and retensioned the belts, using the Gates app to get ~56Hz with a 20in spread. It’s a bit hard to get it to hear the frequency perfect, but it worked. I then brought the gantry to the front and retensioned the belts on the other side of the machine to 56Hz. It appears as though from my initial set up the belts just became a lot looser so I had to retension them, but they also probably weren’t perfectly even to begin with.

Retensioning the belts from both sides with the gantry at Y0 and at the front fixed the problem for me, I am no longer hearing the weird sounds. Thanks so much!


Great, glad you got it sorted, the spreadsheet link is here if you need it again for any reason



I’ve used a guitar tuner app on my phone when I’ve done my belt tuning and it worked quite well.


Oh nice, that’s a great tip, thanks!

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