Stuttering/Jumping Y Axis

Hello, I’m brand new to CNC and just recently assembled my Shapeoko 4 XL. My Dad and I assembled it together, but I think he overly tightened the v wheels.

When I try to initialize the machine, it stutters/jumps and makes a ton of noise on the y axis. It also shakes the belt, even though I’m pretty sure I have them taut enough.

Is this common behavior for an overly tight v wheel? Am I able to remove the side skirts and adjust them without removing all the belts and other hardware? I am hoping to talk to support after the holiday, but I thought this community might be able to help. Somebody on Reddit made fun of me and said I shouldn’t have a CNC, which just made this whole situation all the more discouarging for me :frowning:

Thank you!!!

This can happen when the Y axis stepper motors aren’t working together, usually from being wired incorrectly (yes, it happens) or one of the connectors may be loose in the connector plugs.

With the machine turned off, just check the pins in each of the stepper motor leads, the wiring loom and on the main board are fully engaged, then try again.

(I actually had something similar happen when one of the wires came out of a Molex connector)


Hi @jmillerdesign

Does the machine jumps/stutters immediately on the Y axis even when the gantry is far from the homing position (far right corner of the machine) ? If so, @NewToThis is probably on the money, it could be a wiring issue between the controller and the Y stepper motors.

If the problem happens only once the gantry reaches the Y axis limit switches, this could be a matter of the machine not detecting it has reached the limits, which often turns out to be a problem with the positiong of the limit switches and is easily fixed.

This is most probably not something to do with overtightened v-wheels (by the way the criteria to tighten them is, tighten until they won’t spin freely, but barely)

Sorry to hear that, let the silly internet trolls be silly internet trolls, you will find that this forum is a much more friendly place, lots of nice folks here always ready to help newcomers.

If you can capture a video of the machine initialization, upload to to some file/video sharing site (because the forum won’t let you upload large videos), and post the link here, we will collectively have a look and help troubleshoot what is going on.

Thank you so much for the info! And, I appreciate the honesty and understanding. It’s 5 am where I’m at and Im replying because or course, I can’t sleep!

The stuttering happens immediately when the gantry moves. If I power everything down, disconnect each motor, and manually move the gantry forward, then reconnect and turn the power back on, it happens until it hits the end and keeps grinding.

It sounds like you’re both onto something with the wiring. I’ll look at it as soon as I “wake up” and see what I can find.

I’ll also take and share a video. But should I be worried over any permanent damage I may be causing by letting it stutter and grind.

Lastly, I moved a few of the eccentric nuts counter clockwise during my trial and error. So, should I remove the side skirts and use the tools to retighten/adjust them?

Again, thank you so much!

I understand this as “starting with the gantry placed far from the mechanical limits, upon initialization the gantry does move towards the back but stutters along the way, and in addition to this it also does not stop when it hits the end”. If so, there are probably two problems, one with the Y axis constant stutter (probable wiring/loose connection somewhere), and one with the machine not detecting the limit switch (we can take care of that easily once the stuttering is fixed)

No need to worry, the machine can take it, and support/C3D has you covered anyway. So trying things is ok, but obviously don’t let the machine grind once it has reached the mechanical limits.

It is still possible that if the vwheels on one side if the Y axis have been tightened too much, it could cause the stuttering (due to excessive resistance on one side only). So in any case it is worth going back and loosening all vwheels on the left and right Y axes, and re-tightening them “just enough” (not spinning freely anymore, but not far from it). Regardless of your current issue, ensuring you have proper vwheel tensioning is important for the quality of the cut later.

I sincerely hope you won’t read this just just now and that you are getting some sleep :slight_smile:

1 Like

William at Carbide replied to my support email, which was surprising on a weekend. I so very much all your help and there’s too. I haven’t had a chance to take a video of the behavior, but I sent some photos of the wiring to William and he said it sounds like it’s a y axis wiring issue, as you mentioned as well.

It might not be user error after all :confused:

We’ll see what he says and I’ll report back.

Am I able to post photos here?

1 Like

We have your ticket on this on the support queue, and we’ll get it resolved as quickly as we can there.

Thank you sir! I didn’t expect support to get back to me over a weekend (a holiday for some) so I figured I’d see if anyone here had any insight. You guys are all awesome!!

1 Like

Carbide will take care of what ails the machine but for the internet trolls there is no cure, best way to deal with the trolls is to learn learn learn and put out a product “YOU” are proud of. this is all that matters, Trolls need not be included.

1 Like

Don’t be too surprised at that. @WillAdams is omnipresent and doesn’t believe in sleep, I’m sure! :rofl:


I don’t care how much experience you might not have. We have all been there. Ignore that and keep on going. You will get it in your own time.

Good luck, remember you can always find a friend here


I really appreciate the encouragement! I am a self employed graphic designer and feel like I have the creative side down. I have so many ideas! I just have a lot to learn in this realm, so having this forum and all the smart and helpful people is super encouraging.

We all did and still do. Keep it up, we’ll be here to help as much as we can!

1 Like

Hello again, I received my replacement YL motor cable. Connected it and when I initialize I no longer get the stuttering back and fourth but am still getting that grinding when it gets to the back of the machine. I’ve adjusted the sensor behind the control box up and down, with the same result.

I have an email to support with the most recent update, but boy am I getting really discouraged. I’ve had this machine assembled for 2 weeks with problem after problem.

Inductive limit switches right? Touch the one on the y axis with something metal, should light up the red led. If not it’s the limit/homing switch.

1 Like

Yeah, all 3 of them light up when touched with a metal object.

Then adjust it so that it can detect some metal at the end of its travel.

Pardon my ignorance, but the only adjustment is up and down a little, right? I loosen the screws and move it to as far up or down as it’ll go. But it doesn’t make any difference. I’m wondering if something is assembled wrong and it’s not making contact at all.

For the new inductive homing switches: Troubleshooting: Proximity Switch Troubleshooting - YouTube and Adjusting: Adjusting the Proximity Switches - YouTube

1 Like

Does it light up if when the gantry is at Home?
I’m guessing it needs to be adjusted a bit closer, not touching, to the extrusion.

1 Like