Shapeoko 4 X-Axis stuck / stutter

CNC Machines
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Just getting started with my 4XL. It’s built and tested, and everything is tight and straight. I was having an issue with my first job not contacting the work material, and while I was trying to troubleshoot that I started to have another issue.

I have a piece of material clamped to the board, about 2 or 3 inches away from the leading edge of the table, and right of the furthest left t-track, clamped in. Basically the stock is like 5" from the left edge, and 3" from the front edge. This is important to say I’m not putting stock out of bounds.

My 4XL has a BitRunner Deluxe, BitSetter, and BitZero v2. I start by initializing the machine, which moves smoothly and cleanly to the back right corner, hitting the limit switches as expcted, and then the router moves to the front for a tool change. I put in the peg so I can zero my stock with the BitZero, it sets the correct tool length with the BitSetter, then moves back to the waiting position.

I use the jog menu to move the router over the BitZero, center it up, and drop it below the edge of the BZ. I hit probe to set the zero, and it touches all four sides, the lifts up and touches the top of the BZ. Cool. Everything is done, and the screen shows my X at 10, my Y at 10, and my Z at 19. Perfect. It knows where the zero is and where the tool is.

In the jog menu, I decide to test something so with speed set to 1mm, I hit X-. The router jogs 1mm to the left. I hit X- again, and the router jogs 1mm to the right (opposite direction). Hmm… What’s going on? I keep hitting X- and the router goes left, right, right, left, left, right, left, right, right, left, etc. (This is an example, but clearly indicates something is wrong.

Fast forward. I’ve re-initialized the machine several times, and even gone into Motion and set up as a new machine. I make sure to select my machine as the 4, XL size, with the Z-Plus, and download the settings to the control board. I’ve done this a few times, but the end result is still the same. It’s misbehaving, but only at the extreme left edge of the table.

Eventually, after testing multiple times, now the router won’t move left or right at all. It makes a horrible noise when trying to initialize the machine, but the router never moves left or right at all. It stays stuck wherever it happens to be at. I have disconnected the x-axis motor and run an initialize and that works perfectly fine. Gantry moves forward and backward smoothly and quietly, and the Z-Plus lifts the router up and down normally. If I trip the X-limit when it’s doing the initialize, it “completes” successfully and moves the router to the front of the board and Motion prompts for a tool change. Everything is just like it should be, except the X-axis won’t move left or right at all.

I have checked, double checked and triple checked the wiring. All of the limit switches pin like they should when testing, lighting up on the control board and in Motion as expected. The belt isn’t too tight or too lose. I can pick it up with my fingers and I get about 3/4" to 1" of deflection and it snaps back into place as normal. With the power off and the motors disconnected from the board, I can easily move the gantry through the entire range of motion, forward, backward, left, right. Nothing is binding up, nothing is lose. I have checked the set screws on the x-axis spindle and they are tight and seated fully.

The machines WAS working normally when I first set it up. I only started having issues after an hour or trying to get my job to actually cut the stock. It would never plunge the bit into the material, but always stopped like 1.5mm above the work surface. At this point, that is a separate issue, I think, so I don’t want to get stuck on that. Right now, the larger issue is that the machine will NOT move the router left or right at all. It just makes a loud noise and won’t do anything. If you asked me to describe the behavior / sound, I would say the control board is trying to move the x-axis both left and right at the same time and it’s fighting with itself. The router vibrates just slightly as it is trying to move left and right.

I did start a conversation with support late yesterday, but haven’t heard back since my last update (given that it is Sunday and they are closed0.

Any thoughts or suggestions would be appreciated. I have video of the behavior, but they are large files and I haven’t uploaded them to YouTube yet.

edit: okay, I uploaded the videos.
https://youtu.be/y6rWO4qE9bI - Full initizalize cycle with x-axis disconnected
https://youtu.be/_928vEUPV0o - X-axis noise when initializing

Thanks in advance.

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That sounds like one of the four wires to the X axis stepper is not connected properly, it’s the sound of a stepper with only one of two sets of coils working. Go through the connectors and check for clean solid contact?

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I checked the connections this morning and all of the connections are tight and seated. I will get my multimeter out and test the wires in a bit.

4

When testing wiring connection, it helps to test them through the full range of the machine motion, or at least at the extremes and a middle point.

5

Everything runs through the drag chain and has extra space on either end. Nothing is pulled taut during any part of the process, edge to edge.

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With the help of tech support, we’ve identified a wiring issue with the x-axis motor. They are shipping out a replacement, so for the time being, I think this might be solved. I’ll update once I get the new motor installed and test.

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This is what I did for my connectors.

IMG_2486
IMG_2486480×640 93.7 KB

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My connectors aren’t loose though. They are very solidly seated. In my case, the issue is a short circuit or broken wire, I think.

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Personally, I am not a fan of those connectors. I have dealt with them since the dawn of the PC. That is why I zip them.

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I seem to be having exactly the same problem, also with a relatively new (approx 1 month) 4XL. It had been working very well up until yesterday, when I noticed it cut a couple of pockets that were several inches to the right (+X) of where they were supposed to be, and oddly distorted. I jogged to the XY zero point and found that it had migrated by that same distance in a +X direction. I re-initialized and confirmed that the zero was back where it should be, and a second attempt at the same cut went well. Today, however, I started seeing exactly the stutter described in this post. Hitting +X or -X moves slightly in one direction but then immediately reverses. The apparent X position displayed in Carbide Motion updates as expected, but the tool doesn’t track.

In my case the problem appears intermittent but not infrequent, and it isn’t associated with any particular part of the workspace. It’s happening in multiple places. I’ve confirmed that the X motor connectors are seated properly, but haven’t yet attempted to verify continuity.

What was the problem you eventually identified? Did the replacement part (what was it?) solve the problem?

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In my case, the issue turned out to be the connection where the X-axis motor connected to the cable that runs through the drag chain across the gantry. I had checked all of the connections beyond that and had no issues but I could manipulate the connection by hand (basically grabbing each side of the connection with one hand and jiggle it around) and it would “short out” causing the motor to behave erratically. One thing to note as well is that connection did eventually get warm to the touch. I suspect that something inside the molex is / was loose causing it to short out and send mixed signals to the motor.

Carbide sent me a new motor and a new X-axis extension wire (the one that goes across the gantry) and that has solved that particular problem entirely. I am having another issue now related to the YL motor not behaving right, and I have figured that one out too and I am going to do some testing and report back to Carbide with my findings. It turns out to be a similar issue with a connector, in this case the YL motor connection where the extension across the gantry meets with the transfer wire in the drag chain on the right side of the machine.

Zman pointed out above that he isn’t a fan of the connectors, and I am having to re-evaluate my experience and say that so far I am not a huge fan. I started looking for another option for those connections that I can replace all of them with to eliminate the problem. No luck yet on that front though.

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Thank you for all the info! That’s all sounding very familiar. I tested the continuity of all four conductors of the X motor cable between the motor and the controller board, and can’t find any problems. There is continuity for all four conductors and no obvious shorts. I tried jiggling the various wire bundles and drag chains, and didn’t see any glitches. One thing I did notice was that there is quite a lot of crosstalk between the conductors. When I drive one of them with a square wave I see strong impulses on the other three. This isn’t surprising with long floating conductors in close proximity and no termination (I assume when plugged into the control board and motor these transients are managed), but it initially caught my attention.

Obviously this is all with the machine stationary and no vibration; if there were a connector somewhere that isn’t secure under acceleration it wouldn’t show up here. At this point I’m hoping the Carbide 3D folks have some ideas for where to look next.

Thanks!

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The connector to the motor is a common culprit, check the pins are making tight, consistent contact with the socket.

As for the crosstalk, wait till you see what happens to the signals when those big inductors and magnets in the stepper motor join the party…

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