Z Axis is grinding during movement; video link inside

My Z axis is grinding when I try to move it. I tried doing the Easle included project that’s a little waving smily TV person with your name next to it. I homed it to the lower right corner and then hit Carve. The Z axis didn’t retract when the thing began, though I could hear it strain. It dragged the spinning bit through my wood and started cutting the pattern correctly, but without lifting the Z axis between cuts. I exited the program after hitting my E Stop and investigated- the Z Axis… I don’t think it should do this:

(don’t mind my girlfriend in the background. I told her to click the Z up button every two seconds and she’s a sweet thing that of course would count out loud)

Link to Video

Any ideas what could be going on?

That sound comes from your Delrin Nut. You may want to take it off, use your drill, attach rod to it and go back and forward until you have nice and easy movement. Delrin nuts comes tight from inventables. It took me about 15 times to make it easy to move.


Thanks Alan! I’m off to a Halloween party now but I’ll try that tonight if I have the energy; tomorrow at the latest. I’m so excited to finally get it cutting.

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Mine also enjoyed a few puffs of fine graphite (used by locksmiths but available in most large hardware stores). It’s perhaps obvious, but don’t use a “wet” lubricant (if you need a lubricant at all). I too did what @AlanDavis suggested, but I had to do it quite a few times. A reversible drill/screwdriver/Tec-Screw gun is ideal.


Thanks David. I ended up just running the Z axis up and down like 40 times. It’s moving smoothly now, but during the break-in I noticed the Acme threaded rod wasn’t exactly straight. Should I be concerned about that? I’d say the rod looked about 1/16" bowed in the center from both ends.


My ACME rod had a similar bend in it and as a result the delrin nut threads were not worn in properly. Inventables sent me a new ACME kit with the rod, delrin nut, and locknut. The original ACME rod was causing the Z axis to bind at one end, causing missed steps. I would definitely get a replacement if you can visibly see that the rod is bent.

Thanks Chris. While it kills me to prolong the completing of my X Carve build, I’d rather not deal with a warped rod. It’s still binding at the lowest end of the z axis travel… the most important height. I’ll disassemble it and make sure, then contact customer support.

Do yourself a favor, take that rod to machine shop to straight or do it yourself. If you wait for replacement, 90% chance you will receive rod with same condition. M2c.

My ACME lead screw is also bent. I e-mailed Inventables about an issue I have related to it and was given some information about how to adjust the way the lead screw is set in its bearing. I was told that the delrin nut and v-wheels should take care of the issue, but was never offered a replacement, so I assume they allow for the rod to be bent. I suppose it has to do with how they process the reduced diameter of the lead screw end that fastens to the nut on the top of the z-axis.

I’d need to check closely to see if I’m wrong, but the accuracy of the Z axis is largely maintained by the V wheels on the maker slide. Providing it’s not so tight it’s binding, some inaccuracy on the leadscrew would be acceptable.

Don’t forget, the X and Y axes are moved by belts, which do nothing in the way of guiding the movement along the rails.

Critical to each axis is backlash in the belts or threaded rod and delrin nut, and any potential movement on the makerslide that’s not in the direction intended. Provided these are within tolerance, the leadscrew simply needs to move the head up & down.

I’m happy to be proven incorrect, but I’d not be overly concerned if everything moves freely in the intended direction without backlash or lateral movement.

Sorry to be late to the party. I’ve watched the video twice now and what your are seeing and hearing is NOT the lead screw making the noise in the nut. What you are hearing and seeing is the stepper motor loosing steps from binding of the lead screw in the nut.

There are a couple of ways to go here. 1 take it to a machine shop that has the ability to straighten it. This could cost a fair amount of $.
2 You can straighten it your self. You will need a few things to do this. A piece of plate glass big enough for the lead screw to not hang over at the ends. The thicker the better.
A set of feeler gauges. A sharpy.

Make a set of V blocks out of hard wood. a raw hide hammer or plastic hammer, dead blow if possible.

Now how to go about straightening.
1 lay the lead screw on the glass plate and roll it back and forth. You will be able to see that it is bent.
Mark the high spot when the gap is the greatest between the lead screw and the glass plate.
Using the feeler gauges determine how bent the lead screw is.

Now with the v blocks on a good solid base, say the cast iron top of your table saw if you have one.
Put the lead screw on the blocks with the blocks at the ends of the lead screw.
Roll the lead screw so the high spot is on top.
Now the fun part. Give it a wack with your hammer.
Now back to the glass plate and check again with the feeler gauges. Did you get a change. Yes, good is the high spot still on top Yes, good you did not wack it too hard. No, you wacked it to hard.
If the high spot stayed on top and the distance measured with the feeler gauges got smaller good. Now go back to the V blocks and wack it again with the same force as the first time. Check again. Did the distance change and get less good. Keep doing this until you get the bend down to a couple of thou on the feeler gauges.
Did you get a change. No, you did not wack it hard enough. Wack it again a little harder.
Check again.

You can get the lead screw fairly straight using this method.

If you have good steel V blocks and a arbor press and a dial indicator then you can get the lead screw very straight. If not the above method will work just be careful when wacking it.

Ariel, WA

Yeah, it’s definitely a warped ACME threaded rod. I took it off and rolled it on a glass table. That’s like… a good 0.1" bow in more than one spot.

Check it out, watch in HD

I’m definitely contacting customer support on this one.

Mine looks identical. I think it has something to do with how the ACME rod is processed considering how difficult it would be to bed one.

Mine was like that too.

The replacement I got from Inventables is straight, however.

Inventables Customer Support offered to ship a replacement threaded rod and delrin nut. Very cool of you guys, thanks. I look forward to installing the new parts and finishing this assembly for good.

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I received a bent ACME z-axis rod with my X-Carve a few months back. Tech support said they didn’t think it would affect the cut, so I didn’t request a replacement. But after three months, the z-axis started making noise. Seems that the delrin nut had been worn to the point where there was significant play between the ACME rod and the nut. I assume that the rapid ware of the delrin nut was due to the bent z-axis actuator rod.

Anyway, if you have a bent ACME rod, you might just want to go ahead and replace it, before the bent one wears out its delrin nut.

X-Carve tech support was kind enough to send a replacement threaded rod and delrin nut. The package came with a big “FRAGILE” sticker on it, and the threaded rod was perfectly straight from what I could tell. Just a few minutes ago I threaded it into the new delrin nut and it went in like butter. I could almost flick the nut while holding the rod to make the nut spin around it as it threaded through. I’ll be reassembling my Z Axis tonight and hopefully finishing my whole X-Carve build this weekend. Thanks again Inventables staff. I wonder how many X Carves they sell a day that they can’t check the threaded rod’s straightness, though.

I just stumbled into this thread via searching for an answer to why my Z-axis is making a strange grinding noise when it moves toward the wasteboard. It only seems to do this when moving down during a carve. Or, at least, the noise is much less when the Z-axis is moving up.

When I test run it from Easel it seems to move smoothly up and down without noise. So I’m kind of at a loss to explain what is causing the noise. My X-carve had been working fine without any such noise and the problem only seems to have appeared in the past couple of carves.

Is it possible the delrin nut is just wearing? What else might I look at for the source of the problem? The noise is definitely getting worse and I’m concerned that whatever is causing it is goign to do some damage to the machine.

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i am the same some solution …do you find? thank you