Acme Lead Screw Wobble

I’ve been using my X-Carve for over a year with minimal issues. Today, however, I noticed the Acme lead screw is wobbling. I’ve never noticed it before, but now it is rubbing the back of the router mount. The attached video shows what I am talking about. Is this excessive? Do I have a faulty lead screw? Z Axis Lead Screw Wobble

It looks like its only wobbling on the bottom unsupported portion of the screw. Is your machine experiencing any issue while travelling up and down?

It’s starting to rub and catch at the bottom of the router mount along the back edge. Also, watch the end of the screw at the top where it exits the nut holding the pulley. Seems like a lot of wobbly movement.

I wonder if your top pulley loosen off. Can you see if you can loosen the grub screw and tighten the lock nut on top? Looks like since its wobbling at the top too that the screw is loose in the bearing.

if you’ve been running it for a year without any issues, then it would surprise me if the lead screw was bent.
it looks to me like the problem is in the top end.
Is the bearing shot?

Everything is tight up top. This video shows play in the delrin nut. I’m wondering if it’s become too excessive? excessive play

Oh ya that’s crazy. You might need a new delrin nut. Do you use dry lube on the screw and nut? I’ll have to check mine tonight and see if it’s worn like this.

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try to make a support at te bottom, it’ll go a very long way. Never understood why that wasn’t stock in the first place.

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I think there is actually mounting holes for a second delrin nut, so that’s another route.

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You are right, I just checked the drawings for the mounts. I wonder why I thought that.

@ChrisMonck If you need to check if it’s the screw, remove is and lay and roll it on a known flat surface you should be able to tell pretty quick.

Your best bet is to probably order a new delrin nut as @anon68752607 mentioned. You could also give Inventables a call and see if this is a know issue. I’ll check mine tonight though and let you know if I have any play, I’ve been running my machine for almost 2 years.

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A bearing on the bottom of the ACME rod is a great idea. My X-Carve has one.
It only reduces the Z-axis travel by a few millimetres.

I had to shave the sides to clear my “suckit”

I got all my X-Carve parts from, an Australian company. Lower bearing mount is here.

An update: I contacted Inventables’ customer service today about purchasing a new Delrin nut and included links to the videos I posted here. Jeffrey responded and said they would send me a complete Acme lead screw kit at no cost. He said there have been a few cases of reported bent rods so that might be the issue. At any rate, I am pretty pleased with Inventables customer service.


Awesome, good to hear! Inventables customer service is top notch!

Not that it matters much, but I did check mine last night and mine did not exhibit the same play in the delrin nut. So sounds like you went the right route!

Good luck getting everything installed!

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I have a 3d printer. I could make those plates if I have a drawing or measurments from the plate they sell.
I can make it out of Nylon or Poly Carb. There are other tough materials but I have those 2 on hand.

Couldn’t it be cut out of alum on the x-carve? just an idea…or even lexan…

yes it can be cut on the X-carve however 3d printed would be used prior to getting it cut out of metal.

Like a prototype ?

sorta but more like a temporary