Tool Mount is Impossible to Assemble

After printing out both C and J varieties of 4mm and 6-32, I am thoroughly confused. The assembly instructions imply that the nuts will sit so loosely in their holes that glue may be required, but I can’t even cram them in with a screw. Any attempts to do so only split the piece. I’ve ensured it was printed to the correct size, and even printed out a subsequent piece at 105% which barely accommodates the nut. Is there an obvious solution that I’m missing?

Thanks so much in advance for any help. I’m hoping it’s as simple as correcting my ignorance.

Can you post some pics?

Sure thing! In the picture with the blue piece, you see the measurement I got from one inside edge of the hole to another, the following photo obviously being to show the difference in size I’m getting with the nut. I would have set it in the hole to illustrate, but it’s simply too large.

I don’t know if you can make it out from the photo, but you may be able to tell that, even on the white piece (printed at 105%) it’s still beginning to split after pulling the nut in with a screw.

Your printer is having calibration issues. That hole is 0.32" at the base and has a draft angle on it.

I wondered as much, but these pieces were printed across 2 different printers, both of which have been produced adequately dimensionally accurate parts for other projects with similar demands. It seemed a little unlikely to me, especially given how much I scaled the piece and still without success. Is there no chance there’s another contributing factor I could be missing?

I would try a test block with inner and outer dimensions as well as diagonals. There have been countless prints of these parts in all types of materials and printers. This is the first time I have heard of an issue.

Some residual modifications from a previous object somewhere in the work flow? Try a small part of the holder from scratch, from the original file, cut it out from the original file, so you can shorten your test and investigation cycles.

And if you find a solution, please let us all know. We learn from errors. And sometime an error becomes an innovation.

Good idea, just print a little past the first set of nut holes.


flow multiplier, retraction, extrusion width, filament width, nozzle diameter (odd filament chemistries ruin nozzles), size compensation in your slicer, scaling . There are a lot of things it can be and really at this point the model is the least likely thing that could be wrong.

Been a bit since I’ve had time to revisit this issue. Printed out a calibration cube per everyone’s suggestion. No modifications have been made to the printer or to the profile since printing the tool mount.

As the pictures show, the printer does seem to be calibrated quite well after all.

Not sure what the next step is from here?

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Well that is the most perfect printer I have ever seen. What do the diagonals come out to?

Not sure how to help with your issue though. The nut measures right and the nut holes are drafted outward so there should actually be slop. So unless you have some serious printing boogers in there (white one looks bad) I really do not know what to say.

The diagonals look to be pretty squarely on the 28mm mark!

I’m certain this has to be an error on my end. You’ve done spectacular work on this project. I just don’t know what I could be doing wrong.

Would it be possible for me to order this specific piece from you? It’s not ideal given this is probably indicative of a larger issue, but everything else seems to fit well enough for the time being. Though the carriage is a hair unsquared. I suspect that may be due to the same issue now…


Are you sure you can get them in? If you just thread it and pull them in with a screw, or shave the print boogers off the edges with a blade and they slip in?

Can you post a higher res picture of your print, the previous ones are tiny on my end.

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Unfortunately not. A screw pull decisively splits the piece open - even on the clean holes. Though your suggestion does make me wonder about the possibility of shaving the edges of the nuts…


Let me see if I still have the image! Unfortunately, I threw the parts away some time ago now.

I can confirm OP’s exact problem with my own experience. Only I ordered my printed parts from V1 direct a while ago (A looong while ago). This particular issue presented itself… rather than raise the issue or tackle it myself I set the project aside, life stepped in, this project collected dust, and now I’m back looking for an answer.

Thanks to the OP for posting this. It doesn’t seem a solution has been found just yet, but I thought I would chime in and confirm OP’s issue is real and that it also occurred with this particular part direct from V1 too.

Must be an anomaly of sorts as many, many MPCNCs have been successful. However, this anomaly clearly is attributable to something other than just the individual user’s printer.

I jut grabbed a random toolmount fresh off a printer two different kits, and a nut falls in, a little too loose if anything.

You two are the first I have ever heard of this.

The only way this could happen is if you are trying to use 6/32 nuts in a 4mm mount. Do the toolmounts you are both talking about have a “4” after the letter on the front?

Highprobabuility I just checked your order you indeed ordered the 4mm toolmount and my 6/32 kit, so that is solved.


To the best of my memory, I’ve printed both. That being said, I could easily be mistaken. I’m printing out a test piece now to be certain. I’ll update you as soon as I know!

Yep. facepalm “J4” on the back of the tool mount and 6/32 kit. Must have ordered with the intention of using metric and completely forgot about using metric when the stuff arrived.

I’ll place another order for printed parts shortly. Thanks for the quick reply.


It’s a Christmas miracle! I must’ve gotten the files mixed around. The 6-32 option does indeed work. I knew it had to be something stupid like this. Thank you so much! :smiley: