Printed T-nuts for hybrid table, 1500lb clamping force possible

I have a hybrid table and wanted more T-nuts. I thought that using a heat set insert in a 3d print would be good enough to get me light holding power. I underestimated the holding force possible. The print is a basic Tee shape with a hole for a heat set insert pushed in from the bottom. I used these M6 inserts from amazon.

To test the capability, I drilled a hole in plywood, and tightened down an M6 screw using a torque wrench until the insert failed. Here is what the plywood looked like when that happened.

Why so crushed looking, even with a washer? Because, the insert started to pull out at 80 in-lb. That works out to over 1500lb of clamping force. I usually tighten those screws by hand with a ball end screw driver. I can’t get close to that much torque. This may not work for absolutely every situation, but for the price and strength, it is a totally viable option most of the time. If you have a printer, by all means, print yourself some extra nuts!

Link to the model:


Nice nuts!
I don’t have a torque wrench, but printed some a while ago that use regular old nuts.


I’d love to see the strength comparison between the nuts straight from the printer and salt annealed.

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I bet those would handle even more seems how the metal nut itself can’t get pulled through the slot.

The failure mechanism is the knurled brass part pulling through. I bet some kind of additional post heating that helps flow the plastic into the brass part better would help. It is already kind of ridiculous though.

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