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. https://www.amazon.com/gp/product/B08Z7541M5/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
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!
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.
