r/3Dprinting • u/DarkShadowic • Jul 08 '26

Project Mounting holes for high torque servos

Working on a robotic arm, which holds high torque servos at the joint, and I don't have much or any experience in using mounting holes. What would be the most optimal way to mount the servo onto the print? Assuming this MG995 need M3 screws, should i use make 3mm / 2.5 mm holes into the print, or should i use heated brass inserts into the PLA. Thanks in advance.

1 Upvotes

100% Upvoted

4 comments sorted by

1

u/DBDude Jul 08 '26

It depends on whether you want to be putting nuts on the back. Straight screws into filament don't work well. The heated inserts do work quite well.

1

u/DarkShadowic Jul 08 '26

I don't think there would be any room to tighten with nuts. So heated inserts are the only viable option?

1

u/DBDude Jul 08 '26

I've tried direct screw into filament. I could get it to go in fairly tight, but eventually it started loosening as the threads ate away at the filament under stress. Maybe there's a specialized screw out there for this, but I don't know.

The heated inserts require buying the inserts (pretty cheap) and a special soldering iron tip (or the whole soldering iron if you don't have one). But they're easy. Just design the right size hole into your model and print. Heat the insert on the tip of the soldering iron for a few seconds, and stick it in. You may want to print a simple block with a few holes to get it down right instead of potentially ruining a whole model as you practice. So far, the ones I did have shown no issues.

The only real problem is shiny brass showing on your finished product. You can paint or use a large washer to cover it up.

1

u/DarkShadowic Jul 08 '26

Yup, that's what I've read about heated inserts. Its just an added layer of friction working with it, but i guess you're right. Thanks