Recessed bolt holes

Hi folks, I know this is probably trivial but I may as well ask. I have been able to find tutorials on creating recessed circular holes for screws, but I cant find anything about hex bolts.

I want to make an m4 bolt hole that is recessed for the bolt to snugly fit into. I thought about it for a while and kinda gave up as I didnt know how to go about in getting the process down. Normally I would mess around with something then print, then try to fix the error then print again and see if the part fits. That is totally not the right way so its best if I just ask someone if they can show me how its done.

I have included a pic of what I was doing. The square is the measurement of the bolt which is 6.78mm, the hole is 4mm for the bolt to fit into. I dont know how to get the corners of the bolt, I tried with the calipers but I think I am just doing it the wrong way and the corner measurements are possibly off anyway.



It would help if you drew that on the surface of the part receiving the hole. Push the round hole through and the square face down to create the recess.

Is the head of the bolt square or hexagonal? If the latter, use the Polygon Tool instead of the Rectangle tool.

If it is hexagonal and you know the distance across the flats, hit Ctrl after getting the Polygon tool and setting it to 6 sides. Then you can enter the distance from the center to the flat. If this is to be 3D printed, remember to allow a little clearance or the bolt head will be a press fit.

Oh man, thanks a lot. Thanks a lot for explaining, the bolt has 6 sides and I have an idea what to do now. For simplicity sake when I am trying to learn something I always make a test piece of what I am trying to do until I really get the understanding down then I move back to the piece I am trying to draw it on.

I am going to keep this measurement tight as I want it to be a press fit when I 3D print the hole for the bolt.

Even so, it’s probably easiest to draw something like that on a simple 3D box rather than drawing it flat.

Good luck with it.

Thanks again…


I don’t think you’re following my instructions exactly. You’ve got reversed faces that you shouldn’t have and your hexagonal recess extends below the box. The hexagon doesn’t appear to be drawn on axis, either.

Make the box deeper than the recess you want so the recess doesn’t go through the bottom of the box.

This is what I ended up with, I had posted that pic after I made the recess and was a bit happy to learn something new.


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