What's the smallest/finest bolt you can print on an M2?

[sprior]

I'm pretty amazed at how the Makerbolt on Thingiverse prints and how smoothly it works. I'm wondering how small a bolt/nut with what standard threads you can reasonably print on an M2 and have it come out OK - has anyone done any experiments?

[Tim]

I use bolts to hold things together, but personally, I wouldn't print them. Looking smooth is one thing. Holding up against shear forces is quite another.

[sprior]

There may situations where they could come in useful, I'm just trying to collect info on how small/fine they can be and print well.

[ednisley]

what standard threads you can reasonably print on an M2

From what I've read, 1/4-20 is about as small as you can expect. A 0.20 mm layer thickness gives only 6.3 layers per turn, so each layer occupies a 60° angle: the "thread" won't be very smooth. Of course, you can reduce the layer thickness to get smoother threads, but then you run into the XY resolution limit: a 1/4 inch bolt's minor diameter spans barely a dozen 0.4 mm threads.

I reverse-engineered the thread on a broom handle before discovering (duh) that it was a bone-stock 3/4-5 Acme thread:
http://softsolder.com/2013/04/01/broom- ... ment-plug/

Some OpenSCAD improvements let me add the thread dedendum, not that it really mattered:
http://softsolder.com/2013/06/19/broom- ... -dedendum/

But using a better (i.e., less wrong) thread form made the printing orientation more critical. Splitting the threaded cylinder and printing the two halves horizontally produced much better results:
http://softsolder.com/2013/11/07/broom- ... ientation/

If you wanted a real V-form thread, rather than the crude cylindrical segments I used, the overhang would probably wreck the result.

For scale, there's a 1/4-20 carriage bolt running down the middle of that cylinder:

[jimc]

haha ed thats fantastic. i see you posted the openscad code which i know nothing about. do you have an stl you would be willing to share for that? the two halves i guess.

[sprior]

1/4-20 starts to be interesting because for example I think that's the thread camera tripod mounts are.

Thanks Ed! I started to read your blog without knowing anything about who or where you are, and as soon as I saw the picture at Red Oaks Mill I knew you had to have worked at IBM Pok (I worked Pok, Fishkill, Pok from 1990 - 2000), your posts could only have come from an engineer.

[ednisley]

an stl you would be willing to share for that? the two halves i guess.

Here ya go:
https://dl.dropboxusercontent.com/u/785 ... 2%20mm.stl



It's built for 0.20 mm layer thickness and 0.40 mm thread width, although that shouldn't affect anything other than the glue gutters around the alignment pin holes, which fit 1.75 mm filament pegs.

That'll spin around on my Dropbox account until I need the space for something else, which should take at least a few months...

[jimc]

awesome ed! thanks. i saw that and it just seemed like a real handy file to have on hand.

[ednisley]

camera tripod mounts

I wouldn't screw anything heavier than a webcam onto a printed 1/4-20 bolt, but your mileage will certainly vary!

worked at IBM Pok

A long time ago, in a universe far, far away. Served my time in the Fishkill Factory, too...

[sprior]

Yeah, I was thinking webcam or a small point and shoot, NOT my Canon DSLR.