How well do printed threads come out? Assuming they are not tiny …
Machine shop needs two cap nuts to cover the spindles of the Sherline lathes when not in use. The nuts would need about a half inch of 3/4-16 thread on the inside of the caps.
Thoughts/comments?
ABS cuts fairly well. In the worst case, the threads can be tapped.
What color would you like the caps?
Can you post a picture of the spindles? A snap-thing may work better than a screw-thing. Seeing may help make that clear.
3/4-16 threads will print fine. They may need a little ‘run in’ because of size issues with 3D prints, but once worn in they will work perfectly.
(Machine shop) blue …
3/4-16 cap nuts aren’t that expensive @~$5.00.
https://www.grainger.com/category/cap-nuts/nuts/fasteners/ecatalog/N-1197Z1yzj8tk
of course, if you just WANT printed caps, it’s all cool with me (because pleasing ME is what this is all about!)…
The plastic should help prevent overtorque.
That is a good suggestion and honestly I had not considered that.
In my perfect world they would be printed; partially to prevent overtightening and partially to prevent it from seizing up on the spindle.
And blue would be easier to keep up with.
You might want to add a short lamp-pull like chain on them to the lathe to keep them from walking off, but not long enough to get caught up in the works.
It may be quicker to thread delrin/plastic rod. We have the tap to do it if we want to stay with plastics.
The Form 2 resin printer can easily get that detail level. It would be clear or green rather than blue though.
@John_Marlow, I plan to be at DMS this afternoon. I have a model for a cap nut that I can print while I’m there.
Do you still have a need for two cap nuts?
Have a brand new nut ready for your inspection!
You are so awesome!! We do still need two cap nuts.
Unfortunately I won’t be at the Space for awhile as I’m headed off to miniature summer camp (believe it or not, there is such a thing!)
If you see @Photomancer or @nicksilva, could you share the cap nut with one of them?
And may I please reimburse you for the filament?
Thanks!
Got to try this one first. If it works like a nut I’ll make the second one.
And, this one is the wrong color. Once the mechanics are worked out I’ll get you a pair in the desired color.
@Photomancer is on the phone. Lots of money talk so I’m not going to interrupt.
I don’t know what @nicksilva looks like.
You may NOT reimburse me. Even if I pay “retail” at 8 g of material that’s 80 ¢. I will have to print many many more of these before you and I are no longer square!
I live about 15 minutes away so getting here is no sweat. Just let me know when you’ll be around.
Um, no, sorry. And more characters.
Good thing. You would have been disappointed. I will let you know when version 2 is ready. 
Threads? As seen on Reddit/r/3dprinting this morning:
With help from @jphelps Nut v2 worked. I left it on one of the Sherlines.
That version was annoying to put on. The threads run right up to the lip of the nut so there is no lead-in. I will try a design with a lead-in.
Thanks mucho! I have been traveling but am anxious to see the results.
You are welcome!
I’m up to Nut 4. I will try to get it printed Monday or Tuesday.
Nut 4…
Has the same lead-in as Nut 3. That was a huge improvement.
Has a slightly larger diameter which should make it great for hand-tightening / tool-free operation.
Is round instead of hexagonal. @jphelps preferred hexagonal so it could be removed by tool in case it was over-tightened. Given the cost (dirt cheap; just print another) and the fact that hexagonal was a little uncomfortable hand-tightening I went with round (pliers / plumber’s pliers / pipe wrench would be used to remove it if it was over-tightened).
Has a “hood” that hangs over the left / motor side of the spindle. The idea is to protect the spindle and bearing from dust / liquid / whatever.
Has a taper leading into the hood. This should provide some locking so the nut will not need to be very tight and will likely seal the spindle inside the nut helping to keep out debris.
Is slightly deeper. As far as I know we do not have a 3/4 x 16 bottom tap. The extra space allows ~0.5 inches to be tapped with what we have.
Is slightly longer. This gives a bit more to grip (about 1.25 finger widths / full thumb width) which should make hand-tightening easier. I had thought to go with 2 finger widths but that makes it awkwardly long.
Is slightly larger. This should make it more difficult to lose.
Is nearly hollow. The idea is to make it function like a motorcycle helmet. If something heavy / sharp is dropped the nut should crush absorbing most / all of the force helping to protect the spindle.