Wondering if anyone here successfully prints M3 threads, and if so, whether there were any tricks required.
There’s a particular part that I’m printing a large volume of which has some blind tapped M3 holes which look like they will be very not fun to do during post processing 
Thanks in advance! 
We tried M4 to M12.
Printed a bunch of part with different shrinking to test
It was not that great, and we usually had to re-thread the part.
You’ll need to clean the hole very thoroughly if you want to avoid re-threading a M3
Is this a part that can’t have metal threaded inserts, or self tapping screws?
We’ve made a part that would have had blind smooth holes for self tapping screws. To ease washing, we continued the hole but swept it through 90 degrees to penetrate the outer (could be inner) wall. This way there was a path for the uncured resin and IPA to freely flow in and out of the hole.
Press fitting (mould-in) metal inserts into Tough 1500 has worked well for us.
Thanks. Unfortunate 
Probably not given the geometry. I also have no control over the design but I’m chatting with them about it to see if there are other options. I love self tapping screws for resin prints - use them all the time. When I need more strength or the ability to cycle screws then I’ll use the press fit screw to expand inserts.
can you show a slice/section analysis of what that looks like? Also share the inserts you use?
Screw goes in here (green arrow)
https://www.pemnet.com/eu/products/engineering-guides/si-threaded-inserts-for-plastic/
Yes I’ve done something similar with adding drain hole features for washing. Might not be able to do that for this part but we shall see.
I just wanted to add that we tried to add an helicoil for an M5 screw in an old and brittle Draft part with tremendous success.
And the part hold up well ever since.
So maybe an helicoil can be an option to consider ?
Maybe but that will add to cost and doesn’t really lessen the labor required which is the main part in trying to get away from (not the strength of the thread itself).
What resin is this going to be?
Tough 2000. I’ve been told from an engineer at Formlabs that they routinely print M3 threads in Tough 1500 & 2000 so I’ll give it a shot.
I’m not sure what you are optimising for but it sounds like minimising post processing is a component, perhaps for scaling up production. If that’s the case and for some reason you can’t use self tapping screws, perhaps you can incorporate some of the approach here, where the hole profile is adjusted to make machine screws hold better directly in plastic
(Seems like it would be easier than washing blind holes with 0.5mm pitch threads along the walls.
I always prefer thread forming screws and press fit inserts but I’m working with them now to see if we can make changes to avoid all this hassle around tapping blind holes. Definitely do not want to wash and tap them if I can avoid it 
Just checking you watched the video as you mentioned thread forming screws, inserts and post-print tapping - none of which were Thomas’s recommended (admittedly for FDM) approach 
.
If I had to stick with M3 x 0.5 mm screws, his approach would be the one I’d explore first. The payoff in hole washing seems potentially high, due to the smooth walls.
Yes, I’ve seen that video before. I’ll consider it, but depends on what the client is willing to do.
I’ve printed m3 threads with no issues though I would recommend a threaded sleeves if it’s something that is going to need to bear a load. I’ll share my settings but it’ll be $500.00 
Looks like they’ll be able to redesign the part to accommodate inserts and/or eliminating the thread all together.
That being said, I do have a few other production parts that are currently being tapped after so I’ll try direct printing on those for fun.
Does your $500 print settings guarantee perfect threads?
Oh yeah bro, 100% successful prints guaranteed!
On a more serious note, I generally run a tap through the printed threads just to make sure there aren’t any goobers in there but I’ve had good luck!
yeah chasing out the printed threads makes sense - will try it on the next run of parts that have a tapped hole called out. Cheers!
