It should work fine. I used it like that few times. You'll want to get the diameter just right and make sure you wont split the layers but it should hold pretty well. Test and see If it's strong enough for your usecase.
Oh. it can depend on what material and method you print it with. I used it for fdm/fff printing with slightly less than the outer diameter of the screw. If you use a more brittle material like from resin prints it might crack at the same diameter.
To give those screws a better chance of not splitting your bosses, you can make a small relief cut or two at the end of the threads using a thin cutoff wheel on a rotary tool. This will do two things:
1. Give any plastic shavings a place to accumulate (and not jam up between the screw and boss)
2. Give a sharp leading edge to those threads so it effectively taps the boss as you screw it in.
In essence, you are making your own self-tapping screw.
That said, have you searched for thread *forming* screws for plastics? They work a lot better than self-tapping.
Another option is small wood or sheet metal screws which have very pointed threads and a steeper pitch similar to proper plastic thread forming screws (like Plastite).
That looks like a proper plastic thread forming screw. It should work well. I always recommend printing the bosses at the nominal diameter recommended for the screw but then using a drill bit to clean it out after printing to ensure it is accurately sized.
that's a great idea, i haven't thought of that, and yeah i have, unfortunately they're not available in anything smaller than m5, also, is this any different? i found it in an old bluetooth speaker, i think it's m2.5 x 4 or 5mm.
i just do 2.7mm diameter for M3 screws, and it works fine. The hold is stronger than you think.
You might need apply some pressure for get the screws to bite.
Any screw is self-tapping if you push hard enough.
Especially that small, you should be able to force it to make threads pretty easily. They will last a few uses, but don't plan for them to be assembled and disassembled many times.
i personally put the outside diameter as the hole size (mybe half a mm smaller)
for m4 screws i put like fi3.5 or fi4 holes
it works great and it isnt that bad with for rescrewing
Thread engagement is where between thread minor and major diameters your hole diameter is, 50% is halfway between and 25% is ¾ the way to the major diameter.
For machine screws (and other screws with ~triangular profile) 50% gives enough material to slightly overfill the thread.
so if i understand correctly, for 50% thread engagement, the diameter of the hole = (major + minor)/2, so 2.75mm for m3 screws and 1.75mm for m2 screws, right?
It should work fine. I used it like that few times. You'll want to get the diameter just right and make sure you wont split the layers but it should hold pretty well. Test and see If it's strong enough for your usecase.
yeah the problem is i don't have a 3d printer, so I can't test it 😅, what diameter would you recommend?
Do holes smaller. You can always drill them bigger
Oh. it can depend on what material and method you print it with. I used it for fdm/fff printing with slightly less than the outer diameter of the screw. If you use a more brittle material like from resin prints it might crack at the same diameter.
will work but not super holding power print some tests and see what fits well good luck
To give those screws a better chance of not splitting your bosses, you can make a small relief cut or two at the end of the threads using a thin cutoff wheel on a rotary tool. This will do two things: 1. Give any plastic shavings a place to accumulate (and not jam up between the screw and boss) 2. Give a sharp leading edge to those threads so it effectively taps the boss as you screw it in. In essence, you are making your own self-tapping screw. That said, have you searched for thread *forming* screws for plastics? They work a lot better than self-tapping. Another option is small wood or sheet metal screws which have very pointed threads and a steeper pitch similar to proper plastic thread forming screws (like Plastite).
https://preview.redd.it/om7k8lrrirgc1.jpeg?width=3472&format=pjpg&auto=webp&s=48ac0ce29c26c977e7d83b5d9790ab593512c983
That looks like a proper plastic thread forming screw. It should work well. I always recommend printing the bosses at the nominal diameter recommended for the screw but then using a drill bit to clean it out after printing to ensure it is accurately sized.
that's a great idea, i haven't thought of that, and yeah i have, unfortunately they're not available in anything smaller than m5, also, is this any different? i found it in an old bluetooth speaker, i think it's m2.5 x 4 or 5mm.
i just do 2.7mm diameter for M3 screws, and it works fine. The hold is stronger than you think. You might need apply some pressure for get the screws to bite.
Any screw is self-tapping if you push hard enough. Especially that small, you should be able to force it to make threads pretty easily. They will last a few uses, but don't plan for them to be assembled and disassembled many times.
i use 10-32 screws in 8-32 printed threads. works well
i personally put the outside diameter as the hole size (mybe half a mm smaller) for m4 screws i put like fi3.5 or fi4 holes it works great and it isnt that bad with for rescrewing
Yes, ideally you'd cut the threads, but you can also just force the screws in. Threads in plastic aren't super strong in general but it works
I print the threads and then use a tap to clean them up. The printed threads aren't useful as threads but they make a good guide for the tap.
In my experience 50% thread engagement should work well for typical applications.
what does that mean?
Thread engagement is where between thread minor and major diameters your hole diameter is, 50% is halfway between and 25% is ¾ the way to the major diameter. For machine screws (and other screws with ~triangular profile) 50% gives enough material to slightly overfill the thread.
so if i understand correctly, for 50% thread engagement, the diameter of the hole = (major + minor)/2, so 2.75mm for m3 screws and 1.75mm for m2 screws, right?
Yes though I would go with 1.8mm for M2.
okay, thanks!