Drilling and tapping

i have a form 3 printer and the holes it makes are not good enough to hold a bolt therefore need to tap the the hole. So far i have failed as each time the material splits. Can anyone suggest 1. the best material to use for tapping a thread 2 any tips on using taps successfully

Run correct size tapping drill first then use spiral flute machine tap with a little cutting lubricant. Works for me every time

The holes will tap easier if you cut them before you post-cure the print. The print will be more pliable, too, reducing the odds you’ll split it while tapping (then run the tap through the hole once more after post-cure, since curing can cause some small dimensional changes). And you need to use lubricant because the resin tends to “gall up” the cutter, which makes the cutter too tight for the bore. And goes without saying you need to pre-drill the right size starter hole (or use a tap that also drills).

Tapping works but the threads do not typically last long in my experience (of course this depends on the material). For the last couple years I’ve used threaded inserts from McMaster-Carr.

Formlabs resin will evidently not work using the solder iron heated insert method, so I typically press-fit and or epoxy them in place.

There is a good guide to screw threads here.

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Using the 4K resin and M3 or bigger threads works for me, provided the thread length is long enough. Also done M5 on standard black.
I use FreeCAD and then merge a threaded insert into my model with a boolean operation. (Tools=> Addon manager =>Fastners)
That gets me a model with the thread in it already. Then the printed part can be cleaned up by easily spinning the tap through it before final cure.

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I use NX to do my designs and for all of my SLA print and resins I design and print the actual thread and than re-chase it with same size tap, and do it all after post cure. Works great.

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