Screw Boss problems, Need advice

I’m having problems printing screw bosses in an enclosure. The screw bosses are .16" in diameter and I’m using self tapping screws that are .085". The holes I’m printing are about .075" The problem is the resin is filling the screw holes and partially hardening basically filling the boss up with resin. Ive tried different orientations and I though that having the bosses oriented vertically would let the resin drain but it hasn’t helped.

Any advice? My whole design is scrapped if I cant get these bosses to work. Yes I can drill them out. But that not reliable and may affect my precision and takes time.

Any advice would be greatly appreciated.

What type of resin are you using? If using unless using Tough or Durable (and maybe also Rigid but I haven’t tried it yet) it’s no use trying to screws self-taping screws anyway,

Regarding the holes being filled : it’s a classic issue. One thing that helps is to avoid making blind holes, but that may hinder the design and/or require you to fill the hole afterwards which may not be practical. Alternatively you could also make a small opening, at the base of the boss, facing the inside of your enclosure, this will help the resin pouring off the hole.

Another thing is to really thoroughly clean the holes during the IPA washing : using a wash bottle with a hose and forcing IPA into the hole, then cleaning it with something hard like a q-tip shaft of something will help removing the partially cured resin.

Really, I found that self-taping screws and the relatively small and long holes that you have to make into the parts don’t play well with SLA. When prototyping stuff like that I use metric screws and threaded inserts.

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Try blowing the holes out with compressed air after the IPA bath. I’ve found that blind holes tend to hold a bit of resin plugging the hole during cure.

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I use the dental model resin for this type of project. The standard resins tend to warp! I will be posting a job soon that required this type of precision!

I was using clear or durable. Ive successfully done this print many times so something has changed. And yes I use compressed air after washing, and then I wash again to clear the holes. The problem is the resin is cured in the holes when it comes off the printer before washing. I had another print with a shallow .125" hole that came out completely full of hard resin. The hole almost didn’t exist. Im troubleshooting it with customer support now. I just found some dust on the window that may have been the problem.

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As thick as these resins are in the uncured state; I think it’s asking gravity to do too much work when it comes to small holes as the volume to surface area ratio is pretty close to each other.

I flush them out with IPA using the wash bottle and compressed air. I also just accept that drilling out the holes is part of the game, especially with blind holes.

Self tapping screws are pretty crude compared to using an actual tap that cuts threads. I equate self tapping screws to a meat cleaver and a tap to a surgeon’s scalpel.


Seems to have been a printer problem. After a week working with support I had to buy the support plan to swap the printer in a timely manner.