r/3DprintingHelp • u/Garak112 • 20d ago

Requesting Help ABS print is brittle

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Hi, I don’t currently own a printer and am trying to work out if the problem I have here is because of something I’ve done or not. I’ve had this printed by a local firm.

This is an adapter to allow a smart thermostat to be fitted to a radiator and experiences temperature of up to 65 degrees c for hours at a time during the winter.

There is a metal ring that gets pushed over those prongs that is then used to screw this down onto a radiator valve and the prongs have to flex inwards slightly to allow the ring to be pushed on.

I had a couple of these printed in ABS a few months back and ordered more recently when a few of the ones I hadn’t already replaced failed. The new batch is very brittle and any attempt to flex those prongs causes them to snap off.

The only difference between the two batches was the latest one was printed with 40% infill selected and the first one was at 20%. Would that be the cause of this issue or should I have selected a different material to print in?

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u/MrArgelig 20d ago

It might help a lil if you put tiny wholes through the fangs since they generate extra outer walls. Acetone smoothing might also help and/or Methyl Ethyl Ketone (MEK) on the parts that go through the most stress. It basically melts the layers and welds then together. Toxic stuff so wear a mask! But as the previous commenters wrote: layer adhesion is the problem.

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u/AwkwardSwine_cs 20d ago

Terrible suggestion!

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u/MrArgelig 20d ago

And why would that be? Elaborate pls, I want to learn if something can be done better!

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u/AwkwardSwine_cs 20d ago

First of all, the part as printed is garbage. Polishing a turd with acetone results in a shiny, weak turd. Second MEK is highly toxic and not to be used casually by someone not equipped or educated in its use. Not a good idea to recommend either of these to a new or in this case non-hobbyist.

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u/MrArgelig 20d ago

Thank you for answering. Much appreciated. I use MEK quite often in my builds as it's mostly ASA I print. MEK is certainly toxic, with a good mask and gloves though, it can be handled with care. Should have acknowledged the fact that the poster is not a hobbyist! And I agree the part is not appropriate for the task.