How "hard/tough" are the supposed hard resins for desktop SLS printers?

aarongough said:

A little bit more quick experimentation with the two Siraya resins, 'Blu' and 'Tenacious'.

I poured a little bit of each into the bottom of some plastic cups, and then cured it using the cup as a mold. Ended up with 2 little pucks about 1.5" in diameter and 1/8" thick.

When placed on my concrete floor and struck with the rounded end of a ball-peen hammer the puck made from 'Blu' shattered like glass, small shards went everywhere. When I did the same with the puck made from 'Tenacious' the hammer just bounced. Couple of dozen more strikes with the hammer and the 'Tenacious' puck shows no sign of injury at all, not even dimples from the hammer.

The 'Tenacious' material feels a lot more like a hard Urethane rubber. Thin sections of it around the edges of the puck will dent/roll with pressure from a fingernail and then slowly creep back to their original shape.

I am doing a test print now with a mix of 80% Blu and 20% Tenacious, we'll see how it turns out. Ideally I'm looking for behaviour fairly similar to Kydex or Polypropylene. Moderately stiff, fairly hard surface, but will deform or yield under stress rather than shattering, leading to parts that are practically indestructible.

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1) Parts warp during curing.
Not sure how to mitigate that, but basically if you print a box (like electronics enclosure), can expect that the walls will be crooked.

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2) Parts bleed.
If it's not 100% fill, there is a chance of uncured resin being trapped in the hollows that will later find a way to drip out of the part.

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Billtodd said:

There's lots of good information on the Ameralabs website



This can be mitigated to some extent by heating everything. The resin heats when cured by the UV , heating the whole thing just reduces the differences.
Think about resin printing like a casting process .


walls and larger areas really need to be under 3mm thick to prevent warping (strength v shrinkage again)

I have found it necessary to build supports and sacrificial braces into the 3d model prior to slicing .

Bill

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