Same test scenario as my other thread where I tested the Tough material. To be honest I was totally expecting a failure based on how brittle the standard material can be relative to geometry.
In my experience, standard material doesn’t become brittle until it has some age on it. The pieces I have broken have been from shock load, like dropping them and they break when they hit the floor. You should do the same test on that bracket in a few months and see if you have the same results.
From my results the material is somewhat brittle without any aging. That doesn’t mean that it’s a fragile material though or that it’s bad. It just means that it’s so hard that when it does give in, it does it without much bending before failure. Obviously the geometry determines how well the print performs under stress and impact. I just didn’t expect the Standard from perform this well under load, even when I was pulling down hard on the extinguisher. Pleasantly surprised
If you haven’t seen it, check this older thread where I test Standard vs Tough with impact testing using a hammer and vise. The Standard material just shatters into many pieces because it doesn’t flex much and does not absorb impact like the Tough material does. Video: smash testing the Standard resin vs Tough resin.
I should have said that the standard material become “more” brittle over time. I work for a conveyor company and I make prototype chain links. They are handled by a lot of different people and get dropped a lot. New parts do not usually shatter when the hit the floor. Parts that are several months old almost always do.
If all you want the bracket to do is hold the maximum load, you will generally do better with the GP resins than the tough. The most relevant mechanical property for this use case is the tensile strength. In the fully post cured state, Clear is ~50% stronger than Tough.
Tough’s key strong point is it’s impact strength which is more than double Clear’s impact strength. Impact strength is, roughly speaking, a measure of how hard you could hit the part or throw it at a wall without it breaking. This is also relevant for a practical wall bracket if you are concerned with it getting banged around in the process.
Tough datasheet: http://formlabs.com/media/upload/Tough-DataSheet_qx90Cxq.pdf
Clear datasheet: http://formlabs.com/media/upload/Clear-DataSheet_YgKm6wc.pdf
@MaximLobovsky yes I have some clear valve bodies I’ve printed that are rock hard. I am making videos for each material and haven’t printed the bracket in clear yet. So far just the Tough and Standard. The only purpose really is for others to see how each material Formlabs offers behaves under the same test conditions.