My last print with a mix of B9-red and Spot-A-HT was a failure. I printed this cannon from GrabCad:
All came out fine, even the thin explosive fuse. But after two days the cannon tube bursted. It is well known that Spot-A-HT cures faster and is more brittle but I didn't believe that a 2.3 mm thick wall would burst.
I have printed several hollowed objects of similar size with B9-red but never seen such a burst.
Could it be due to the mix or is Spot-A-HT generally not suitable for hollowed prints?
PS. Exposure time was 12 seconds, diameter of the wheels 57 mm, layer thickness 75 µm.