Well it got off to a good start, but the whole back top of the skull didn’t print.
I guess my first lesson is I can’t trust the automatic supports which was one of the primary reasons I purchased a Form 2 over other options. Which of course is very disappointing.
I used the default for everything.
Any suggestions as to why it may have failed and any insight on when to not trust the automatic support generation would be appreciated.
Oh yeah - i forgot to mention I used the auto-orientation feature as well.
Post a screen grab of the object with supports in PreForm. Not possible to see meaningful details with the pictures of the print itself.
I used a black sharpe to help highlight where it apparently stopped growing (to the best of my ability).
Still kind of tough to see what the printed part actually looks like. But I don’t see anything particularly wrong with the screen grab from PreForm.
I would tip the part the other way, so the more massive back end of the skull is closer to the build platform and the tapered jaw is what’s pointing away from the build plate.
Did you hollow out this object (meaning there are voids inside the “bones”, or is it solid?
OK - I guess I will try that.
So getting prints to come out is trial and error I guess? With FDM I could tell easily what required a support or not and the best way to orient parts. I thought I was getting a system that would just work most of the time - which is a critical aspect for doing production work. But as time consuming and as expensive the resin is, this first print experience is rather discouraging.
Correct; I hollowed out the geometry to a 2mm shell in Meshmixer.
With FDM, I bet you had to learn what required support or not and the best way to orient parts. Same is true for SLA. Same is true for CNC machining, too. It’s as much art as science. You have to learn how to make the most effective use of the tool. Advanced capabilities and “push button operation” are not entirely compatible with each other!
Hollowing out the geometry is probably a key factor in the print failure. You need to “vent” enclosed hollows. If they’re sealed, hydraulic pressure from the open end of the void being submerged in the resin can cause a “blow out”, particularly with thin walls (you also capture some uncured resin if you don’t get a blow out). Punch some small holes through from the interior void to the exterior. Probably you can find a place to make holes on inward facing surfaces that won’t be visible unless you poke in to the interior with a dental mirror.
Note however that in my experience it’s best to have a hole at both the top (end nearest the built platform) and the bottom (last layer to be printed). When you go to rinse your print in IPA, the void is going to fill up and having holes at the top and bottom is key to getting all the IPA out of the void, you can get it to flow through the void through the holes…
I bet if you printed the model without the bones hollowed out, it would print perfectly.
True, I had to learn. But you don’t even see anything wrong with the supports - so how is someone new going to be able to tell?
I will add too that this printer is marketed towards business people that just want a solution that works without fiddling around.
Actually; there are holes, and they are near the top of the bottom. If I don’t add holes at all - the print won’t even come into PreForm as a shell (I think you gave me that tip).
I don’t want to print solid - I absolutely need to be able to print parts hollow for my casting process to work optimally. The plastic gets burned out - the less plastic the better the chances of a keepable cast.
Here are a couple macro shots of a couple of the holes.
This first one looks clogged - but that is just an internal support beyond the hole:
Another hole would have printed but that part didn’t print.
Meshmixer is a great tool for accurately hollowing your models and also allows you to add holes to your mesh.
That is precisely what I used. 
Well I guess I’m not all bad news - at least the 2nd attempt came out - the horns for the skull. Just started the 2nd attempt of the skull.
Note that all four pieces are hollow as well - with a hole at the top and bottom of each piece.
Here’s one with the failed build. 
Thanks for the advice Randy_Cohen, the 2nd attempt came out. I guess I will always make sure the biggest portion is closest to the build plate. I was thrown off, I guess, by the fact that the software recommended the opposite orientation, and since it was my first build I wanted to do what it recommended.
When a print fails from a FDM print not having proper supports it was obvious why, but it is still not completely clear what actually failed with the first attempt so its kind of hard to learn much more than printing the big side down. Still - seems like a good rule of thumb.
My logic is that the part of the model that needs the most support during printing should be closer to the build plate. Unlike FDM, there’s a peel process in SLA that puts a lot of stress on the print and its supports. Orienting the model so the supports are spread out and densest closer to the build platform seems like it should result in higher tolerance to the peel forces…
For better results I would even tilt the head back further, the back of the skull is easier to have supports on and it would require fewer supports though it would take longer to print since it would be taller. An issue with that print could also be some thin walls.
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