I just started using my Form2 printer. I am working through the Preform tutorials.I cant seem to find anything about the “printability” button in Preform.What is this for and how do I use it?

Just gives a visual indication of how likely the print is to be successful. So if you try one layout and it shows a red circle with a line through it, then it will most likely fail. Check marks are good and should, in theory, work fine.

OK thanks. I am used to FDM printing with a Raise3d printer so object placement and supports is all new to me.I did go through the preform tutorials.So I guess trying different orientations and supports may be necessary prior to printing ? I printed an Eiffel tower and it came out pretty good even though the printability had a red line through it. I dont think I cleaned it well enough because it was still a bit sticky and I damaged it removing the support.Are you supposed to let it set before you remove the supports? it was pretty delicate.


All 3D printing requires support and orientation thought before hitting go. The concept is the same, just have to get used to most things being printed on a raft with supports. Similar to FFF, you have to support those flimsy areas like arms and thing overhangs. Orientation is more key here to get the best success rate.

If you printed on the build plate as intended, that is why it was red.

Generally you are better off to cure it with supports on to prevent warping and other such things. I always take supports off post-curing so they just snap off or cut off. Doing so prior to curing, I’ve heard, is easier since they pull off, but if it is slimy, then you didn’t soak or spray it long enough.

The Fuse1 and other laser sintering machines, and printers that add glue to corn starch don’t need supports.

My habit is to tilt parts 10 deg. to avoid having faces parallel to the build platform.

It is true that SLS doesn’t use traditional supports, but it does get support from the nature of the process. I guess I should have clarified specifically the two types that need manual supports.

If you notice, Preform always tilts objects and it is for good reason. 10 degrees is the lowest I’ve seen it tilt.

The main difference for supports between SLA and FDM is that SLA can’t really do bridging, so that’s why you have to angle parts so that a flat surface is not parallel to the build platform (so it builds up the flat parts across many layers).
Orientation is really important because you get better results on the top of the print and anywhere a support touches the print will not turn out as good so get supports on areas that are easy to clean and get the important detail on the top.

What is the size limit where bridging is no longer recomended, I have been looking at some slicing in preform of jewelry pieces and I seem to see a lot of what I think would be “bridgeing”

Sure, though I’m not sure how far that can go. But–one thing about SLA is that since it supports the layer while it’s curing it can be a bit larger than the previous layer where FDM would sag a bit around the edges without support. That’s why an SLA print can start from small support points and build up where FDM prints largely need to have a large amount of support structure.
The issue is that the layer will stick to some degree to the bottom of the tray and that along with suction will put stress on the layer and cause it to flex or come apart since it’s very thin.
There are printers like the Carbon 3D printer where there’s no issue there, there’s a thin layer of uncured resin under where the print gets made and that means the layer isn’t curing against the bottom of the tray and it can easily pull up without much suction since the liquid resin is already underneath. Printers like that can print continually without having to stop to lift up after each layer.

This was written up for the Form 1+ but I think it still applies to the Form 2. According to the FormLabs Design Guide the Bridging Gap should be no more than 5 mm. Here is the link to the design guide. Open the PDF and scroll down to Bridging.

Thanks for those replies, With out having a form2 yet I am trying to get a good visualization of how the layers form, and to do this I am primarily looking at slices and seeing what the layers look like. Some times its hard to avoid the dramatic horizontals that suddenly appear in a model slice, and I can see how this is supported by the silicone as it hardenes, But yes its the peel I wonder about most since I have no feeling for how much stress is ocurring when the tray pulls to the side. It seems like these sections would just get pulled off?

I had a couple print jobs where this type of bridging happened. The bridge was between supports and they were about 3 to 4 mm apart and about 1.5 to 2 mm wide. I was printing using Tough V4. Like most resins it is very soft until it has time to dry and UV cure. Anyway some of these bridges did peel back and de-laminate. Some of them even broke loose and ended up getting fused into the printed parts later on. It didn’t ruin my prints. It was just interesting to note. In the future I will try to orient the printed parts differently.