We use a Form 3 printer in our lab with Clear V4 resin. I have noticed recently that it tends to bulge at the bottom of the print (towards the build plate). This has only become important recently, which is why I have noticed it so clearly. Initially I only angled it in one direction, such that it prints starting from a line after supports. I was told I should print it with two angles such that the print starts from a point rather than a line to reduce warping. In the first picture, I have printed from a line, and there is a uniform bulging. The T-hooks were printed first
If I print from a point, there is still bulging, but now it grows “outwards” from that point (as might be expected), see picture 2. It is difficult to capture the warping exactly because of the clear resin.
I have looked at the FAQ sections and it does not seem to address the problem. I have cleaned the LPU window. The resin I use is slightly old, but prints seem fine for the most part. The dimensional accuracy is slightly low, but not more than 1-2% in the worst cases. These artefacts also seem to happen during printing, not post-processing. For the first case I used 100 um layer thickness and for the second case I used adaptable layer thickness (to see if that’s good for holes).
What could be causing this warping and how can I fix it?
Thanks for posting! It looks like you are asking about dimensional accuracy. As a first step, we recommend checking out this Formlabs support article: Dimensional inaccuracy (SLA) | Formlabs
Once your issue is resolved, please mark the topic as Solved.
Thanks for posting! It looks like you are asking about warping. As a first step, we recommend checking out this Formlabs support article: Warping (SLA) | Formlabs (On a Fuse/SLS printer? See Warping (SLS) | Formlabs )
Once your issue is resolved, please mark the topic as Solved.
I never remember to save my PreForm files, but I always use automatic supports, so if that is deterministic then at the very least this should be case 1:
I know I printed that with an angle of 52 degrees, though the exact placing on the build plate might have been different. I dont know the exact angles for the second case (eyeballed it), but it should look something like this:
From what I can see in the PreForm files, a couple of things stand out.
Unless I am mistaken, the orientation shown in the PreForm file does not appear to match the orientation in the actual print image. In the photograph, the area highlighted in red appears to be where the supports are concentrated, whereas in the PreForm file, the support concentration appears to be in the area highlighted in green.
There are two distinct things happening in these cases.
In Case 1, the part is relatively long — approximately 97 × 31 × 26 mm — and is solid, weighing around 8 g without supports.
In Case 2, the part is also solid, with a volume of roughly 20 mL, and based on the orientation shown, is approximately 62 mm long.
Printing the part at two different angles to minimise unsupported regions is a valid approach, but overhang behaviour is not determined by angle alone. The cross-sectional area being exposed on each layer, release forces, and the amount of material being supported also matter.
For example, a large solid cross-section can experience significantly higher release forces during printing. At the same time, a long or relatively heavy section can place more load on the supports and increase the tendency for the part to flex, shift, or deform during printing.
Because of this, although it increases material consumption, a more robust approach would be to add additional supports in critical areas. These supports do more than simply prevent an unsupported overhang; they can also act as guides and reinforcement, helping constrain the part and reducing movement or deformation during repeated release cycles.
PreForm’s automatic support generation may indicate that a model is sufficiently supported, and it will probably work in many cases. However, it is still worth manually reviewing the support layout, particularly when printing parts that are solid, long, have large cross-sectional exposures, or combine several of these characteristics.
In those situations, adding a few strategically placed supports can provide considerably more margin than relying only on the minimum support configuration suggested automatically.
