Build Your Own SLA/SLS

Hi all, I'm running a homebuilt Top down DLP over saltwater and have been struggling with sagging...top sides of my model look perfect but the bottom sides droop down

I've tried curing times from 10s down to 5s and it doesn't seem to ever get sharp

Anyone have tips for this?

Thanks,
Vaughan

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When FDM prints "droop", the answer is more support material, so you may try that. However, the rules are a bit different with DLP, so I'm not sure here.


Do you have any pictures?

Thanks for the tip...I've tried adding tons of supports but anything facing down still looks...mushy in general

I've never used a top down setup, but maybe floating more resin on the saltwater would help?

When you say "droop", does that mean that on the bottom side, there is more solid material cured than you expect?

You may be experiencing overcure/light bleed where the light for a layer is penetrating through and curing the previous (lower) layers.

If so, there isn't really a settings-based solution for that. The only way to mitigate light bleed is to add pigments to the resin mix to make it more opaque and reduce the amount of excess light penetration.

Exactly JKAO. Isnt it weird that its only happening on bottom sides though? Tops side looks very nice and crisp

If it is light bleed, it would only affect one side of the part. The side closer to the projector would be fine and the side away from the project is getting an extra dose of light in this case. For some types of transparent or translucent resin, the cured part itself acts as a light pipe that directs the excess light down to the bottom of the part. For instance, if the whole part glows while you're curing, that would be a hint that light is being carried through the part and may be being directed to unintended locations.