Gooey underside of print

When I print a part, the resolution is great for the most part, but the broadest side facing the raft always comes out gooey. It’s like a pile of material got stuck between the supports and cured on that side of the print. I don’t know if that’s normal or if prints should be oriented on an angle to prevent this. Any suggestions would help.

Underside surfaces that are co-planar with the build plate will be distorted. You want to avoid positioning the model that way. If you came from FDM printing, you know that’s actually the best orientation. But for SLA, not so much. Think of a pyramid shaped object. If you set it on the build plate with the bottom of the pyramid aligned with the build plate, the bottom will be distorted (puckers around the supports). If you flip it over so the peak of the pyramid is pointed at the build plate, you’ll have a little more post-processing clean up to do after you remove the supports, but the surfaces should print with little or no distortion.

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You need to angle the parts.
A flat horizontal surface will cause a cross section which will prevent the excess resin from dripping and also involve force.
A flat surface is always nice but there’s that.

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Great, thanks I’ll try that!

You don’t want a flat surface parallel to your build platform.
If you must, try building directly on the platform.

The other workaround is to tilt the model to 30 degrees or so the resin doesn’t collect on the surface while printing.

Increasing the length of supports can help in some instances.


What resin are you using?

Doesn’t matter the resin. I’ve had it on draft v2, rigid 10k, and high temp. I think the angle will work.

Fair enough. I was curious as to the resin as we had poor results with Tough 3000 (with similar symptoms to what you described) no matter what orientation/angle.

We’ve had far better results since switching to Grey Pro which is a far better choice for the type of parts we’re prototyping.

I’ll try that out, thanks!

Edit: The resin we had poor results with was Tough 1500.

I have noticed a big improvement with the latest release of PreForm (3.22.1). The gooey underside was very noticeable when printing with Grey V4 previously. It wasn’t a major problem for me, given the very small figures and vehicles that I print in 1/285th scale. Last week, however, my son asked me to print some 1/56th scale models of reptilian fantasy figures. I noticed the new style of touchpoints in PreForm. The size was set to 0.3 mm. The prints have been the best I have seen with the Form 3. The features on the undersurface, nearest the build plate, are clear and sharp. My son has been very pleased with the results.