When do failed prints damage the PDMS?

This post was an attempt to separate this discussion:

The answer to why some users get bad tank damage and other don’t is starting to appear like they are not using FormLabs resin when printing, and the cheap resins get extremely hot during cure.

Last night I left the printer running.

Printer is a new Form1+ and the tank was also fairly new as it had been used with less than 1 liter. I was using FL Clear resin and part of the print sticked on the bottom of the tank and made the whole thing fail. Needles to say that I feel frustrated with the waste of time and money. This is a project I’m doing for myself, but if it was client work with a deadline I would be in trouble.

Very gently I pulled out the layers sticking on the bottom of the tank and can see still see some marks where the print was being made. I don’t think I can clean them and don’t want to risk another failed print so I replaced the tank and I’m trying with new resin.

I did follow all the recommended procedures for checking the resin tank gently with the scraper, I mixed the resin and used a fine comb to filter any small bits before the print (not that I saw any… but just in case).

So… I followed all the rules and I had a failed print.

Can you post a picture of what you are making? (Even a screen grab from the Preform software?) Have you made successful prints in the past?

I created a new post with all the info here:


The damage to your tank is almost unavoidable with that model unless you can make the supports shorter. The tank gets cloudy when the laser hits the same spot over and over and I am sure you are seeing marks where the tall supports are. I have the same problem with many of my parts because they are tall and it is a cost I have had to build into the parts when they come up. As far as the failure, and making the supports shorter, try making the part slightly more vertical so that the cross section is less and there is less overhang. You may be able to eliminate the tall supports and as long as you do not make it vertical, the parts should still come out dimensionaly correct.

`Thanks for the tip! :wink:

Hi Nicolas,

Judging by the pictures, it looks like your model is solid. Does it absolutely need to be? 396ml is a lot to try to push through in one print, especially at 50um. This isn’t to say the machine can’t do it. I’ve printed some pretty massive/high volume pieces before. However, even hollowing it slightly will help cut down on the amount of resin used and the wear and tare on your tank.


Hello @Clark_Anthony,

yes, the part has to be solid. It is the lens of a lamp that will be PMMA if I take it to production. I need the solid PMMA to conduct the light.


How about printing it hollow, then buying a clear epoxy to fill it? Probably cheaper and faster too.

That won’t work. The refractive index will be different.
If you want an object to refract light like a solid object would, it needs to be filled with material that’s exactly the same refractive index, otherwise it will appear hollow.

Yea I figured it wouldn’t be perfect. I’ve never heard of the term refractive index, good to know.