Build Your Own SLA/SLS

Hi,
this is my new VAT with 0,05 mm Fep film.
I made my first print with 0,1 layer thikness and everything went well!

From the second print i have some problem becouse the prints don't fix well to the base of the print plate.
As you can see from the VAT_SECTION image, the problem is that the weight and viscosity of the resin do bend the fep tape at the centre of the vat. So when the print start the first layer is not fixed to the plate.

Any suggestions?

Francesco

Wow your vat looks incredible! Try holes in the build platform and/or some thin acrylic under the FEP to prevent sagging in the middle. Also higher exposure times for the first couple of layers and you also can sand your build platform (to make it more sticky). Hope that helps, Matthias

The weight of the resin is definitely making the FEP sag, I deal with sagging by using very high tension on the FEP and a riser only slightly larger than the build plate. You could modify your mount/riser plate so that the throat of the riser is only slightly larger than your build plate this would make a smaller area under the build plate for the resin to weigh down. Placing acrylic or glass under the tensioned FEP as Matthias said (with venting of some kind) is also an option and would probably work well for a vat area that size.

BTW very nice looking vat.

HTL

Francesco,
Just like everyone else said: very taut tension and holes in build plate. One thing I would add is a longer pause after the build plate comes down and before exposure to allow the resin hydraulic pressure to equate. Very nice vat, what is your build area?

Thank you,
this evening i will try some of your advices.
My build area is 125x70 mm max but the dimensions of the vat are calculated for a 0,71 liters.

Francesco

Ok,
yesterday night i made some tests.
First off all I added some central supports to the base of the vat to support the FEP film...but using a build plate 130x80 mm was not sufficient.
So i decide to use a smallest build plate 70x50 mm.

In attached some photos of a dental bridge (xy: 58 micron; z: 50 and 100 micron).

I think that the next step will be to test:
1) Placing acrylic ( 3mm thickness) under the FEP (not tensioned);
2) Using a microforated build plate

I think that i solved my problems using microforated plate.
Thank you for your advices!!!

I treated my prints with IPA 70% for 30 seconds; water and UV postcuring for 2 minutes......after that appeared some white spots...anyone knows why?

Francesco

For some reason dunking a print in water after IPA causes a weird color bleaching effect...I have no idea why, but skip the water.

Thank you

@chemstar, where did you get the FEP film?

Or someone else knows where to get it? I live in Belgium btw...

Because the coating of my petri dish Always rips to pieces :s