Improving Print Accuracy?

We recently got a Formlab SLA printer (Form3L) and i had been playing with it for some time now…

I had printed out some parts with Draft resin this week for prototyping and notice some issue with the print accuracy
Most of the part printed is oversized and some sagging at unsupported area, leading to fitting issue (which ended with lots of sanding and filing) (The part is not scaled in preform and oriented about 45deg)

So i am wondering, is there any way to improve the print accuracy?
For example:

  1. Will changing the print orientation (eg: Smaller tilt from vertical instead of 45deg) help?
  2. Will changing the type of resin provide better accuracy?
  3. Is there any way to calibrate the printer (Form3L), eg: XYZ fine tuning?

In general, the more parallel a surface is to the build plate, the greater the amount of dimensional variation. Think of a cube. If you print it with one face co-planar with the build plate, that surface will be heavily deformed. If however you rotate the cube so the apex of one corner is pointing straight down towards the build plate, the error will be minimized. The problem is, instead of having one face to clean up after removing the supports, you’ll have 3 faces that need to be cleaned up. The things that tend to minimize distortion during printing are the things that maximize how much work you have to do after removing the print from the supports.

Draft is designed for speed, so it’s not a surprise that other qualities suffer.

As a QC check, can you try using one of the higher order engineering resins? It’s not a cheap test, but it’s what I’d do.

Tough 2000 is my resin of choice for accuracy and stability post printing. It’s quite lovely on all counts.

Rigid is also very stable due to the inclusion of glass fibers and that might be preferable for your use. It also has a beautiful surface.

Good luck!

Thanks. I will try changing the orientation and see how it turn out…

Will you be able to share some experience/data of the accuracy when using those resin?

I don’t have anything with precise data to give you.

I do know that when I make keys and holes in parts that get glued together, Rigid was the best.

I didn’t have to ream out the hole so that the key would actually fit.

I don’t have info on Tough 2000 since I now have a 3L, and haven’t yet needed to make prints in parts. But it seems to hold it’s shape pretty well.

I have learned to keep the wash time to a minimum, since prolonged immersion in IPA really hurts accuracy. If you can take a cloth and wipe off resin after a short wash, that removes a lot of loose material. Then you can polish off the cleaning with another short bath in fresh IPA.

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