Hello everyone,
I’m using Formlabs v3+ printer to print simple microfluidic devices, with clear resin V4.1. This is an old machine sitting around in the lab, so I installed a new resin tank and a fresh cartridge of resin as well as cleaned the optical window (maybe this was unnecessary).
I’m printing with the default settings at a 50 µm layer height and following the recommended post-processing procedure. After the initial wash, I also rinse the parts with 100% IPA using a squirt bottle, allow them to dry completely, and then perform the final UV cure.
However, even with these measures the printed device consistently have rough surfaces. For example, the attached image shows one such device. This is the case with fresh resin (well-mixed) out of a new cartridge in a brand-new tank so I believe I’ve ruled out degraded resin, debris in the resin, and tank-related issues. This is the case for almost every design I’ve printed so far.
I’m unsure whether this level of surface roughness is typical for a Form 3+, or whether it suggests another issue that I haven’t considered, such as a problem with the LPU or another hardware component. I would appreciate any insights or suggestions. Thanks.
@aksh99formslab I’m sorry to hear that you’re having some issues with your prints having rough surfaces. The best way for us to get you printing as expected is to open a support case if you haven’t already. Sending along a photo of the prints, not enlarged by a microscope, would also be very helpful.
What I find is the case with any clear resin is that they need to be post processed; the layer lines however small will prevent the part from being clear by refracting.
I had luck sanding with rough to fine grit (say 200 → 400 → 600 → 800 → 1000 → 1500 → 2000 → 3000, you don’t need to follow exactly, just rough to fine works), and then a bit of clear coat. Not sure if there is a bio-safe clear coat but you can also “paint” over the model with the uncured clear resin (a super thin layer) to fill in the tiny spaces between the layers and then cure again.
Make sure you use clean IPA, but I assume you are since you mentioned a squirt bottle!
good luck 
My guess is that is the surface roughness of the printed part between the layer lines, curing bleed and peel force artifacts. I’ve been able to polish Clear v5 clear enough to use for PIV testing in the past. Depending on the part you may also have to deal with internal bubbles and defects (which can partially be reduced by reducing the wiper speed in the print settings editor). Wet sanding was the way to go. I think I used 320, 500, 800, 1500, 3000 and then the Novus 1 thru 3 scratch remover and polish. Tl;Dr. it can work, but it is laborious…
