Resin Printing First Impression!

Hi everyone - I'm happy to announce that I'm the proud owner of a Prusa SL1 resin printer, meaning that I'm going to have a whole new set of 3D printing lessons to learn and then write about!  Since I just finished my first real resin print, I guess that this is an appropriate time to write about my first impressions, and specifically how resin printing on a Prusa SL1 differs from PLA printing on a Prusa MK3.

The first and most apparent difference for me is the amount of effort that goes into a print.  When I want something on my MK3, I just plug in the SD card, wipe down the bed with IPA, then start the print.  I check on it every hour or so to make sure that nothing's gone terribly wrong, then a few hours later, I come back and turn off the machine, pop the object off of the bed, and remove the supports.  It's nice and simple.  Resin printing has a lot more process to go through.

First, you double-check that everything's clean, then you measure out your resin in the tank (you shouldn't store it in the tank, in case it gets exposed to light and cures in there).  How much do you need?  Well, that depends on two factors: how much does your print require and how much is the minimum printing amount.  In my case, printing a mini takes about 4 ml of resin.  The minimum printing amount for my tank to ensure good spread of the resin is 70 ml.  So, I need to pour in 70 ml to run my 4 ml print... and they say that you're not really supposed to re-use resin, as it can have partially cured patches that might mess up future prints.  That said, I'm not 100% convinced that I'm reading my slicer's output correctly, because 4 ml seems like a tiny amount.

Anyway, after the resin't been poured in, assuming that you don't need to clean up any spills (and be careful, because you're not supposed to touch the uncured stuff with bare skin!), you start the print... and cross your fingers.  Because the printing bed is going to be below the rim of the vat for a few hours, you can't really see anything.  So, cross your fingers and hope that the print's going well!

Once the print's done, you've got to get all of the excess liquid resin off of your object.  That means rinsing it in IPA; try to do this process without getting liquid resin all over the place, because remember, it's toxic!  After it's rinsed (some people say to do 2 IPA baths, one in "dirty" IPA and one in clean), you need to expose it to additional UV light to 100% complete the curing process.  I've got the Prusa CW1 machine to take care of the curing and washing steps, but there's still some labor there.  You've got to pour almost 2.5 liters of IPA into the cleaning bucket, then pour it back into your bottle when you're done for storage (so that it doesn't all evaporate while awaiting your next print).

That finishes the print nicely (well, I mean, you need to remove supports still, but that's no big deal), but you've still got more clean up to do!  You need to store your used resin (because I don't want to waste ~66 ml of of resin!) in a used resin container, then completely clean out the tank.  You can't use IPA to clean the tank because the FEP film on the bottom would be ruined by it, so you need to just absorb as much as possible with paper towels and then rinse any remaining residue with warm soapy water.

So, by now you've got a small pile of paper towels that are impregnated with liquid resin.  They're hazardous waste until they're cured, so now you need to cure them!  You can either leave them outside in the sun for a while, or throw them under the UV lamps.  Either way, once the resin is cured, they can go in the normal trash.

Phew, there's a lot more going on when dealing with resin!  I see why people load up the build plate with as many models as possible: it wastes less resin, it doesn't slow down the print process (since it cures a whole layer at once), and it gets you more figures per moment of cleanup time!

But, it's all worth it for those sweet, sweet prints with nearly invisible layer lines and incredible details!  Here's my first SLA print (the mini, not the base).  It was super hard for me to both get it in focus and get the lighting good enough to show the details (and this guy is primed, which helps make them more visible):

I'm sure that there'll be more to come!

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