Resin Printer Temperature Mods And Continuous IPA Filtration

Two essential parts to producing successful resin 3D prints: keeping resin at its optimal temperature and lots and lots of IPA to clean the printed parts with after printing. Unfortunately, most consumer MSLA printers do not come with a resin tray heater, and tossing out IPA after every cleaning session because of some resin contamination is both wasteful and somewhat expensive. These are two things that can be fixed in a number of ways, with [Nick Wilson] going for the ‘crank it to 11’ option, using a high-tech, fully integrated solution for both problems.

The vat with IPA is kept clean through the use of a diaphragm pump that circulates the alcohol through two filter stages, one for larger — up to 5 micrometer — particulates and one for smaller 0.5-micrometer junk. A 405 nm LED lighting section before the filters is intended to cure any resin in the IPA, theoretically leaving the IPA squeaky clean by the time it’s returned to the vat.

For the resin tray heater, a more straightforward 12V 150 Watt silicone heater strip is stuck to the outside edge of the metal resin tray, along with a temperature-controlled relay that toggles the heater strip on and off until the resin reaches the desired temperature. None of these are necessarily expensive solutions, but they can be incredibly useful if you do a fair amount of resin printing.

34 thoughts on “Resin Printer Temperature Mods And Continuous IPA Filtration

  1. I remember seeing this, or something like this on Reddit a while ago. It’s a really nice setup, but one important question was unknown: “How many KG of resin can the filter clean before you have to replace it?” Throwing out used IPA is expensive, but constantly replacing filters is also expensive.

    1. If you pick a common filter so you can be sure it will be available and massively mass produced they are very cheap, seems like both filter will be roughly $10 using the filters he lists to me, at least buying in multipacks so you get even more sets and get your house water filtered as well…

      And using filters that are expecting to filter water for many months for the whole house full of humans, I’d suggest that filter won’t saturate even for a heavy user in the printers lifespan (assuming those filters, pump etc can take IPA exposure long term, which I can’t see any reason they wouldn’t). I might be wrong there, but I’d bet compared to tossing out your IPA after a few prints the system will pay for itself, probably in only a bottle or two of resin consumed. Assuming you were not trying anything else to cure and settle the resin to eek out the IPA life the filters would be paid for in a single bottle easily, as you would have to spend about the same on the Iso as you did on the filters to have enough volume of cleaner to do anything at all, and that stuff will only be good for final cleaning a few times (maybe even only once depending on just how much your parts are going to hold resin).

      1. Remember, he’s curing the suspended resin before it goes through the filter so that the filter will collect solid resin particles. Unless you have really really bad water, it won’t have nearly as much solid particles (per gallon) to clog up the filter.

        For it to be cost effective, it has to clean significantly more than $10 worth of IPA per filter. It’s fairly likely that it will clean that much, but, we can’t know how much until someone who has a setup like this shares the data.

        Though, it may also be worth it to people who want the simplest setup even if the filters cost more than the IPA to not have to dispose of as much IPA, or to not have to deal with multiple wash cycles (dirty, clean, final rinse).

        1. True we can’t know till it is tried or we have more data on just how much waste there is clinging to the average print run. But the filters are expected to process such a stupidly large volume of water that won’t be all that clean I think it unlikely to have problems paying for itself. The filters are really really cheap, and IPA really isn’t.

          p.s I do think there are probably much more cost effective methods to keep the IPA around a long though perhaps not as long number of cycles.

    1. Isopropyl alcohol (aka IPA) is hardly what one would call “good ale”. It is toxic and has some pretty awful effects on the human body when drunk, including rendering the drinker blind if they drink enough of it.

          1. For drunk values of fine.

            Methanol is the one that causes lots of blindness and deaths. Mostly because it is left after poor distillation of ethanol. And because in some places someone though denaturalization with it is fine, when non-toxic products are available.

          2. IPA is not exactly benign either. IPA is quickly broken down in the body into acetone, which has a long biological half-life of about 10 hours, so it accumulates into the body and the “hangover” from IPA lasts for days. However, acetone is actually less toxic than the isopropyl alcohol itself, so you’re not advised to drink ethanol to slow down the metabolism. If you do, you may need dialysis to get rid of the IPA.

            An average person may drink half a liter of vodka and get very drunk, or half a liter of 40% isopropanol and get very dead.

      1. Not true. IPA is pretty neutral. It’s the methanol (wood spirit) that makes you blind and I guess in US if you buy technical spiritus it’s going to be methanol. Not in Europehowever. Why? Funny enough ethanol is an antidote to methanol. Before 2004 denaturat (technical spiritus) was a mixture of ethanol and some methanol and was even marked with skull and bones to suggest it’s poison. But truth is everyone drank it like it’s vodka because ethanol neutralized any harmful effects of methanol (and it cost 3 złoty instead of 30 złoty). After we joined EU, denaturat is 92% ethanol, 8% water and a drop of Bitrex (bitterant agent). It’s supposed to be so bitter that it can’t be drunk. However, after you “acquire a taste” for Bitrex it’s not a problem to drink it anymore. I can attest this from personal experience since I drank a lot of denaturat (some shops called it denaturin) while in academic (university housing) during my polytechnic student years. Drinking denaturat is like smoking, first cigarettes are coughing and feeling nausea but you start to like them.

        1. Ethanol is NOT an antidote to methanol poisoning. Methanol becomes poisonous when the liver breaks it down into formaldehyde, which destroys your nervous system, and ethanol slows down this process. Ethanol has the effect that the enzymes in the liver prefer to break down ethanol first, so the methanol has time to exit through other means such as urine, sweat, and breathing before it is converted to deadly poison.

          Some methanol is always converted when you drink it, and the damage to your nerves (especially the optical nerve -> blindness) happens every time you drink spirits that contain significant amounts of methanol. Ethanol DOES NOT neutralize methanol – it only keeps the amount of poison in your body to a low level so you’re not immediately killed by it.

        2. >after you “acquire a taste” for Bitrex it’s not a problem to drink it anymore

          Maybe not for yourself. You also start to stink like a hobo when you drink the bittering agent, because it comes back out through your sweat.

      1. depends.
        We distill ours under partial vacuum at ~18C
        Pretty safe really. Biggest hazard was some dipstick forgetting to turn on the chiller once, wrecking our vacuum pump. Now we have a controller for the feed pump, heaters, vacuum, and chiller so its just a single button operation.

  2. I print a full plate every single day, and you don’t have to have IPA this squeaky clean. It still does a decent job until its basically grey and murky. When that happens, I just decant the top off with a rubber hose and syringe. Let the IPA/resin mixture settle, put the hose above the resin, and use gravity to pull all IPA into a jug. Set the remaining sludge into a washing machine drip pan in the sun for a few hours and the IPA evaporates, the resin cures into a sheet which is easily discarded. To keep the vat warm, just don’t keep your printer in a non-temp controlled area. This all seems like over engineering for the sake of engineering. Which is fine, but not a good solution for most resin hobbyists.

    1. The properties of resin in IPA varies from one resin brand to another, and probably on saturation of the IPA. I’ve had stuff cute and settle out as you described, but I’ve also had it cure into a solid block of jelly.

    2. ‘Don’t keep your printer in a non-temp controlled area’… So instead of adding a little heater to keep the resin happy you want to heat an entire extra room, that probably isn’t well insulated as it is likely to be a shed/garage workshop?!?! Not to mention with the resin stink you will want it to be a well ventilated space! That to me seems like massive over engineering for little point.

  3. The problem is, filtering only removes insoluble particulates. Resin has many soluble components that will build up in the IPA and be left behind on your parts when the wash evaporates. One such component is the photoinitiator which is one of the more toxic and dangerous chemicals in resin – it’s known to cause contact dermatitis and allergic reactions. So this is at best only a partial and not entirely safe solution to re-using isopropyl.

    1. That’s what I was thinking about as well, but shouldn’t photoinitiators dissociate under UV light and mulitple passes? At least when stepping up the game to UV-C.

      Now waiting for someone to build a compact solar still for IPA :)

  4. I just let the ipa sit for a week or so then siphon off the top. As for heating I have a microwave specifically for resin bottles. Warm them to 35-38c (3min on power level 3 for a full bottle) then poor in to the vat, bring the bed down into the resin to soak up some temp (about 32-33c resin now) and hit go. The burn in layers raise the resin temp to about 40-45c depending on how much is on the build plate then comes back down to the mid to high 30’s about mid print and stays there. Not a single failure in over a year

  5. You folks that are leaving the ipa out in the sun–do you realize that what you distill out is a fraction of the original strength? Your 90% ipa absorbs moisture from the air like silica gel and comes out as more like 50% ipa. It will need a salt treatment after that. From curing to filtering to distilling to salt, it’s hardly worth it.

  6. Hi @Nick Wilson, thank you so much for this! For the past year, can you tell us after how many kilograms of printed resin have you finally had to change the filters (and which one clogs first if you’ve done the test)?

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