3D Printering: Will A Resin Printer Retire Your Filament-based One?

Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

Adding a resin printer to one’s workbench has never looked so attractive, nor been so affordable. Complex shapes with effortlessly great detail and surface finish? Yes, please! Well, photos make the results look effortless, anyway. Since filament-based printers using fused deposition modeling (FDM) get solid “could be better” ratings when it comes to surface finish and small detail resolution, will a trusty FDM printer end up retired if one buys a resin printer?

The short answer is this: for users who already use FDM, a resin-based stereolithography (SLA) printer is not likely to take over. What is more likely to happen is that the filament printer continues to do the same jobs it is good at, while the resin printer opens some wonderful new doors. This is partly because those great SLA prints will come at a cost that may not always justify the extra work.

Let’s go through what makes SLA good, what it needs in return, and how it does and doesn’t fit in with FDM.

When SLA Is Good, It’s REALLY Good

Objects with organic curves and no real “up” or “down” are much better suited to SLA than FDM.

The sweet spot for resin printing is this: small objects with smooth finishes, organic curves, and surface details. With SLA, these objects print more reliably and at a consistently higher quality than with FDM — as long as the operator does a good job with layout and support placement, anyway.

A big reason for this is that SLA does not produce layer lines the way FDM does. FDM prints are notorious for visible layer lines, and those lines are at their worst when spread across curved surfaces. SLA still creates objects one layer at a time, but the process doesn’t leave obvious lines.

There is also more freedom in part orientation when printing in resin. Unlike FDM, resin prints are isotropic. In the context of 3D printing, this means that the printed object’s physical properties do not change with respect to physical orientation. As long as a part is supported enough to print properly, a resin printer doesn’t much care in which orientation or at what angle it builds an object; the result will come out the same. This gives SLA printers more flexibility when it comes to part orientation, which helps when trying to keep presentation surfaces and details free from supports.

Niche Applications for SLA’s Strengths

One example of a niche for what resin printing is good at is gaming miniatures and figures. Tabletop enthusiasts are buying printers and resin, and designers of gaming-related models are finding success as well. The more successful ones thrive on sites like Patreon, with thousands of monthly supporters.

Engineering applications can have a place with SLA, so long as the objects are small enough. The build volume of most SLA printers is revoltingly tiny compared to FDM, but they make up for it with the ability to handle shapes and details that FDM would have problems with.

Beware SLA’s Added Costs

SLA printing brings some annoying buddies everywhere it goes in the form of added costs. These aren’t costs for the machines themselves; hobbyist SLA printers are very affordable. These ongoing costs are for consumables, increased time for upkeep and part processing, and storage space.

SLA requires more setup and cleanup than FDM. Printed parts need to be washed (usually in an alcohol bath) after printing, and possibly post-cured with additional UV exposure. Since resin is messy, disposable gloves and a spill-resistant work area are required. Another thing to consider is that resin isn’t meant to be left sitting in a printer for long periods, so when printing is done for the forseeable future, it’s time to empty the printer and clean the parts.

All of this takes time, but it also takes up valuable space in a work area. Bottles of resin, containers of alcohol, wash bins, gloves, a drip-proof work space, all of it takes up storage and table space. SLA printing as a whole will take up far more room than just the printer itself.

The other thing to consider is the need for manual post-processing. Resin prints tend to require a lot of supports, and those supports need to be removed by hand. These leave behind small marks that may need to be sanded away. With FDM, supports are a last resort that are used only if needed, but with SLA they are the rule rather than the exception.

Things FDM Is Still Good At

A well-maintained FDM printer is a fantastic tool for prototyping, iterating on designs, and creating functional parts. FDM also has other advantages that really stand out when contrasted with resin printing.

FDM is perfectly happy to wait patiently until needed, at which point a print can be started with a minimum of fuss. The consumables are few and reasonably priced. Filament is best stored in a dry environment, but besides that, it doesn’t ask for much. Swapping filament types or colors is simple, clean, and easy. Even a failed print doesn’t usually involve much more than sweeping away a mess of plastic and trying again.

The biggest disadvantages are related to layer line visibility, the resolution of surface detail, and working with curved organic shapes. None of these can be waved away, but they can be mitigated to some extent. Variable Layer Height tries to address layer line visibility, and it is a feature that has worked its way into most slicer software. The ability to render very small details and features can be improved, to some extent, by swapping a printer’s standard 0.4 mm nozzle for a smaller one.

FDM printers are most challenged by being asked to print curved objects that have no flat areas and no real “up” or “down”. One option is splitting these objects into smaller and more easily-printed ones, but that’s not always practical. Printing a tricky model will require supports, and supports with FDM always result in degraded surface quality. Water-soluble support structures can help mitigate this, but doing so requires multi-material printing. SLA, on the other hand, is far more suited to such objects.

Is There Room for Both?

Resin prints look fantastic and it may be tempting to think of SLA as superior to FDM, but that is not the whole story. They are different tools, and good at different things. Unless your needs are very specific, you’ll probably benefit from access to both.

If you need to print small objects with good surface finish and detail resolution, and you can deal with the added hassles of working with resin, then SLA is definitely for you. But even if you only print small objects, a working FDM printer can easily earn its place on your workbench with the ability to create functional parts without any significant setup and cleanup. If you’re considering an SLA printer, don’t plan to ditch FDM just yet.

I regularly use both but personally, I always choose a filament-based printer if possible; even if a final model will eventually be printed in resin, it’s simply cheaper and faster and easier to prototype and iterate with FDM.

If you have access to both, has this also been your experience? Do you know of a niche for resin printing that hits the spot in a way nothing else does, the way SLA has done with tabletop enthusiasts? We want to hear all about it, so let us know in the comments.

25 thoughts on “3D Printering: Will A Resin Printer Retire Your Filament-based One?

    1. I bought a LD-002R and going to give it a try but this will be a WORKSHOP only machine and I will use thick rubber gloves and a respirator. Trying some normal resin for now and might try some of the water cleanable stuff that is allegedly less toxic. Clearly they are a whole different thing than FDM printers.

    2. Listen buddy do you smoke Or drink?
      Both of those are toxic. One slowly damages your lungs while the other is a literal poison Lethal in large quantities.
      Some of the spices on your kitchen could kill you if consumed in large quantities.

      I let one into my bed room and don’t use an PPE. I’ve had no problems. Just don’t get it all over your hands and not wash them. You’ll be fine. I wash my hands within 2 minutes if I do get some on them.

      You likely won’t use the machine every minute of the day since resin is expensive. Unless you run a shop with it.

      1. I understand you were making a point, but BOTH nicotine AND ethyl alcohol are poisons. Nicotine has been more popular in uses such as vermin control/extermination, not so much in humans. It is in fact a natural pesticide, that’s why nicotine is in tobacco leaves. Certainly “alcohol poisoning” is sadly a common occurrence in humans, so I’m not surprised that a “regular Joe” might not know how poisonous nicotine is.
        But then, I have a hard time swallowing your argument, comparing resin printing to two highly addictive substances, and emphasizing the “literal poison” status of one, when that description fits both; literally.
        I really want to be on your side, recommending common-sense safety measures, but you’ve made it difficult to do so with this post which seems based on an emotional appeal, not a logic or rationality And I couldn’t resist a little public service announcement: keep pet rodents, dogs and cats away from places nicotine might concentrate, such as wet outdoor ashtrays. Drinking the overflow can kill them, although animals tend to have a natural aversion to water that smells or tastes of tobacco.

    3. A stovetop is quite literally a fire box that you may use on a daily basis
      As long as you use the proper precautions you’re fine
      And I’m sure it’s dangerous to eat SLA but you’re not going to

  1. This, something that gets throug nitrile gloves and eats into your underskin, and then eats the fatty material as it hardens, no thank you.

    Also, they are very messy to work with.
    And only for small object, at least the size of the hobby ones. I’ll keep my fff printers, and not print ASA or ABS on them…

  2. the thing is FDM is “good enough” and my experience with running SLA has been a nightmare, sure your prints may look smooth, but thats about it, the dimensional accuracy is actually pretty crap. yes you might be able to get crazy resolution for tiny stuff but big SLA parts are often times way off from final dimensions, I suspect this has to do with the nature how laser based SLA works but may be avoided in LCD style setups. SLS printing in the otherhand stands to be a real gamechanger in the home lab if we can get that up and running. using conventional powdered materials is a much more attractive option than gooey resins that can pull through the blood brain barrier in your skull.

    1. I have no experience with expensive SLA, but I do own a cheap MSLA (Elegoo Mars) and it’s much more accurate than my MPSM. Both printers have a small amount of ‘expansion’ where pegs will be a tad big and holes will be a tad small, but that can be compensated for.

      The main dimensional issue I’ve seen with MSLA is more about print setup and supports, where the part shifted slightly and got “yucky melty” from that. Again, can be solved by the user.

  3. The article missed a major point: the resin it self.

    Several comments already mentioned health issues.

    But material choices is a serious issue for SLA in that outside of the “standard” resin, and the “ABS-like” the others are prohibitively expensive. This effectively limits you to 2 material choices: brittle AF, and it shatters when I sneeze.

    Printing environment also matters for most resin; you need to have it in a reasonably warm area (70°F or higher) that is well ventilated and free of dust & other floating debris. I’ve had a fair number of prints with a dog hair embedded in the middle.

    Personally, I love both my Elegoo Mars and my MPSM, but for non-decorative prints, I default to the FDM.

    My Mars takes up a whole folding table of space (on top and underneath) but if I cleaned up and organized, it’d be about half that much space.

    Otherwise, this article seem spot on.

    1. Indeed. I use FDM for everything but my miniatures. I agree with your assessment of “standard” and “ABS-like”. Stuff is so brittle it shatters like glass. The others like you said are so expensive I won’t even consider them for experimentation. There are more materials available for FDM that are affordable.

      1. I think the brittleness of the resin is brand dependent. I’ve been printing functional parts on my Photon for a while and they are quite tough. Unfortunately I’m running out of Sparkmaker lcd-t and it seems to have been discontinued :-(

    1. Echoing this sentiment. I have been using FDM for 6 years and i keep yearning for something without the downsides but this article quickly reassures me that my fear of the mess of resin is justified.

      As an aside, i have been using formfutura easyfil PLA and i found it mitigates a lot of my complaints. i leave the filament on the printer in my wet basement for months at a time and it doesn’t become brittle or bubbly. the prints are *never* “great” but they’re reasonably strong, dimensionally accurate and stable. they almost never break unless I’m doing something that I know is pushing the limits. mostly i just appreciate how forgiving it is to all the dust and humidity in my workshop. it really is just always there for me whenever i have an idea, the setup cost is just the 2 minutes it takes to get up to temp. it *usually* gets good first layer adhesion even as my printer goes slowly out of calibration and the layers of blue painters tape get all crapped up.

  4. I have both printers myself and ideally if possible I’d recommend getting both to people if they could afford.

    I find myself that the resin to a certain extent is much easier to just slice a file, put in and click print. Where as more often I have to do tweaks to get a FFF print working reliably. But at the expense of a lot more time.

    One thing forgotten about here is that while the negative safety aspect of resin itself is pointed out. Often we’re advised to never leave FFF printers unattended, on overnight etc due to the heaters. Where as with my Resin printer sure a print may take 12 hours but I can leave it on overnight unattended in the garage as apart from a little bit of heat from the LEDs which are cooled by the fan it’s much lower risk.

    The cost is mixed, but not a lot more as I find because prints failed much less on my Resin printer (about 1 fail in every 50 prints) I was wasting much less plastic.

    Another slight advantage of resin printing is compared to FFF, if an FFF is printing 1 of an object it’ll take 30 minutes for example. 2 Of that object may take 50 minutes, constantly increasing. Where as with resin weather I print 1 or 10 (or whatever fills the build plate) if it’s where it’s the same height it’ll take the same time for that 1 or 10.

  5. For now, i think the 2 are kind of like jet printers and laser printers. Jet giver you better quality, but i prefer a network connected laser printer that is ready and requires no maintenance while i can change the toner every 3-5 years.
    But I think that with new resins coming up and automated post-processing machines they might win in a few years.

  6. Does anyone here have experience with the Formlabs printers? They seemed to address the resin handling portion and the storage of the resin. I don’t know about the smell though. I’m hoping someone here can lend insight. I’m in the market for an SLA for some prototype development.

    1. I use 2 Formlabs printers, F2 and F3. Mainly for anatomical modeling. A good example where, I think, SLA is a better choice than FDM.

      I have to say that Formlabs printers are doing very well with consistent print quality. You can print very complex parts, every nights, for weeks. With 100% success rate. If the user is doing well, so does the printer.

      The user also better to have “handkes” for removing supports and finishing parts depending of the quality requested.

      I have a small and semiventilated workplace. Organization is the key for maintaining and stocking everything, printers, resins, other consumables as well as for cleaning and recycling everything, avoiding dust… Being perfect in all these points is almost impossible for one person.

      But I’m still very happy in regard of my needs, my resources and my objectives. I get the same if not better results than with industrial and far more expensive equipment.

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