Getting Back Into Resin Printing: First Results

When we last left off, I had just set up a new SLA resin printer and was on the verge of doing the initial round of printing to see just how resin printing in 2026 compares to way back in 2020. Surely SLA printing had to be easier and less fussy than it was in 2020?

During these weeks of printing, setting up printers and taking a gander at the various workflows that certain printers and their manufacturers try to push you into I have both produced a series of not too shabby prints and some delightful spaghetti. I also flipped a few proverbial tables and formed some strong opinions on 3D printing workflows, of which some can considered to be family-friendly.

Without further ado, let’s get into some updates, a bit of ranting, and even some printing results.

Going With The Flow

Although workflows are a fairly personal thing in terms of preferences, we’re all creatures of habit with a strong tendency towards laziness. We also tend to prefer workflows that are easier for that reason. This is where after the very manual approach of the Ender v2 I really liked much about the Neptune 4, ranging from its much faster and open source Klipper firmware to a semi-automatic bed-levelling procedure, and of course the Fluidd web interface.

With this I can just pop open an interface in a browser tab and manage the printer, watch the webcam view, etc. from there. Somehow there’s now a third option that seems to be taking over, however. Although a web interface seems straightforward and easy for the average user, there’s been this move towards requiring the use of the slicer via a special API or such that leads to fun access situations as we have recently seen with Bambu Lab printers.

Out of a sense of morbid curiosity I decided to look at what I’d be dealing with if I were to upgrade to the latest & greatest Elegoo (CoreXY) printer if I ever grew tired of my Neptune 4, and noticed that they seem to have gone more in the direction of Bambu Lab. The firmware is Klipper-like but closed, with the most recent FDM printers like the Centauri Carbon series also requiring access via a slicer and/or a special mobile app with a lot of Cloud things mixed in.

To me this seems hugely cumbersome, since one of the things I like with the Neptune 4 is that I can access it from anywhere on a system with a slightly modern browser and print models that are stored on the internal memory. This is where the the GK3 Ultra scores pretty well in my book, too.

Certainly, this resin printer doesn’t do fancy web UIs or APIs, or much in terms of remote-anything. You do get Ethernet, a Wi-Fi USB dongle and the rather nifty ability to set up an SMB file share that you can dump sliced models onto before waddling over to the SLA printer. It’s low-tech yet also universally supported and open, while more convenient than plain Sneakernet, though that’s also an option using the front-mounted USB-A port.

Can I just briefly say how much I love having a USB-A port for Sneakernet purposes, rather than a tiny USB-C port or microSD slot? The Ender 3v2 offered either microUSB or microSD for inputs, none of which really made me like that printer more.

Finally Some Printing

For this first printing round, I printed the same parts on the Neptune 4 in white PLA and black PLA. For the GK3 Ultra I just used the ABS-like (AL) clear-blue resin, to not have to switch resins just yet. The prints include a range of items like bottles, some figurines and a bunch of LEGO Technic-compatible parts. The latter two serve to give dimensional accuracy a good workout, along with basic durability testing.

Starting with FDM printing, this was largely uneventful, though I upped the difficulty challenge with the N4 by using a spool of extra-brittle white PLA. Somehow even that came out fine, aside from an unfortunate spaghetti incident that required some PVA glue to be slathered onto the PEI build plate.

On the resin side of things, it was pretty much as I remembered it from my LD-002R days, just with an absolutely massive build plate, the auto-feeding of resin and of course the use of this rather nice transparent blue ABS-like (AL) resin.

On the slicer side of things I kept things as boring as possible, with OrcaSlicer for FDM, and ChituBox’s free version for SLA. I did look at Lychee as well, but they require registration for even the ‘free’ version, so that one was out for now. I’ll also say that ChituBox got a bit heavier resource-wise than since I used it six years ago, and somehow its UI still feels rather unintuitive, though that’s a bit of a central issue with slicers.

To be fair to Uniformation, they also provide their own slicer on the USB stick and as a download, but since the latter involves a random Google Drive, it triggered my system security-related anxiety. It’s probably a perfectly cromulent slicer, but using ChituBox was the less exciting option for me here as a first try.

Comparing Parts

Since both Elegoo FDM printers come with an example model in the form of this happy Buddha figurine, I figured that I’d also print it with the GK3 Ultra. Here you can see how these compare in a sloppy smartphone photo for which I apologize:

The model was clearly intended to be printed on FDM printers, so the SLA version doesn’t really add a lot, other than a lot of weight. Unlike FDM prints where you have aspects like ‘infill’, an SLA printer can print everything 100% solid with zero time penalty. In fact you want to do this so that you don’t need to drill a hole in it for liquid resin to leak out.

Of course, you can totally hollow out models to save resin and weight, but in that case you do need to add those drain holes lest you end up with liquid resin sloshing inside forever.

Moving on, I also printed a miniature knight figurine on the N4 and GK3 Ultra, which was a bold decision for the former:

Removing supports on this approximately 32 mm tall model was a bit of a nightmare with the SLA version, and I still need to clean it up better, while also rethinking ChitBox’s insistence on angling it upside-down for some reason.

I didn’t even bother with removing supports on the FDM version, although I was somewhat surprised at how much detail it still had when pushing layer height to its ‘super fine’ 0.12 mm setting, though the SLA printer with the ‘sloppy’ 0.1 mm layer height preset is simply in another universe when it comes to preserving fine details.

Clearly layer heights between SLA and FDM are at best the fuzziest of all overlaps, with even the knight’s cape in the SLA version capturing the flow of the fabric and details in the helmet that the FDM version had obliterated.

Finally there are the LEGO Technic-compatible shenanigans:

There is obviously a lot of variability and improvement possible simply by the orientation you print things in, the type and placement of supports. SLA has the massive advantage here that support points on models can be made absolutely tiny and correspondingly leave almost no mark. This made e.g. printing LEGO-compatible parts a snap on SLA, but a nightmare on FDM where I struggled to find an orientation and support/brim configuration that didn’t lead to misprints and/or interfered with the part’s functionality.

The thing where ChituBox really did me dirty, however, was that it went crazy on supports, even adding lots of supports inside these latter parts that still have to be painstakingly poked out if I want to actually properly use them. This is however a slicer issue and potentially a skill issue on the side of yours truly.

Flipping Of Tables

Even after just this first round of printing there’s quite a bit to unpack. On the FDM side of things the workflow is definitely the easiest, especially in terms of post-processing. I did have some bed-adhesion issues, however, which is where SLA tends to be significantly less fussy with just the long-exposure first layer. For the FDM side of things I had a few misprints as a result, which was annoying.

On the SLA side of things there wasn’t too much to upset me, other than some table-flipping at the automatic resin feeding system which I mentioned in the first article. After starting the print, the system seemed to work and began filling the vat with resin, albeit very slowly. At some point I got a ‘material in/out time-out’ error, following which I retried printing, with the resin system again trying to fill the vat for a long period of time.

Ultimately I decided that since I only needed just over 60 mL for the print, and it had already poured in about half the resin bottle, I’d just cancel it. It’s likely that I missed a step here, such as I’m not sure whether you need to pop open the bottle for this to work, but the manual did not mention such details.

Popping over into settings I disabled this auto-feed system and tried to printing again, which worked without issues, other than the backstabbing by ChituBox and a persistent resin smell. This latter issue I tracked down to the slot for the resin bottle, which may or may not be related to the auto-feed issues. After sealing up the gaps the resin smell faded quickly, making it seem at least plausible that the active-carbon system of the machine does something.

After printing I did the usual post-processing, just with a scraper to knock the supports loose instead of something more gentle with a flex plate. The parts were tossed into IPA for a quick clean, including a trip through the ultrasonic cleaner. This was followed by another quick IPA rinse and finally some tanning with a UV lamp in a water bath. This latter step is to keep oxygen away from the curing process and thus speed up the curing, which is one of those details that have worked well for me in the past.

First Conclusions

Despite some flipping of tables, it’s been a fairly positive experience that at least has allowed me to set a bit of a baseline. My overarching feeling at this point in time is that FDM is rather okay for large parts with little detail, such as a CD rack that I already printed in PLA. Not having to deal with smelly resin and involved post-processing is also generally nice.

That said, the sheer quality and level of detail you get with SLA is just a whole other ballgame than FDM. Although it’s been a few years since I previously printed with resin, I still have quite a few prints from that time, including an absolutely miniscule fox figurine that I scaled down on the LD-002R for fun and which still is very much recognizable. The SBC cases and such printed in resin from back then have this level of smoothness and solid feeling to them that you just don’t get with FDM.

An elephant in the room remains that of ABS and ABS-like printing. Such engineering-grade materials are essential for anything in production, and I definitely have to give this Uniformation ABS-like material a good workout. That said, I’m still very hesitant about printing ABS and ASA filaments with FDM, due to the health hazards this poses, mostly caused by the release of styrene.

Although I already wear a respirator with A1 filters backed up by P2 prefilters against VOCs and kin while processing SLA prints, styrene pushes the hazard levels a few notches higher, since unlike most organic vapors it’s not just an irritant, but a known mutagenic toxin. Here an active carbon filter in a closed-chamber FDM printer would seem to be at best optimistic.

To me this aspect alone makes the idea very appealing to use SLA to print high detail models and production parts, while using FDM for sloppy prototyping in PLA, PETG and of course TPU, but this is something that I’ll have to poke some more at. Any input here would be most welcome so that I can do even better with the next article.