It’s a whole different world. And really not great for functional parts. I’d say 90-95% of the resin printer users are just interested in printing figurines. So most of the info out there about them is directed at those users.
I just got mine back in July, I wound up with two due to my impatience and a quirk or where/how I bought the first one. I shared my whole learning process on a another forum here: Experimenting with Resin printing (MSLA) for detailed parts | FliteTest Forum
The detail you can get with resin is remarkable. But…it’s very difficult to get accurate parts due to the physics of how MSLA printers work. There are other styles of resin printers that can do better…but they’re a LOT more expensive. And the other big problem is that most resins are really brittle. There are exceptions but the engineering grade resins are at least twice as expensive as the standard resins and are much slower to print.
Here’s my finger wrench I posted earlier but printed on the resin printer:
Looks pretty good…and even looking closer the detail at first glance is pretty amazing:
This is on my Phrozen sonic mini in Siraya Blu engineering grade resin.
It really captures every detail of my design like the .5mm chamfer which my FDM printer just kind of fudges.
But…it’s not perfect. The other side:
Is pretty ugly. Because it was facing down. It’s usable and grips nuts just as well if not better than the FDM version. But it’s just not very clean. The reason is the supports. I printed this on it’s side at a 50 degree angle. And that means it had to be supported. The blemishes are where the supports attached.
Why not just print it upright like I did FDM? Well, a couple of reasons. First (but least important here) due to the physics of SLA printing you generally get more detail with prints at an angle since the z resolution is finer than the X/Y resolution. But I don’t care about that here.
So the other reasons are - elephants foot. With SLA printing you generally have to overexpose the first layers to get the part to adhere to the print bed. And that means you loose accuracy and get bad elephants foot. I’ve found I can generally avoid that with strategically sized chamfers…but it’s hard to get them right.
But it gets worse…you kind of need that elephants foot to keep the part in place sometimes. There’s actually a LOT of forces on the parts trying to pull them off the bed as each layer is added with SLA. The parts stick to the FEP plastic at the bottom of the print vat as each new layer is exposed. Then the print bed raises and the part is “peeled” off. This is actually a surprisingly complex process where the speed and distance that it’s raised has to be carefully tuned for each resin and exposure. If the print doesn’t have enough surface area against the build plate then the peel can easily pull the part off the print bed and then you’ve got a mess in the resin vat to clean up and a failed print.
Also - vertical height equals longer print times. It’s totally different than FDM. The more you put on the plate with FDM the longer it takes. With resin…the time stays the same…but the physics of the peel get more complex. (the plastic at the bottom of the vat actually flexes as the prints are pulled off - so where parts are on the build plate can dramatically change the forces on them!) But - every layer of SLA printing has a fixed time associated with it - the exposure, plus the peel time. So how tall the tallest part on your plate is determines your print time not how much is on the plate. Tilting this part cuts almost 3 hours off the print time…and it was still a 4 hour print vs. 1 hour on my FDM printer.
On top of all that SLA printing is messy and nasty. REALLY messy and nasty. I made a HUGE mistake starting with it in July when paper towels were still hard to find. And it’s still difficult to find isopropyl alcohol at the stores even now and it’s pretty important for cleaning prints. You can use denatured alcohol, but if you live in CA you can’t buy it…and here in AZ it’s more expensive…and the smell bothers me more than the smell of isopropyl. Also, nitrile gloves. You’ll go through a LOT of them - you don’t want to get resin on your skin. Exposure builds with time - you may be fine with it now…but at some point you will probably reach your bodies threshold and then any exposure will set off a reaction. So it’s best to be careful and always use gloves when exposing yourself to uncured resin. Plus there’s odors. The resin stinks - some worse than others but they all smell more when they cure (though they don’t smell once cured - and are generally inert once cured, there are even body safe resins used by dentists and doctors but they’re really expensive.) The alcohol for cleaning stinks. The other options other than alcohol don’t work as well and tend to stink as well.
I’m glad I have my resin printers…but it’s hard to recommend them. FDM is just so much easier and more useful for most things.
As far as synths go…the best use I’ve found for a resin printer is for printing knobs. And even then it took me a lot of experimentation to get something decent. I print my knobs in two parts. An inner core printed in special expensive flexible resin - and an outer shell in cheap resin (which I’m now custom tinting) to get the look/feel I’m after. Even then printing the shells is really tricky due to the peel effects if they’re printed directly on the bed…and the distortion if they’re printed on supports. I’m getting results I’m fairly happy with…but I’m kind of waiting until I have a 100% full case to print knobs for so I can do them all in one batch to make sure they match.
All that said…the price on Resin printers has dropped a lot lately. And the price on wash/cure stations has come down as well and they REALLY help minimize the mess and how many gloves and solvents you go through. (I LOVE my Elegoo Mercury Plus wash/cure station.) I have both the Phrozen sonic mini and the Elegoo Mars Pro. Both are great printers at a great price. But I’m really torn as to which I prefer. The Elegoo is a more polished package, but the Phrozen has a superior LCD and I had more early success with it. They’re both about the same price (and probably just got cheaper because newer higher resolution models just came out) and have nearly identical print capacity. The Phrozen is slightly faster…but I’d really caution against letting that sway your opinion as they’re both quite a bit slower than FDM.
I can go into more detail if anyone wants…but…fear I may have gone into too much already 