How is the SLA "expectation vs reality" compared to FFF/FDM?

So I asked this question about SLA print quality and reliability/maintenance to a number of people and got these answers:

  1. Compared to other techniques and industrial or sub 10K printers current SLA printers like Form1 can print at finer detail.
  2. But the printer isn’t reliable, most prints have artifacts
  3. laser requires calibration
  4. print adhesion is sometimes a problem, the bed needs to be replaced over time
  5. the cured resin can be destroyed when left under UV/sunlight so isn’t useful for printing “functional parts”
  6. the claimed resolution of the printers is not very honest as the laser beam profile isn’t a perfect circle and it’s not clear if the fading edges are counted as well and how that affects the true resolution.

As someone owning FDM printers I know how these are a pain to calibrate and use. I thought I’d ask the same question here to people actually owning and using an SLA printer on regular basis on their opinion.

FDM printer users can have ton of issues when trying to get their printer to print properly.
Many people have mechanical, other hardware of software issues and either rage quit or become tinkerers.
Many, many calibrations needed to avoid issues like backlash, delamination,
blobbing, overextrusion, underextrusion, bed leveling issues, bed adhesion issues, hotend clogging issues, support issues.

What do you SLA owners think? How would you compare SLA vs FDM in therms of reliability, calibration and print quality?
I know most of you have already made your choice since you are here and SLA works for your needs. But if you were asked for an honest opinion, what do you think? LIke I said, I personally own FDM printers but can be unbiased and list all of the issues of these machines.

I’m asking this because maybe I’ll consider getting an SLA printer. But I hope I’ll get unbiased suggestions this time unlike when I got my first FDM printer which was a mess of a machine.

I have used a professional FDM Style printer and I was one of those guys who had lots of issues with the printer (due to a move and my management being too cheap to pay someone to move it so we had our internal maintenance guys move it… not a good idea) My opinion between the two styles of printers is as follows:


  1. The SLA is way better resolution if you want detail this is far better than your traditional FDMs.
    2)You need to follow proper orientation rules with SLA which limits you on being able to print something using a lower Z axis height like a FDM printer has no issues with. SLA printers do a peel process in which more surface area can create higher stress which can damage the print and the resin trays.

I have been able to print both very fine detail prints that are delicate that no FDM could ever print and I have printed large bulky mechanical parts all from the SLA with only minor issues.
FDM usually prints a ABS like material… I know there are more but SLA especially formlabs the resins are very particular. They are hard but very brittle one little micro crack and you will have a failed part my type of mechanics tend to come with impact breaking ask I have parts flying through a channel. Many have combated this short fall with SLA by mixing their own resins. I am still new to the SLA world and I have not tried that but there are many on this forum that have and had success.

While there may see like a lot of people on here have needed calibrations and had LASER issues from what I have see this is a small percentage of the total volume of sales. I have cleaned my mirrors once and I have not had any print issues that were not caused by my stupidity and carelessness. If there is a calibration that is needed it is simply to adjust the table build height up or down and then there is a setting to toggle in the x and y directions for the laser galvo mirrors. Again I have never needed to touch the calibrations since the day I opened the box. (about 4 months)

Material costs seem lower to me though I am running the SLA more than I was with my FDM. One Liter of Resin for U.S. residents is about $150 while for my FDM printer I was running 50 in^3 for about $260 per cartridge and would need both support material and building material. SLA printers use all the same material so it feels like I run through my material faster but that could just be the amount of printing I am doing now as well.

Build plates do not need to be replaced unless there is sever damage on the SLA machines as a matter of fact the little scrapes from removing the parts seem to help the print stick better to the build platform. My old FDM printer one plate would usually mean one print and you either had to spend the time to clean it with out damaging it or throw it away at a loss. I have only replaced my build platform once in my Form 1+ because my first one had a loose screw and was wiggling on the peel process causing bad parts.
The Resin Trays are another “consumable” for the SLA machines which in FDM terms I would compare to the Extruders, I have gone through about 6 trays in 4 months with my SLA machine since the LASER passes through the plate any defect or foggy spots will cause bad parts. Though I have found that RainX seems to increase the life and help prevent some fogging of the tank they still are a pain to clean and reuse with different materials. To which the FDM its a simple pull the plug and run the new stuff. Tanks can get expensive at $75 a tray but I remember not too long ago buying a set of extruders for $125 because I had material develop bubbles in the support lines and when the machine heated up those bubbles blew material all over the build head.

Lastly I have noticed being on this forum lots of people are running these machines in garages or shop floors where temps and air quality are inconsistent. These would not usually be an issue for FDM it seems from what people have been discussing here that it is a big issue with SLA resins.

In sort because I know I got long winded …
My reliability has been great with the SLA provided that I follow what I have learned here and from my own experiences there is a steep learning curve but it is manageable, as long as you have the desire to learn and have some common sense about printing you shouldn’t have too much of an issue.

Calibrations are easy to do within the software but I have not had to touch mine at all I have only had to clean the mirrors which was a task to do but it was nothing that I had any issues with.

Print quality is much higher but if you are planning on using it for mechanical or cyclically loaded parts you may have lots of failures. while mixing materials may result in better mechanics I cannot say it would work or not as I have not tried it. The parts seem brittle but it does take a lot to break them. Also you can use a UV blocking paint (clear acrylic spray paint) to keep the part from over hardening.

Unfortunately they both have their positives and negatives. I have done FDM printing for 7 years and SLA is a huge change but I have adjusted just fine and have not missed FDM yet. Just my opinion.

Good luck

I have owned both SLA and FFF printers. I had the Form1+ first. It arrived in February 2014. I had 4 or 5 replacement printers in 2014, I forget. The last 2 or 3 were Form1+ upgrades.
The Form1+ is only good for things you look at, like toys. The FormLabs resin for more useless that you can possibly imagine. It’s not near as good as plastic. Also, my success rate was around 50% with the Form1+ printers. That was expensive.
Now I have a FFF printer. It’s “just a Da Vinci 1.0” that I paid $400 for, but I love it. The parts are real plastic. And my success rate is nearly 100%! And there is no sticky, messy, and time-consuming washing and post-curing. It’s so awesome that parts hold their shape. And I can actually get a better surface by doing a vapor-polish than the Form1+ could print. And that is so much faster than sanding a Form1+ print. No complaints on the FFF machine! I would have paid $3,300 for the Da Vinci!

The best FFF printer I’ve seen is the Zotrax. The print quality is almost like injection molding. You can’t even tell it’s printed.

Like Josh said, for useful everyday items that you want to touch, FFF is better than SLA. But for making figurines, jewelry casting, highly detailed prints, SLA can’t be beat.

Why would you need to sand a 25 micron print? 25 micron is the resolution used by $30000 3d wax printers used by jewelers for lost wax casting.
And if you weren’t using 25 microns but needed a smooth finish, then maybe you should have used 25 micron resolution because you were wasting time smoothing the print later manually anyway?
Just saying, printing at 100 microns on a Davinci is pretty slow. It is considered the minimum layer height in many FDM printers and maximum layer height for many SLA pritners for a reason.

No FFF printer can give quality “almost like injection molding”. Zotrax claims layer height resolution of 100 microns. Even if it is a perfect machines with no errors, 100 microns cannot produce a smooth finish like injection molding. 100 microns layers are visible to the naked eye. Even if the machine can be made to print at 50 or even 25 microns layer heights and extrusion diameter, the mechanical limitations (motors, rods, bearings, belts) will not allow an FFF/FDM printer to run fast enough with no errors at such resolutions to be considered in any way practical.

Sanding is required to get rid of the support marks. Even at 25 micron. Furthermore, it’s not always possible to print at 25 microns because of the peel forces it generates on each layer. Printing large solid objects at 25 microns will most likely result in a failure. So, depending on shape/size/volume of the model, it’s needed to choose the right layer height settings for the best result.

Support marks are there with FDM printers as well.
If you don’t need fine details of 25 microns and the results are satisfying for your needs with the chaotic, uncontrollable chemical smoothing of, say, acetone for ABS then go with FDM.

But if you need lower than 100 micron detail and/or need to smooth it manually by sanding then FDM is no better, I’d say its worse.

My Da Vinci (with S3D software) can be set to 10 micron. Does that make it better than the Form1+? Layer height is not the only thing that affects resolution. For starters, the Form1+ prints using about a 1000 micron circle (Proof here). The Form1 was smaller we believe. And I would be willing to bet that $2000 FFF printer Monger mentioned is better built than anything you or me have ever seen, so I believe it can be incredible.
And believe me, sanding is a reality of the Form1+. Check out Ante’s pictures and then tell me sanding is not real. Then on his re-print he also got 1mm errors.
And don’t expect to print anything much bigger than a ring on the 25 micron setting. That is a common beginner mistake. You asked about expectations vs reality.

1 Like

That printer prints at 25 microns layers now. I’m just telling you what I saw at the 3d Printer World in Burbank. I’m not a big fan of FFF printers, but that particular machine impressed me. The print quality was amazing.

I’ve been given some info about how SLA printers work. I thought I’d share my knowledge of FFF printers in return.

Just because you can set 10 as layer height in Simplify3D doesn’t mean your machine can actually print at 10 micron resolution, or even 25, or 50…

Assuming the best microstepping, pulleys and motors are used and there is zero backlash (which is a term you don’t even need to know with SLA) and settings are just perfect in Davinci, you will get a resolution of 0.011mm for each step on X, Y and Z. However, to actually print at that resolution, you will need to replace the hotend nozzle with one with smaller hole, so the plastic diameter will match the motor step lengths.
I do not believe a 10 micron or even 25 micron hotend exists today, or even if plastic extrusion will work at that scale.
You will then need a very fine filament, which I’m not sure exists, as any impurity (small non-plastic that can get stuck in a 0.01mm or 0.025mm nozzle hole) in the filament will cause a clog and failed print, and very likely a damaged hotend.
Your side fans blowing on the print might not be enough anymore as the hotend stays much longer in the same “area” unlike before and the print has more time to overheat and cause decomposition of the plastic and charring.
You also can’t print regular support anymore as your hotend can’t print much smaller than the perimeters are. But I guess if you used a dual hotend with painful to maintain (because its extremely moisture sensitive) water soluble PVA filament for support then this might not be an issue.
Support or thin walls are an issue now as fans can displace them while printing. if you turn off the fans, you melt or burn the print as I described above.
Assuming some unlikely situation where all these conditions are met, your printer now takes about 10 times longer to print than at 100 microns, which is already slow with current FFF machines.
Only if you’re printing something 1-2 cm in size would this be in any way practical as at those sizes you might finish your print in less than 24 hours.
That size is hardly enough for even printing most rings.
Most of these issues are still true for 25 or even 50 microns.

There are some companies that are advertising their FFF printers can print at 25 microns. This is true and also dishonest at the same time, as you can print at 25 micron layer height with any printer by just changing the settings in your software or changing the software. But in any case you are talking about 25 micron layer height, not width of the extruded plastic (X and Y resolution, so no 25 micron corners).

This is just some objective info for you if some FFF company has impressed you with the “25 micron” claim and made you consider purchasing their machine. They were likely printing something where X and Y resolution was less noticeable than the Z, like an object with flat top, sharp angle top or not many corners to notice the extruded plastic is too wide compared to layer height.

If I knew FFF machines could print at 25 micron resolution just fine, I wouldn’t be posting here asking about info on SLA printers because I wouldn’t care about them as my machines would do what i wanted from them already.

I don’t think I understand what you mean.

It means the Form1+'s nozzle is over twice the size as the typical FFF machine.
And I never said the Da Vinci @ 10 micron was better, I was saying it wasn’t. But hey, you seem to be the expert. Good luck.

Umm that’s only applicable to the X and Y resolution. The Z resolution can be much less than the diameter of the nozzle hole. For example I just quite successfully and with no difficulty printed something on my FFM printer which has a 400um nozzle diameter at a Z resolution of 100um. As for the X and Y resolution the Form1+ only claims a resolution of 300um minimum detail size, in reality I don’t think this number is accurate, I’m pretty sure it’s not that good, however we will assume it is correct switching to a 250um nozzle should allow me to beat that slightly, and for a very well tuned and built FFM printer it can. So now the issue is can I get my Z resolution down to 50um or 25um. Some users have done it.

This is only because these printers are usually built with good anti-backlash nuts, like the Form1+. You can, and I have used them on an FFM printer if you want.

Right, which is exactly my point. If your resolution in Z is 25 but the X and Y is still say 200 that doesn’t mean your printer can print in 25 micron resolution, only in 25 micron layer height. Most FFF printer companies only like to talk about the Z resolution (layer height) when advertising their printers and hide this simple fact.

With SLA printers you have one source of backlash, the Z screw. With FFF you have to add the belts and pulleys to the list of possible backlash sources.

Yes, you didn’t. That was a mistake on my part because I didn’t get what you meant by this

(btw, the link leads to blank page for me).
I’m assuming now you meant the diameter of the beam, or “beam profile size”.

Most of what I said in that post is still true for “25 or 50 micron FF printers” so ill keep the info there for others.

Nozzle? This is still confusing. I think you mean the beam profile is 1000 microns? 1000 microns is 1mm. Are you saying the X and Y resolution of Form1+ is only 1mm?
This is pretty important info that is lacking in the SLA printer specs like the X/Y nozzle size in most FFF printer specs on their sites.Thanks for pointing that out.
I’m pretty sure a laser beam can be focused to a smaller diameter than that. And the pixels on a DLP projector can be smaller than that. So if this info is true I might start looking into other SLA or DLP printers.

The “Proof here” link is repaired. See the last picture on that post.
I said nozzle to adapt my terminology to your experience. It’s a trick you learn with many years of explaining technical things.

Thanks. Link works now.
I didn’t read the whole thread, it’s massive. But I got the info that many Form1+ come with terrible beam profile (“flare”). Maybe related to bad or badly calibrated optics and/or poor quality diodes to start with.

I’m stunned by lack of quality control. These SLA machines don’t cost $600 to justify such a flaw.

Check here the feature size (beam profile) for the Form1+ is supposed to be 300um not 25. I can easily get a 250um nozzle. When an SLA printer claims 25um it too is only talking about Z resolution.

Thanks. At least that info is right there on the product page on most of the SLA/DLP printer sites I checked. Even though “feature size” seems a confusing term to me.

300 is not impressive at all… this is coming from a FFF printer owner. You can easily get a 100um nozzle too.

Some DLP printers claim a 50um or even 30um on the X and Y. I wonder how true that is.