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Two Years In: Why I like my Form 2 better than my Form 3

It’s been over 2 years since I received my Form 3, and I figure it’s a good time to share some thoughts.

I was really excited when the Form 3 was announced. I preordered one soonafter, and even sold my Form 2 and all its accessories with the intent to jump all-in to the new ecosystem. I figured with two SLA printers under their belt (more if you count incremental upgrades and prototypes), the latest model should be a win.

There were substantial growing pains with the new product, which I won’t get into here. I wound up buying back a used Form 2 in order to do my own comparison tests, and to get me by until the issues were addressed.

Formlabs has come a long way with software updates and resin tuning. My Form 3 performs much better today than the day I received it, and I want to thank the engineers, testers, and whole team for their hard work.

That said, over the last two years I’ve come to the conclusion I like my Form 2 better than my Form 3. A few reasons are below, in hopes the engineers and product managers at Formlabs consider my feedback. There are a still a lot of low-hanging software tweaks that could go a long way to improving my experience with the Form 3. And as for the rest, hopefully it’ll spur some thoughts on next-generation hardware.

It’s able to achieve better accuracy

This is a difficult and no-doubt controversial one, and it took me a while to reach this conclusion. Most of my prints are engineering-type work rather than artistic. Dimensional accuracy and consistency are really important. I also do a lot of direct-on-base printing.

For a desktop SLA printer, I’ve found the Form 3 produces reasonably accurate parts with very tight dimensional consistency (i.e. when dimensions are off, the error tends to deviate consistently across different areas of the build platform and between runs). Fresh out of the box, I’d say the Form 3 had better and more consistent accuracy than my Form 2.

However that doesn’t remain the case today. I’ve had to detach the tank carrier on my Form 2 a couple of times to repair the heater cable, and developed a lengthy process to improve its calibration beyond factory default - at least for the types of prints I run.

As an example, one of the test parts I use for calibration is a pattern of nine square cubes, 1cm to each side, distributed across the build platform. Here’s what they look like, and the results of my tuned Form 2 compared to my Form 3:

The measurements were taken after curing (at the recommended profile of 15 mins at 60°C), but similar holds true fresh off the printer. (EDIT: I updated the photo after tuning the Form 2’s Y axis even further since I first posted this).

After dozens of these prints (along with others geared to calibrate different metrics), I’d venture a guess that GiddySnail is one of the most dialed-in Form 2’s in existence. The remaining Z error comes down to slight bowing across the build platform (e.g. the center cube is always ~0.25mm taller than the corners, and one of the corners is consistently shorter than everything else, when using that platform), which I’m considering sending away to get sanded to a more perfect plane.

The irony is the Form 3 seems like it might actually have better consistency (at least across some axes), but there’s no knob to calibrate it against real-world measurements, leaving it perpetually trailing what I can squeeze out of my Form 2 for these types of parts.

I tried Fit Tuning the Form 3 but it hasn’t been officially sanctioned yet for anything other than Model resin, and when I printed it in Clear the peg didn’t fit into any of the holes. And at first glance the feature feels a bit complicated (only applies to jobs submitted in the future matching the same material and layer thickness) and doesn’t seem to provide a mechanism to simply adjust the X/Y scaling based on feedback from real-world measurements (so while it may improve relative fit of parts, I don’t see how it could do much to improve absolute accuracy).

Z Fine Tuning

This one’s important for direct-on-base prints. I find the Form 3 goes overkill on the first few layers, making parts harder to remove, and resulting in a larger rim around the circumference of the part where it meets the build platform (also known as bleed, “elephants foot”, etc). This used to be a lot worse and has gotten better over time, but there’s still generally too much adhesion for my taste.

It also results in more base compression than is neccessary. I’ve “tuned out” most of the compression on my Form 2 and regularly print with the build platform raised by 0.5mm. (I do still lower it for bulkier parts that have small footprints compared to their volume).

I really wish there were a user-adjustable way to control adhesion on my Form 3. It would make it easier to remove parts (for those of us not using the Build Platform V2), and improve the quality of direct-on-base prints.

Open Mode

The initial marketing literature implied the Form 3 would support Open Mode, and my sales rep at the time swore up and down the feature would come eventually. At this point I think it’s safe to say it never will (unless Formlabs releases something like OpenFL when the Form 3 finally sunsets).

I don’t use it very often, but it’s nice to know the feature is there if I want to experiment with more economical resins that weren’t engineered specifically for Formlabs printers.

Surface Quality

The engineers and QA at Formlabs deserve a most-improved player trophy for this one. On release there were some pretty terrible artifacts that would crop up on Form 3 prints, especially on vertical walls. The latest profiles have dramatically improved this, but overall I still tend to get more satisfying flat surfaces on my Form 2. I suspect this may be in part due to something like “dithering” from the larger laser dot size (so in a way my opinion may be unfair).

The Form 3 still can produce ugly surfaces on the undersides of prints between support contact points, but I hear that’s something the 3+ fixes.

More robust tanks

This is the biggest pain point for my workflow. I like to stock a variety of resins, but sometimes months will go without using them. The short shelf-life of tanks exposed to certain Engineering resins is a deal-breaker for me, and as such I’ve completely stopped using several of them in my Form 3.

I’ve experienced leaks on both 3 and 3L tanks, and they aren’t pleasant. Leaks in Form 2 tanks are less common, and are always due to visible damage rather than just “leaving them sit”.

The fact that resin can break down the adhesive sealing the tank film is a major design flaw in my opinion. This is a non-issue for folks with higher throughput as they’ll wear the tank out long before “lifetime exposed to resin” ever becomes an issue. And in fairness the printer is pretty clear about telling you when your tank is up.

Some users have managed to stretch their tanks to 2X to 3X the rated exposure time, but it’s risky.

Kudos to Formlabs for allowing the user to override and use the tank anyway at their own risk. I imagine there were camps in the company who were strongly opposed to that decision, and as a user am glad the choice that puts in me in control won out.

Quieter (after modding)

This one’s a cheat as I installed rubber vibration dampeners on all my Form 2 motors. It was a bit of a job, and if I was to do it over I’d probably only place them on the loud ones (e.g. Z axis motor). But the reduction in noise is noticeable - from the next room I can barely hear my Form 2 now when it’s operating. And anecdotally it feels like the reduced vibration could be beneficial for reducing wear on mechanical components and extending the lifetime of the machine.

I really wish Formlabs would design such dampeners right into their product!

Conclusion

There are certainly things I like better about my Form 3. It’s quieter than my Form 2 was out of the box. The replaceable LPU promises to extend the printer’s life beyond how long my Form 2 will last when the laser eventually gives out. The smaller dot size is great for fine features, and the transparency of Clear resin is remarkably better (if you don’t post-cure). While it used to be painfully slow compared to my Form 2, lately they’ve gotten the speeds closer to what I’d expect. You can achieve smaller touchpoints (although I regularly do 0.4mm and sometimes even smaller on my Form 2), and the new rectangular, easy-peel support lattice rocks - I really wish that one got backported! I’m guessing we’ll also start to see more resins released which aren’t made available on the Form 2 (like ESD).

But I’d still sooner sell my Form 3 than my Form 2. Granted, I might be a little biased because of all the TLC I’ve given it over the last couple years, and I know other users who strongly prefer the newer printer.

All along I’ve wanted to love it more, and might still eventually if Formlabs can keep working on achieving superiority in the areas I mentioned.

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I’m curious as to the firmware and PreForm version you’re running with your Form 2.

One thing I love about the Form 3 is that I don’t have to constantly clean optics and/or come back to a surprise print fail because of dirty optics.

It was getting to the point near my Form 2s life that I would literally have to clean the optics every several weeks which was a major pain.

This was especially annoying because a) my laser power was dying and b) I print in quite a lot of black resin, which is the hardest material to print in.

Replacing the LPU is also amazingly easy and I am a big fan of that.

Definitely agree the growing pains were annoying and unexpected…but I would definitely choose a Form 3 over a Form 2 any day.

Formlabs has even changed the chip with extra features to prevent anyone from using a 3rd party resin. It’s safe to say the promise was a lie. :wink:

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I’ve had the same experience as you with some exceptions. I don’t build on the plate, or require such accuracy. In general, my Form3 is running well now, after the “growing pains”. I have had the heater fail and gotten different responses from Formlabs Support on how to address this. My solution has been to run a space heater next to the machine for a couple of hours before printing.

With all that, the time limit on the tanks is a killer. I use my Form3 at home for concept development and home projects. It is not a money making machine. I’d like to have a few materials around for special needs, but the time limit takes that out of the equation. Now I simplify and use clear and gray. This is such a problem that I’m investigating the lower cost-offshore brands to provide a variety option.

I’m in the process of specifying a new larger SLA printer for the company I work for. Sadly, this time limit is forcing us to look at alternative machines. Engineering resins range from $400 for 2L of ESD to $600 for 2L Rigid material. The tanks are $300 (3L) each and rated for 10 weeks after exposure to material, that becomes a huge loss if we don’t use that tank. We might have $700 to $1,000 in resin and tanks invested that must be used up in 10 weeks?

But, no resin should be lost when the tanks are changed. Resin should be filtered and decanted from the tank into a light-proof container and then it can be stored until it’s needed for the next tank.

I think by “huge loss” they meant the cost of the tanks (i.e. throwing 'em away every few months and replacing if you’re only printing intermittently).

Also in fairness, you do loose a little bit of resin each time you transfer to a new container, it sticks to the surfaces and whatever tool you use. Not much but I guess if you do it a lot it adds up.

All that plastic waste generated by the tanks and cartridges is one of the reasons for us to switch to a different printer brand though. It just feels bad having to throw away a perfect box when you replace a tank.

I was looking some days ago at this site ProtoART - Cartridge in case I could buy the universal cartridge for using other resins. Anyway, there is a pop-up saying that they buy your empty cartridge, shipping is on them. 8 euros for wax, 5 euros for draft v2. They may be buying other resin cartridges too, may be worth asking them.

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That’s true, so call it a $300/10week cost of ownership for each material you want to have on the shelf. Another way to look at that is having extra material cost $30/week in tank life, if you are not using it. That’s really not very much money for a company that makes 10’s of millions per year, and has a prototype budget in the $100k/year range. It’s hard to separate my at home point of view from my work point of view.

This has become an issue at the company I work for. The EHS department is not pleased with all of the waste that is generated by using Form 2 & 3. As we have purchased more machines and are using them more often it has become a bigger issue. Enough so that I think I will eventually be forced away from Formlab machines. It is not the wasted resin but all of the other stuff that is non-recyclable and must be thrown away. Especially the Form 3 tanks as they are just a waste as I do not see any advantage to them as a user and the do not last as long as the Form 2 tanks.