Form1+ real "feature size" and "feature size" vs beam profile and "effective spot"

I really didn’t see a need to start a new topic for this and lock the old one, it really just gives bad impression about the company, but as suggested I’m starting a new thread about these specific questions.

Problem I find with using the “effective spot” as the “feature size” is the remaining beam profile around it will still cure the resin a little which when exposed to uv light outside of the pritner later will harden too and so increase the “feature size”.
Unless Formlabs has proof that anything after some point in the beam profile which you’ve determined is so slow or ineffective at curing the resin that what I said doesn’t apply. In which case I’ll ask evidence for that.

I’ll need some info to explain how exactly Formlabs determined the “feature size” and “effective spot” and some results as proof of it (ruler next to a print like some other companies). A photo of the beam profile would be nice too. If you have it then please link to it. Thank you.
Do not suggest sending sample prints as proof. I do not consider them as proof. I know how lasers work and your lasers might be better calibrated for the test prints then on the printers you send to buyers, furthermore with sample print I have no way knowing on what printer it was done. On top of that, the sample prints might not have the parts I use for testing resolution myself to be sufficient proof for me.
This is also the case with photos, but then I don’t need to go through the hassle of getting a package delivered.

As for suggesting doing post processing, except for support material areas, if I had the time to postprocess, I wouldn’t be here. FDM printed ABS can already be post-processed with or a combination of the following: acetone vapor, laquer coating, spray or acrylic painting, sanding, sandblasting and rotatory/vibratory rock thumblers. And maybe ultrasonic cleaners, haven’t tried myself.
If these additive or subtractive postprocessings were done on a 25 micron print, many tiny details would be gone which are the reason you’d want to print at 25 microns, to have tiny details.

This is not “accusatory & prosecutorial tone”. This is someone being skeptical of a company I have no experience with and have heard mixed reviews about and being honest about it instead of politically correct.

I think you should take the word “minimum feature size” with a grain of salt. It’s not an exact measurement.

It all depends on orientation of the model, how thick the walls are and the resin you are using.

For example if you have a 0.5mm wall that has a 0.5mm hole on it. I don’t think you will have any issues printing that. However if you have a 2mm wall, that same 0.5mm hole may be closed off a little from the residual curing, because of the many more passes that the laser has to make ( in combination with peeling the layers)

Also, sometimes I have noticed that printing at 50 microns for examples will give me sharper details and more exact holes than printing on the 25 micron layer thickness. And other times it’s the reverse. Again, it all depends on the model.

So, again, just as you will not find a “resolution” explanation with DLP printers, you will not find an exact answer for SLA.

So instead of demanding answers, etc. from Formlabs, perhaps it’s better to explain what exactly you are trying to accomplish and maybe many people here how have lots of experience with the Form1 can give you some answers if it’s possible or not.


I have read the last thread and this one. I have to agree with Monger. The Form1 is a tool like any other, and as such it really depends on exactly what you are trying to accomplish to tell you if the machine can produce satisfactory results. Unfortunately, no technology on the market has “hard” perfectly set results that anybody can place exacting numbers with. What we can do (as current users of the product), is take a look at whatever you are attempting to do and tell you (with either examples or just experienced advice) weather we think it will work or not. If what you are trying to do is exceptionally novel or new, you will likely get a few of us interested enough to run a few tests. If it is old news, we are very likely to be able to point you to many already run tests (with picture examples!). I have personally found the smallest “real-world” resolution of the printer to be as advertized when I design and plan for it. Holes are their own bag of issues with a SLA machine of this type. Like monger said, your layer height and repeat of the laser over the same hole edge can seriously effect the outcome of the really small detailed prints. I have found ways to compensate for this. If I print one hole at one size and layer thickness I will not necessarily print another hole at a different size and layer thickness the same way. All I can say is I have become much better at using this particular tool to accomplish what I want it to do. And the resolutions I can get out of it are very satisfactory on very small detailed parts.

On a side note: I have visited the 3D Systems located in Denver, and saw one of their SLA machines in action. These machines cost more than $100,000. They use a very different method to make sure the Gaussian effect is minimized (all very proprietary and patented technology). They sell pretty much all the top-of-the-line powder deposition printers on the market and they still said to me point blank “The SLA printers are STILL the gold standard of 3D printing”. Looking at the parts that came out of their machines (as we watched and waited in the seminar), they are correct; Nothing beats a really good SLA machine… yet. I am just glad that Formlabs can bring us some of this technology at a much more affordable price. Is it quite as good as the high end machines? No. But it is certainty able to accomplish what I expect at a VERY reasonable price.

Hit me up for any questions (and possibly tests) to show you if this machine is what you are looking for.

e.g. play with the cards you’re dealt, learn how to play the axe, and be pretty grateful this thing even exists. dig it. I’ll bitch with the best of 'em here, but really, I could not even entertain trying to create a prototype and develop a product without it. It’s not perfect, but it’s an incredible enabler.


We just want you to know what to expect. I am grateful too this product exists too as it will surely yield an even better generation of SLA. Your “expectations vs reality” post definitely salted a wound, but I hang around to help. You will get much better info if we see examples of what you want to print.

I really don’t get what you mean when you ask the question “what is it that you want to accomplish”?
I would want to print a number of things, from miniature sculptures to replacement gears of old mechanical machines to phone cases to optics equipment and maybe other things in the future. I can’t give a definitive list just like I can’t say exactly what I will be printing with my inkjet printer in the future, or my FDM printers.

I know you can answer the question if you have printed the same thing and it has worked for you.

But you can also answer the question if you understand how the machine and technology works. And that’s the kind of answers you get when asking about the FDM printers in our FDM forums. With FDM “it also depends” on the print, but there are number of (actually a lot of) reasons it depends and you learn the reasons and then can answer. “It depends” doesn’t mean every single model is different and the only way to know is to try.
We have to remember there’s physics behind everything. And a company which sells these products should have these answers, and it’s very logical to ask for such info before investing in a product.
You can ask almost the same question to us (me, FDM users, companies manufacturing these machines) about FDM printers, how “nozzle hole size” relates to size of the plastic that comes out and how different it is between different filament types and we can answer that. And trust me, plastic extrusion is not simple topic compared to laser beams and UV curing resins, there are whole books written about it.
If Formlabs doesn’t know how the technology works in a product they are selling, that’s another story and then I’ll just look for another company.
If this was a Reprap printer then it would be perfectly normal for me to ask and learn solely from the experience and knowledge of its users, but it isn’t, this is a product made by a company.

If you don’t know the reasons why “it depends”, then that’s okay, you don’t know the answer then. Doesn’t mean there isn’t an answer.

I gave few examples of what I will be printing. You can let me know if you have printed such thing and how it worked out for you. That will be helpful no doubt, but that won’t really be an answer to the general question.

Miniature sculptures - I think you will be very pleased with these results. It’s what the Form1+ is best at.
Replacement gears - This is what the Form1+ is worst at. The material is not like plastic. It is very brittle and warps when shaped like a gear.
phone cases - These will print and photograph awesome. But will not stretch to install. Also will break when dropped because it will be brittle.
Optics equipment - The clear resin is not optical grade, but Craig did sand some clear down to make a nice homemade magnifying glass here.

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Also take a look at Monger Designs profile and the posts he has made on his resin mixes. He really does a good job at pushing the machine to the smallest feature sizes it is capable of. I’ll try to find a link for you later.

Thanks. I did not mean lenses, but optics equipment like lens holders, etc.
Lasers at the power I’m talking about will melt/burn resin even if the quality was adequate.

Here is that link I promised. Looks like he has settled on the black with the Form1+ as the best option for crisp detail and best feature. Scroll down the follow up posts to see prints even smaller. It should give you a nice idea how small and reliably detailed a From1 + can go. Form1+ and Black Resin = Almost Perfect

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