Buying resin is a terrible experience

Hello. What other printers were you looking at? I am considering buying a form 2 as I hear the 3 is meh. Any info on b9?

By looking at the posts on the forum you may get a wrong impression that Form3 printer is a failure. The truth is that the majority of the Form3 users (like me) are happy with how the printer works, how the materials were supplied and especially with the supreme quality of the prints. And happy customers just don’t write posts on this forum.

For me personally Form3 is the best purchase I made last year, I got quality and precise prints, no failures, great support, regular updates of the firmware and the software.

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What sorts of parts do you print - figurines, engineering parts, something else? It seems that user satisfaction is at least partly a function of the type of part that is printed. I’m personally interested in printing parts that would be functional and would need to work mechanically with other printed or machined parts. It seems to me that the Form3 would not be a good choice for that sort of work right now.

I’m printing mainly engineering parts - shells for miniature enclosure boxes and bodies for custom sockets for fingerprint sensors. In the sockets I’m using metal levers to retract the pogo pins and the design works flawlessly.

All detail dimensions are on spot, printing speed (if placing multiple parts on the platform) is comparable with my FLM MakerBot printer.
My guess is that the main complains come from people who use Form3 printer for artistic purposes - small figures, miniature models, etc. For engineering purposes I find Form3 to be just perfect for me.

Thanks - those are encouraging results. I may have to re-think getting a Form3. One of the 1st things I’d make would be small parts for 3:1 scale model of a Curta calculator:

I’ve got 90% of it done in FDM parts but the really small ones can’t be easily done in FDM so SLA or MLSA seems like the best option for them. If that doesn’t work, I’ll have to try machining them. Here’s an example - does this seem feasible with the Form3?

What resin are you using? I tried with some “artistic” tasks and support side is just awful. anything else is quite good. I suppose you are using rigid one?

If the Form 3 is your first SLA printer, you’ll probably be happy with it. If you’ve had a Form 2 or other SLA printer before, you’ll probably be disappointed with it. (In my opinion)

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I would not 3D prints these parts if I can make them on lathe. If you’d like to make a working copy of CURTA the 3D printed details will not have enough strength . For example a shaft with 0.8mm diameter will break very easy - normal Form3 resins are brittle, don’t have experience with tough resins. But if you just want to build a non working precise model of CURTA - printing is good option.

I’m using white resin and this is my first SLA printer so I can’t compare it with other SLA printers. But the results are so good that there is no point of complaining, especially for mechanical details I’m printing.

In the beginning I really had problems with the print quality, but it came out that by orienting properly the details and by correctly cleaning/curing them the parts are just perfect for what I do.

I understand your point of view - if you had better experience with Form2, if you spent lots of money for the new printer and the expensive resins - you might find that Form3 is awful, which is not the case. If you compare the results with other resin 3D printers you’ll see how good is Form3.

Also take a look from engineering point of view - mechanically (how it’s made, what kind of hardware was used, how was tuned, etc.) Form3 is state of art compared to other hobby class 3D printers.

Anyway, I know that once you’re disappointed from the printer, the issue becomes emotionally colored and it’s hard to see the good sides of having Form3

I know you weren’t talking to me, but I have to say, this isn’t an accurate assessment of the situation. A more accurate statement would be that many people are upset because most Formlabs resins in the Form 3, do not print anywhere near as well as the black resin on the same printer. It doesn’t require any comparison to any other printer. I honestly don’t think anyone would be complaining if all resins printed at the same quality they are getting from black.

Thanks for the insight. Some of the smaller parts won’t be as easy to machine as that example would be. I would like the calculator to be functional even if only a few times a year in demonstration to others. Seems like my only hope there would be some sort of durable resin.

Fully agree with you - people can be upset because of the Form3 resins and the fact that most of them can’t print as good as the black one. It’s not officially mentioned from FormLabs but one of the main reasons for this is the parasitic curing of the resin - during printing there is some diffused and reflected light which cures partially the residual resin, trapped on surface part because of the surface tension and low viscosity.
The parasitic curing is much stronger on the side facing the platform and especially in the places around the supports. If you orient the detail parallel to the platform, the resin can’t flow out so easy from the side facing the platform, it stays much longer there (trapped by the surface tension) and the parasitic light is curing this resin. Personally when I orient the details and placing the supports, I’m thinking a lot how to make the resin to flow faster away.

Parasitic curing can explain well why black resin yields excellent results - black is the best for absorbing the light and in the same time it’s the worst for reflections. I’m printing flat shells with white resin and I found that the supports are “projected” on the walls like shadows - i.e. there is parasitic light that cures partially the resin.

See below digitally processed images from the surface (increased contrast and details) revealing the projected supports on the surface



It is definitely an issue of overcuring, but it isn’t entirely dependent on orientation and supports. Comparing parts printed in black, grey, and the original CAD file of a cylindrical object oriented at an angle in all three axis, there is overcuring in all axis in the grey resin. The grey part is swollen in all directions, with a general softness of detail overall. Yes, it’s worse around supports, and it is worse on the support side, but the overcuring is present across the entire part. This behavior is not present in the black resin. It is within spec of the CAD file in all axis, including the support side, and around support contact points.

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For me it seems the same parasitic resin curing effect, but manifested in swelling the part in all directions. Maybe FormLabs can’t tune the laser for this particular resin - if the resin is properly cured the diffused light from the laser spot can partially cure the resin in the close vicinity which is causing the swelling and smoothing details effect. If FormLabs decreases the laser power, the resin maybe becomes softer and this is causing bigger problems (like breaking the supports).
Theoretically the swelling should be little bit different in Z direction,

I’m not familiar how they use the laser, but for me (as software/hardware designer) it looks possible to modulate the laser power during printing and get better results:

  1. In overall decrease the laser power and hence reduce the parasitic resin curing
  2. Increase the laser power when printing an area which belongs to the supports (we can overcure the supports until they are away from the detail). Having stronger supports is improving the quality and reliability,.
  3. Decrease further the laser power when printing the last layer of the outside walls of the detail - this will reduce the parasitic curing of residual resin on surface

In short the idea is to change dynamically the laser power during the resin curing depend on the area (is it support area, internal volume of the detail or the outside walls of the detail).

This sounds very sophisticated but it could be precalculated and prepared on PC side, where there is no lack of processing resources.

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Personally, I believe they are not properly accounting for the light scattering of the translucent tank bottom on the Form 3, as opposed to the optically clear bottom on the Form 2. But that is just a guess based on observation of print results, not any detailed analysis of the hardware or software.

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Welcome to our working world - at work we spend a lot of time configuring resins to operate with different printers (often directly for the printer manufacturers). Those include Masked LCD, DLP and other printers that use a laser as the light source. The reality is that most resins (in fact almost all) are chemically configurable to work very well with different printer types. The base formulation for the resin remains consistent, its simply the components that alter how it cures (speed and depth of cure) that are varied between different types of printer.

In general terms a resin can be adopted to almost all printer types chemically. However the process is time consuming and lengthy. Utopia for us is when we can also alter the printer settings for time of exposure and the power is variable. Formlabs certainly is able to do that inhouse.

If we look at the resin cure then two things influence it, the first is how reactive it is, the second is how well it allows the UV energy to penetrate through the cured / uncured material (at a certain wavelength).

If the energy penetrates too far then different chemicals can be used to stop the penetration (we know these as light blockers) There are also available things known as light “absorbers”,

Light “blockers” and “absorbers” work in very different ways, generally the absorber takes the UV energy and changes it to heat (Remember the principle established by Émilie du Châtelet in about 1730, that energy cannot be destroyed or created, it can only be transformed or transferred from one form to another) The transfer from UV energy to heat energy is an undesirable effect for us as it leads to the warping of prints and effects the adhesion of the print to the build platform.

Light "blockers work in a very different way, that relies upon the fact that different photoinitiators work at different rates of efficiency dependent on the amount of energy at a set wavelength (in the case of the Form 2 and 3 around 405nm)

If that light was at a wavelength of say 450nm then the resin would not really cure.

Light blockers work by taking the energy that remains after the cure (polymerisation) has been effected at a certain depth of penetration and they fluoresce That takes the form of taking the 405nm energy and then transferring it form a visible glow at a different wavelength (in this case around 435 to 460nm) which is beyond the range for the photoinitiator to work efficiently.

Unfortunately the chemicals used to create colours (the pigments) are made up of materials that show very different characteristics (some absorb UV, some fluoresce, some do a little of both)…In practical terms this generates unique problems for each colour (and often varies dramatically from one pigment manufacturer to another - due to factors such as particle size, suspension or material used for the pigment) .

The chart below gives a little insight into just how complex this is:

The reality is that black is a particularly difficult colour (as is white - but for slightly different reasons), black generates a lot of heat when exposed to the UV energy source (due to the black pigment) and the depth of UV light energy penetration is much less than say a clear resin (or a blue pigmented resin). Its good to see that black now works well, that demonstrates that mechanically the Form 3 is a sound design (accurate).

I realise that the Form 3 uses a different laser (higher power) than the Form 2 and wonder about Formlabs intention to make all resins cross platform compatible (so they can be used on either Form 2 or Form 3) in reality thats unlikely to achieve best performance from the Form 3 (you would need to run the more powerful laser at lower speeds and power - which results in longer print times)

Hopefully Formlabs will see the light and optimise both the resin formulation AND the Form 3 profiles to take maximum advantage from its higher power laser… Rather than simply trying to match the Form 3 to Form 2 performance to suit the existing amounts of photoinitiators, light blockers / absorbers used in their resins for the Form2


I’ve wondered about this. For what purpose is the bottom of the Form 3 tray frosted?

I guess they thought it would work better? I mean, it’s looking like they were wrong on that, but I have to assume the intention was to make a better machine. Maybe there wasn’t a clear film that gave them the properties they needed? Just guessing. I don’t know that they will ever answer.

I have worked with FDM printers and other SLA printers. The form3 asks nothing and gives much. I print relatively small parts for my own designed model kits. With my experience of designing printable objects and the form3 I have a succesrate of 100%. I only use grey resin because the model building parts will be (spray)painted anyways.

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My last orders have come in very quickly…no complaints!

A lot of discussion that doesn’t belong in this thread. The start was that the user had bad experience buying Resin. Delays, no notification, nothing indicating back-order…etc.
Yes, there have been times that FORMLABS had issues with giving information about orders, but I don’t think that’s true anymore. We had issues trying to get Surgical Guide when Covid hit because we switched to making 3D swabs and custom test vials and it seemed we weren’t the only one switching to this material. So, yeah, many delays, and long lead times but FORMLABS seems to have resolved most of that. I have not tried the Grey Pro. But after reading several articles, it seems to be a staple resin for a lot of people. Be patient and order early before you think you need it. Popular products almost always have long lead times. As for actually buying the Resins… I love the Formlabs store. I wish all vendors had E-stores.

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