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I have been doing a lot of FDM for the past 10 years, but a few years ago, for FOMO reasons, I got really hyped up about resin printing. I got an Elegoo Mars an

I have been doing a lot of FDM for the past 10 years, but a few years ago, for FOMO reasons, I got really hyped up about resin printing. I got an Elegoo Mars and a very large expensive Chinese resin printer that I never got to work. I ran into three problems that I was not able to overcome, even after tons of trial and error: - Warping. With ABS, a heated chamber, ABS slurry, heated glass bed, completely solved all warping. With resin, I was unable to predict or fix warping issues. - Model not sticking to the bed. Behaviour was inconsistent. With a good printer like the Form, that is probably not a problem. With FDM, having an all metal printer, with a glass bed and a good Z probe solved this for good. - Mechanical performance was garbage. Very brittle. - Always needing supports. With FDM, if you fully control the design process, you can completely eliminate supports (at least in my case, of course this imposes design constraints). With resin, you always need supports. The supports are more complex and harder to remove. I still think resin may be the future, because the level of detail with resin is just amazing.

torginus 2y ago
The warping one is strange, warping is caused by thermal expansion/contraction and resin doesn't really change temperature during the printing process. That's one of the reasons you Sounds to me you either aren't printing at room temperature, don't have the resin dialed in or you got a bad batch of resin/ The other criticisms are fair, but not necessarily dealbreakers and can be mitigated. PLA is brittle as well, about the same as standard resin. Just like with FDM, there are other formulations, but the materials are different, and perhaps there are no good analogs for FDM materials. Imo resin printing is mostly useful for tabletop minis, not engineering prints. As opposed to you, I don't think resin's the future, certainly not in the hobbyist space. The fact that it involves highly toxic chemicals and fumes means you need a separate space and be really cognizant about materials safety at all times. It does have its niches, particularly in mini printing, where the high detail is useful, and you can load up the whole area with minis at no penalty to print time and have an entire army's worth of minis printed in a span of hours.
- michaelt 2y ago
  > The warping one is strange, warping is caused by thermal expansion/contraction and resin doesn't really change temperature during the printing process. In my experience with resin, you can get misshapen parts for a bunch of reasons: 1. Resin will change size a bit during and after curing. Not by a large amount, and of course it depends on the type of resin you use etc - but enough. And of course if your design has some thick bits and some thin bits, one might shrink more than the other. 2. Every time the machine exposes the resin, it sticks to the previous layer and to the projector screen/LCD. The machine then lifts the model, to unstick it from the projector screen. This applies force to the model, and can cause it to bend by a tiny amount - which can gradually build up over several layers. 3. Resin has to be somewhat UV transparent, for each layer to cure all the way through in a short exposure time. Because of that, UV curing later layers can pass through the part and cure resin that shouldn't be cured, on earlier layers. This is particularly the case if the shape has areas resin can pool up and won't run off. > PLA is brittle as well, about the same as standard resin. Just like with FDM, there are other formulations, but the materials are different, and perhaps there are no good analogs for FDM materials. For many printers, resin has to be brittle because of the way the printing process works. You cure a layer, it sticks to the previous layer and the projector screen/LCD, then you raise it to unstick it from the screen. If the resin is flexible, the unsticking process would cause the layer to bend, giving poor dimensional accuracy. So resin is formulated to be stiff and unyielding. FDM can print flexible materials like TPU - common 'print upside-down' designs of resin printers simply can't. Although you undoubtedly could engineer a printer that could, such as a resin equivalent of an SLS printer, which doesn't face the unsticking issue.
  - varjag 2y ago
    You absolutely can print flexible materials on resin printers.
  - mdorazio 2y ago
    This is factually incorrect. A quick search will show you plenty of flexible resins. Here's one: https://www.youtube.com/watch?v=eely3rxr2to https://www.youtube.com/watch?v=eely3rxr2to Resin is also much less prone to size changes than standard FDM filaments. If you've printed FDM you should know how much tolerance you have to have in your parts (ex. hole diameters) to account for shrinkage post-print, not to mention the difficulty of printing things like ABS. Resin has MANY drawbacks and in my opinion kind of sucks as a general user experience, but warping, material quality, and material options are not worse than FDM.
varjag 2y ago
The main cause of warping is inadequate supports and/or unfortunate angles you place the part with. Remember you have both gravity and separation force pulling on the part each cycle, unlike with FDM. Align the bed, clean it thoroughly with alcohol before printing and increase base exposure. Make sure there is no debris in the vat. It'll stick. All printer resins are variation of acrylic and you have to design your parts with material limitations considered. However there's a range of premium resins for performance prints, look into Henkel Loctite or BASF offerings. We use BASF RG 35 and RG 9400 for small volume production parts. Also, make sure you do not overexpose: print an exposure target for any new resin to zero out the settings. Supports are certainly unavoidable but are largely a skill issue. After hundreds of prints it takes me minutes to depanel very elaborate designs.
michaelt 2y ago
> Model not sticking to the bed. Behaviour was inconsistent. Crank the exposure time for the first 10 layers up. Way up, like 10x the exposure time for normal layers. They'll come out noticeably oversized, maybe 0.3mm bigger than you wanted. Adjust the model to compensate. (Assuming you've already levelled the print platform etc in line with the manufacturer's instructions and your resin is OK)
- iCarrot 2y ago
  The common wisdom (this is back when I was still fiddling with an Elegoo Mars 2-3 years ago) was to print the model at an angle and elevated from build plate. There should always be rafts and supports under the model.
numpad0 2y ago
I learned hard way that you have to: - have GOOD ventilation and don't bother with water washables, - nail down Resin XP2 Matrix test prints, - use BOTH stirrer wash and ultrasound, and dry prints for hours before curing to mitigate swelling(marginal effects), - and use 10-15x longer exposure for first layer curing time, for SLA prints. Otherwise resin crumbles apart, leaves ugly marks on surface for first half inch, and so on. If magnetic beds are used, Z limit switch trigger arm must be adjusted too. Support-free is possible, people doing skyscraper towns are to some extent cargo culting.
bearjaws 2y ago
From my experience you will have these problems with Form Labs printers. Especially as a novice in resin printing.

torginus 2y ago

The warping one is strange, warping is caused by thermal expansion/contraction and resin doesn't really change temperature during the printing process. That's one of the reasons you Sounds to me you either aren't printing at room temperature, don't have the resin dialed in or you got a bad batch of resin/ The other criticisms are fair, but not necessarily dealbreakers and can be mitigated. PLA is brittle as well, about the same as standard resin. Just like with FDM, there are other formulations, but the materials are different, and perhaps there are no good analogs for FDM materials. Imo resin printing is mostly useful for tabletop minis, not engineering prints. As opposed to you, I don't think resin's the future, certainly not in the hobbyist space. The fact that it involves highly toxic chemicals and fumes means you need a separate space and be really cognizant about materials safety at all times. It does have its niches, particularly in mini printing, where the high detail is useful, and you can load up the whole area with minis at no penalty to print time and have an entire army's worth of minis printed in a span of hours.

michaelt 2y ago
> The warping one is strange, warping is caused by thermal expansion/contraction and resin doesn't really change temperature during the printing process. In my experience with resin, you can get misshapen parts for a bunch of reasons: 1. Resin will change size a bit during and after curing. Not by a large amount, and of course it depends on the type of resin you use etc - but enough. And of course if your design has some thick bits and some thin bits, one might shrink more than the other. 2. Every time the machine exposes the resin, it sticks to the previous layer and to the projector screen/LCD. The machine then lifts the model, to unstick it from the projector screen. This applies force to the model, and can cause it to bend by a tiny amount - which can gradually build up over several layers. 3. Resin has to be somewhat UV transparent, for each layer to cure all the way through in a short exposure time. Because of that, UV curing later layers can pass through the part and cure resin that shouldn't be cured, on earlier layers. This is particularly the case if the shape has areas resin can pool up and won't run off. > PLA is brittle as well, about the same as standard resin. Just like with FDM, there are other formulations, but the materials are different, and perhaps there are no good analogs for FDM materials. For many printers, resin has to be brittle because of the way the printing process works. You cure a layer, it sticks to the previous layer and the projector screen/LCD, then you raise it to unstick it from the screen. If the resin is flexible, the unsticking process would cause the layer to bend, giving poor dimensional accuracy. So resin is formulated to be stiff and unyielding. FDM can print flexible materials like TPU - common 'print upside-down' designs of resin printers simply can't. Although you undoubtedly could engineer a printer that could, such as a resin equivalent of an SLS printer, which doesn't face the unsticking issue.
- varjag 2y ago
  You absolutely can print flexible materials on resin printers.
- mdorazio 2y ago
  This is factually incorrect. A quick search will show you plenty of flexible resins. Here's one: https://www.youtube.com/watch?v=eely3rxr2to https://www.youtube.com/watch?v=eely3rxr2to Resin is also much less prone to size changes than standard FDM filaments. If you've printed FDM you should know how much tolerance you have to have in your parts (ex. hole diameters) to account for shrinkage post-print, not to mention the difficulty of printing things like ABS. Resin has MANY drawbacks and in my opinion kind of sucks as a general user experience, but warping, material quality, and material options are not worse than FDM.

varjag 2y ago

The main cause of warping is inadequate supports and/or unfortunate angles you place the part with. Remember you have both gravity and separation force pulling on the part each cycle, unlike with FDM. Align the bed, clean it thoroughly with alcohol before printing and increase base exposure. Make sure there is no debris in the vat. It'll stick. All printer resins are variation of acrylic and you have to design your parts with material limitations considered. However there's a range of premium resins for performance prints, look into Henkel Loctite or BASF offerings. We use BASF RG 35 and RG 9400 for small volume production parts. Also, make sure you do not overexpose: print an exposure target for any new resin to zero out the settings. Supports are certainly unavoidable but are largely a skill issue. After hundreds of prints it takes me minutes to depanel very elaborate designs.

michaelt 2y ago

> Model not sticking to the bed. Behaviour was inconsistent. Crank the exposure time for the first 10 layers up. Way up, like 10x the exposure time for normal layers. They'll come out noticeably oversized, maybe 0.3mm bigger than you wanted. Adjust the model to compensate. (Assuming you've already levelled the print platform etc in line with the manufacturer's instructions and your resin is OK)

iCarrot 2y ago
The common wisdom (this is back when I was still fiddling with an Elegoo Mars 2-3 years ago) was to print the model at an angle and elevated from build plate. There should always be rafts and supports under the model.

numpad0 2y ago

I learned hard way that you have to: - have GOOD ventilation and don't bother with water washables, - nail down Resin XP2 Matrix test prints, - use BOTH stirrer wash and ultrasound, and dry prints for hours before curing to mitigate swelling(marginal effects), - and use 10-15x longer exposure for first layer curing time, for SLA prints. Otherwise resin crumbles apart, leaves ugly marks on surface for first half inch, and so on. If magnetic beds are used, Z limit switch trigger arm must be adjusted too. Support-free is possible, people doing skyscraper towns are to some extent cargo culting.

bearjaws 2y ago

From my experience you will have these problems with Form Labs printers. Especially as a novice in resin printing.