Hi All,
I think anyone who has a Form 3 knows that preventing warp of thin-walled parts can be a real challenge. Someone on the forum here recommended that heat not be used in the Form Cure and the time be doubled. I have found that to be effective and is what I generally do. However, these parts are mostly but not fully cured, I can tell by how they feel. Do these parts continue to warp over time? I suspect they do but don’t have solid evidence to support that.
I personally usually just recude the amount of heat I use for my thin walled parts and do not turn it off completely. Using 35-40°C has proven quite effective in most cases.
Could you maybe share a couple pictures of your pieces?
The more important part to counter warping is to leave the supports attached during post cure and have good orientation during the print.
I’m the one who you probably heard suggest no heat and 3x the duration.
I found in the past that even with lower heat, some parts would still warp. This is highly dependent on material choice and geometry though.
I’ve newly discovered that drying is actually the number one factor for warping. I dry parts for at least 24 hours air dry, or I throw them into a dehydrator for 3 hours. For parts that I used to think would warp, do not anymore if you follow this protocol and I always remove supports first for post processing ease.
There may be edge cases but I’ve found this new process extremely reliable.
Interestingly drying on soft material is important two fold - one because the HDTs are low…and two because the softer more flexible resins correlate to higher IPA absorption…so it’s even more critical on those materials not only for warping but also for dimensional accuracy.
I’ll make a YouTube tutorial about this at some point when I have time.
Great information. I never have time to wait for 24 hours. Haven’t tried a dehydrator but I’ve found that hair dryer dries parts better than compressed air. I’ve always removed supports after post processing. Makes sense that removing supports before post processing would be easier and could leave a better surface finish.
I looked and yes you are the one who advised the 2X no heat Form cure. So, thanks again. One more question, if you don’t mind, For parts that have been dehydrated, do you use the standard Form cure settings?
I will never post cure parts immediately after blowing with compressed air - it’s really not enough time to get rid of all the absorbed IPA. Again - this will affect parts differently depending on material type & geometry. I suspect you will encounter the same problems even blowing with a hair dryer (unless you are doing that for an hour 
)
Yes. I have found that parts which have been dehydrated are surprisingly resilient to the standard cure protocols. There have been parts which I was sure were going to warp, but didn’t.
Again - there might still be edge cases, but I’m much more confident in the post cure process now. I was previously often curing without heat for 3X the duration, but like you mentioned in your original post, you end up somewhere in between the “green” and “post cured” mechanical properties which I didn’t love all the time.
I haven’t done the extensive testing and comparison on this as I would like due to time & cost constraints but hopefully one day for the YouTube video I mentioned.
My standard process is now to do this, and if I ever see warping then I’ll fallback to the no heat, 3X duration method.
That seems kind of extreme and do you think the removal of the supports before curing plays a big part in this?
My thoughts are that leaving supports on helps…if you didn’t dry your part properly…but I’ve encountered instances where leaving supports on still resulted in warping, so that alone doesn’t solve the problem.
Also, a picture is worth a thousand words. This initial test is what leads me to continue dehydrating parts. Again, I need to document some more in depth testing in a video, but that will take a lot of time that I don’t have right now.
From right to left:
The support structures here are actually the perfect shape and geometry for exaggerating the effects that otherwise would be less noticeable on thicker parts.
Another interesting thing here is that all three of these parts looked identical before placing them in the curing oven. It wasn’t until heat + UV that warping occurred. Probably due to some kind of internal stresses introduced in this step.
The context here is that I was actually helping the materials team test warping on a previous part that I had issues with several years ago but upon re-printing last year noticed it warped less. We chalked it up to potential improvements in print settings, but I was curious because I knew that my process around drying had changed over the years so I ran this test.
I also was never really satisfied with how random warping on parts seemed, but over the years started to see a correlation with warp during rush jobs where I didn’t have time to air dry for a prolonged period of time versus other jobs where I had the time to leave parts out.
This also ties together very strongly with dimensional accuracy issues I’ve observed with Flexible and Elastic resin - which are also very much caused by IPA absorption (see link below). In these extreme cases, you can see how significant IPA drying can be on swelling of these elastomer-like materials so I believe that we can, with some confidence, also assume IPA is absorbed and trapped in rigid materials as well, causing swell, stresses and warping during post cure (as well as dimensional accuracy issues but at a much smaller scale than we see on flexibles).
I guess I can at least regurgitate this up in a blog post sometime in the next week 
Thanks for sharing; seems like some good info so far.
By the way, what are you using to cure/heat your prints?
That is great information. Thank you for sharing. The part on the right is what I would expect to see with a tall support structure. My dehydrator should arrive soon and I’ll immediately test it.
Standard Form Cure!
Yes, let me know! I’d love to see this knowledge disseminated and feedback on whether it helps others.
Just make sure you don’t crank the dehydrator above the HDT!
I’ll make a blog post over the next week, and then hopefully a video in the next several months
Hey @brownsabre700 did you ever manage to test and compare results after using the dehydrator?
Yes, and the results are good. Curing with heat and even without supports. However, still some warp with a small black standard part. I’ll try reducing the Form Cure heat to 35 or 40 C as mentioned at the top of this discussion.
Awesome to hear! There may still be cases and geometries that warp but I’ve found those cases shrink vastly after dehydrating 
Also - I’m hoping to do some more experiments for YouTube…so if you would be willing to share any models that exhibited warp here but improved upon dehydrating, I would really appreciate that (even the small warp you still see on the black part would be interesting).
What experiments do you have in mind?
