Hi. Wondering if anyone had issues using Black resin during curing. We’re using it to prototype parts with thin walls (0.1" thickness), and curing it per recommended times and temperature (30 minutes at 60 deg C) causes warpage throughout the part (interior and exterior). I’ve tried both ways to keep the supports on, and to take it off before curing to see if it helps, and still major warpage.
I’ve cured parts without heat and sometimes that helped but not always, Like Jennifer mentioned, layouts and supports might help but also I’ve been adding a designed sacrificial part that gets attach to the print with supports and discarded after cure, I know this does not look anything like your build but the idea was the the same, the “spoons” were bending in cure and in this case this completely solved this.
Thank you for your input @jantarek! I agree that anchoring the part in place as much as possible, potentially by adding additional “sacrificial” pieces, could help guard against warping. Another point to double check is to ensure that parts are fully dried prior to being post-cured. If issues persist, getting in touch with Support would be the best course of action as Jen mentioned.
Black seems to be one of the worst when it comes to warpage. As stated I have found that letting the part dry completely for 24 hours is best for me. Then cure it. Lessons the issues. If you are taking the part from wash to cure right away it’s not a good practice. Let the part dry on it’s own first.
Although those walls of your print are thin to begin with but I have printed thinner than that and not have it warp with the 24 hour practice.
We encountered a similar issue with thin areas of a print (gray resin) warping and after some trial and error realized minimizing the wash time to just wiping the print clean with ipa wipes was part of the solution.
Reducing the temperature in the curing oven also helped in solving the issue, as well as a dry time of about 12 hours.
Awesome tips and advice. Thanks so much @jantarek. That’s a neat and clever idea to print your own sacrificial support. I’ll try that around the footprint of the enclosure.
@Titon@leonhart88@RD_lab I do have an issue with black resin as well. I’ve been letting the part dry before curing, but not 24 hours long. Only more like 30 minutes. I’ll let it sit to dry out as you mentioned and see if that helps.
I would also suggest giving yourself time post cure before completing any project. I understand sometimes there is a need to get things out fast but from my experience the printed model changes over a 5 day period. What I mean is the feel of the completed print changes for me anyways. I can produce a print with thin walls that’s changes over 5 days even when you cure it. The bond seams to get stronger especially with the soft resins like Gray and Black. Now tough 1500 different story. What “fit’s” with Gray or Black V4 is completely different than tough 1500.
I have had exactly the same issue with Tough 2000, such that I gave up using it (although it is a really nice material). I don’t use IPA, TPM is much better, with no fire risks or evaporation. The Form Cure L timings and temps seem a little “off” to me, 80C for some materials is much too close their TG points (where they start to soften) which means the supports then sag and so does the part geometry.
I often part cure, then fully cure, I haven’t yet found a material that you can easily “over cure”, I tend to be using the engineering resins, and now have success with touch points of 0.25.
If in doubt, just cure slowly. You can always do a final post-cure to get best mechanical properties if you are interested in these.
When I did tests to compare lower temp curing vs curing with no heat first then full heat, I didn’t find any difference, parts would still warp.
The only way I’ve prevented parts from warping is to forgoe a heated cure all together at the expense of mechanical properties (I cure for 3x the time).
Also tough resins will creep. For example if you stuff them in a box for a prolonged period of time and they are being squished, they’ll eventually permanently deform, so definitely need to be careful with them over time
I think post cure warping is due to both sides not getting the same cure light exposer. Looks like your inside needs more. You can try curing with the inside facing the sun first or modify how it’s held in the form cure.
0.1" thick? That’s just over 2.5mm. That’s a lot of warpage.
Try a few of these tricks:
Don’t soak the part long in alcohol. (10min, constant rinsing, very clean 99% alcohol)
(also, let it completely dry out before starting the cure phase. I think the alcohol gets soaked into it and then outgasses during cure)
Cure it in natural sunlight. It’s longer (10hrs worth or more) but it doesn’t warp as much. (use a rotating stage if you can. They sell solar powered display stages on Amazon)
Use a buck to clamp to while it cures.
Sometimes the intense heat and then the cooldown can cause the warp. I’ve clamped shapes into edges, nooks and crannies to keep these shapes after it cools down. It has helped tremendously. The hard part is just finding the shape and clamping it.
In the long run, i’ve changed materials. most will warp, but they do so at varying degrees depending on the materials. The TOUGH and the DRAFT seem to have less warp than just the standard color resins.
After reading the instructions for TPM wash, It almost seems like it’s a lot more work. I’d rather just rinse with alcohol. And now that someone has suggested ways of recovering your alcohol, there’s even less reason to use TPM.
Is TPM that much better at cleaning the resin off than alcohol?
Just like with injection molded plastic part design, variations in wall thickness will cause differences in thermal stress/strain that can cause warpage–especially in thin walled parts like yours. Unlike injection molded plastic part design, you can add internal supports to minimize the heretofore described effect. Also, be sure to wash and cure it without removing the supports first–this will help it to maintain its shape.
Another thing you can do is design sacrificial (i.e. removed after print) geometry into your part geometry that will help it maintain it’s shape. Looking at your part, I would say adding a flange that extends normal to the wall planes in both directions would work nicely. The cross section would be T-shaped and connected to the part by a number of small tabs that can be easily snipped away.
Sometimes it’s good practice to use methods from other processes. For instance, you would not create features like you’re showing in injection molding without adding structural ribs. If possible, add ribs to the (looks like a fan or speaker) mounting area. In short, you need more structure there. You’re asking a lot of that feature to maintain shape. Warping like that in any material is due to differential stresses such as heating/cooling at different rates. Even if that is taking place at ambient temperatures.