Hi everyone! I recently contracted someone with a Form2 printer to print some small parts for me using tough resin (25 micron). The problem is they came out REALLY flexible–basically like a soft pencil eraser of the same size, and accordingly are totally not what I was expecting and are not at all useful to me. I asked about the IPA wash and UVA postcure and was told it was done exactly as recommended, and this is just how the tough resin is. (The dimensions of these parts are pretty accurate, and I’ve had the same parts printed using standard black resin on the same machine and they were perfect, but just brittle).
So, is there something wrong here, or is this just what the “tough” resin is like???
I’ve included a picture of the part being bent by more that 180 degrees, which can be done repeatedly and VERY easily at room temperature. It is supposed to be straight/ flat.
Tough V2 (the version you have) has some flexibility, but what you’re seeing is pretty extreme here. Judging by the color of the material, though, it doesn’t look like it has been sufficiently post-cured. If you can leave it in the sun for a day or so, you should get stiffer properties. Also a good time to give a shout out to tough V3 (the version formlabs is currently shipping), which less flexibly than V2.
Thanks Craig. So for the post cure, obviously the amount of time required is heavily dependent on the source, but is there such a thing as too much UVA post cure? (Can they be left under the lamp for a couple days?) Also, for a part this small, what is the recommended time for the IPA bath?
Oops! I have been spreading rumors that there are only two versions of tough. V1 and V2 are similar with quality of life changes and V3 is the newest, greenest, stiffest Tough, correct?
While I know the general consensus was that Tough V1/2 was too flexible (I have heard it affectionately referred to as “Stale Gummy Bear” material) I am still quite fond if it and I am sure I am not alone. Are there any plans to continue production of the more flexible tough and offer both versions for sale? While applications were a bit more limited Tough V1/2 was still quite a remarkable material.
A different name would probably be required. I bet @ChristopherBarr would sell you his Tufflex branding. =]
@david_nedlabs over-curing can cause discoloration to some of the resins (clear especially). I have seen FL employees recommend setting your item on a window sill for a day or two on shorter, cloudier winter days. I imagine a couple of days in a UV chamber would be over-kill however and could possibly damage the print…although I am not positive.
Regarding IPA bath, if you are using 91%+ IPA 10 mins in each vat should be sufficient provided that it is new IPA. Slightly longer if it has been used for a while. I normally let it go a bit longer, 15-20 mins per vat.
Oddly enough I once had a piece printed in white resin similar to the shape and size you have above and I accidentally left it in the alcohol over a 3 day weekend. When I came back the part flexed just like your part pictured above!
I’ve put about 3L of Tough V2 through my Form2. With the flexibility you’re showing, the resin isn’t fully cured. Tough V2 is actually a little too flexible, parts tend to “creep” over time, but bent far enough, cured Tough will exhibit the same glass-like break you’d get with less stress out of a resin like Clear. I haven’t tried V3 yet, but it’s supposed to be better in this regard.
I cure in a UV box, and I recently left some parts in the UV for a few days. The parts fluoresce fairly uniformly, all over, when first put in the box. Over time less and less fluoresces. When I finally pulled the parts out, only the very deepest center of the print was still fluorescing. My assumption is that only uncured resin fluoresces. My conclusion is that curing with only a few Watts of light can take a long time.
