Hi Tim! I’m a service engineer on Dan’s team and I thought I’d chime in with some the thinking behind the wiper design. We definitely had more in mind than just mixing the resin, although that is one of the major purposes.
The wiper does three main things: keep the resin well-mixed and homogenous, help with failure recovery, and make sure the resin and tank surface are oxygenated. Of the three, keeping things mixed is actually probably the least important (although it’s still very helpful.)
I find the description of the wiper making failures worse interesting, because one of the main ideas of the wiper is to improve the results of a failed print. Without a wiper, once a part starts failing, the failed “pancake” on the tank bottom will stay there and grow bigger over time, wiping out more and more of your part and often getting so big it interferes with other parts as well. With the wiper, however, the hope is that as a failure starts, the seed of the “pancake” will get swept away and deposited at the side of the tank where it will be out of the way, and the part that was beginning to fail may be able to recover, or at least avoid affecting other parts near it.
The wiper getting stuck on things in the tank and “flicking” resin is certainly an issue (and, as you’d expect, not something we intended!) but we find that it happens very rarely combined to doing its intended job of taking an incipient failure and turning it into a successful part. In this case, it looks like your parts were just too far gone for the wiper to save; I can see how, once you’re in that spot, the wiper moving the failed chunks around is less than helpful. Did you nail down what was causing those failures in the first place? Black 04 is always going to be a bit softer than Grey 04, but it shouldn’t be failing on you like that—if you wanted to open a support case with our team, we’d be happy to dig into why that was happening.
The third job of the wiper, and actually the most important one, is keeping the resin in the tank oxygenated. I was confused to hear you say that you worry about froth in your resin—I’d love to hear more about why it’s something to worry about. In our book, bubbles in the resin aren’t just not a problem, they’re actively good, since they show that the resin is well-oxygenated. Oxygen in the resin keeps peel forces low, reducing stress on your part, which has myriad benefits: lower failure rates, less warping of the part, less obtrusive layer lines, and so forth. It also slows down the pace of clouding in our standard resin tanks.
We’re certainly not going to try to stop you if you’re seeing good results running without a wiper, but I hope this helps clarify the reasons we included it in the Form 2 design. Definitely let me know if you have any more questions about any of the above!