I am growing a little tired of the PDMS layer folding up due to the wiper and ruining a perfectly good resin tank. I have had 3 tanks now that have done this. Also, considering that after just a couple prints, the PDMS layer starts to glaze, throwing it away at 20 prints seems extremely wasteful. I ordered several LT tanks which promised better life, but have been waiting for months.
Seeing as PDMS layer has nothing special going for it other than it is non-reactive silicon that is optically clear, has anyone out there tried to use an optically clear castable polyurethane? (Example: Smooth on Clear Flex). As long as it is vacuumed before pouring, optically it should work. However, someone would need to test how reactive the polyurethane is to the curing resin.
There are threads online and videos on how to re coat the pdms with the same exact material used by the company. Its far cheaper and from my own tests on the Moai printer more durable then what you get from the factory.
As someone whose trying to mindful of the environment I find the whole SLA print system completely wasteful. Why not make a replaceable PDMS cartridge or sheet instead of tossing the whole tray, lid and wiper arm.
Polyurethane may achieve the same relative Shore hardness, but it won’t have the non-stick/non-reactive properties of silicone. If the resin doesn’t adhere to it immediately, you can bet it will when the laser hits it. In the same way that you wouldn’t use urethane rubber to mold an object as you would with silicone, even though they may look and feel similar.
That said, clear urethane covered with a thin sheet of PTFE Teflon was discussed awhile ago, mainly on the Google Formlabs group, but nobody followed through to a conclusion. However, I have a sneaking suspicion such a setup may be at the heart of the new FL tray. The only lingering question was of the UV-transmissive qualities of these alternative materials: would they reduce the curing power of the UV laser? Nobody among the users ever found out for sure.
Polyurethane will turn yellowish over time. It’s a reaction to visible light and primarily the UV spectrum. Imagine what will happen when you hit it with a UV laser.
I have built a few guitars a few years ago, and some of them have been coated with Polyurethane, especially over the natural finish of the neck. Over the years, the color has turned to a nice amber yellow, giving it a nice aged look. And these guitars have not seen sunlight, they are on rack or on wall displays, yet they have yellowed in time.
One of our primary goals related to Form 2 development has been to extend the lifetime of the tanks, and you might check out Resin Tank LT which lasts considerably longer. The process for replacing PDMS can be a bit challenging for the average user, but the Zvat glass tanks seem to work well for this if you are looking to go the PDMS re-coating route.
Might want to check out? I ordered 3 total since Jan and none have shipped. I also inquired last week about a status and heard the “oh, 2 should ship this week”, but nothing… Im not angry as I know you are struggling to ship the new tanks, but please don’t patronize me on something you can’t ship at the moment.
Wasn’t meaning to be patronizing, just wanted to make sure the thread was aware of the LT tanks as they are a bit more costly, but might prove more efficient in the long run as compared to replacing the PDMS. We’re working to get these fulfilled as quickly as we can.