why, exactly, do you need the pdms layer? i am not an optical engineer - just curious.
dennis
PDMS affords less adherence to cured resin. Without PDMS, the printer would not be able to consistently peel each layer off the bottom of the tank. Since peeling forces would be much higher, even successful peels would likely cause damage to the print from the high stresses.
The only wearout part in the tank is the PDMS, which loses a little material with each peel until it is too hazed or pitted to print reliably anymore.
Whether the tank and its window was made from Acrylic or some other plastic wouldnât make a difference to how often the tank would need to be replaced. All that probably mattered to FL was that the material of the tank last at least as long as the PDMS is expected to last. So the Acrylic isnât a bad choice. Itâs cheap and itâs translucent so you can see how much resin is in the tank.
Could FL offer a ârefurbishingâ service for resin tanks? Probably. Should they? I wouldnât if I were them. There are any number of logistical challenges to address; Customer return process, packaging (returned tanks will be âwetâ but cannot be allowed to leak/leach in to the packaging during transit), accurately tracking tanks, cleaning (which would require the removal of the old window and adhesives to install a new one), and most importantly, some kind of recertification to ensure the newly refurbed tank was watertight and in a mechanically sound condition. Itâd be a very labor intensive process and the yield would be less than 100% (some tanks will get rejected because of defects or damage). While I have no idea of the costs, I bet itâs probably less expensive to make new tanks than to refurbish old tanks. I suspect ZVAT discovered this harsh reality which is why he gave up on his rebuild service. The cost/benefit analysis doesnât favor rebuildable over disposable.
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So how do you know know when the tank needs to be replaced?
Do you just replace the tank after 2 liters of Resin is processed?
I print at 100 microns
When print quality starts to degrade. Pay attention to the Supports on your prints. If they start to take on a âblobbyâ look, your tank is about played-out (or youâre using a Form1 and you need to clean your mirrors). Dashboard has a new feature called âHeat Mapâ that helps you see where and by how much a tank has been used so you can position those last prints where theyâll come out the best and squeeze as much as you can from a tank before retiring it. Though in my experience, getting more than 2L from a tank is unlikely. I just replace the tanks after 2L nowâŠ
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Is it a third party resin?
I had such issues with Photocentricâs Flexible UV but never with a Formlabs resin.
The tanks I worked on are made of HMPE: very chemical resistant and easy to clean. With interchangeable glass window so you could soak all parts of the tank in IPA or something else to get them brand new. Thatâs much less effort than cleaning existing formlabs tanks for refurbishment.
Still⊠If Z-vat stopped producing refurbished tanks, Iâm willing to look into making a batch of more durable tanks.
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Should find out why Z-Vat stopped making theirs, maybe it was a legal thing?
Would your tanks still use a pdms layer or Teflon pads? Pads seem like a good idea, just peel off the old one and put on a new.
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Iâm not sure why you think that. I just went to their web site, and I can buy either one of their vats (1 or 2).
What makes you think theyâre not making them anymore?
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The tank would still use PDMS. I tried different FEP configurations(thickness and designs) but they donât work with slide-peel as the adhesion to the FEP is too much. It only works for very small parts.
I do not know of the existence of PDMS pads. Do they exists? Never tried to cast PDMS as a sheet myself, maybe that works.
I ordered and received a message from Zach stating just that. No longer manufacturingâŠ
HmmâŠI wonder why the option to buy is still there.
I do remember that he stated somewhere on the forum that he asked FL if it would be a problem if he refurbished and sold them and they said no.
If we can build a batch of letâs say⊠20 vats, itâs feasible. They should last a lifetime. 
I had thought about a mold for pdms, you could use a urethane mold but the surface would have to be perfect. Ideally you have your gate on one corner. I think the bigger problem would be putting the pad into the tank and the risk of it peeling up from the edges if a print is near it.
Would the FEP work on the Form1âs?
Really all Formlabs needs to do is change materials for the tanks frame and bottoms. Even if they sold them as a heavy duty version.
FEP will probably work for the F1âs as the mechanism is different. But you need to change the peeling speed.
I do not see a reason for FL to sell a heavy duty tank. They aim for a ready to run product, which is great for most professional users and brings in the most revenue.
It only happens with Dental. We consumed 200 ml of material and 2 broken tanks already. I have a ticket open and I am waiting for a reply. Here it is⊠the movie⊠http://www.print3dbucuresti.ro/wp-content/uploads/2017/03/video-1488391897.mp4
Enjoy.
TIP: I am not trying to destroy them on purpose just to have them replaced. No strange fetishes :))
And anyone from Formlabs can probably check my dashboard to see how much resin we used and how many tanks.
We did not clean with the spatula in the corners or anywhere else. All prints untill now were PERFECT. .
Clear resin tank for Form 2 is still ok after 200 ml of resin consumed. In Form 1+ tanks never had problems with the silicone layer. Some were cracking at the back, on the upper side.
I made an order today for new tanks because I urgently needed them. But this is not normal.
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I canât say Iâve ever seen the PDMS detach from normal printing. Thanks for getting in touch with our support team and Iâll make sure to follow that ticket largely out of curiosity for whatâs causing this.
And I donât want to buy alternatives for tanks. I want to buy the tanks from Formlabs, but in normal circumstances. 
Images with my dashboard attached
Clear resin tank is still very very good.
The video is hard to argue with. It sure looks like the PDMS is sliding on the bottom of the tank. But⊠Since the tank is no good now anyway, Iâd suggest you remove it from the printer and then remove the suspected-PDMS, and then wash both with some IPA so we can get a good look at the bottom of the tank and also at the stuff you removed from the tank.
For you to have had two in a row do this same thing, but the Forum not be flooded with other users using Dental who are also having the same problem suggests the problem is unique to you some how (note: this does not mean itâs your fault!). Like maybe the bottle of Dental resin youâre using is defective somehow or thereâs some environmental factor wherever it is that youâve got your printer located or where the resin trays are being stored (or if they arrived in the same shipment, maybe something that happened in shipment like exposure to high temperature or humidity).
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I donât say itâs someoneâs fault either. I just want to identify whatâs causing this.
The first tank was staying inside the printer since we bought the printer. It was used for about 15 prints. The silicone in the first tank was already split in small pieces when we noticed the problem. The problems were starting from the left corners of the tank. The center of the tank was ok, but small pieces from the corners were floating inside the resinâŠ
The second tank: we used it for just a few prints and we put it on the shelf to keep. When we had an order for it, we placed it inside the printer and noticed the silicone was completely removed.
We keep the printer in the office, on my desk, and there are no high temperatures or humidity. The heater in the room is far away from the printer. If there was any humidity we would have problems also with FDM printers filament. And itâs not the case.
And we are not using the spatula too often or aggressively . In most of the cases we donât use it.
I will search for the tanks and tell my colleague to clean them.
