Is the FEP layer replacable in LT trays

I’ve started using the Form 2 LT resin trays and wanted to know if the FEP layer is replaceable when it gets foggy?

It is not easily replaceable and does not get foggy. It fails mostly due to damage caused by resin particles or scratches from the wiper.

It also degrades from Rigid resin. It is the only resin we have that degrades the tray, it gets wavy at the bottom after a month or two of storage. A bit frustrating since these are supposed to be the long term trays, but we love the precision of rigid. Might consider storing it in another container when not in use to increase wear time.

Possible not easy to replace the FEP layer in the LT Resin Trays but I still want to try it. I’ve done a lot of things others have said are too hard. :grin:

So, has anyone actually replaced the FEP layer in these trays. I’d like to hear how you did it.

Also, I’d like to know how you clean the resin out of these trays. The Orange trays would crack it you used IPA but what about the Grey LT trays, are they still prone to the same problem? Also, how about using Ethel Alcohol instead, does that work?

Yes, that’s something I’d like to try as well when the time comes. I’ve not worn out any LT tanks as yet (I’m with you; they should be called trays). I’ve refurbed a few std tanks replacing the acrylic window as well as the PDMS layer.

So , when I come to replacing the FEP layer I plan to use some silicone primer on the FEP layer and then attempt to lay this on top of the uncured PDMS layer. Who knows, it might work! :wink:

There’s some information on cleaning the LT tank here:
Here’s a quote from the relevant section:

Cleaning the tank frame exterior

To clean resin on the chemical resistant tank frame, use a paper towel and a small amount of clean IPA. Avoid getting IPA on the clear acrylic tank window because the IPA can lead to cracks in the tank window and can cause resin to leak.

Incidentally I’ve been using my own concoction for about a year now to clean the std tanks with no apparent ill-effect. It is really fantastic at getting the tanks spotlessly clean and is reusable too. It’s not so great for washing parts but it’s still in development.

That tutorial does say not to use IPA on the trays. So how does one clean out all the residue of the resin? That’s my question.

I’ll test some Ethel Alcohol on a tray just to see what happens. I have LT trays that have and the FEP damaged. I’ve worked around these areas to get prints. I upgraded Preform to the latest as well as the Firmware on each machine and ended up with a disaster on both. I then rolled back to an older version and most all issues cleared up.

One thing I did run into was the support points I’ve been using for years on inventor product prints failed and I had to clean the FEP layer. Some of the stuck bases where extremely hard to get free thus some slight damage was done. I only use the plastic spatula trying to stop as much possible damage. What I need to do is round the corners of that spatula so it can’t gouge the FEP layer.

I wouldn’t use silicon under the FEP but adhesive FEP is what should be used. The silicone will not smooth out to an exact layer I feel.

If you scroll about half way down the page I linked to you’ll find the text I quoted. ie you can use IPA on the LT tank frame but avoid getting any on the acrylic tank window. The LT tank surround appears (from what Formlabs are saying) made from a different material to the std orange tanks.

From what I can ascertain without destroying one of my LT tanks it looks to me like the LT tanks consist of three layers: Acrylic/PDMS?/FEP. It seems far too squidgy (technical term :wink:) to be just FEP directly on the acrylic. Unless that squidgy layer is a thick adhesive? I’ve not looked into it too deeply yet but would be interested in anything you might find upon disassembling one!

I used that link and watched the video. They show an LT tank and say not to use IPA on it or it will crack. I also thought that wouldn’t be the case as it seems to be a different plastic.

What I’ve seen on the FEP is that it comes with an adhesive coating. I’d be real surprised it there was a PDMS coating under it as the idea of the FEP was to get away from the PDMS layer.

I also switched to using the metal spatula as that’s what they used in the video. Seems to work a bit better and hopefully doesn’t dig or scratch the FEP layer as easy as the plastic one seems to.

I’ve disassembled a few LT tanks so I can tell you how they are constructed:

The green part is not sensitive to IPA. You can clean it safely. Just as with the orange tanks. However, the acrylic window cannot be cleaned with IPA. If you do, it can crack.

There is a thin release layer(possibly FEP) with a black foam adhesive under it of 0.8~1mm. Between the acrylic window and the release layer, there is another clear soft layer(possibly PDMS or another silicone). The release layer is first assembled together with the acrylic window and then the soft silicone is pushed through one of the two holes at the back of the tank. So no pouring from the top.

So yes, there is PDMS or something else in this tank. The LT tank is not there to get away from PDMS. It is there to be more resistant to more aggressive and difficult resins(like the rigid resin) and last longer as the surface of the release layer does not get micro cracks/fogging as with PDMS.

The silicone layer under the FEP is most likely there to reduce stretching of the release layer when the platform lifts out of the tank. I’m reasonably confident your tank will fail if you manage to stick a FEP sheet on the right height in the tank.

That’s very interesting, thanks for the info.