Downcycling ruined LT tray to Regular via PDMS, is it possible?


#1

Since LT trays have not yet disclosed their surfacing formula, I assume that damaged units cannot be user-resurfaced back to original condition. However, can the damaged LT surfaces be removed and replaced with PDMS like the older orange trays? What I don’t know is if the chip in the LT tray tells the Form2 to behave any differently from having an orange tray, such as a different peel process. Is anyone able to confirm or dispel this proposal? Thanks!


#2

Hey there @Volguus, there are specific resins such as Grey Pro and Rigid that require an LT tank and using those resins on a surface not designed to handle it would probably end with some pretty nasty results.


#3

I know of a few people who have done this process successfully. The amount of PDMS is a little different, but removal of the acrylic window and converting it to glass is much easier than with the orange tanks.! Make sure to close the two small holes with some silicone.

No guarantees of course. :slight_smile:


#4

Since I try to learn from failure, I dissected the dead LT tray and came up with the following:

There is indeed a different adhesive holding in the clear window. It reminds me of 5-minute epoxy and while it holds oto the tray for dear life, it snaps free of the window before the prying force damages anything. So replacing with glass should be far easier than with the orange tanks.

It looks like the first thing to go inside the tray is the ring of double-sided-adhesive foam. The foam (likely VHB) stretches very far with no indication of tearing and the adhesive - impervious to everything I threw at it (isopropanol, acetone, naphtha, white spirit, WD-40) - is equally amazing. Only slow physical peeling set it free.

Next, I believe the optical window is covered with clear polymer until it’s even with the top of the foam. I do NOT think it’s PDMS, but rather a sticky viscoelastic polymer like you might find in those “wall walker” insect-shaped toys that slowly crawl down when you toss them at a wall or window. Worth noting is that it was immaculate; no trace of the gouging or fogging seen in the photo. That was entirely in the top layer…

Finally the top layer, generally held to be FEP sheet. I don’t think it’s adhesive-backed, in fact I think it’s pressed into the tray while the polymer is still uncured, because there are two holes in the tray that look like escapes for excess polymer as it is pressed out.

Ironically, I think the FEP sheet is the weak link in an otherwise imaginative concoction. Unlike FEP I’ve seen on other resin printers, this is at least as thick as paper and not the least bit flexible… Under the least bit of stress it snaps and tears like the skin of a grape. I feel this completely neutralizes the benefits of such soft foam and polymer beneath it, like taping a huge sheet of paper tautly over a trampoline.

In fact, I began to question if it was even FEP at all. I stuck a piece of normal Scotch tape to it and it stuck as much as it does to anything else. Only at the very edges of the FEP did the tape show signs of not sticking. So until I save up for a new tray to use as a control, I hypothesize that the FEP sheet, as it gets scratched by the wiper arm, loses its non-stick quality either by the Teflon being scraped away or (if the film is solid Teflon) by microgrooves making the surface rough enough for things to stick.

In any case, if things haven’t changed enough for the better, they probably won’t now that all focus is likely on the Form 3. But my need to know is satisfied, so that’ll do.


#5

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