December 11, 2019, 12:25:34 PM
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Topic: Silicone resin tray for 3d printer  (Read 671 times)

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Offline MaxPt

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Silicone resin tray for 3d printer
« on: October 17, 2019, 05:30:50 AM »
Hi everyone
I want to make a 3d printer resin tank, it has a 6 mm glass, 2 mm silicone on top of it and a layer of fep on top of the silicone, So I'm looking for 2 component optically clear cheap silicone that sticks well to the glass and also a proper way to add the fep layer to the silicone.

Offline Enthalpy

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Re: Silicone resin tray for 3d printer
« Reply #1 on: October 17, 2019, 05:48:03 PM »
Silicone uses to adhere easily on glass. But cheap and silicone isn't really compatible. As a clear silicone, I know DC93500 at 100$/kg. There may be other ones.

FEP is difficult to let adhere to anything, and silicone is a bad substrate for adhesion. I suggest to buy a FEP film that includes the pressure-sensitive adhesive film and a removable liner. Some exist at 3M, possibly Dupont too. This FEP film is already treated to promote adhesion.

Then, you will probably still need some primer on the silicone. Check what glue producers propose as primers for silicone.

I don't quite grasp the design. You have a FEP film on a silicone layer on glass? I feel there is one layer too much then. Or does the silicone only glue glass plates at their edges?

Offline MaxPt

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Re: Silicone resin tray for 3d printer
« Reply #2 on: October 17, 2019, 06:11:14 PM »
As I said, I need a 2 component silicone to be able to pour it easily, I tried some like PDMS, it peels easily from the glass and won't stick well.
I can use FEP and directly paste it to a glass or stretch it over the glass but that won't do want I need, The goal here is to use a FEP film with a soft bed. The silicone will act as the soft bed and also will somehow make the FEP film, flat.
There are some adhesive-backed type FEPs that I can use to paste on top of the silicone, but I don't know a good method to paste a very thin film without causing bubbles. 
I'm looking for something similar as:
https://www.youtube.com/watch?v=P0TkPiPsqS4
But this one doesn't have enough quality, I'd prefer to make something like:
https://envisiontec.com/product/m-type-basement/
I can buy from them but my sizes are different.

Offline Enthalpy

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Re: Silicone resin tray for 3d printer
« Reply #3 on: October 18, 2019, 08:33:55 AM »
OK, this tank is where printing takes place. That's clearer to me now.

Most silicones are PDMS, up to rare exceptions. But families exist depending on the solvent, the catalyst. Usually, all adhere to glass. Was the glass clean enough? My transparent silicone (I believe it was DC93500) adhered to glass and silica easily.

Remove bubbles from a film of viscous liquid like silicone by using vacuum.

Gluing a film without bubbles is difficult and needs essentially practice. You can check how it's done for strain gauges. It involves laying the film at one corner first, then pressing with a finger as soon as you establish gradually the contact. A cloth around the finger tip helps, or fabric gloves. A needle can punch bubbles if you application tolerates than. I did it for a satellite: several people are better than one, and 1h practice is an absolute minimum. You configuration, in a concave location, makes it more difficult. I'd prefer to cover separately each glass plate before assembling them, if possible.

Could an unmoulding spray replace the FEP film?

Do you really want a silicone liner that adheres to glass, and a FEP film on top? To unmould the printed part, maybe you could disassemble the transparent tank (glass, PMMA, PC...) and then the silicone liner is easily removed from the printed part without any FEP.

Offline MaxPt

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Re: Silicone resin tray for 3d printer
« Reply #4 on: October 18, 2019, 10:22:50 AM »
The process of printing is a not what you think, a 3d model will be sliced to layers and then a light engine will project each layer to the tank surface, and cures the photopolymer material, then each layer must be seperated, so a normal model might have around 400 layers, so the seperation takes place, 400 times. This might make it more clear:
http://robotsinthesun.org/monkeyprint-an-open-source-3d-print-software/
So let me change the question a little, I have 3d printer material tray, and there are many trays from different manufacturers that are like it, I want to make one too.
Tried to disassemble it, it contains a 6mm glass, 2mm silicone, which I couldn't peel from the glass, even with a cutter, and it was very clear, and a 0.6mm FEP film with one-side treated to make it stick well to the silicone and a silicone wall, around it.
I tried to use some 2 component silicones, after it's cured, you can peel it off easily from the glass. I also have one-side treated FEP film, but how can I paste it to the silicone? Should I paste it before the silicone cures? Or I should use some kind of glue? I've also tried some uv glues but they are not good.
I hoped there would be some techniques or machines to help the process.

Offline billnotgatez

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Re: Silicone resin tray for 3d printer
« Reply #5 on: October 18, 2019, 11:35:12 AM »
@pouryatorabi
I am following this thread and wonder what make and model is the 3D printer system you are using.

Offline MaxPt

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Re: Silicone resin tray for 3d printer
« Reply #6 on: October 18, 2019, 03:34:53 PM »
I have built my own. With uv dlp light engines.

Offline Enthalpy

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Re: Silicone resin tray for 3d printer
« Reply #7 on: October 21, 2019, 03:51:53 PM »
OK, illuminate each layer from the bottom through the transparent tank, then move the made item upwards. Not as usual, illuminate from the top, then sink the item further. Hence each new layer must be separated from the tank, justifying FEP on silicone.

What about a shear shock propagating in the silicone, to detach it from the item? At a side of the tank's bottom, hit downwards with a wide straight hammer.

As you need FEP and silicone essentially at the tank's bottom, putting them before assembling the tank's walls looks simpler. Bubble-free is standard practice but it does need training for sure.

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