The Hell Ya Beller Fun with hot, pointy, sharp, and caustic stuff.

27Aug/115

Mendel build bed rebuilt….and a new build surface.

 

I've been using kapton as the build surface but I accidently gouged it after my Z-axis home switch got bumped out of position.  200mm sheets with adhesive aren't cheap so I started looking for alternatives.  It occurred to me that window tinting film is cheap, easy to find, and pretty durable.  It also has an adhesive.   Surprisingly, I didn't find any references to tinting film on the reprap wiki or forum.

Car windows can get pretty hot parked in the sun, but I wasn't sure the material would handle 100+ celsius.  A little research on Google tells me the stuff is vinyl but that doesn't help much.  Kind of like calling Bigfoot a 'critter' - Might be true, but ain't really saying much.

There's lots of manufacturers but the websites are thin on details about the plastic.  The wikipedia page is also weak in this area.

3M seems to be the big player and their site did have an MSDS.  Their film is PET with a metal oxide coating.  Score! -  PET has a melting point around 250C.

I called a local tinting retailer and they gave me enough scraps to easily cover 8 or 10 build plates, way more than I need.  I got samples of two different thicknesses.

My first attempt was just to clean the glass well, peal and stick.  What looks like water droplets are actually air bubbles.  But, my first test prints were very positive.  ABS stuck as well as it did to kapton and separated easily as the bed cooled.

My next attempt, after googling a bit, was to clean the class and then spray with a mild soap solution.  Then peal the film and lay it onto the wet glass.  Squeegee the water out.  Much better.  But when I heated it, I got some large bubbles.  I assume trapped water is boiling.  Perhaps I should lay it in the sun for a few hours/days before heating it.....

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  1. my advice for you is isopropal alcohol or distilled water, do not use anything like windex or any soap and water mix. you will end up with bubbles. to keep the bubbles out with some of the ones i have used i you can leave a film of those fluids there and that will help eliminate bubbles from the air

  2. Thanks Mike. I’ll try it.

  3. I have good experience using very mild soap water on both sides on the film, just to make the squeegee slide with less friction. You also need a high quality small squeegee to make it work properly.
    If you have big bubbles you can puncture them with a needle and push the water/air out. Film purists will probably frown upon this, but in this case it’s function over aesthetics, no? 😛
    Looking forward to see how it holds up over time. I believe nophead and others have been using PET tape for a while, so hopes should be high.

  4. Since my second attempt came out so much better than the first, I peeled the film off the old one. It left behind a very uniform adhesive residue. I cleaned it and tried a third attempt with alcohol. It came out very nice but I’m going to let it sit for a couple days before I try to heat it.

    But I had another idea: I found some very inexpensive 12″ square sheets of kapton on eBay but they don’t have adhesive. If attempt #3 works well, I’ll peel #2 but leave the adhesive residue in place. Then mist it with alcohol and apply a kapton sheet. Basically, recycle the adhesive. Probably won’t work, but worth a shot.

  5. i would try making the opperation inside a bathtube practically all submerged under water – in order to have no bubbles.


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