🧵Week 16: Wild Card Week: 3D Printing on Textiles
Project Heros
A flexible chess board printed directly onto a cotton sheet, and heat pressed to flatten.
The Plan / Research.
3D printing on textiles is a skill I have always wanted to do but never gotten around to, so in this week's wildcard week for fab academy we explored just that. I have seen it around in the 3d printing community for a while and this 2018 video seems to be the seminal guide on how to do so. This process involves printing the first few milimeters of an object, pausing it, then laying over a very fine nylon netting material, and continuing the print from there with the nylon sheet getting trapped within the print.
I have also seen some other incredible work to do with printing on stretched fabrics which fold into incredible organic geometries when they shrink back down like in the image below. This doesn't use the nylon netting method, but instead appears to print on the fabric directly itself which is a lot nicer of an alternative. So I researched around and couldn't find much on this. It appears that this is a bit of a niche in the 3d printing community and printing directly on fabrics is a niche within a niche, so this week I thought I would experiment and find out some information myself.
So that leads us to the plan, I want to try and print directly onto the fabric itself (as it is quicker, simpler, and easier) and make a foldable chess board that doubles as paint ball armour, more on that later.
CAD Model
Starting off, we need a CAD model, I booted up onshape and extruded a 1 inch square that was 4 mm tall.
Then I used the linear pattern tool to make 64 clones of it with a 2.5 mm spacing, I have no clue what spacing they need to make this thing foldable, but this is what this test is all about.
And then I went through and deleted half of the squares. This will be one colour of the board, and if we horizontally flip it, the other colour of squares should perfectly line up.
And thats it on the 3d modelling side!
Testing Materials and Process
To start off with I want to test a few differnt materials to see if there is any differences, spoiler alert: there was. I start off by printing out 2 squares at a time as I could load a different material into the 2 print heads of the S7. I sliced these settings on the default 0.2 mm fast settings as I have no clue of what to dial in at this point, and it should be good enough for us.
I then grabbed my fabric (we are using cotton because it is nice and heat resistant), and stretched it across the print bed, clamping it down with some bully clamps. I would caution anyone who trys this as the bully clamps can get in the way of the printer's gantry, I watched the whole print like a hawk to make sure they wouldn't get in the way of anything.
Then I ran my gcode and printed it. After anxiously watching the first layer, it appeared to be put down nicely and looked like it had stuck to the fabric really well as the plastic had melded with the fabric texture!
I was really relieved with this and left the printer to finish the sample, but when I came back I was met with a terrible suprise. WARPING! The 2 test squares had warped terribly.
I thought maybe my initial judgement was wrong and that the plastic didn't adhear to the fabric well, so I got some cheap glue stick and covered the fabric hoping that it would stick to it better. But that had no effect on the warping.
So I tried to peel the test squares off the material and found that they were actually really well stuck onto the fabric (the glue stick actually made the plastic stick adhere to the fabric less!). I had to use quite a lot of force to peel the first sample off, even with the edges already starting to peel. After watching another sample run I saw that although the first layer would go down perfectly, as more layers were put ontop, the bottom cooler layer of the plastic would start shrinking and the fabric was too stretchy to resist that warping. Ususally adhesion to the solid bed fixes this, but with the fabric acting as the bed, it was warping with the plastic. So I cut the height of the print down from 4 mm to about 1.5 mm and saw a great deal of improvement, still some warping but it was servicable. I then went ahead and printed these test squares out of different materials.
It is a little difficult to see the warping in the photo but on the left we have PLA which warped the worst by far, the middle 2 are polycarbonate and PETG which did alright, but the best of my test prints was ABS which was a very supprising result as it is ussually notorius for warping due to thermal contraction. But it produced the best results, so I we will be using it.
Printing the Chess Board
Now with some knoweldge gained from testing, I loaded up the full chess board pattern into CURA, and sliced it. I kept the lower print height of 1.5 mm, and I raised the bed temperature up to 110 degree to try and help keep the print hotter and prevent warping.
I loaded up my black and white ABS into the machine, tensioned the fabric over the bed as much as I could (with as many bully clips as possible which seemed to help) and hit print.
Its such a shame because that first layer goes down really smoothly, I think there is credibility in maybe even printing 1-layer high patterns into fabric with a 3d printer, whether its to just create custom designs or there is a benefit or application for a layer of plastic on a t-shirt or material. Althought I have seen Prusa doing this by printing the first layer and then ironing it on, and I wonder if there is any benefit in printing directly onto the fabric.
Regardless, after a couple hours of printing the chess board came out on our fabric and besides the tiles warping, there were no miss-prints which was suprising given the number of tiles printed and that this whole process has been "a little janky" so far. I also found that the inner tiles were warped a bit less than the outer ones, probably because they can't flex as much.
Fixing it in Post
The great thing about working with thermoplastics is that you can manipulate them with heat, and I think we might be able to flatten the tiles with it. I initially was going to hit it with an iron, but when making a chicken and cheese sandwhich at 2 am, I found a better tool - a sandwhich press. To run a test on, I printed another set of 2 tiles to try and flatten, put a layer of baking paper on the top and bottom, put it in the sandwhich press, and turned it on. I had no idea the best way to do this, but I let it reach max temperature (about 175 degrees celsius), for about a minute, turned it off, and let it fully cool down. I applied a tiny amount of force to the top as I didnt want to melt and pancake out the tiles, just warp them a little.
I didn't get much photos of this process as it was late at night, and I eagerly tried to rip the tile off the fabric as soon as it cooled down to see if it was more adhered to it. AND IT WAS! I cant quantify it, but it was way more difficult to peel off. And it was a lot more flattened, still a tiny bit warped and its hard to see in the photo.
With that working, I repeated the same process for my chess board.
(Please note this is a recreation photo I took the next day at the office - I did not melt plastics using the lunchroom sandwhich press.)
And it came out well! I trimmed the edges and I had our final board which was reasonably flat, not as flat as the other tiles came out, still a little warped, but definitely a lot better. The heat flattening process could do with some investigation.
Conclusion
All in all, I'm happy with how this came out, my expectations were a little low for printing directly onto fabric, and althought I couldn't print many layers high, I'm happy with the results and experimentation. I had concerns about the plastic not adhering to the fabric, but it stuck well and I think there is some viability in this process.
Starting off with my goal of making a chess board, well now I have a flexible chess board. I have had a project I've been wanting to make a while where I have a bag of chess pieces and the bag unfolds into the chess board itself. I wanted to sew a long pocket around the edge of this board and put some draw-string in it to make the bag, but this won't work on this. The square pattern of the board allows it to roll up it up like a newspaper really well, but not to shape it into a bag, it will only fold along one axis. I think with some creative shapes, or a grid of hexagons, or something like that, I can make this work using this method.
The other thing I mentioned was paint ball armour. About 5% - 10% of the time you get hit with a paint ball, the ball doesn't break apart and it hurts a great deal more, often leaving a welt. Another idea I had for this process was to print plastic shapes onto paintball gear with gaps in it exactly like the chessboard. This would mean that when the paint ball hits, there are sharp edges everywhere to crack the paint ball. I think for this I would need to print the tiles to be a bit thicker, and I don't know if they have adhered to the fabric enough to last being scraped through trees and bushes, but I will be taking this chess board to the paintball course in the future to investigate it. There is also the opportunity to print with multiple materials a camoflarge pattern with gaps inbetween them.
Well this was a fun little investigation into the feasibility of printing directly onto fabric instead of the normal way of using nylon. If anyone were to try this in the future, here are some tips:
- The more stretchy the material is, the more warped the pieces will be if its not held down.
- It might be worth adhering the material to the bed to prevent it from warping with the print.
- If you can't adhere it, a smaller print bed, and lots of clips to stretch the material over it might help.
- Ensure that your material won't melt under the print temps, cotton was good for me.
- If the 3d prints are not sticking, I have read that some fabric glue on the back can help.
- Keep the print height in the z-axis as small as possible if warping is an issue.
I think this process has legs and It has some niche applications, but If I am to attempt to make some paintball armour, I might just opt for printing on to nylon.