V4 Sheets interesting results
Here we are gonna start sharing the different sheets that the sheetpresses are able to produce. The idea is that everytime that we achieve a good result or we have some conclusions about what went good or what went wrong we post it here.
In conclusion this thread will become the place where everybody can show his results (sheets) and discuss about them so we can together learn from each other’s experiences.
Also, make sure to subscribe to the index thread if you are interested in the materia.
Showing the machines
In order to put in context, it makes sense at the beginning to talk about the machines we are currently using to make the sheets.
At the Eindhoven workspace we have two different machines that even though they still need to be improved, they are fully up and running and are providing us sheets every day.
The first machine is called the “Hot press”. Is called that way because it has heating elements both top and bottom. It’s an all in one machine that heats and press the plates together.
– Very user friendly and it requires comparatively less metal.
– It only needs a very simple metal frame with the dimensions of the plate.Bad points:
Energetically inefficient and very time consuming.
– It needs to use teflon sheets in order to prevent the plastic to stick on the surface of the press and this teflon sheet generate wrinkles.
– Pretty slow.
The second press is called the “Cold press”. This is a two step process where first you heat the mould with the plastic on the oven and then you move it to the press where you press it.
– It’s more efficient since you don’t have to cool down the machine every time you make one sheet.
– Kinda fast.
– It’s significantly more precise watching the output that it’s been delivered.Bad points:
– It’s much more difficult to make.
– The process of making one sheet requires much more equipment and is more dangerous since you have to carry the hot mould from the oven to the sheet.
– Mould making expensive and difficult.
Test: Trying to make an PP sheet.
Objective: Make a nice PP sheet.
Machine: Cold press
Tools: 1000 x 750 x 13mm Mould
PP is relatively easier to process than HDPE. Lower viscosity makes it easier to spread into a sheet. The material shrinks around a 4% and that helps to take the piece out of the mould. The sheet we made is 1000mm x 750mm in size and 13mm in thickness. It was made with 10kg of blue PP granule.
PP is slighly less good material to work with than HDPE depending the demands. It’s softer than HDPE so it’s easy to cut, but difficult not to make scratches.The result has very smooth finish, almost marble-like look. It feels really tough and durable. You can see that on the center of the plate the pellets are easily recognizable. Meanwhile the rest of the surface has a direction towards the edges. PRovably because we put a bigger amount in the middle.
Test: Trying to make an PP sheet.
Objective: Make a nice PP sheet.
Machine: Hot press
Tools: 1000 x 1000 x 13mm Frame
Same than previous one, but with the hot press.
– This machine leaves some wrinkles on the surface.
– They come from the teflon foil.
– This machine gives the user the opportunity to have a more expected result. Since you are putting the pellets inside the frame and you don’t cover the result until you press it.
Test: Trying to play with different colors and the flow when it press.
Objective: Achieve interesting patterns by putting different heights of pellets.
Machine: Hot press
Tools: 800 x 500 x 10mm Frame
This time we wanted to try different colors and how do they behaves when they are at different heights. We set different mountains of colors as you could appreciate on the pics below. We put the pellets when the press was still cold, after we pressed different times every 20 min. And once the plastic was fully melt (more or less) we pressed it till the corner of the frame.
– The mountains help create a pattern that could be used to design interesting sheets.
– The plastic should have been few more minutes on the making, few pellets are not fully melted.
– We didn’t placed the frame in the middle of the press and that affected the result. (pellets not fully melted near to the edge of the machine.) plus that could brake the machine if we do it again.
This is so awesome. Upscaling is the shiznit and sheets and beams are the greatest.
my question is how is it all coming down to a real DIY project. the shredder is hard enough to make (I think most people have failed in fabricating a shredder that can actually shred), and it’s not like there are good-enough compressors and pistons laying around in scrapyards.
This is great for project kamp, for building in general, and as a potential income source for PP – but how can the community use this information? Will the end result Sheet Compressor be cheap, available, reproducible, and durable enough?
Anyway – you guys amaze me. truely.
I love your hydraulic cold press machine, I wish I can use it as a case study to build my press
@shhigg Yes indeed, making the machines easy to make and replicable is one of the objectives. But also getting good quality products from it is a must. We are aware of the problems that come along making the actual machines and we are also working on that.
But take in mind that for the next generation of machines we want to prioritize quality since it’s been demanded from the community in order to be able to produce valuable products. And for that a more engineering background is going to be needed. So if people don’t have it would be a matter of finding the right partners to work with. Also considering that good quality products are going to be achievable a bigger investment is justified.
Anyway thank you very much for your comment, let me know your thoughts.
HEllo @maltiti, here you can find the post where Mark explains his full process while mking that machine. And during the upcoming months he is going to work improving that machine in different topics. 🙂
Test: Trying to achieve a transparent PS sheet
Objective: Trying to make a transparent sheet
Machine: Hot press
Tools: 800 x 500 x 10mm Frame
We tried to put shredded CD cases in the hot press to see the result, unfortunately it went not fully transparent because most of the plate inner structure ended up being amorf. I don’t know exactly the good parameters to make it. We put 220º on the press for one hour, and when the temperature was more or less there we put inside the frame and we fill it with flakes. We distributed the plastic evenly and left one mountain in the middle and 4 small ones near by the corners. After 1 more hour of compression we turned off the machine. and at the following day we had the result. We noticed that maybe it was too much time with the heating on since few yellow spots due to burning plastic appeared. see pics below.
– Not fully transparent, still need iteration in terms of Tº, timing and pressure (maybe?)
– Less than one hour needed since it was slightly burnt.
– Still some wrinkles characteristic from the hot press (teflon sheets).
– The frame deformed a little bit in the middle because of the pressure the ended result is not a perfect rectangle but a little bit rounded sides.
this is some cool news. you guys work really fast.
Please be carefull working with PS on 220 deg. you hardcore geeks. keep on the great work!
very interesting work.
perhaps a stupid question: regarding the cold press model, what would happen if you didn’t press it and simply let it cool down in the mold?
i assume the surface facing upward would be uneven and have some bumps and perhaps a few bubbles. but would it be a cohesive sheet which e.g. water wouldn’t penetrate?
Have you guys tested the strength properties of these yet? I’ve been working on my own sheet press and can make some very attractive, uniform, void-less HDPE and PP sheets, but they tend to be brittle. They have a lot of strength for bearing weight, but sharp impact with a hammer shatters them like glass – especially the PP. My most recent HDPE was pretty tough though.
According to academic literature, cooling speed seems to be the biggest factor – the faster you cool them, the less crystallization that happens, resulting in lower strength, but higher toughness.
I’ll keep experimenting with it all and eventually start my own thread.
What if you use teflon coated baking sheets and weights in the cold press method?
I found these on Amazon, but they are available all over the world. Even in the Philippines at department stores and the markets
@btmetz, this is how I’ve been experimenting and it works just fine. However, these sheets are far too small for what they’re trying to achieve. Also, the teflon will eventually wear off, so something else is necessary. Vaseline doesn’t really work well. Some form of silicone is probably the way to go.
@nick I can get teflon coatings made here in Manila at the same place that does anodizing and powder coating. It lasts a long time on cookware.
Also have you also considered high temperature RTV silicone gasket material as the metal coating?
For my compression oven I use silicone mold release spray in mild steel molds
Hi Varella, could you share like blueprints and electronic to us?
Hi there! I´m Juan Pablo, starting to think of building a sheet press. My first Question about sheets is if anyone has ever tryed to make a PET sheet. Hope to hear from anyone soon!
@hanifkaruna, No worries, we’ll show all the details at the end of V4 in October. For now the process still under development and you can always follow the process on this following topics:
-Index (not complete)
-The machine development till now
@jpbarg, The only case I heard of is a Netherlands based company called New Marble. They don’t show much of the process but as far as I know this is the result of a research project done by Better future factory. We would like to know more about how to, but for now we are going to focus on HDPE, PP and PS.
@shhigg, actually you are right we are trying not to go above 205 or 210. But the oven heating distribution is not even so we always wear masks in order to prevent the toxic fumes.
Test 1: Make a sheet playing around with different size of pellets
Test 2: Make a sheet playing around with foils and pellets
Objective: Get interesting results with different size of pellets and also foils
Machine: Cold press
Material: (blue, white, transparent) HDPE bottles, (blue and transparent) HDPE foils and (red) Bottle caps
Tools: 1000 x 750 x 13mm Frame
In the process we shredded in three different ways in order to get three different types of pellets:
1. For small size pellets (10x10mm) we shredded twice the bottles in the dual axis shredder. That means you shred it once for making strips, and then you shred the result again to obtain finer pellets.
2. For the strips (30x10mm to 50x10mm) we shredded once the bottles and leave the result aside.
3. For the big pieces (30x30mm to 50x50mm) we just destroyed different bottle caps with a hammer.
* Tip for shredding foils. Since it generally gets stuck spinning in the shredder and doesn’t pass through it’s recommended to put in the hopper some solid plastic to help push the foils out of it. Could be a the strips that has to be shredded again or a full bottle. doesn’t matter.
– The amount of plastic we put in was not enough. Generally we put half a kg more in order to make sure it fills the whole. This time we put slightly less than that and the top surface didn’t look completely flat. Looks organic. Could be that the foils reduced its volume drastically, but we are not sure. Also we found few bubbles inside due to it.
– The mixture of pellets ended up having good-looking results. The small pellets make the whole consistent while the medium and big pieces of plastic contribute to the composition in interesting ways.
– Some foils ended up being burnt in the surface. Could be a problem of the mould being overused. Or maybe the foils are easier to burn since their thickness is ridiculous.
– While CNCing the plate later on, we found out that because of the foils it ended up being a little bit messy. It’s like lamination but at micro level. Didn’t affect the strength of the plate at first sight, but it’s inconvenient while milling because needs cleaning after. Or maybe passing again a second time.
– On the corners we found more flow marks than in the middle as it’s being usual with this types of plates.
Nice results and info! I have a few questions though.
What temperatures and times did you use for those sheets?
I notice that you’ve made a few different sized sheets in the hot press. Are you using the same mould design as Mark’s cold press or something else?
Also, the sheets are sometimes larger than the cold press, yet it only has one hydraulic jack, which presumably has considerably less force than the 4 jacks on the cold press. What is the force of this jack and do you find that it is sufficient? Does it make completely flat sheets or is there some deflection given the central location of the jack. If the sheets are satisfactory, then perhaps the cold press could be made considerably smaller/lighter weight/lower cost – my suspicion has always been that it’s significantly over-built and most of the force just rests on the steel depth spacers rather than on the plastic.
Finally, do you have a build thread for the hot press somewhere?
The last plate I posted is made out of the cold press. Sorry for the mislead.
The cold press works with moulds of 1000x750mm with variable thickness.
The hot press on the other hand works with frames up to 1000x1000mm and the thickness of the plate comes from the thickness of the frame itself.
Hope that explains better what machine makes what. The question about the hydraulic jack I pass it to my college @markbertbach which will answer you with a more in depth answer.
Here you have an answer for the second part.
The single jack has 8ton pressing force But spreads the plastic over a longer period of time. Which requires less power. The cold press needs to spread the plastic fast since it is already cooling. This is especially important for HDPE which is still very viscous when molten. The hot press has a less consistent thickness output.
Here you go, hope I solved your questions!
You got some amazing outputs, and im very proud and excited that the community is doing so muchh.
It’s good to know you take caution – but why don’t I see pictures of the masks you use? Is this not part of working with the new tech / material? You are suggesting people should try this at home (again – not mentioning the fact that finding parts for these machines in some countries is harder then importing an equivalent small industrial machine). promoting diy = teaching about using the right tools and keeping safety first. The fact that working with PS is in fact hazardous shouldn’t be swept – it should be written all over. Especially if you can give a good example of how you keep yourself safe and never let anyone near fumes without the proper equipment.
Keep up the good work 💪
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