The progression of technology and DIY fabrication

[Blackthyne]

There was a man by the name of David Gingery who once wrote a series of 7 books titled “Build your own Metalworking Shop from Scrap.” The series was split into a progression of specific machines that could be used in a progression, each helping build the next.

It started with the charcoal foundry in the first book, teaching you to sand cast aluminum and other low melting point metals. From there you graduated onto the second book where you cast parts for a metal lathe and in some cases, use what had been constructed of the lathe to turn parts to finish it. Then you had the metal shaper, milling machine and drill press in a similar vein. The idea behind it was starting with nothing but maybe a couple of buckets, some wood, charcoal, and a few other things, you could bootstrap your way up to an entire machine shop. It’s almost like crafting progression in a video game.

That said, the books were released in the early 80s, and not only has technology advanced, it’s also become more accessible. After some though, i had the passive idea that maybe there should be a spiritual successor to it, but using modern materials in fabrication. Precious plastics did something like that, but the machines that they sell aren’t really things you make yourself, although they are open source.

Polypropylene(PP) is commonly used plastic that is a huge portion of the waste that makes in in the oceans, gets stuck in landfills, etc. It’s actually pretty easy to recycle manually, just on an industrial scale it gets to be really difficult due to cleaning and such. It’s very chemically resistant, and is extremely durable. Alongside Polyethylene(PE), It makes up the vast majority of consumer plastics.

So, my question is what do you guys think about starting a project where we work on a progression system to teaching people to fabricate plastic and using various processing methods, focusing on PP.

I’m not sure what machine we’d start with, nor which ones we’d work toward, but any thoughts?

[Blackthyne]

After thinking about it, I think a viable way would be to consider weaving newer tech into David Gingery’s progression. The ability to process aluminum scrap and casting it into parts is the core part of 90% of the first 3 books, possibly more as i haven’t really gotten that far into the latter books.

It’s mentioned in them that the books are just a guide, not an instruction manual for the most part. The books just show a possible path to the goal, ymmv. He gives schematics, step by step guides and all, but there is always room for improvisation.

That said, the spirit of it is to show that it can be done, and largely using abundant material (aluminum). The question is what things can be changed about his books to fit with more modern fabrications techniques.

The reason i mentioned focusing on PP is because it’s abundant, workable at a low temp, durable, and chemically resistant, and i could imagine it would have an amazing synergy with aluminum. It can be worked in most any way wood or aluminum can, it can be injection molded, 3d printed (with proper calibration and such), and doesn’t absorb moisture from the air, unlike most other plastics.

A couple of ideas i have are things like something that cleans and extrudes billets of pp as a preprocessing stage, as well as designing a 3d printer hot end specifically to print using rods of PP form the preprocessor.

I’d like this to be an open source project, and if anyone is interested, let me know, or any feedback would be appreciated. I’m thinking of having like a dedicated github or something to base out of.

[Wistellia]

This is a really cool idea that I don’t feel knowledgeable enough to contribute to, at least for most of it, but I’ve dove down the 3D printing rabbit hole a few times, so I might be able to provide a few pointers for that specifically

@Blackthyne

It can be worked in most any way wood or aluminum can, it can be injection molded, 3d printed (with proper calibration and such), and doesn’t absorb moisture from the air, unlike most other plastics.

@Blackthyne

as well as designing a 3d printer hot end specifically to print using rods of PP form the preprocessor

While polypropylene can be 3D printed, from what I’ve heard it’s one of the most finnicky, difficult plastics to 3D print (at least at a reasonable price point^[1]). A better alternative, at least for the beginning stages, would probably be polyethylene terephthalate, or PET (the stuff that soda bottles are made of). It’s really similar to PETG^[2] (I’m not looking up the chemical name, sorry), because PETG is just a modified version of PET that’s a bit easier to 3D print. There are plenty of videos detailing how to make workable filament from bottles, but it’s probably not that hard to cut the bottles up into pellet-adjacent chunks if that’s the direction you want to go.

The reason I suggest this is because you don’t need an enclosure to 3D print PET (although it might help a bit), which broadens the possibilities for using (or potentially modifying) existing open-source 3D printer designs, like The 100, the Rook, or even a prusa (although that one has sheet metal parts that might be more difficult to get, I don’t know if/when those are covered in Gingery’s books)

As I said at the start though, This is a really cool idea, and I’m excited to see where you go with it!

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1. There are a whole bunch of other plastics that are technically more difficult to print, but they’re either so difficult to print as to be completely non-viable for 3D printing, or superpolymers so expensive that they’re well beyond the point of being viable for hobbyists (and most of those are really hard to print too) ↩︎

2. one of the most popular 3D printing materials. It’s pretty widely considered to be basically the happiest of mediums; its physical properties are outstripped by something like ABS, but that’s counterbalanced by being easier to print and not spewing toxic fumes everywhere while doing so ↩︎

[Blackthyne]

The big three plastics as far as waste is concerned are PET, PE, and PP. To explain my reason for considering PP over the others is because while PET is easier to print, it requires extensive drying as it’s very hygroscopic, though PP and PE Are both not. While not necessarily a deal breaker, it would mean dehydrating it twice, pre-processing, as well as possibly again before printing.

PE and PP are very similar, but while PE boasts a higher chemical resistance and lower melting point, it doesn’t stick to anything, including itself. Poor layer and bed adhesion paired with an insane amount of shrinkage is a terrible combo.

PP has amazing layer adhesion, the problem is that it ONLY sticks to itself. The most common suggestion is to put packaging tape on the bed, but the layer adhersion makes the shrinkage stronger than the tape’s adhesive. Ive seen a couple of people use a PP build plate, which is something to try. I ordered one yesterday, so ill have more insight to how viable it might be soon.

I’ll keep you posted, because im hoping that a printer could be designed around and optimized for our target plastic.

[its_ameise]

I think injection moulding may be the way to go ive seen people make what is basicaly just a cup and big leaver with a piston to squirt it into the mould but then you get the problem of it requireing a decent amount of tools to make
(Its possible ith just a drill butsignificantly easyer with a welder)

I dont know anything aboout cleaning pp tho

[Blackthyne]

Yeah, i don’t care for cleaning my pp either. :/

[Drill]

Would it make more sense to describe a means of recycling the necessary plastic out of plastic waste than making new?

[Blackthyne]

Well, unless im misunderstanding you, that’s exactly what im talking working on, mostly. The idea is taking single use plastics and/or broken plastic of the correct types and using them to craft with.

The problem with recycling plastic on a large scale is the difficulty cleaning it,the damage to the polymer chains from repeated recycling, and separating different plastics as to not mix them which would alter the properties.

Most of those can be either minimized or mitigated on a small scale, save the polymer chain damage but that takes a lot of recycling to be a problem.

Most plastic recycled is actually just clean plastic offcuts from product manufacturing, most of your recycled plastic actually ends up in a landfill or an ocean anyway.

[Blackthyne]

This is a schematic i drew for a machine that turms plastic waste to 3d filament, for example.

[Drill]

Oh. I think I misunderstood you. This is a great project then!

Would this be like a companion to the previous book where you use scrap aluminum to make some of the tools?

[Blackthyne]

Im thinking that it might be a good idea to do something like a whole new thing based on it. Im thinking something sorta like progression in minecraft mods, where you can, for the most part, pick the route to take depending on what’s avaliable to you.

Like say you need a hole on the end of a rod. You can use a lathe, which will be more precise, but there are other things that can do the job. Like using a drill press if that’s all you ve been able to get a hold of/make.

The progression is very linear in the books, which for a single matetial type makes sense, but a tech tree would work better for more modern processes and matetials.

Making it all open source would be amazing too.