![[JHG]](JHGlogo.png "Howard Gibson")
3D Printing
3D Printing
Soon, we all will have 3D printing machines in our homes! No longer will we drive to the store or log into Amazon to buy stuff. We will download 3D models and make what we want using our 3D printing machines.
Is this really about to happen? What are the social and ethical issues of home 3D printing? Is 3D printing the only way home hobbyists can make stuff?
Let us digress a bit into a related subject. Computer Numerical Control or CNC, was a hot new technology back when I was in college. Instead of manually turning the knobs and levers of a milling machine, you would write a program, and the machine would automatically execute the movements of the cutting tool. We were told that CNC machining would be economical for batches of ten to a hundred parts.
When I graduated and I started to design machined parts and send them out for fabrication, the machine shops did everything manually. They looked at my drawings, and they operated the controls of their milling centre or lathe. It would be ten years before CNC machining kicked in. Then, the shops fired up their CNC machine even for single parts. I am not sure what happened. Definitely, the programming software had become way more user friendly. CNC programming means that you make virtual mistakes, not real ones that trash the expensive billet you waited a month for and have already spent a week working on. The machine shops were willing to quote on complex machined parts, so I set to work designing them. If you have a machine shop with something like ten skilled machinists, you can switch from ten machining centres, to maybe three, plus seven computers. You reduce your capital investment.
CNC is used extensively on milling machines and lathes. It is also used by sheet metal jobbing shops. You use the CNC punch to make the flat sheet, then you take it away and bend it, and possibly weld it. Bad welding can trash a week of work. If the bending and welding are tricky, you punch out multiple pieces, and if/when you mess up, you try again.
The technology was cool, and ultimately successful. It was not obvious to us how it was going to work out.
![[Howard Gibson with table saw]](TableSaw.jpeg)
The author with a dangerous toy
3D printing is commonly referred to as rapid prototyping
.
As far as I know,
all 3D printing is the depositing of material
in some sort of 3D raster (XYZ) pattern.
You use some sort of software to create a 3D model.
Your software, or some other software
converts your model into a form your 3D printer understands.
Typically, this is an STL file,
with STL standing for Standard Tessellation Language
.
Printing the 3D part takes a long time.
Even a simple part will take several hours.
You can easily create a model that takes days to print.
The 3D models are generated by CAD software. Even the old, 2D AutoCAD can generate 3D models. You can design in 3D parametric CAD. There are all sorts of artistic modelling packages, like Blender, which has been released as Free Software.
3D printing was sold to us as a design visualization tool. There is no substitute for physical hardware in your hands. 3D printing vendors advertise their ability to deliver parts in the next day or two. This contrasts with regular fabrication shops which quote deliveries of a month or two. A 3D printing machine in-house will deliver parts even faster, unless you have a queue.
There are few safety issues with 3D printing. Most fabrication processes cut, shear, punch, or melt metal. They can cut, shear, punch or seriously burn incautious operators. All 3D printing can do is melt plastic. I have found an article on 3D printing safety — 3D Printing with Filaments: Health and Safety Questions to Ask.
Wikipedia calls this Fused filament fabrication, a term I have seen nowhere else. I am used to the term fused deposit modelling. Molten plastic is extruded through a nozzle, fed by a filament usually provided on a spool. The whole thing is mounted to an XYZ translation head controlled by a computer. The material is a thermoplastic of some sort.
FDM parts are finished in a basket weave pattern. This is due to material being squirted out of a nozzle as a filament. If you want a smooth surface, you will have to sand and polish it. This is a problem if you want to make food service parts like bowls and spoons.
Almost all 3D printers available to home hobbyists are FDM.
Wikipedia — I have no idea what the letter "A" stands for. The machine has a tub of special liquid. A laser or digital light processor will illuminate a spot, causing the liquid there to fuse into a plastic.
SLAs provides surface finishes and precision way superior to FDM. The plastic is structurally, not very good. Some SLA machines can print in multiple colours. Some SLA machines can print in investment casting wax, allowing you to produce metal parts.
Sintering
is defined by Wikipedia as
the process of compacting and forming a solid mass of material by heat
or pressure without melting it to the point of liquefaction
.
High powered lasers are used to fuse powdered material,
in this case, thermoplastics like nylon or polyamide.
I don't know much about the process.
Apparently, the machines are expensive,
and unsuitable for home hobbyists.
There are processes for printing 3D metal parts. My local 3D printing vendor claims that the process is expensive. All3DP's website lists a series of 3D metal printers with prices starting at $99500US. I would expect the machines to use a lot of electrical power. I don't expect them to be in the hands of hobbyists any time soon.
You can create a plastic part! You can create more than one part, and you can assemble everything into a functional plastic device of some sort.
Wow!
The current technology conveniently available to home hobbyists will not produce metal parts. This reduces the mechanical strength of the parts, and it rules out electric circuits. Obviously, there is no problem creating an enclosure for an Arduino board or a Raspberry Pi single board computer. Since your 3D printed plastics are not conductive, you may have problems shielding the boards from EMI/RFI. 3D printing your own printed circuit board (PCB) requires the ability to manage molten metal and molten plastic all at the same time. This will be quite the technical challenge. You can make your own PCBs at home, but the process is not 3D printing.
Most plastic parts in your home are fabricated by injection moulding. Injection moulding machines are expensive. The actual injection moulds also are expensive, costing tens of thousands of dollars each. Once you have the machine and mould, you can manufacture the parts at very low cost. You need to manufacture a lot of parts to amortize your tooling costs. A lot of commercial injection moulded parts contain glass fibre, which makes the parts stronger, more rigid and slightly heavier.
As a mechanical designer, I have designed all sorts plastic parts to be fabricated with machine tools — vertical mills and lathes. Traditionally, machining is how most one-off parts are fabricated. If my part is a simple, orthogonal shape, it is easy to fixture and machine, and it is easy to write the CNC code. Plastic moulding, metal casting and 3D printing allows for crazy, unmachinable shapes.
I have never dealt with the production levels needed to justify injection moulds. 3D printing allows me to design non-orthogonal plastic parts, and fabricate them economically in quantities of one only. 3D printing vendors will print out your part, and use it to create flexible urethane moulds, which they will use for a run of perhaps thirty parts. The material will be a thermal setting plastic like epoxy. This is doable by home hobbyists.
I have been told by 3D printing vendors that they can make casting patterns in wax suitable for investment casting. I have seen articles claiming that you can use thermoplastic FDM models as investment casting patterns, although they don't work very well. I have even seen a book in the library on home sand casting. You can compress your sand moulds by driving your car over them! A carefully designed FDM model should make an adequate sand casting pattern.
YouTube — How to turn a 3D PRINT into METAL | Lost PLA Metal Casting | ASMR
When you do web searches on 3D printing, you see a lot of fantasy characters. If you are playing Dungeons and Dragons, you may need a token that signifies that you are a dwarf or an orc. You can buy these figurines in the appropriate stores, but there is lots of stuff you can download and run through your 3D printer. I wonder how many people actually run the 3D software and design their own figurines?
In the late nineties people
started to upload music and video to streaming channels,
free of charge.
There has been little sympathy in the online world
for the holders of copyrights.
Information wants to be free!
Industrial designers and engineers have not been affected by this because manufacturing is difficult and expensive. 3D printing will provide an alternate way to acquire hardware products. The time, effort and cost of developing and testing new products will receive the same respect artists and musicians have been getting for the last twenty years.
I don't play Dungeons and Dragons. What is the copyright status of the dragons and elves you downloaded from the internet?
Like artists and musicians, designers and manufacturers need to get paid. If stuff can be posted online and downloaded for free, engineers and designers should look forward to very strict non-disclosure agreements (NDAs), and strict computer security, as conditions of employment.
Liberator Pistol — Wikipedia graphic
In 2013, crypto-anarchist and gun-rights activist Cody Wilson founded Defense Distributed. The company posts open source models and drawings of firearms on their website. This includes the Liberator, a 3D printable gun. Liberator There are a bunch of issues here...
Here in Canada, a Montreal based manufacturer of paintball guns made a batch of TEC-9s. These have been turning up at crime scenes in Quebec and Ontario. Guns can be manufactured using standard machine tools which are available to small businesses and home hobbyists.
An engineer or an industrial designer comes up with a product that can fail catastrophically. They post the drawings and models on the internet. These could be pressure vessels, containers to be filled with nasty chemicals, large and/or elevated structures, or vehicles that can crash at high speed. Companies manage stuff like this in manufacturing often by strict quality control. This rules out home fabrication.
None of the above scenarios are good applications for any current 3D printing technology. There are all sorts of outfits who post on the web or otherwise publish drawings of products that home hobbyists can build. These can be anything from scale models and carpentry projects, to boats, and real aircraft.
Most Rutan aircraft, including the Long‑EZ that John Denver was killed in, are kits to be constructed at home. The builder (it was not Denver), located a fuel cock awkwardly, which contributed to the crash. People have been building and crashing kit planes definitely since the 1930s. Read up on the Flying Flea. Some of its crashes were caused by the aircraft's tendency to not recover from steep angles of descent. Others were caused by sloppy workmanship, and the inability of British hobbyists to understand the original metric drawings.
There is case history of people publishing dangerous instructions, and then getting sued. The Google searches are fun.
If you post models of 3D printable, dangerous stuff, the courts will know what to do about you.
It would be nifty to have a machine that melts thermoplastic and makes filaments out of it, preferably rolled into a spool. You would be able to recycle your FDM models, and possibly other plastic stuff you have lying around.
3D printing conveniently produces plastic parts. You can use 3D software to design parts. You can download files from the internet and print plastic parts. Most functional products contain metal parts for strength and/or electrical conductivity. At present, there is no convenient way to 3D print metal parts. You will not be downloading and 3D printing appliances any time soon.
In nearly forty years doing mechanical design, I do not recall ever not knowing what process would be used to fabricate my parts. I take advantage of the good features of my process, and I account for or otherwise minimize the bad features. 3D printing is just another fabrication process. We can create plastic parts, even extremely non-orthogonal ones, in small quantities, safely. 3D printing does not provide new, unique hazards, to home hobbyists, or to people encountering home hobbyists.
If you have a computer with 3D software, a 3D printer, and kids, they can do something more creative than watch TV. Heck, you can something more creative than watch TV!
In discussions of intellectual property, the terms Free, and Open Source keep getting used. These originated in the software community, and it helps to understand precisely what they mean.
Free Software was originated by Richard M. Stallman (Wikipedia RationalWiki), also known as Saint IGNUcius. He started the GNU Foundation to advocate for and to develop Free Software. GNU stands for GNU's Not UNIX. The recursive acronym is a little C programmer's joke. Stallman argues that we should all develop and run software that respects the users' freedom and community. This is an ethical issue. Stallman lists the following four essential freedoms...
Starting the numbers from zero is C programming practise. Stallman emphasizes that when he uses the word "free", he means "freedom of speech", as opposed to "free beer".
The term Open Source came out of the Free Software community. Programmers were critical of Stallman's ethical and moral philosophy, and were more concerned about commercial possibilities. Industry interprets free as meaning free of cost. The seminal article on open source is The Cathedral and the Bazaar by Eric S. Raymond (Wikipedia RationalWiki). Raymond argues that Open Source is a software development paradigm that improves quality. Many eyeballs on the source code catches and corrects more errors than a secretive, closed source process.
Both Richard M. Stallman and Eric S. Raymond have written Free Software, and published it under the GNU Free Software license. Note how all this applies to computer software, not hardware.
Here is Wikipedia's article on open-source hardware.
FP‑45 Liberator — Wikipedia photo
Cody Wilson's Liberator pistol was named after the FP‑45 Liberator pistol. These were absolutely simple, single shot .45 calibre pistols that were to be dropped all over territory occupied by the Germans during the second world war. People could take one of these guns, shoot a German soldier, and take his rifle and ammunition.
There were concerns about whether or not a single shot pistol was a useful payload for a bombing aircraft. Somebody, somewhere must have noted the German habit of shooting hostages in numbers way out of proportion to the number of actual Germans killed. Some of the guns were dropped in the Orient, including the Philippines.
Here is Forgotten Weapons' Ian McCollum's description of the Liberator.
None of my sources mention this, but in my professional opinion, the sheet metal parts were fabricated in a progressive die, another expensive tool. You could punch and hammer this thing on your home forge. Probably, it would be easier for you to machine everything.
My college CNC project
I am a mechanical designer with close to four decades experience. I started on a drafting board, I used AutoCAD 2D CAD for five years. I have been using 3D parametric SolidWorks CAD for almost twenty years now. I have been solving design problems, designing parts, selecting materials, and planning for fabrication processes.
Most of my parts have been machined. I have designed lots of sheet metal, and quite a few weldments. I have designed some glass and carbon fibre reinforced plastic parts. I have investigated castings and mouldings of both metal and plastic. I have designed parts to be 3D printed, and I have operated the machines.
The photo to the right is my college CNC machining project. The punched paper tape contains my CNC program. The thing is machined into a piece of foam insulation because the people teaching the course assumed that sooner or later, we would forget to lift the cutter before translating at 10ft/sec.
| Acronym or Initialism | Meaning |
|---|---|
| CAD | Computer Assisted Design |
| CAM | Computer Assisted Manufacturing |
| CNC | Computer Numerical Control |
| STL | Standard Tessellation Language |
| FDM | Fused Deposition Modelling |
| SLA | Stereo Lithography |
Howard Gibson —
Email
hgibson@eol.ca
—
Last updated:
2022/02/21