An Introduction to 3D Printing

Do you dream of owning a fiddly bit of equipment that requires constant re-calibration and still never seems to give you what you wanted? Have you ever wanted to constantly clean up mildly toxic liquids? If so, then 3D printing may be right for you!

Humorous pitches aside, there are a few different kinds of printers out there, each with their own pros and cons. I thought I would take a moment to at least go over the two most popular types.

First, however, I would address the more general idea of what 3D printing is and isn’t. Mostly isn’t, I think.

It is not a technology for the impatient. I would say the typical print job tends to take around 6-8 hours to complete. I’ve printed some small bits that only took around 30 minutes, and I’ve run my fair share of 14 hour jobs as well. It’s not a Star Trek replicator. This also assumes that you can locate an appropriate 3D model, or create one yourself, and understand how to set up the print job. On top of that, you will inevitably find one of the layouts/job types that don’t work well (tall skinny objects, I’m looking at you) and nothing else goes wrong. Seeing a 14 hour print fail at the twelve hour mark, or having the power flicker and terminate the job is quite inconvenient and typically requires you to start over from the beginning.

As pieces of equipment go, they’re also quite fiddly. Certain things, such as the distance between the print surface and the business end are fairly precise and prone to shift. If you don’t have it set properly you’ll fail right out of the gate and if you’re far enough off, damage the equipment in the process.

There’s also emerging research suggesting it’s not a healthy indoor activity, but something that needs ventilation. This is without considering some of the solvents involved in the cleaning process. If nothing else, I imagine repeated exposure to 91+% isopropyl is not great and some people go on to process their prints with acetone or chloroform as well.

Last, there are always going to be some trade-offs in quality somewhere. Most items made of plastic or resin in our daily lives are injection molded. That process has a much more refined finish than 3D-printed bits do. Most hobbyist 3D printers are limited to various forms of plastics and resins, only some of which are recyclable and even then I’m not sure how many of them are commercially recyclable. Certainly not a particularly green technology.

With all that said, there are two main types of hobbyist printers, the FDM machines that print using polymer filament and the SLA units that use a UV light to solidify a liquid resin.

FDM apparently stands for “Fused Deposition Modeling,” though I personally prefer to think of it as “Filament Deposit Machine.” It’s basically what happens when someone decides to put a hot glue gun on a CNC machine. It forces plastic string through a small hole and using a series of motors to move the head and the platform draws objects with the temporarily liquid plastic.

Of the two, it is probably the most versatile. They can typically make much larger objects out of a pretty wide variety of materials. It can also produce hollow parts much more easily. The main downsides are the characteristic “liney” appearance of the parts, which can require a lot of post-processing to cover up, and the fact that it requires constant calibration. While I have seen people claiming to be able to replace a few parts and stay calibrated for months at a time, I do not feel that this is realistic for most people. The level-ness of that print bed relies on springs under tension. Since environmental factors such a temperature will alter the properties of the springs, living in a temperate area with wide swings from day to day means that I have to constantly check and adjust.

These things also generate quite a large amount of waste plastic. The plastic “spaghetti” from the failed print in the picture is one example. I’ve been collecting mine in a small box, but the gear requires to process and extrude it into re-usable filament is prohibitively expensive.

SLA stands for stereolithography. These are the UV resin printers. While there are some varieties that use laser(s) to draw much like the FDM printers do, most models use an ultraviolet display to cure an entire layer at once. Dusty parts aside, this leaves a much smoother finish.

The primary advantage to these things is visual quality. The parts they produce are much more detailed, as the resin can be cured in thinner layers (0.05mm v 0.1mm) as well as in whole layers instead of line drawings of a layer. For a similar sized object, I would say the resin tends to be a bit faster, though this varies heavily from printer to printer. They don’t seem to require as much mechanical maintenance and calibration either.

The first major downside is that this liquid resin is both toxic and messy. The build platform and the parts come out covered in the stuff and must be cleaned with isopropyl and/or degreaser. Any time you experience a print failure, or at least once a day, you must also pour all the resin out of the vat, through a paint filter, back into the original container, and very carefully clean the vat as well. The whole process generates a fairly large amount of trash as it consumes paper towels and microfiber towels to do these jobs properly.

While I find the resin printers don’t require as much hardware calibration, they do include a fair amount of software calibration. Finding the right exposure times and travel speeds can be a bit frustrating. I’ve spent the last couple of week off and on doing exposure tests and test prints, and it looks as though I’m going to end up pretty close to where I started.

For either type of printer, I would say that the time and material sink probably outweighs any monetary savings. When you consider how many hours are required to (re)calibrate them regularly, that cost adds up. The failure rate and losses to experimentation do as well.

So why would anyone do it then? I for one enjoy playing with it, but it has some more practical applications as well. It’s advertised use is “rapid” prototyping. I suspect a skilled tooling technician could easily outpace it, but if you don’t have the equipment or labor on hand, this is a passable substitute. I believe a jeweler and/or metal artist could find a way to print masters or wax copies for casting, though it seems to me that physical sculpting and 3D modeling aren’t different enough to make much difference.

I do know that many of the resin printers can handle dental resin as well, so there is at least some medical application. Having said that, I’m not sure how I feel about the idea of putting something from a hobbyist printer in my mouth. That seems… counterproductive.

For me it’s the best parts of my day job combined with an interesting but impractical home technology. Having said that, my wife seems to enjoy to products it can produce, if not exactly the speed at which I can produce them. It can produce the odd difficult to locate gift, such as this Sheikah Slate one of my children requested, but I’ve also printed some car trim with custom mounts, decorate corbels made from a composite wood filament that my wife claims is stainable, and a number of other little odds and ends.

There is always a small chance that familiarity with this technology could be of benefit at work, though most industrial applications use a third type I didn’t discuss here, selective laser sintering or SLS. I don’t see my own employer going down that road any time soon. I just can’t foresee it competing with multi-ton hydraulic presses any time soon.

Either way, I hope you learned something you wanted to know. Y’all take care.

2 thoughts on “An Introduction to 3D Printing

  1. I for one learned a lot from this. I didn’t know absolutely nothing about 3D printers besides they could do cool stuff and cost way more money than I’d like to spend on it.

    With all this information now I know it is definitely not for me. Maybe when the technology advances, becomes more idiot-proof so even someone like me can use it and is more ecologically-friendly, I will consider it more seriously.

    Thanks for writing this post! 🙂

    Liked by 1 person

    1. You’re welcome!

      It’s slowly getting there, I think. It looks like there’s pressure to move in a manufacturing direction too. Seeing a lot of newer units featuring a conveyor belt print bed for continuous/bulk printing. Curious how bed leveling works on those, but they’re all 1000€+ right now.

      Liked by 1 person

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