In this first of a two-part series I’ll be diving into the
topic of 3D printing. I'll start with a broad overview, move on to discuss available options for getting your own printer, and finally I'll pass along some troubleshooting tips I've learned along the way. In the second, arguably more interesting, post I’ll detail the process
we use to create our own head cases that can drastically reduce subject head motion
inside the MRI machine.
A quick disclaimer before diving in, this post is NOT
intended to be a comprehensive look at 3D printing and printers. This is a massive field with what can seem like unlimited design option and choices, many
of which are still foreign to me as well! So whenever possible I will provide
links with information for those interested in learning more and possibly want
to build their own.
What's the deal with 3D printing?
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| Figure 1 - 3D printed prosthetic limb |
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| Figure 2 - Unpainted 3D printed mask |
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| Figure 3 - Fully painted 3D printed mask |
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| Figure 4 - 3D printed gears. Almost impossible to buy but super easy to print! |
Now that I’ve piqued your interest about possible uses,
you’re probably wondering where someone even begins with setting up their own
print station. Thankfully the open source 3D print community is thriving
online. With the power of Google you don’t have to look too long in order to
find general information
on the topic. One could easily fall down a rabbit hole and the sheer
amount of options available could turn you off to the idea all together. But do not despair! I will fully admit that I
knew next to nothing about 3D printing when the decision was made to build our
own here. It was a learning process; it
was frustrating, definitely caused some hair loss and at times I felt way over
my head. But eventually one day the stars were aligned, kinks were ironed out,
numbers were dialed in, and the world of 3D printing seemed a little less
intimidating. I don’t have all the answers, and it would take me longer than
I’d care to admit to detail the process of building a fully functional printer
from start to
finish, but I’m able to use our setup and troubleshoot the issues we come
across. And because the online community is so active it is easy enough to search the internet for answers whenever I need them. Always remember that Google is your
friend!
Printer styles and choosing what's right for you
I could write an entire post about the various styles
of printer; describing the components needed and the software toolchain they follow,
but that’s not within the scope of this blog. More importantly, people with far
more knowledge than I on the topic have already done that! Follow the previous link and you’ll find information on various
styles of printers and learn how to go from an STL file to a fully
printed 3D model in no time. Well maybe not in "no time", but they will definitely get you there faster than I alone could!
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| Figure 5 - Kossel style 3D Printer |
After various internal discussions my team decided on
building our own Kossel, which is a delta style printer. Our
reasons for going with this one were:
- A printer bed with a 300 mm radius for printing larger components
- A delta-style printer allows us to build tall pieces that aren't possible with other styles
- Fully open-sourced which allows us to custom pick the software we want to use
- A stationary printer bed which is more stable, especially when printing taller pieces
- A vertical build design, so takes up less space than other models
- Capable of printing at faster rates than other models due to it's stability
- Supports open source add-ons such as a headed bed for better model adhesion and automatic bed leveling before every print starts
If
all those features sound great to you then a Kossel or other delta style
printer might be the way to go. You’re going to have to do some research
and figure out which style is right for your facility. A few questions to
consider before making your decision include:
- Do you need a large printing platform?
- What sort of items will you be printing?
- What are the size limitations where you plan on setting it up?
- Does the speed at which it prints matter to you?
- Do you need an enclosed system?
- Can you machine the parts when necessary? Or have access to a machine shop?
- Does open-source sound appealing?
- What’s your comfort level when it comes to programming languages, EEPROM, etc.? Are you willing to learn?
- How much troubleshooting are you willing to do? And how complicated are you able to handle?
There are plenty of other
questions to consider when deciding on a printer. Price, complexity, form,
function, etc. can all be overwhelming! But focus on what you currently need
AND try to plan for the future as much as possible. The great thing about building your own 3D printer is
the potential to modify and add-on to it later on. Once you’ve become an
expert, of course ;-)
Building a printer takes work
Lets fast forward through many many months of building, calibrating, and troubleshooting more issues than I care to remember, and take a look at our finished 3D printer. Below you'll find several pictures to give you an idea of what your setup might end up looking like. It's not the prettiest, but it's reliable, accurate and I've grown comfortable enough to fix the issues that arises.
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| Figure 8 - Our Kossel style delta printer finishing up a head case print |
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| Figure 9 - 3D printer electronics, including RAMPS board and Raspberry Pi |
As you can see, there's quite a lot going on with our printer! It would be easy enough to cover up all the wires and make the whole system easier on the eyes, but that limits access to the electronics. I need to be able to get in an out quite often when things break or need upgrading.
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| Figure 10 - Printer bed, carriage w/extruder and an attached webcam for monitoring prints remotely |
It's not as easy to tell from the photo, but our print bed has a glass plate on top and bed heating electronics underneath. The glass bed provides a more consistently flat, level surface than the regular aluminum plate alone and heating the bed helps dramatically with bed adhesion. Both of these features were added on after the printer was built.
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| Figure 11 - 3D printer station with control PC, custom built delta printer, and purchased Makerbot Replicator 2 |
Thankfully we have enough room in our electronics shop to keep both our printer, materials and control PC in the same area without taking up too much space. Although I haven't mentioned it yet, I am sure you have noticed the Makerbot Replicator 2 printer on the right. We did indeed purchase a prefabricated printer some years back to use as a backup of sorts for our own, but let's just say we are less than satisfied with it's performance. I'll discuss that a bit more in detail later on.
I completely understand going this route is an undertaking most researchers don’t have the time or resources to complete. But you get far more freedom to customize the device your own way and it can't be understated how much knowledge you'll gain by getting your hands dirty. It will do wonders for your confidence and building skills, not to mention troubleshooting is far easier and quicker when you know the machine inside and out.
Don't wanna build your own printer? Thankfully you don't have to!
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| Figure 6 - MakerGear M2 printer |
These printers tend to be quite a bit pricier than other available options, but the convenience can be worth the cost for some. You won't spend hours and hours getting your printer up and running, but you might spend the same amount of time dealing with customer support and printer errors. The very nature of closed-system devices means home troubleshooting is limited to power cycling, restarting a print, or being convinced you have to buy new components. Mileage may vary though, so maybe your experience will be better than the one others have had, i.e. us! (Note 1)
If you’re like most people and caught somewhere in the middle between buying a pre-fabricated printer and completely building your own, well then have I got the solution for you. There are plenty of printer kits available for purchase online. This will likely be the go-to route for the majority of people. Nowadays kit manufacturers do a pretty decent job of explaining how to setup your printer after purchasing it. Simply find the one you want and they'll ship you the parts to build it.
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| Figure 7 - Printrbot Simple Pro kit |
They’re cheaper than the pre-fabricated printers and some models can even be comparable to building your own. In fact for all intents and purposes you ARE indeed building your own printer when you purchase one of these kits, just without the hassle of putting together a parts list and ordering from multiple vendors. Most kits I have seen don’t have proprietary software either, so you’re going to be using a bunch of free software to complete the toolchain and get the printer going; just like you would have to do if you built your own from scratch. It’s a relatively simple process once you’ve set it all up. Plus there are plenty of great open-source options to choose from, allowing for even more customization. I strongly recommend going this route if possible as it has the most benefit with the least amount of headaches. If I ever decide to build another printer I will definitely be buying a kit.
Helpful Tips & Tricks
The most useful advice
I can offer is how we overcame many of the problems that popped up while building our printer. Information and solutions for all of the technical issues you'll likely come across can be found in handy guides
online, but I am going to run through some specific issues we encountered frequently and helpful tips we learned along the way.
- This calibration technique for fine-tuning the extruder is extremely intuitive and easy to do
- For fine-tuning the entire system, including tower position, rod length, etc., this is a great calibration test piece. Fair warning, you’ll probably be printing this thing more times than you can count!
- Delta printers can be tricky to calibrate, but there are procedures out there that will walk you through it. Yet another fair warning, it can take a bit of time!
- When you first start calibrating and doing test prints, keep the temperature of your extruder on the lower end of the working range and slowly raise it as you continue. Temperature is a big factor when printing, but it's also one that can be easily changed, so focus on other factors first. The range is from 180° C to 220° C for PLA
- Applying blue painters tape to an unheated bed does wonders for initial print adhesion. Yes, it has to be blue. I don’t have the answer for why, but the online community has established that other colors just don’t work as effectively\
- This might sound even crazier than the previous tip, but if you are using a heated bed (I highly recommend it!) applying a thin coat of hairspray will help the print adhere better
- Check connections and tighten screws, belts, tracks, etc. about once a month. During the calibration process specifically you’ll be printing so often and changing so many settings that things might shift out of place
- PLA is our filament of choice with whites, greys and blacks being the colors we usually stick with. While we do occasionally use other colors, the consensus online seems to be that colored filament tends to jam more often than blacks and whites do. You can always paint them any desired color afterwards anyways
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| Figure 12 - Various spools of PLA |
- Store your filaments in airtight containers. Leaving them exposed to the open air can expose them to microscopic contaminants, which jam the extruder and lead to ugly prints
- Keep your active spool of filament on a roller so it feeds directly into the extruder – thus drastically reducing the possibly of it tangling up as it rolls out. We keep ours mounted above the printer. The last thing you want after printing for 15 hours is for a filament jam to ruin it all during the final minutes!
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| Figure 12 - Spool of PLA on roller being fed down into the extruder |
- For the last step in the software toolchain we went with the free software Octoprint. Check out their website for a full rundown of features, but one of the coolest is the option to hook up a webcam and monitor your print in real time from anywhere. You can also adjust the settings from their online interface on a whim. I highly recommend going with this web-based route for printer control
- Consider adding a heated bed and glass plate if the printer you decided on doesn't already have them. Print adhesion and a level print surface are both major factors in determining the quality of the overall print and these two add-ons do wonders for addressing those issues
- Thankfully our university has a PLA recycling program. They take unwanted PLA prints, grind them up, and melt it back down into spools for use in student print labs. If you don't have a recycling system like this in your facility, consider setting it up. All those failed prints have to go somewhere, and they might as well be put to good use
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| Figure 13 - Recycle bad prints whenever possible |
What's next?
Now that you're all experts on 3D printers and have your own set up, it's time to have some fun! In my next post I'll be diving into a unique project. I'll be going over the procedure used to turn a person's hi-resolution anatomical MRI scans into a custom 3D printed head case that fits inside our 12 channel head coil and drastically reduces subject movement inside the magnet. Stay tuned! (Note 2)
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| Figure 14 - Hi-res MPRAGE slice |
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| Figure 15 - Custom 3D printed head case made from the above MPRAGE |
