A crash-course on 3D Printing

Author: Albert Shih

Congratulations on deciding to use 3D printing to augment your simulation training! 3D Printing is a great way to reproduce unique models that can closely replicate more expensive anatomic models for practicing procedural skills. One such example is the 3D-printed cricothyrotomy trainer as discussed in Evan Strobelt’s article.

Before you start, however, the most important thing to know is that 3D printing can be a great investment for long-term savings on your simulation projects, but definitely comes with some significant up-front costs. Additionally, it does require a decent amount of tinkering and trouble-shooting which this article will begin to prepare you for.

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Although 3D printing technology has advanced significantly, short of an industrial 3D printer(which is probably outside of the scope of what we are doing), it is not 100% fool proof (see an early attempt at making the cricothyrotomy model).

That being said, there are two main routes by which you can get your models printed which I will discuss below.

Method #1- Have someone else print it for you

This is arguably the simplest option. You don’t have to maintain your own machine, you don’t have to worry about the minutiae of how to set up the software, optimizing printing settings, or finding the correct filaments. Depending on where you have your models printed, there may even be a guarantee for the final product.

Have it printed online

There are online websites where tons of people with professional 3D printing experience offer to print models for a fee. The benefit of such a service is that you can print objects that utilize a variety of materials, such as using a more flexible material for the trachea models. The most popular websites are 3d hubs and shapeways.

Find a local library/university

If you want to look locally, sometimes the answer to printing your model can be right at your doorstep. Many universities and libraries are now investing in 3D printing technology to provide this service to their students and staff members. Many universities with an engineering program will have a fabrication lab that will help you get your models printed for a nominal fee. Many medical schools are now also starting to invest in maker spaces to help develop anatomical models for research and teaching purposes. For example, for students in my hometown of Houston, Texas, Rice University has a fabrication lab that offers 3D printing services.

UPS Store

Believe it or not, some UPS stores have 3D printing services as well. If you are looking for a more commercial setting (May be important if you need to generate PO orders), some UPS stores will provide this service for a fee, albeit more expensive than online printing services or universities. You can search for locations near you from their website, but make sure to call first before showing up with your flash drive.

Find a local makerspace

Makerspaces are places where people go who share a passion for creating and making things. It’s easy to search for these places by just searching for “[your city] Maker Space” on google. For example, New York City has a very prolific maker space with tons of expertise that can help you get your model printed.

Method #2- Do everything yourself

For the more adventurous types, getting your own 3D printer and printing the items yourself may be preferable to relying on others to do it for you. Keep in mind, however, that while 3D printing can be a lot of fun, it can also be a significant time and financial investment. The flip side is that you can constantly print out new test models yourself and be able to print replacement parts relatively quickly for your simulations without waiting on others. In the long run, printing yourself can be a more cost-effective way of printing out a large number of models.

Going into detail about how to troubleshoot every aspect of 3D printing is out of the scope of this article, but a brief overview of the 3D printing process, common pitfalls, and considerations in finding a 3D printer is discussed here.

The process

The general workflow for 3D printing goes something like this:

1) Find your model

Typically, this is the model you want to print. You can either create this yourself in a modeling software or use a pre-made model that you can find either in publications or on websites that are designed for creators to share their designs. One popular website that has tons of designs is thingiverse. Membership is free and you can find many great models there. Note that these models require a lot of time investment from their creators, so provide acknowledgements to the original designer where applicable. Typically those files should have the extension .stl or .obj

2) Finding the right software

3D printers are usually unable to figure out how to print your model from the model files alone. You will need software called “slicers” to help interpret your model and create step-by-step instructions for your printer to follow. This is also where you can change settings such as how hollow you want your model to be, how much detail you want printed, and tell the printer what type of material you are using.

The most popular slicers are:

Cura -> Free- works with most printers

Slic3r -> Free- works with most printers but require more troubleshooting

Simplify3D -> $149 USD – works with the most number of printers and is the most user friendly and has advanced features

3) Printing on your printer

Once you are done generating your “sliced” file, you should get a new file that has the extension .gcode or .x3g depending on the type of printer you have. Now, we need to get this file to the printer, so it can begin printing. Some individuals will print directly from their desktop or laptop by connecting the printer to the computer via USB cable, but this is not recommended as any hiccups with the computer (freezing, screen saver, power saving mode) can interrupt and destroy your print. The best method are loading your files to an SD card or USB flash drive depending on the capability of your 3D printer

4) Remove your finished product

Once you are done printing your model, it’s time to remove it from the plate (known as the buildplate). Make sure everything on your printer has cooled down prior to attempting this, as you can burn yourself if you are not careful (3D printers print at up to 240C and the buildplate can get up to 110C).

Printing on your own: Getting a printer and filament

So, you’re leaning towards making the initial investment and printing to your heart’s content. I’ll quickly go over how to select a printer and filament to get you started.

Picking a printer

While picking a printer requires a detailed discussion on various factors that are beyond the scope of this article, there are some recommendations as to what you should look for in a 3D printer. Your time is valuable and finding a printer that is time-tested and has quality support is worth its weight in gold.

Some important factors to consider:

1) Build volume

This is the maximum size the printer can print. The cricothyrotomy model for example, requires a printer that can print at least 220mm, so any printer that can’t print at that dimension will not work for your purposes. Keep in mind, build volumes are usually stated as X dimension by Y dimension by Z dimension. So if a printer can print 250mm x 200 mm x 180mm it is able to print a model that is 250 mm wide, 200 mm deep, and 180mm tall.

2) Customer support

Is this a printer that requires you to troubleshoot everything on your own when something goes wrong, or does it come with a manufacturer backed warranty? It is worth noting that many more economical printers have either no customer support or limited support. It makes a huge difference when you can have the manufacturer overnight a loaner 3D printer so you can continue your project while you troubleshoot your old one.

3) Reliability

Most of the commercially available printers have numerous reports on their long-term reliability. The worst thing you can do is invest in a 3D printer that breaks on you and sits unused because no one can find parts for it, or worse, waste valuable time and material with numerous failed prints.

4) Safety

3D printing can be a long process, sometimes taking over 24 hours. You want a printer that won’t burn down your building while you are printing your project. Keep in mind however, that you should never leave a 3D printer completely unattended. You are burning plastic after all.

5) Quality of life features

3D printing is hard. The most common point of failure in starting a print is improper leveling. Finding a printer that does auto leveling can remove one of the common frustrations of 3D printing. Some newer printers even allow you to recover your print job even if the power goes out.

While I won’t recommend a printer directly here, 3Dhubs provides a guide on some of the top printers they’ve reviewed here.

What type of filament should I use?

PLA, PLA, PLA. There is a large selection of filaments you can use when you pick up 3D printing. However, each filament comes with its own set of challenges. PLA has the best combination of durability, cost, and ease of use. ABS can be more durable, but printing ABS is very challenging and produces toxic fumes.

Common issues encountered in the printing process

So, you made the investment and you’ve got your printer and your filaments but you’re running into a few problems. I’m going to outline some of the most common issues below to help you trouble-shoot this process. However, there is already a wealth of information regarding many of these issues that is already available on other blogs, so I won’t go into too much detail here.

My print won’t stick to the build plate!

This is a common issue that is usually due to improper “leveling”. In most printers, prior to starting your print, the printing head needs to be level with the build plate so when it oozes out molten plastic, its close enough to the plate so it’s smooshed on. A typical rule of thumb is that when the print head is being leveled, you should be able to pull a piece of printer copy paper between the print head and the build plate with some resistance.

The printer seems to be printing nothing!

If this happens, it’s very likely that something jammed in the printer. Most printers have a mode that lets you heat up your print head without actually printing, and you can try hand feeding the filaments to see if you can get it to un-jam. Matterhackers has a great article on how you can clear jams.

I can’t get my model off!

A little bit of elbow grease goes a long way. Sometimes the models can be difficult to remove and this is normal. Depending on the type of build surface you have, you can use a putty knife to help get under an edge and work your way around circumferentially until the whole piece comes off. If that doesn’t work- power off and unplug your printer and spray some isopropyl alcohol at the base of the model. Sometimes this helps loosen the bond between the print and the build surface.

Model doesn’t look right?

Simplify 3D has a great visual article with examples of common 3D printing errors and gives suggestions on how they can be addressed.

How do I know what temperature I should set my print head?

This is one of the most vexing issues in 3D printing. Most materials have a manufacturer recommended temperature range at which to print their filaments. Some of the programs take the guess work out of this with some preset temperatures you can try, but the reality is different printers will print different materials best at different temperatures and therefore may require some optimization. I’ve even found that some filaments printed on the same printer will have different ideal temperature settings if you change from one color filament to another (even when both filaments are made by the same manufacturer). However, here are some rules of thumb I typically go by:

PLA:        Print head: 190C-210C

Bed temperature: 60C

ABS:        Print head: 225C – 240C

Bed Temperature: 100C

 

Thanks for your time and happy 3D printing for your next sim session!

 

 

 

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