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Prusa I3 MK3 - medical 3D printing workhorse


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The last three weeks was a busy time for me. I purchased the best 3D printer of Fall 2018 - Prusa I3 MK3. I ordered it as a kit, the build itself took me 8 hours - my obsession with the electronics payed off -  and immediately after that the printer was ready for some action. Prusa I3 is the most common 3D printer in the world - 70% of all printers are Prusa clones. Prusa MK3 is manufactured by the designer of the printer itself, Josef Prusa and most of it's parts are made by other MK3's in the Prusa's 3D printer farm. The printer is robust, tough, with very useful automatic functions and can print with most types of termopolymers (Polycarbonate included) with minimum layer thickness of 0,05 mm. Now I'm preparing an enclosure with automatic temperature and humidity  control, Hepa and carbon filter and Octoprint upgrade for WiFi control. I bought cheap secon-hand server rack for this purpose (Fig. 4) - if it can keep a constant environment for the servers, it can do it for my printer, right?
y first print was the object on Fig. 1 (what is the name of the organ?) Then I had more than 300 hours of unstoppable 3D printing and the printer doesn't made A SINGLE bad print. The only issue was the printing surface after print #12 - the next print didn't adhesed properly, so I had to wipe the printing surface with isopropyl alcohol. I was printing with PLA, now I'm starting with the first roll of PETG. 
My next step was to contact my colleagues from the orthopedic surgery clinic and to show them my first prints. They was exited by the result, so they provided a 1 mm. slide thickness CT scan of a Pylon fracture. Then I used the following workflow:
1. Slicer 3D, Resample Scalar Vollume to resample the set to 0,5 mm.
2. CurvatureAnisotropicDiffusion with 3 iterations. 
3. Editor module for segmentation, model maker for the conversion to stl.

4. Autodesk Meshmixer for remeshing, editing and sculpting, Blender for smoothing. I prefer Meshmixer than Zbrush because it's much simpler and user-friendly. I'm also pretty good with it :)
5. I sliced the final stl with Slic3r, Prusa Edition and sliced the model on 0,150 mm slices, with support from the building plate, with 15% Gyroid infill (it looks exactly as a spongy bone), with Natural White PLA (17 euro per kilogram, from a local supplier) with the Natural PLA preset on the slic3r.
6. The print took 14 hours, the support was easy for removal (Fig. 2).
7. The orthopedical surgeons did their magic, first on the model (Fig. 3), then on the patient. They claimed, that the operation was very successful, thanks to my model and their skill. The chief surgeon is Dr. Preslav Penev MD PHD. 
My second project was a Pilon fracture of the ankle with multiple fragments, which I made with the same workflow. The patient is in operation right now.

I also have two more projects, for a congenital aplasia of the talus with pes varus and for luxatio of the Lisfranc joint, so I hired two medical students and I'll teach them how to model (I already sent them Dr. Mike's beginners tutorial) for my future projects.
I'm the first physician in Bulgaria, who performs preoperative 3D printing, which is very good for my career development. My colleagues called me a "pioneer" and I'm thinking about a 3D printing lab. I already ordered the Multimaterial Upgrade, which means SOLUBLE SUPPORT MATERIAL (I have to wait till January, it's in production right now). Jo Prusa's STL printer looks quite appealing too. Those printers are ridiculously cheap, considering how efficient never-stopping beasts of burden they are. I guest I should hit the vascular surgeons next...


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Fig. 2.jpg

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This is terrific work! I'm really coming around to FDM being the future as opposed to STL. I'm getting tired of dealing with drippy gooey resin all the time.  Go with Octoprint - it is a huge time saver especially if you are running multiple printers, and it allows you to monitor remotely. 


I like your enclosure idea. I built my enclosure with housing insulation styrofoam from Home Depot. It allows the temp to rise to about 10-15C above ambient, but it is not precisely controlled like your server rack. That is a good idea. I'll check out ebay to see if they have something. 


Great job!


Dr. Mike


P.S. You going to RSNA?

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The build was easy, there are no parts which requires soldering. The manual is really good and helpful, the Haribo candies also helps a lot. The cable assembly part is a tricky one, I asked a friend from the Tech university for some help, but at the end I assembled them by my own and my friend just ate my extra Haribo package (and also ordered a Prusa MK3 kit for himself). You have to be sure that you're building the printer at the flattest and most horizontal surface available - the belt assembly and calibration part  are the most important steps and if you do them correctly, you won't have further problems with the printer. 
The software is very good - Slic3r Prusa Edition is a freeware and have a lot of advanced features, advanced support material management included. When I started to edit my layers manually, the quality of the prints was increased substantially and I made some impossible prints.
The whole kit deal is really good one - you can't find printer with the same effectiveness at the same price, it's an out-of-the-box experience and requires a simple build, which will make you familiar enough with your new printer in order to maintain it properly. If you're living in USA, you can order the Seemecnc Rostock Max printer - it's an excellent delta printer with 32 bit controller for 1000$. The reason I got Prusa are the custom taxes - Rostock comes to Europe two times more expensive and Prusa is the better deal. I hope that after the Trump nonsense I'll be able to get one...

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