Printing with tungsten PETG on the mk4 with the Obxidian nozzle  

Printing with tungsten PETG on the mk4 with the Obxidian nozzle

I’m pretty used to printing in engineering materials such as PC-CF, or PA-G, PA-K or PA-CF, but the tungsten was a new material. But I am a physician and work in our surgical innovation center where we develop a lot of surgical instruments most commonly for orthopedics, but I also work with our thoracic surgery and colo-rectal surgery divisions. In this case orthopedics needed something to improve a fluoroscopy guided procedure (can’t give the details yet, until we get the paper published, but that’s not improtant). This print was going to be challenging as there was no choice but to use supports and with Arachne it was going to be 2 paths thick with the Obxidian 0.6 nozzle. Now some folks might swap nozzles but I don’t have time so I have the hot ends loaded with the different nozzles, I also have a mk3 with the revo upgrade and that I just swap the nozzle part, but the mk4 is still an annoying swap of the nozzle itself but the hot end takes less than a minute. This project is comparing the performance of the tungsten against a DMLS printed 316L Stainless Steel version.

anyway: to the PETG-T experience so if you haven’t figured it out, you need to download the config bundle file from the filament page on the store, although not sure why 2.6.1 doesn’t have it already added in since that came out much later than the filament did. Given the thin nature of the part I put a raft underneath and the very, very thin bridges (about 15mm) which are almost ephemeral when you see them needed supports as well. I test printed it in regular prusament orange PETG and the supports snapped off easily.  Here are my thoughts:

• the tungsten PETG tends to leave a lot of little strings but not like regular PETG these are short little curls
• peeling a raft off was extremely difficult and I started with an x-acto knife (but the steel blade rapidly got dull but then I remembered I had ceramic blades from a project), the surface is not smooth where the supports were, this might work better with a dissolvable support
• the surface is a lot messier and rougher than typical PETG 
• the part is surprisingly heavy when you pick it up
• the supports didn’t crack off when I removed them like simple PETG, it more “mushed off” than cracked off, which this part was scary to do, as I was sure I’d damage some of the thinner elements
• for the bed I used the satin sheet, and I think in the future I will skip the raft, as it left a terrible surface on the bottom of the part
• luckily this part only needs to be radiologically good and not visually good.
• note: before someone freaks out, we are not testing this on patients, we are taking the x-ray photos by itself on a testing rig at various angles of both prototypes and doing measurements on the resulting images. This is purely a materials evaluation. And even then our IRB was all concerned as it involved “ionizing radiation” (my favorite question they asked was if there was chance someone would get irradiated, and I’m thinking are they worried the x-ray tech is going to put his face under the emitter to photo-bomb? I had just explained like 3 times that nobody was in the room with the fluoroscope (the rig is controlled by an Arduino and some servos), we are all in the control booth, the measurements are all done after the fact…