A good friend of mine has a dad who’s suffering from dementia. He’s a farmer and spent decades building and fixing things, and he still likes tools and things he can manipulate with his hands. Unfortunately, there are times when he throws things.
I printed him up some big nuts and bolts in PLA but realized that if they were all screwed together they’d make a pretty hefty projectile. So I wasn’t entirely sure what to do. Then, I remembered there were some 30g sample packs of TPU sitting around and collecting dust, so I figured I’d see if I could do something with them.
Having never printed TPU before, it was a few hours worth of DuckDuckGoing (I know it doesn’t roll off the tongue as well) before I’d learned that yes, it was possible to print TPU on a CR-10. I’d also learned that no, it wasn’t possible to print TPU on a CR-10. Interestingly, it was also possible to print TPU on a CR-1o, but only if you installed anywhere from $0.50 to $250 worth of modifications.
I opened one of the packages and played with the filament. Rubbery, stretchy, a little squishy… definitely different from the PLA and PETG I’m used to. So, I loaded it into the printer, started a print, and sat there for the entire thing so I could dial the settings in while it printed (thank you Octoprint!!!).
Here’s a bendy wrench:
I then fused what was left of one pack with the other pack I had (and set off the smoke alarm, whoops). After things calmed down, I drew up and printed a nut and bolt, which came out really well:
I did this on my CR-10s with a 0.4mm nozzle and no modifications, and the TPU I used had the following recommendations listed on the pack:
- Colour: Black
- Material: TPU
- Dia: 1.75mm
- Nozzle: 220C-240C
- Bed: 75C-85C
After a bit of experimentation, here’s what I found worked for me. Again, this is on a stock CR-10s with a 0.4mm nozzle:
- Level your print bed. Actually, go level it now even if you’re not going to print TPU. It fixes sooo many problems.
- Clean the outside of the nozzle before you print.
- Purge whatever was in there before. Do not mix TPU with another material, even if it’s “just a bit”. Trust me.
- Bed surface: Glass with two layers of Elmer’s all-purpose glue stick, applied after the bed is at temperature.
- Bed temperature: 75C (all layers).
- Nozzle temperature: 240C (all layers).
- Fan: 0% for first layer, 100% for rest of print.
- Flow rate: 105% (all layers).
- Retraction OFF.
- Print speed: 18-21mm/s.
- Layer height: 0.2mm for first layer, 0.25mm for rest of print.
- Print with a skirt, at least 7-10 lines wide.
- After the hotend and bed are heated up and just before you’re ready to print, raise the hotend 100-150mm and wait until the nozzle stops drooling TPU. Clean up the debris, carefully wipe the excess TPU from the nozzle, then start the print. It will take a while for the hotend to fill up again – print with a skirt to give it time to fill back up (see above point).
With these settings on this printer and with that particular flavour of TPU, I was able to get good strong prints that looked pretty good. There is some stringing between parts, but it cuts away easily with a small pair of scissors or snips.
I lobbed the wrench at my wife, who reported that it didn’t hurt. I screwed the nut onto the bolt and threw it at the front door and it bounced nicely without leaving a dent. I think these might work for my friend’s dad.
I’ve ordered some more TPU, and of course I couldn’t find stuff with the same temperature recommendations as the sample packs. I will give it a shot and do up another post with what I find out. At this point, though, I’m pretty comfortable with saying that yes, you can print TPU on an unmodified CR-10s and it can turn out well. Just go slow. And level the print bed!