I’ve started my next project, which is to design and print myself custom shoes. I’m gonna start with something simple: pool shoes.

Pool shoes are typically designed to be close-fitting and put as little material around the foot as possible. So they’re ideal to iterate through the design of my shoes to find the perfect fit without wasting too much filament. And I need a new pair anyway…

I ordered a bunch of TPU with different Shore hardness and the rolls have arrived. So now I’m designing the shoes.

I have no experience with TPU, but a colleague at work does: he told me he tried to print a remote-control-like flexible sheet of rubber buttons that was 2mm thick, and the sheet readily delaminated when he pulled on it.

I want my pool shoes to be as thin as possible - apart at the front where I need protection. So bearing in mind what my colleague told me, I opted for a wall thickness of 2.5mm. Do you think this is enough?

As for supports, the printer I use at the moment only has one extruder head (it’s not mine) so I’ll have to print them out of TPU too. Is there a good strategy to limit the amount of material used and maintain structural integrity on such a large print? I’m thinking of drawing the supports myself inside the shoes to control exactly where they will be and limit wastage.

  • riodoro1@lemmy.worldEnglish
    1·
    7 months ago

    I’d say experiment on your own and find out. Your friend might’ve printed it wet and TPU is by my experience the most hygroscopic of them all.

    You need to dry the spool first and then keep drying it as you print. Seriously. I’ve printed two small bumpers out of tpu recently and after drying the filament one of them came out fine and the other had zits and blobs just 20 minutes later. Its insane how fast it absorbs moisture and how much it affects it.

    • ExtremeDullard@lemmy.sdf.orgOPEnglish
      0·
      7 months ago

      For pool shoes, that’s concerning 🙂

      I don’t think he printed it wet. We have a filament dryer and we put all our filaments in there regardless of what they are. I’m pretty sure he must have waited at least overnight before printing. He’s pretty thorough. But I’ll ask him.

      I didn’t know TPU was that sensitive to humidify. That’s good to know. Thanks!

      I do know it shrinks like crazy and it’s not good at staying put on any of the bed sheets we have though, so I know it won’t be a walk in the park - especially with prints that size.

      • HumanPenguin@feddit.ukEnglish
        1·
        7 months ago

        Just to confirm. Hygroscopic does not mean the material is unsuitable for wet conditions as a finished product.

        Your comment suggested that was your assumption.

        The issue is that FDM (and all plastic 3d printing) depends on the molecular bods reforming as plastic is melted and reshaped. Almost all physical materials absorb moisture from the air. But some more than others. Highly hygroscopic materials when melted below glass transition temps. The moisture within the molecular bonds dramatically affects the materials’ ability to rejoin and reform those strong bonds. This results in some very odd effects on the final product, making effective production impossible.

        The general rule is heat (30 to 90c depending on material) and time is needed to remove the absorbed water before printing. As for how long. Well for every 5c below the perfect temp for your material, the time doubles. This time starts at 4 to 12 hours depending on the material. (data is online) So yeah the time can become days if not using the perfect temp.

        I am currently struggling with this myself with ASA. As its my first time trying it. (im new to all this).