Hand-Crank Fan

Discussion in 'My Shapeways Order Arrived' started by vertigopolka, May 3, 2011.

  1. vertigopolka
    vertigopolka New Member
    I just received a print of my "Hand-Crank Fan" model in WSF.

    This model is a single print with six moving parts, and is specifically designed for the loose tolerances of Shapeways' WSF material. The entire model is printed with all of the parts in position; nothing is assembled post-production.

    The 1:9 gear ratio (made from two sets of gears each with a 1:3 gear ratio) makes the fan blades rotate nine times for every single rotation of the crank. The grip of the crank handle freely rotates as well.

    Based on this latest print, I will be making a some minor adjustments before releasing the model for sale.

    Hand-Crank Fan in action (video): Hand-Crank Fan video
    Model page: Hand-Crank Fan model





  2. Magic
    Magic Well-Known Member
    Wow... Very interesting and very elegant! I notice that the gears have very pointy teeth. Is is a way to deal with the loose tolerances of WSF?
  3. vertigopolka
    vertigopolka New Member
    @Magic: Thanks! Yes, I found that because of the tolerances, I needed to put an extended, rounded tip on the teeth in order for them to mesh correctly. Otherwise, they would slip by each other. The tips on the gears help to nudge the other gears around just enough to keep everything turning very smoothly.
  4. ana_xyz
    ana_xyz New Member
    Looks like quite a feat of (3d printed) engineering.

    When do we get a video of it in action? :D

    Edited: Note to self -- look closer...
    Last edited: May 3, 2011
  5. vertigopolka
    vertigopolka New Member
    @ana: I put the link to the video in the original post (I don't know how to embed video in the forums).

    Oops, just noticed your "note to self," but here's the link again :): Hand-Crank Fan video
  6. bitstoatoms
    bitstoatoms Member
  7. stuartar
    stuartar New Member
    Flinkin Blip!... single print, So COOL!
  8. dizingof
    dizingof New Member
    Very cool !

    What's the gap length you used between the parts ?
  9. vertigopolka
    vertigopolka New Member

    Some of the gaps are pretty tight; it really took a while to free up the parts. I'm working on some slight modifications.

    There is about 1mm vertical space between the gears and the brace, and I added little semi-sphere nipples on the brace to help keep the gears from wobbling too much. I also curved the sides of the holes in the brace; a .6mm straight gap around the shafts would be too loose, but I also did not want the gap to be too small, so this is how I compromised.

    Screen shot B 2011-05-03-01.jpg
  10. dizingof
    dizingof New Member
  11. vertigopolka
    vertigopolka New Member
    It took about 20 minutes to get the parts moving. I figured I was pushing the limits with some of the tolerances. I've had pieces fused before. The .4mm gap for the bumps is only at the tip/tangency, so there is a lot of space around it and didn't expect any problem there. I've tried straight cylindrical walls around axles/shafts, but they are either too loose or get fused. The rounded walls seemed to keep it from fusing, even though it's tight around the edges. I'll probably open that up, just slightly.
    It's definitely difficult to try to get this all working with the WSF material.
  12. stop4stuff
    stop4stuff Well-Known Member
    Rounded walls definately work... I tried out some dragonscale earrings with 1mm 'wire' and 0.2mm gap between the rings - image here...the rings looked like they were fused, but a few wiggles back & forth losened them up.

    Did you try the 'freezer trick' to loosen up the parts?
    (WillLaPuerta - It Arrived - Toy Car and Pocket Reaper)

    vertigopolka - you might have a fan in hand, but you also have a fan of your designs in me.... great stuff [​IMG]
  13. vertigopolka
    vertigopolka New Member
    @stop4stuff: really cool earrings; it's amazing that they weren't fused! I definitely had to do a lot more than just a few wiggles on mine. I read about the "freezer trick" earlier; haven't tried that yet. Not sure if I agree with the reasoning behind it, but I would give it a try if nothing else is working. :)
  14. stop4stuff
    stop4stuff Well-Known Member
    Thanks :)

    I was pondering stuff today, musing about various things I've done with LEGO, and it struck me... LEGO is ABS with smooth surfaces, for lube on moving parts, I use a spray on silicone/PTFE oil which reduces friction to around 40%... it might not work the same with raw WSF as-is but it might work with polished/ground/sealed WSF, like after a few spins to get everything losened up and working - just a thought