Aller au contenu principal

A laborious but interesting way to construct a sphere

Commentaires

15 commentaires

  • Jacant

    It reminds me of a Reuleaux tetrahedron.

    One here if you want to buy one.

    https://www.shapeways.com/product/F59KPNTJC/reuleaux-tetrahedron-solid?optionId=4758668&li=marketplace 

    0
  • Buk

    Interesting shape.

    In turn, it reminds me of something that fascinated me for years. If you use the 3 surfaces in the following pic as cutting tools on the cube, what shape do you end up with? :)

    Not sure if it has an official name.

    0
  • Tim Heeney

    Jacant -  At 2.5cm cube, it's quite small...

     

    0
  • Tim Heeney

    Buk.

    It's a kinda a 3 axis rolling ball.

    Yes, it's cute...

    0
  • Jacant

    The Reuleaux tetrahedron is exactly like a 'rolling ball'. I had a request on Shapeways to make this. They ordered four. The size is because they wanted it to be 1".  Have you seen the price of a printed model. If you had four of them and put a flat surface on top, you could roll the surface as if they where on balls.

    0
  • Buk

    Yes. Like this.

    My brother in the US has one that is about 4" a side, made of crystal. It sits on/in a larger slab of crystal that has a dish-shaped, circular  hollow in the top. If you position the tet at the side and give it the gentlest of nudges, it rolls around the bowl for quite a while.

    I was with him when he bought it; I bought this at the same time. It has a pump in the base which pushes water up through large crystal lump and causes the crystal sphere to spin. There's also a light inside which looks very pretty at night. (Looks like it needs a damn good clean; hasn't seen any use for a while.)

     

    0
  • Buk

    Rob,

    In case you were at all interested, and because I was VERY bored, this is (roughly; its been 15+ years since I saw it) what my brother's Reuleaux Tetrahedron ornament looked like.

    The round thing in the middle is a spirit level bubble; and the blue threaded discs are adjustable feet for getting it level.

    (The texturing leaves a lot to be desired; and as they say on Amazon: "Stone is a natural product; the colors shown are approximate only" :)

    A bit better:

    0
  • Buk

    Tim said: "Buk.It's a kinda a 3 axis rolling ball.Yes, it's cute..."

    I only just saw your comment Tim. Assuming you're referring to my cube round in 3 directions (rather than Jacant's RT), then yes, it rolls in 3 axies, but ONLY those axis, which has some interesting engineering applications.

    It gets really interesting when you use something other than a simple circle as the cutter shape:

    0
  • Tim Heeney

    Buk.

    yes, modeled it and saw only 3 axis of rot.

    In your latest exploration, this would translate nicely in only X and Y dir on a plane grid of matching teeth, plus this plane itself  could also rotate about Z...

     

    Perhaps some sort of X +Y translation slide plus a rotatate axis might be envisaged - normally these devices are stacked upon one another...

    Sadly i'm a man too limited by what i see as practicalities though...

    0
  • Buk

    Tim: Sadly i'm a man too limited by what i see as practicalities though...

    I can't think of a use for the gear version, It was just  easy to produce as I had the gear profile lying around, and I thought it was look interesting.

    The circular version has application as a sort of constrained ball-joint.It can rotate forward and back, or side to side, but only one of that at a time, starting from the centred position.It also cannot twist about the third axis.

    0
  • Jacant

    Here's a use for it. There are people out there that would buy it. You could resize it and make a pair of matching earrings.

    0
  • Jacant

    ooooh I got a Pending Approval

    Email sent

    0
  • Buk

    If Wonder Women attached a pair of those to her ears with elastic, when she did her famous spins, she'd macerate her enemies :)

    0
  • Tim Heeney

    Buk.

    on a stick, it would make a novel 3 axis crusher of some sort - let the brainstorming begin...

    0
  • Tim Heeney

    Jacant.

    In the wacky world of 3d printed earrings, almost anything is possible - got me thinking now...

    0

Vous devez vous connecter pour laisser un commentaire.