A laborious but interesting way to construct a sphere
I'm not sure if this constitutes a bug, but it is weirdly interesting.
(Numbers relate to images left-to-right, top-to-bottom.)
- Draw a short line (20mm ) up from the origin and then rotate pattern 3 to give 120° spacing.
- Delete the pattern and the original line.
- Copy rotate the two remaining lines 180°
- In 3D mode, copy rotate the top two lines 90° arounf the vertical axis.
- Delete the two lines you copied.
- Select the 4 lines, click the cylinder tool and type a diameter (5mm).
And in addition to the jumping jack shaped solid, you'll get a perfectly formed sphere as a bonus!
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It reminds me of a Reuleaux tetrahedron.
One here if you want to buy one.
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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.
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Jacant - At 2.5cm cube, it's quite small...
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Buk.
It's a kinda a 3 axis rolling ball.
Yes, it's cute...
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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.
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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.)
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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:
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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:
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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...
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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.
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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.
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ooooh I got a Pending Approval
Email sent
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If Wonder Women attached a pair of those to her ears with elastic, when she did her famous spins, she'd macerate her enemies :)
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Buk.
on a stick, it would make a novel 3 axis crusher of some sort - let the brainstorming begin...
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Jacant.
In the wacky world of 3d printed earrings, almost anything is possible - got me thinking now...
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