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Hemi-demi-sphere

by VeryWetPaint, published

Hemi-demi-sphere by VeryWetPaint May 2, 2010

Featured Thing!

Description

A quadrisection of a sphere into four identical parts with some novel attributes:

1. The parts have no overhangs.
2. The flat 'bottom' is completely concealed after assembly; there are no flat spots on the exterior of the sphere.
3. Exterior is made entirely of 'sidewalls' where the resolution of FDM really shines.

My test samples were built in transparent PVC on a Solido SD300 Pro, but my goal was to design a Makerbot-friendly shape. Based on feedback from friends, I've adjusted the contours so the pieces 'grab' onto each other after assembly.

More pictures and discussion at my SD300 blog entry at mysd300.blogspot.com/2010/05/novel-decompositions-of-sphere.html

Recent Comments

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Thanks for a really neat print, keep it up!

They print really nice and quick, I wanted something to show at my work and downloaded this, printed and had it assembled within 45 min. Printed it at 0,2 mm layers, 3 shells. (4 bottom ones) @ 80mm/s. No cleanup required! Makes for a really nice proof of concept piece. If I were to change anything I might try rotating it 45 degrees on the bed before printing to see if I could get the pesky seam to be inside the ball when it is assembled, it would really add to the finish in my case.

Printing this on the MakerBot with a raft results in each piece being one layer thicker than desired. The linear stripes of the leftover raft bits make base-adjacent pieces mesh together more solidly, and each pair being slightly thicker than designed makes the model stay assembled much more strongly than the minimal friction offered by an ideal print. I have to throw the ball at the wall exceptionally hard to make it break into pieces. I love this model!

If you post a hollow one, you can bet I'll be printing it as soon as I see it!

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License

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Instructions

After you build four of these they should fit together to form a ball.

Note: the parts fit together with their build planes at right angles, so it'll doubtless be affected by any geometric distortions.

Comments

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Jaknil on Mar 6, 2012 said:

Thanks for a really neat print, keep it up!

They print really nice and quick, I wanted something to show at my work and downloaded this, printed and had it assembled within 45 min. Printed it at 0,2 mm layers, 3 shells. (4 bottom ones) @ 80mm/s. No cleanup required! Makes for a really nice proof of concept piece. If I were to change anything I might try rotating it 45 degrees on the bed before printing to see if I could get the pesky seam to be inside the ball when it is assembled, it would really add to the finish in my case.

sparr on May 17, 2010 said:

Printing this on the MakerBot with a raft results in each piece being one layer thicker than desired. The linear stripes of the leftover raft bits make base-adjacent pieces mesh together more solidly, and each pair being slightly thicker than designed makes the model stay assembled much more strongly than the minimal friction offered by an ideal print. I have to throw the ball at the wall exceptionally hard to make it break into pieces. I love this model!

Anonymous on May 5, 2010 said:

Great Idea to take a idea like a Tennis Ball and dissect it like this. :-D
http://tenniscrowd.com/blog/wp...

Anonymous on May 4, 2010 said:

That is an awesome design, i would like to get my hands on one just to set around the house and make people ask questions!

Anonymous on May 4, 2010 said:

or if you could get the extruder to switch colors a few time during each piece and get some kind of layered effect on the final product

BungleX on May 4, 2010 said:

Sweet and simple, I like.
Suggestion: Try a little manipulation to make each piece "bulge" at each end and thinner in the middle. This would make them clip together and not fall apart.

VeryWetPaint on May 5, 2010 said:

Sure enough, a lot of interesting tweaks are possible. The 'bulge' can probably by accomplished by rotating the conical cuts off-center slightly. The OpenSCAD source is attached, so feel free to play around with it.

I also built a hollow 2-piece version that can be used as a container; I'll post that one later.

wizard23 on May 4, 2010 said:

brilliant design! I always wanted to print a sphere on our reprap :)

Anonymous on May 3, 2010 said:

They could be used in large scale ball bearings.

2ROBOTGUY on May 3, 2010 said:

Very cool!

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