90 Degree Tube Twist Mechanism

[IAmTheClayman]

Please excuse the photo, I'm at work so I just sketched this on the bag I got at Dunkin Donuts. Does anyone know of a mechanism to achieve this type of rotation? Ideally it would need to fit inside aluminum tubing with an inner diameter of 3/4"

 

[robn1]

All I can think of is a universal joint on the inside.

 

[IAmTheClayman]

I thought of a U joint, but I don't know how to get it to spin 360 degrees freely within the tubing.

However, I did find a link to this which I think solves my problem: http://www.thingiverse.com/thing:115805. It's a 360 ball joint inside of a 90 degree joint, and considering that the tubing would spin 180 degrees as it "bends" 90 degrees makes sense. Just having trouble visualizing my own 2d image in 3d space

 

[rbeach84]

I, too, am having difficulty understanding your query. Are you saying you need a way to allow the tubing to change from a straight orientation to a 180 degree bend configuration by rotation of the pieces?
R/ Robert

 

[nick daring]

 

[IAmTheClayman]

Yes. Or to make it simpler, I want to take 1 piece of aluminum tubing and cut it cross-sectionally on a 45 degree angle and put it back together. Then, by twisting one of these pieces, I want the pieces to now meet at a 90 degree angle.



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View attachment 510363

Shhhhhhhh, soon...

 

[nick daring]

Such a fun solution to a weird old comicbook design concept.

 

[IAmTheClayman]

Such a fun solution to a weird old comicbook design concept.

Oh yeah, I just started reading the Waid/Samnee run and I fell in love with the design. Plus, I think I figured out how to make the full concept work: standard cane, separated billy clubs and grappling hook all in one prop, unlike what the 2003 movie did (and the Netflix series didn't even attempt.)

…Well not actually work, there's no spring reel on earth small enough to fit inside the cane that could actually support the weight of a person, but I think I can get over that haha

 

[Aku]

I think you're overthinking the mechanism, What you want to achieve sounds a lot like the joint in the old "Magic Snake" toys



Each joint could rotate like you suggested



I'd make it like this.

1. Blank off each end of the pipe.
2. Drill center hole
3 Thread through this bolt with the washers held in place with thick springs.


I think I have that right. The springs hold the washers tight against the blanking space, but give you enough movement to rotate.

Alternatively, buy a Magic Snake and gut it!!

 

[rbeach84]

Center the hole in the 'cut' plane so when rotated, the ends line up properly. You could also use a pin & curved slot to limit the rotation to the correct angle.
R/ Robert

 

[IAmTheClayman]

I think you're overthinking the mechanism, What you want to achieve sounds a lot like the joint in the old "Magic Snake" toys

View attachment 510398

Each joint could rotate like you suggested

View attachment 510399

I'd make it like this.

1. Blank off each end of the pipe.
2. Drill center hole
3 Thread through this bolt with the washers held in place with thick springs.

View attachment 510400
I think I have that right. The springs hold the washers tight against the blanking space, but give you enough movement to rotate.

Alternatively, buy a Magic Snake and gut it!!

Center the hole in the 'cut' plane so when rotated, the ends line up properly. You could also use a pin & curved slot to limit the rotation to the correct angle.
R/ Robert

This is a great solution! Since I'm working with aluminum tubing I'll probably 3d print the blanks so they fit snug, but since they have to rotate exactly 180 degrees I'll probably use pins and grooves as opposed to a guide slot.


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[rbeach84]

Too bad you can't make it from solid billet so it has some real strength. Also, one other possibility is to use a sprung, pass-through steel cable instead of pivot bolts. You'd still want a 'locking' mechanism of some kind to keep it 'clicked' in place, but with the pins & grooves, you could limit the amount (and direction) of the 'twist stress' imparted to the cable.

R/ Robert

 

[IAmTheClayman]

Too bad you can't make it from solid billet so it has some real strength. Also, one other possibility is to use a sprung, pass-through steel cable instead of pivot bolts. You'd still want a 'locking' mechanism of some kind to keep it 'clicked' in place, but with the pins & grooves, you could limit the amount (and direction) of the 'twist stress' imparted to the cable.

R/ Robert

Yeah, unfortunately weight is an issue for the project I have in mind so billet would be a bit overkill


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