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Posted

'elp me 'elp me! how do you figure the curvature for the top and bottom of a tapered tube so that when the ends of a flat piece are put together to make the tapered tube they look straight?!?! ack! brain... hurts! the top has to be 24" around and the bottom 17 1/2".

frissenfrassenmussafrussen...

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Posted
'elp me 'elp me! how do you figure the curvature for the top and bottom of a tapered tube so that when the ends of a flat piece are put together to make the tapered tube they look straight?!?! ack! brain... hurts! the top has to be 24" around and the bottom 17 1/2".

Drac:

If I am correct, is this what you want to do: take a flat piece & make it conform to a tapered cylinder with the top & the bottom having the correct curvature so that when made into a cylinder everything lines up?

You can do it scientifically by using specially designed CAD programs, slide rules or asking your genius friends if they could help you.

Or you can do it the common sense way (which, btw, doesn't always work).

Take a tapered cylinder

wrap paper around it & fasten (temporarily) with tape

trim the top

trim the bottom

draw the seam line

use exacto knife to cut along the seam (cutting both layers of paper)

unfurl & you have your pattern (allow extra for the thickness of leather)

If this is NOT what you're trying to do, sorry, my bad! :dunno:

russ

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Posted

Your pattern will be a trapezoid. The long side will be equal to the circumfrence of the large hole and the short side equal to the

circumfrence of the small hole. The distance between will be the length of the tube. Your cut seam will be made by drawing

a line connecting the ends of these lines on each side.

('suppose that's a clear as mud :) )

Posted

whinewine

that's pretty much what I wanna do. I'm a computard though so the programs won't work for me and as for genius friends, that's what this forum's for, right? *L* I'd use the "wrap around something" method but don't have anything that coresponds to the correct size. never had a prob with that method so far as long as whatever was wrapped was the correct size/shape.

hedge

yeah, that's the idea, but I need to know how to figure out the circumference size for the circles so that everything is level once cut. therein lies the rub.

frissenfrassenmussafrussen...

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Posted (edited)

C = 3.14159 x dia.

(but you already have the measurements you need. 24" and 17 1/2"...right? )

whinewine

that's pretty much what I wanna do. I'm a computard though so the programs won't work for me and as for genius friends, that's what this forum's for, right? *L* I'd use the "wrap around something" method but don't have anything that coresponds to the correct size. never had a prob with that method so far as long as whatever was wrapped was the correct size/shape.

hedge

yeah, that's the idea, but I need to know how to figure out the circumference size for the circles so that everything is level once cut. therein lies the rub.

Edited by Hedge
Posted

hedge

hmmm... methinks I probably wasn't clear enough on the bit that I need. if you lay a properly done gauntlet flat for example, the top and bottom are curved. I need to know how to figure the size of those curves.

frissenfrassenmussafrussen...

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Posted

Ahhh!! Now, I see what you're talking about. Hmmmm...I've never done that execept by eyeball. Not even sure there's a 'standard' curve

to apply. Sorry, Drac. That one's beyond my ken. :unsure:

hedge

hmmm... methinks I probably wasn't clear enough on the bit that I need. if you lay a properly done gauntlet flat for example, the top and bottom are curved. I need to know how to figure the size of those curves.

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Posted

Drac:

I think what you're gonna need to do is build an actual model. Get, or make, a hoop of the top dimension & do likewise, for the bottom. Find the corresponding height & attach connecting rods, fastened on angles (they will be longer than the height, because they go from the longer hoop on an angle to the shorter hoop- does this make sense?)...

If you can construct a model from styrofoam, in sections, using an electric knife, or a lathe-type of arrangement, where you can turn down the styrofoam to the appropriate dimensions, would work...if you want to go to all that trouble... the wraparound method is probably the most sure method of doing what you want.

good luck.

russ

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Posted

Good show! For some reason I got it in my mind he wanted an angle on the openings.

(not good at multi-tasking...like breathing and thinking at the same time! :rolleyes: )

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