Figuring Length of Tape Needed?

,

Helix

d = diameter of helix

l = lenght of one turn of helix

t = pitch, or rise in 1 turn

n = number of turns

pi^2 = 9.8696

Solve for:..................... Formula

lenght of one turn ...............sq.rt.(pi^2)d^2 + t^2

pitch or rise one turn t ........sq.rt.(l^2) - pi^2 d^2

Total lenght or nl....... ...............n[sq.rt.(pi^2 d^2 + t^2)]

Review the source formula

Reference:

http://www.cgmrc.com/Reference/Formulas.html

....And still the same area !! (without edges...)

GA. Simple and straightforward.

GA but use the OD of the pipe not the nominal diam.

I am embarrassed for asking such a dumb question. As I lay awake in my bed last night, I realized I was not dealing with a helix, but just a plain simple geometric problem. I am dealing with the area of a cylindrical surface and no matter how I wrap the tube, whether it be along the length as in cigarette paper, spirally non-overlapping lay or in rings 3" wide. It's the total surface area that matters. In all practicality, any method will use the same amount of tape.

A 10' tube 1" dia has a surface area of Pi x D x L or 377 sq in. A 3" wd tape, 10' lg covers 360 sq in, so it's a bit short, but not enough to be an issue. I was hoping to post this before anyone else read it and realized how dumb I was.

Guys our age have forgotten lots of things some would take for granted.

Civilizations our age have forgotten lots of things some would take for granted.

Not dumb at all. If it had been posted as one of those Newsletter Challenge Questions, the number of replies would run into hundreds.

I'm in meltdown pondering how much 'waste' there might be if the pipe had a few bends. It's easy enough to calculate for straight pipe, then consider the surface area once the whole thing is bent, but there must be an optimal angle of wrap for something like a toroidal shape.

Yeah, yeah, the tape will not lay flat on a toroid, but there must be a practical answer. I'll bid on a very high angle - one complete turn (+ that 3") for each time around the toroid.

So Del was right then!

The pipe's OD will work if the tape is thin, but if the tape is thickish, then the calculations should be done using the (OD+2 x tape thickness) which is the OD of the finished assembly.

Not the problem, but how about paint it? Plastic coat it? Treat/dip it? Whatever?

jt

Mary taught kindergarten. One day during the art lesson, she
was walking around looking at what the children were drawing
and, she stopped at little Maria's desk. Maria was hard at work.
Mary asked, "What are you drawing Maria?
"I'm just drawing God!" announced Maria.
Mary paused and then said, "But Maria, nobody knows what God looks like."
Without looking up, Maria replied, "Well, they will in a minute!"

Forget about the spiral. If you mark an imaginary line along the length you will clearly see that there are 10'/3" wraps ( read circumferences ).

My imaginary sharpie doesn't write on pipe
Del

Pipe ? !

You done done yoreself, and my very serious toroidal spiral wlll haunt you.

I notioce that nobody has figured how to wrap a toroid,

One of those hand held blenders is very good for 'instant mix'. Bugger if you leave it for a few hours. Dang thing was stood fair rigid.

Chickens - nobody has accepted how to wrap a toroid with maximum efficency.

So, how is the best way to wrap a strip[ arounmd a toroid.

Buy extra tape, and keep the receipt!

it is really confusing at 1-st

here's a wire length calculation for a coil from my excel spreadsheet

L_W = ²√[(N_T·D_R·¶)² + L_R²] = ²√(|AB|² + |BC|²) = |AC|
where
L_W = length of wire
N_T = number of turns i a coil
D_R = coil diameter from center to center of a wire
¶ = 4·arctan(1)rad
L_R = length of a coil
A
.
|\
| ·\
| · ·\
| · · ·\
|_____\
B · · · · C