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In a message dated 00-05-19 05:01:08 EDT, SHogarth@pactiv.com writes:

<< Subj: OT:Linear length of material on a roll

Date: 00-05-19 05:01:08 EDT

From: SHogarth@pactiv.com

Sender: owner-rp-ml@ltk.hut.fi

To: rp-ml@ltk.hut.fi

I need to know the linear length of material I have on a roll. I know the

ID and OD and the thickness of the material, can someone supply the

formula I need.

Thanks in advance

Stuart Hogarth

Pactiv (UK) Ltd

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Hi:

I couldn't recall the formula, but we used it a lot years ago when I was

working on tape equipment. A quick perusal of the net turned up "Ask Dr.

Math's Site":

http://www.forum.swarthmore.edu/dr.math/problems/d14now.6.21.96.html

Here's the answer to someone's similar question:

------

Date: 6/22/96 at 11:37:6

From: Doctor Anthony

Subject: Re: calculating material length on roll

The area of cross-section of the roll can be expressed in two ways.

When stretched out in a straight line it is a rectangle of area L*T

where L is the length in inches, and T the thickness viewed edge on.

When rolled on the drum, this same cross-section will be pi*R^2 - pi*

r^2 where R = outer radius =(D/2), and r = inner radius (=C/2)

So we have L*T = pi{D^2/4 - C^2/4}

L = pi/(4T){D^2 - C^2} inches

Length = pi/(48T){D^2 - C^2} feet

= (0.06545/T){D^2 - C^2) feet (T,D and C in inches)

Try this in real life. It will be sensitive to the value of T you

use, so measure that carefully.

-Doctor Anthony, The Math Forum

Check out our web site! http://forum.swarthmore.edu/dr.math/

------

I checked the last equation for the heck of it against an 1800 ft roll of

tape here and it came out exactly, showing that the roll is a little longer

than the indicated length and by about the right amount. Also keep in mind

that tension can cause a material to stretch and the cross section to

decrease enough to affect the results.

Have fun!

Ed Grenda

Castle Island Co.

19 Pondview Road

Arlington, MA 02474 USA

781-646-6280 (voice or fax)

EdGrenda@aol.com (email)

http://home.att.net/~castleisland/

For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/

**Next message:**rayt@indy.net: "keltool"**Previous message:**Alain BERNARD: "Re: 3D-Laser Scanner"**Maybe in reply to:**SHogarth@pactiv.com: "OT:Linear length of material on a roll"**Next in thread:**Scott Nelson: "Re: OT:Linear length of material on a roll"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

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