As I am not as experienced as most of you guys please humor me for a moment. I am trying to wind cork tape around the butt of a surf rod blank. The blank is 7/8" at the butt and tapers to about 9/16" at the point just behind the reel seat. The distance from the butt to the rear of the seat is 23". Is there any formula for telling me how long of a section of cork tape I need so I can cut off that amount and not have to work the whole roll? Plus any formula of what angle to lay the tape on at? The tape is adhesive on the back side and I am having trouble getting the angle right. Also should I wrap from the butt towards where the reel seat is going to be or the other direction? Thanks for any advice.

Ed,

A simple way to do it is to take low tack blue masking tape and just use tape to both experiment with and to also get the measurement needed. Select tape that is the same width as the cork tape and depending on whether you plan to overlap the cork or to simply wrap the cork so that the previous wrap just touches the next wrap - wrap the tape on the same way.

When you get the layout the way that you want - peel off the tape and measure it. Then, cut off an extra foot or cork or so and rewrap the blank using the cork.

Good luck

p.s.
I think that no matter the direction you wrap, you should have something handy so that for both short and long term use; you have something to secure the ends of the cork wrap so that the cork does not want to unwrap from the rod.

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Edited 1 time(s). Last edit at 05/14/2015 10:41AM by roger wilson.

Thanks. It never occured to me just to do a trial with tape. Duh! Still wonder if there is a formula.

As a general rule, multiply the length of the grip by 3 and you should be good to go.

I use the blue painters tape to get the diameter of the blank where my cork tape wrap starts. I then use that piece laid on the cork tape to get my angle for the wrap. I lay the blue tape at an angle starting at the corner of the end of the cork tape. that corner to where the blue tape end lays on the opposite side gives the angle of the wrap. This probably doesn't make as much sense as just seeing it done. I start at the reel seat (not really sure it matters though). I put a little bit of rubber cement on the blank as I go to help with adhesion. Once I start the wrap, I put painters tape around the beginning to hold the little pointy end of the cork down. I finish the cork tape wrap at the butt where the butt cap will cover it. I again use blue painters tape to hold the end until it sets up. The length times 3 seems to be a good rule on the length of cork tape needed.

Wrap a piece of stiff paper around the blank behind the seat and mark at the overlap. I usually add 1/8" lay the paper across the cork tape so the mark is on one edge and the corner of the paper is on the other edge mark that angle and cut it. That should give you a good angle to work with

Wrap a piece of stiff paper around the blank behind the seat and mark at the overlap. I usually add 1/8" lay the paper across the cork tape so the mark is on one edge and the corner of the paper is on the other edge mark that angle and cut it. That should give you a good angle to work with

Short answer - yes, you can calculate the length.

Long answer - here's the equations (note that I can't use standard math text in this forum so it may be a bit inelegant to read)

The conical spiral with angular frequency a on a cone of height h and radius r is a space curve given by the parametric equations

x = [(h-z)/h] r cos (a z)
y = [(h-z)/h] r sin (a z)
z = z.

The general form has parametric equations

x = t r cos (a t)
y = t r sin (a t)
z = t.

This curve has arc length function, curvature, and torsion given by

s(t) = 1/2 t sqrt[1 + r^2 (1+ a^2 ^2)] + [(1 + r^2) / 2 a r] sin h (-1) [a r t / sqrt(1 + r^2)]
k(t) = a r sqrt[4 + a^2 t^2 + r^2 (2 + a^2 t^2)]^2 / [1 + r^2 (1 + a^2 t^2)]^3/2
"contour integral of" (t) = a (6 + a^2 t^2) / [4 + a^2 t^2 + r^2 (2 + a^2 t^2)]^2

Or, as Roger suggests the KISS method - you wrap the blank with tape of the same width, then pull it off and measure it. ;-)

Typical engineer. ;-)

Just typical?

;-)

Just typical because you didn't create a table with a range of tape widths and solve the equation for length. You could have then created a nomograph to simplify the calculation for all possible combinations of tape widths, and radii along a cone. ;-)



Edited 2 time(s). Last edit at 05/15/2015 03:18PM by Steve Hartzell.