Re: Re: Rubber cross-section

From: William Gowen <wdgowen_at_gmail.com>
Date: Tue, 17 Sep 2013 15:33:01 -0400

First let me say that this discussion has gone in a direction I didn't
intend. My original statement was intended to say that telling another
person the width motor that you're using doesn't convey much in the way of
useful information. By the same token asking another person what width
motor they're using is not going to be very helpful to your own efforts to
understand what they are doing. What's important is length and weight and
how you arrive at those parameters can certainly be done many different
ways.

To answer Gary's question I usually cut 2 or 3 one inch pieces from my
unstripped rubber, make a trial cut of one of them with my stripper and
weigh the cut piece. If it's not what I want I make an adjustment to the
stripper and try again. When I get a piece that I consider correct I'll
usually do another trial cut using a 2" piece. If that looks good then I'll
cut a piece a little longer than the motor length I want and use the cut
piece to make a motor. I don't use anything to measure the width of the
strip at any point in the process.

After doing things this way for a couple of years I actually don't know how
wide any of my motors are. If you ask me about motor width and you get kind
of a blank stare from me then that's the reason.

This is the method I use and it's what I'm comfortable with. It's like a
lot of other techniques used in indoor building and flying - there are lots
of ways to accomplish any given task and you just have to decide what makes
sense to you and what gives you the outcome that you are looking for.
On Sep 17, 2013 1:44 PM, <Warthodson_at_aol.com> wrote:

> **
>
>
> Bill, Mike or anyone,
> But the catch-22 is that first you must *accurately* measure the width of
> the strip, then *accurately* set your slicer to cut a specific width in
> order to end up with a specific weight loop!
> For the sake of this discussion, assume there is no max. motor weight
> requirement & you wanted a loop weight of 1 gram, what tolerance would you
> consider acceptable?
> How many test cuts do you usually need when trying to cut a new width
> strip? I would say it typically takes me at least 3 short test strips.
> Gary H
>
>
> From: William Gowen wdgowen_at_gmail.com
>
> So you calculate the density of your 1/8" rubber and then calculate the
> strip width based on the density. I rest my case.
>
> On 9/17/2013 10:50 AM, mkirda_at_sbcglobal.net wrote:
>
>
> Here is an example for F1L.
>
> Find the loop length that you want. Cut a bit of rubber to be the length
> plus 2 inches.
>
> i.e. 14" loop, cut (14+1)*2 = 30 inch length = 15" doubled.
>
> Measure the width of the rubber with micrometer - i.e. 0.128"
>
> Weigh the length of rubber. i.e. 2.54 grams.
>
> You decide you want the rubber to weight 1 gram exactly.
>
> Here is the math:
>
> 1/2.54 * (15/14) * 0.128 = .05399
>
> Strip it to 0.054" and you when you tie off a 14" loop it should be
> precisely 1 gram.
>
>
> I set up the spreadsheet to have only 1" additional length, but the math
> above is the same.
>
> If anyone has problems with this, I will define variables and post the
> math that way.
>
> Regards.
>
> Mike Kirda
>
>
>
>
Received on Tue Sep 17 2013 - 12:33:02 CEST