I think the potential problem in my version of this technique is whether you're going to damage the working part of the rubber when you move the first knot to the end of the strip. I've never felt like this caused a problem until I realized that I get a large number of breaks in front of the knot - in other words where the first knot was tied and then moved. I don't really know if I'm damaging the rubber, but changing the knot has given me higher breaking torques than I'm accustomed to. This could also be from implementing Fred's winding instructions in an earlier post.
Mark has told me to keep the motor stretched for 50% of the turns (correct Mark?) and Fred said the same thing. I've been a little bit chicken about doing this and usually start relaxing the motor earlier. My better results might be better technique, a better knot or just luck. I don't really care which as long as it holds up in the future!
----- Original Message -----
From: LeRoy C Cordes
To: Indoor_Construction_at_yahoogroups.com
Sent: Saturday, April 28, 2007 10:13 AM
Subject: Re: [Indoor_Construction] Making motors to weight...
Bill that is the same technique I use although for larger motors mostly -
I go to 1/8" occasionally. When I started I tried a number of different
knot styles, including tying the ends with thread or using a drop of CA
on the ends, and finally settled on the double overhand knot. I began
being very careful to reverse the direction of the separate knots and
since have given up worrying about it all and I don't think I've ever had
a knot come loose. It is important to lubricate the knot area liberally
before pulling on the knots - I find that a liberal dose of saliva does a
fine job (In other words just spit on it ! <G>)
LeRoy Cordes
AMA 16974
Chicago, IL
In God We Trust
On Fri, 27 Apr 2007 15:21:07 -0400 "Bill Gowen" <b.gowen_at_earthlink.net>
writes:
> I maybe misunderstood this technique when it was first described, but
> I do it a little bit different. There is a possible disadvantage in
> that the rubber is subjected to more stress.
>
> Lube the untied strip and put 2 o-rings on.
> Cut the strip to the exact weight that you're looking for.
> Tie one overhand knot as close to end as possible and pull tight.
> Move this knot as close to the end of the motor as you dare by
> pulling the strands apart inside of the knot.
> Tie a second overhand knot inside of the first one and pull fairly
> tight.
> Pull the second knot into the first one.
>
> I don't reverse the second knot and my knots don't come loose. I
> don't fly F1D so can't say how well this would work for F1D motors
> that are stressed to 99.9% of maximum.
>
> ----- Original Message -----
> From: Fred Tellier
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Friday, April 27, 2007 1:52 PM
> Subject: Re: [Indoor_Construction] Making motors to weight...
>
>
> Its called the double overhand knot, the advantage is that you can
> adjust the weight by tying a second knot and cutting off the old
> one, in fact you can tie only 1/2 knot if only a little over. The
> trick is reversing the direction of the knots so they lock together,
> the motor can be tied with lube applied and no CA is needed on the
> knot.
> Check this link http://cloudbustermac.tripod.com/knot-page.htm
>
> Fred Tellier
>
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>
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> [Non-text portions of this message have been removed]
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>
> Yahoo! Groups Links
>
>
>
>
>
LeRoy Cordes
AMA 16974
Chicago, IL
In God We Trust
[Non-text portions of this message have been removed]
Received on Sat Apr 28 2007 - 08:44:07 CEST