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Re: [TowerTalk] More friction needed

To: john@kk9a.com
Subject: Re: [TowerTalk] More friction needed
From: Richard Karlquist <richard@karlquist.com>
Date: Tue, 08 Nov 2022 14:29:02 -0800
List-post: <mailto:towertalk@contesting.com>
I have one of the K7NV clamps, which is on my K7NV prop-pitch.   

I agree that Kurt's passing was a great loss to us, but as far as  this 

clamp is concerned, it is possibly "too brilliant ... by half".  The
trouble 

is that the target mast must be: 

1.  Perfectly smooth. 

2.  Have excellent "circularity", as opposed to "eccentricity". 

3.  Have a diameter very close to 2.000 inches. 

or else it may only sort of work, but not as well as you might think. 

There is a certain amount of "luck" in meeting these requirements. 

Then there is "physics": 

Static Friction (IE "stiction") is a function of total clamping 

pressure, period.  Having a lot of area doesn't help.  In defense 

of the K7NV clamp, it is designed to have multiple clamping bolts, 

so we can count the combined clamping pressure of the N bolts. 

More physics:  read up on cylinder head bolt design and the need 

for the head bolts to be elastic.  Inelastic U-clamp bolts deform 

the clamp instead of stretching. 

If your K7NV clamp works really well, then I am happy for 

you ... that you were lucky, or maybe you tightened it with a 

24 inch breaker bar.   

I will also say that it is way better than the M2 clamp (also own 

one of those). 

---
Rick Karlquist
N6RK 

On 2022-11-08 13:46, john@kk9a.com wrote:

> I don't think adding a friction material will help. There are better mast
> clamp designs out there.  K7NV(sk) came up with a brilliant idea of clamping
> a round mast using a round clamp (imagine that). I thought that you also
> manufactured a replacement clamp that used u-bolts which could be properly
> tightened and remain tight.
> 
> John KK9A
> 
> k7lxc wrote:
> 
> Howdy, TowerTalkians -
> I need more friction between an M2 mast clamp and the mast. How could I
> do that? What materials would work? Tnx. Cheers,Steve      K7LXCCell:
> 206-890-4188
> 
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