[TowerTalk] Help with antenna

Jim Lux jimlux at earthlink.net
Wed Aug 24 18:59:55 EDT 2005


At 11:40 AM 8/24/2005, Larry Bush wrote:
>Cutting boards work fine. Been using for several years. Only
>drawback is, it does not machine very well.
>
>Larry , W5NCD

Cutting boards (the white ones) are usually High Density PolyEthylene 
(HDPE) or UHMW (Ultra High Molecular Weight) PE. You can look up the 
material properties at somewhere like http://www.matweb.com/ or any of a 
zillion plastics suppliers.

Real low friction (aka poor man's teflon), fairly good dielectric 
properties (somewhat lossy at HF and higher, compared to some other 
plastics) (It's great for HV DC insulators)

The real problem with using it is that the melting point is quite low, 
which makes for trouble machining, and if it's going to sit outside with a 
static load because it will ooze.

You need very, very sharp tools to work it, with the right (fairly 
aggressive) feed rates. You want to cut, not melt.  There are some 
techniques for setting up the cutting edges on your tools if you're 
obsessive, but the real key is sharp steel cutters, and making sure the 
chips get pulled away well and don't get mashed into the cut by the back 
side of the tool.



>----- Original Message -----
>From: "Jim Miller" <JimMiller at STL-OnLine.Net>
>To: "TOWERTALK" <TOWERTALK at contesting.com>; <n8de at thepoint.net>
>Sent: Wednesday, August 24, 2005 9:51 AM
>Subject: Re: [TowerTalk] Help with antenna
>
>
> > What about the stuff they use for standard cutting boards now?
> > It is cheap
> > and looks like it would just fine.  I just bought a small one
> > to cut up and
> > test for strength but haven't gotten that far yet.  Has anyone
> > used this
> > stuff and how did it work or why isn't it a  idea to use it?
> >
> > 73, de Jim KG0KP




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