[TowerTalk] [Bulk] Re: Black UHMW ?

[Grant Saviers]

Good question.  Static control UHMW has carbon black as a filler so it 
is probably a bad choice.  Black virgin UHMW that I bought is FDA and 
USDA approved, so I think it is unlikely that the coloring agent will 
cause a problem.  As an element insulator block or insert it should work 
fine since the voltage stress is low.  However, note that it has a low 
creep resistance so don't use it as a boom plate.

It is easy to cut with saws, but I find it unpleasant for machining 
since it is so slippery, gummy, and springy.  It's very hard to hold any 
close tolerances.  Acetal/Delrin, ABS, and nylon are much easier to work 
with.  A twist drill needs to have the edged stoned flat a bit or it 
augers in, badly on UHMW but also for brass and some other plastics.

Some white UHMW thrust+radial mast bearings for 3" mast came with some 
beams I purchased.  After 7 years exposure they did show deep crazing 
but were still solid.  That is why I am going with black.

There is always the stick it in the microwave and see how fast it melts 
test, although a bit of overkill for HF.

Grant KZ1W


On 8/15/2014 3:47 PM, Chuck Smallhouse wrote:
> The idea of using a chunk of black UHMW bored out for a bearing sounds 
> interesting.  I fell in love with UHMW, when I HB'd a full coverage 
> skid plate for my UTV, of the stuff.  It was very easy to work with 
> (cut with a band or sabre saw), tough as nails and didn't dent or take 
> a permanent set.  I understand that they use it to line the beds of 
> garbage trucks ?
>
> My question is the black version at all conductive ?  I'm considering 
> using scrap pieces of it, cut into plates, to mount yagi elements to 
> their boom ?   Someone mentioned that the white variety can 
> deteriorate, when exposed to UV ?
>
> BTW,  the use of a basketball hoop attached to a gin pole, to be of an 
> aid in raising tall items, like a pole vertical to the  top of a 
> tower, or even small tower sections such as Rohn 25, is a terrific 
> idea.  This is now added to my R & C  notebook (Research & Copy) !   I 
> need to start visiting garage sales to find a used one.
>
> Chuck,  W7CS
>
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