[TowerTalk] center insulator material

[jimlux]

On 2/8/20 8:57 AM, charlie carroll wrote:
> I need some help selecting some type of material to build some custom 
> center insulators.  I have what approaches zero experience in this area.
> 
> The insulators will be used to support near vertical dipoles for 
> 160-meters.  The antennas will be installed in the Caribbean and will 
> need high resistance to UV and salt water.  I also want to install an 
> SO-239 and home made common-mode choke on the insulator.  It would be 
> preferable that I be able to fabricate the final shape with common home 
> workshop tools and not have to rely on a machine shop.  The insulators 
> won't be under a lot of tension because of their orientation, but low 
> weight material would be preferred.  The insulators may be subject to 
> some winds containing sand particles.
> 
> I'm looking for some help selecting some appropriate material (UHMW, 
> Ultem, UV augmented HDPE, ...) that I can investigate further.
> 

Most any UV resistant plastic would work. The shape is almost 
immaterial, you can get flat bar stock, drill holes, and be done.

http://www.sdplastics.com/ultravioletresistance.html has a bunch of info.

I've used Acetal Copolymer (aka Delrin) with UV inhibitors. There's 
decades of experience with it. Ultem is very good (we use it on 
spacecraft), but probably costs more than what you want.

Looking at the McMaster Carr catalog, i see they they have a VHMW 
Polyethylene which is weather resistant.  I'm not sure that I'd use PE 
though.


Speaking of machine shops - you might look at one of the prototyping 
companies like First Cut Protolabs: 
https://www.protolabs.com/services/cnc-machining/ - there's a fair 
number of these places around, and they typically stock all the useful 
materials, and will turn it around in a few days.