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Re: Help identifying material

Original poster: BunnyKiller <bunnikillr@xxxxxxx>

Hey Michael....

considering the overall design description of your box ( wood and some black stufff) I am willing to bet it is Bakelite ( Leeds & Northrop was basically a 1950-70 era company...Bakelite was kewl then).

Bakelite is consistant in color throughout the material, it is a "cast" resin thermoset plastic with fillers ( once heated it is cured hard, you cant remelt it). Your presumption of it being brittle is correct, it does shatter, crack easily when machined with "standard" home tooling.

If you want something to "look" as close to bakelite as possible, I would consider black acetyl ( also called delrin IIRC) plastic. Altho it doesnt take on that "polished" look fresh bakelite has when new, it is easy to machine, but leaves a "fuzzy" finish to it if machined. If you can do minimal machine work to the surface, the "virgin" surface is relativitly "sheeny" ( not shiny but not dull more like "aged" bakelite). Fresh bakelite designed for eletrical use is near black but takes on a brown color when aged or machined. Here's the caviat... black acetyl isn't as insulative as Bakelite... so consider the voltages you are wanting to impose upon the material....

Garolite in colors are completely thru ( I had some blue Garolite and it was colored thru). The problem with Garolite ( colored) is that you can see the fiber matrix in the resin base. Machining Garolite ( especially G-10) leaves a "fuzzy" edge where it has been cut. And , yes Garolite is a real pain to machine ... especially the glass filled version. Now mind you, "Garolite" comes in different "fiber matrix" configurations.... paper,cloth, linen, glass... each one becoming more stiff, durable and harder to machine...

as far as availability... my first choice would be McMaster Carr.. ( I love that place) but it is expensive when it comes to "engineering plastics" and to be honest with you I havent seen any dealers lately who handle Bakelite ( too expensive to make it compared to other options and progress marches on...). but I wouldnt give up... do a search for bakelite and see if there are any providers of the material.... you might get lucky and find a source if you want to get an exact replacement.

hope this helped

Scot D

Tesla list wrote:

Original poster: "Michael Doyle" <msdoyle@xxxxxxxxxxx>

I have a pair of Leeds & Northup resistance boxes in which I plan to use
the wooden box portion to house some of the components of a small coil I
am building. The actual functional components of these boxes are mounted
on a 1/2 inch slab of black material screwed to the top of the wooden
boxes. I was wondering if anyone knew what this material is so that I
can recreate the look of the boxes without damaging the existing boards.
I have heard it referred to as bakelite or phenolic but the experience
that I have with either of those materials is that they are hard and
brittle and do not machine well. I see that some grades of garolite are
available in black but not sure if the color/finish goes all the way
through the material and I know it is hard to machine. I considered
using a black delrin but cannot find any locally. Any help would be
appreciated I have only basic tools no lathe or mill so tips or comments
on machinability and finish of the material would be great.

Michael Doyle