RE: construction materials

["David Dean" <deano-at-corridor-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Michael,

G-10 is available from McMaster-Carr as well as many good plastics
suppliers.
I got some from a company called Regal Plastics a couple of years ago but
they
no longer stock it. You just have to keep calling around. If you can find
someone
close by who keeps it in stock and cuts to size, you may be able to find a
scrap
or two suitable for your needs at a reduced price.

As so the stand, motor mounts, etc. it is hard to beat steel. My newest SRSG
has
a frame made of 1 1/2" X 1 1/2" X 1/4" angle iron with a 1/4" thick steel
plate
for the motor mount. This plate has slots milled in it to allow adjustment
of the
motor position and setting gap distance.

As for the electrodes, brass is a poor choice. I used that because I had
some on hand,
and was in a hurry to get the thing running. The brass tends to erode rather
quickly.
This produces a lot of metallic ions and I have had some problems with
flashover to the
primary, and when the metal explosion shield is in place it has a tendency
to power arc
to the shield. I used tungsten electrodes on my previous SRSG and had
neither of those
problems. That gap used 1/8" tungsten electrodes cut from TIG welding
electrodes set
into brass holders. Worked fine at lower power levels, and a 7" long stick
of tungsten
only costs $7 or so. At higher power levels, it burned up rather quickly due
to the
lack of heat dissipation. If I adjusted the gap to provide less stick out,
hence better
cooling, the sparks would start out on the brass holders and then climb up
the tungsten
electrodes. This made for some problems with varying dwell and timing
between bangs.
If you are running at 1.5KVA or less then 1/8" tungsten is probably OK. At
higher power
levels more massive electrodes are indicated. Pure copper works fairly well
in place of
tungsten, better than brass at least. One of the simplest, cheapest ways,
and one that
has been used by others, I have not tried it myself, is to use copper bolts
as electrodes.
Copper bolts can be had, again, from McMaster-Carr. They are called "silicon
bronze", BTW.
You won't find a listing for "copper" bolts.

As to the Rotozip, I can't help you there.

later
deano



> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Monday, August 14, 2000 8:49 AM
> To: tesla-at-pupman-dot-com
> Subject: construction materials
>
>
> Original poster: "acmnovak" <acmnovak-at-email.msn-dot-com>
>
> Hello everyone,
>
> I'm rounding up parts for my next coil, which will utilize a sync
> rotary gap.
> As for the rotary, I've seen some really 'different' materials used. I was
> wondering where one might purchase g-10, or bakelite. I'd like to use G-10
> for my disk, and bakelite for my motor mounts. Has anyone ever tried using
> hardwood for the stand? I'm trying to make a stand as rigid and sturdy as
> possible. I was looking for lexan earlier this year, and could
> only find it
> in the form of cutting boards. as suggested, Ilooked in the yellow ages
> under plastics and such, but the results weren't too promising. I called
> the place that does windows and whatnot, and they wanted about $5/sq ft of
> 1/4" plexi. Is that steep or am I just really cheap?
> Also, what kind of electrodes are best? I've seen some nice tungsten
> electrodes, but aparently they are hard to machine, and quite expensive.
> However, I was leaning more towards brass. Does this stand up well to TC
> abuse? I have some big pieces of brass (3/4" x 6-8") which have a
> porcelain
> collar. they came from an old a/c unit with a HUGE current draw. I've used
> them as high current contacts and they are showing some signs of decay...
> Is this comparable to how it will perform in a rotary as the stationary
> electrode?
>
> A while back, I heard someone say that a rotozip tool was a "must
> have" for
> any serious coiler... so I bought one :þ Is it true that they can cut
> through steel? I tried aluminum, and had no problems, but steel may be an
> entirely different story. The main reason I bought it was, I needed
> something to make clean cuts in lexan, and a decent band saw is well above
> my price range. My table saw always sucked the plastic towards the blade
> and made a jagged cut. The rotozip cuts it perfectly when I used
> a level as
> a clamp on fence. Anyhow, I need to know whether or not it can handle
> steel, because I might try and use it to take of an NST casing. I'd just
> use an angle grinder, but the MMC bulk buy will be approaching soon and I
> can't afford it.
> Also, are these rotozip saw suitable for cutting G-10 or bakelite?
>
> Thanks,
>
>     -Michael
>
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