Re: AW: [TCML] Coil pic w/ SRSG

[Gary Lau <glau1024@xxxxxxxxx>]

I cut my tungsten rod using a Dremel tool and the cheap brown (~1" dia,
fragile) cutting disks.  It chewed through the disks pretty quickly, but
ultimately the disks did the job.  I think I finished the job by putting the
cut rod segments in a drill press (any drill would do) and grinding the ends
flat with some other Dremel tool grinding bit.

Are your rods tungsten (welding rods), or tungsten carbide?  I'm not sure
that tungsten carbide comes in rod stock, but could be mistaken.

How do you make a secure electrical/mechanical connection between your
rotating rod segments and the copper ring?  Bear in mind that the current
through the gap peaks at hundreds of Amps, so I'm thinking you need more
than the casual pressure afforded by having the collars snug against the
disk and ring.  I honestly don't know how others make that connection; I
just sidestepped that issue by using a propeller gap.

Regards, Gary Lau
MA, USA

On Mon, Jul 5, 2010 at 1:52 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx> wrote:

> I agree about the long (2") electrodes.  I couldn't get them shorter from
> McMaster Carr.
> So I figured I'd get the 2" long ones and cut them.
> Then I figured out I didn't know how to cut tungsten.  I mean - don't you
> need something harder than  tungsten carbide to cut tungsten carbide?
> Rather than shattering the electrodes, I just put them in as is for now,
> but I do need to cut them in the final build.
> Any advice on cutting tungsten rod would be much appreciated - I mean, if
> the answer is using a hacksaw and a bi-metal blade, I'll just do that...;-)
> Joe
>
>
> On Jul 5, 2010, at 2:09 AM, Fritz W. Egli wrote:
>
> > May I succest that you mount a protecting shield over the (long ...)
> > rotating electrodes - ? There is some leverage, some centrifugal force at
> > speed.
> > Perhaps you can also shorten the electrodes.
> > Opinion, succestion of a mechanic.
> > Kind regards, Fritz W. Egli
> >
> > -----Ursprüngliche Nachricht-----
> > Von: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] Im
> Auftrag
> > von Joe Mastroianni
> > Gesendet: Montag, 5. Juli 2010 02:11
> > An: Tesla Coil Mailing List
> > Betreff: [TCML] Coil pic w/ SRSG
> >
> > Pics of Coil v1.2 -
> >
> > New 30ga 22" secondary - wound by Dan M....  New Toroid, bought at
> > amazing1.com
> >
> > 3 deck MMC - each w / 18 series  CDE 942C20p15K-F (each shorted with 10M
> > 1/2W resistor).   Same Terry filter.
> >
> > Sync motor acquired from Alan in Mn, with 4" garolite wheel.   Inserted 4
> 2"
> > tungsten rods with collars into the garolite.  I actually also acquired
> from
> > mota.com a 1/30 hp sync reaction motor (oriental motor) upon which I
> will
> > base my next attempt at an SRSG - but Alan's motor came with a mandrel
> and
> > so made it easier.  Cut a copper disk and epoxied it to the back of the
> > garolite disk to short out the tungsten rods.   If anyone has any methods
> > for cutting copper sheet other than using a metal nibbler and filing your
> > brains out, do let me know.
> >
> > Gaps are about 1/16".   As it turned out, I didn't have to move the
> > insulators upon which I mounted the stationery tungsten gap rods I had
> been
> > using for my static gap.   I merely rotated them 90 degrees to point to
> the
> > rotor and used taller insulators.  So I also left my squirrel cage fan,
> > which I'm hoping doesn't hurt anything.
> >
> > I now don't have to have the variac voltage very much more than 1/2 to
> get
> > breakout.  I've tried adjusting the phase, but once you've got the disk
> > dwell dialed in, the phase adjustment is kind of tweakage to get max
> spark
> > length (I have found - may be doing it wrong).
> >
> > Will take pictures/video of the coil running as well.
> >
> > http://yfrog.com/emfcj  is the start of the 3 pic series.  Only iPhone
> > pictures (don't own an actual camera...have to get one.)
> >
> > Cheers and thanks for everyone's great help, especially John and Gary!
> >
> > Best to all,
> > Joe
> >
> > _______________________________________________
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