[TheForge] was cutting 1/4 copper now welders

[Grover Richardson]

Actually, my interest is work related.  We are doing some work with
arcs/plasma.  The gas is conductive and will provide a longer arc distance
than just air.  According to the manual, it will strike an arc easily, so
that would make sense with the higher Voltage startup.  As I remember, the
startup arc is ac.  So, essentially (it appears) an arc may be struck at
most any reasonable distance, and then the operator would move the electrode
into the proper working distance.

Me, I'm an old stick person, and never messed with a tig/mig before.  Except
for repairing a few.

The welder we are using, TIG, has a arc starting circuit which generates a
very nice spark plug type arc (bounces around and very thin), which
initializes the main arc.  I guess I need to look closely at the open
circuit Voltages.  I need to take the welder apart anyway, to get inside and
take some measurements.  Will make the startup measurements also.

I had warned my student about Voltages being dangerous, but now the warning
will be increased!!

Thanks.

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Steve Smith
Sent: Wednesday, April 13, 2005 9:47 PM
To: Sponsored by ABANA
Subject: Re: [TheForge] cutting 1/4 copper


On top of that you need a higher open circuit voltage to strike the arc. 
300V comes to mind, but I don't know where from.

Steve

Grover Richardson wrote:
> Hmmm.  140 VDC, 40 Amps.  That's enough to fry a monkey.  I didn't 
> know it was anywhere near that high.
> 
> -----Original Message-----
> From: theforge-bounces at mailman.qth.net 
> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Kevin D
> Sent: Wednesday, April 13, 2005 12:11 PM
> To: Sponsored by ABANA
> Subject: RE: [TheForge] cutting 1/4 copper
> 
> 
> Grover,
> 
> Just looked this up on; http://store.cyberweld.com/milspec625.html  
> for a MILLER SPECTRUM 625 PLASMA CUTTER
> 
> 
> Quick Specs: Spectrum 625
> Rated Cutting Capacity Rated: 1/2 in (13 mm)
> Quality: 5/8 in (16 mm)
> Sever: 7/8 in (22 mm)
> Rated Output 40 A at 140 VDC, 50% duty cycle at 40? C / 104? F Plasma 
> Gas Flow/Pressure 6 CFM at 75 PSI or 170L/min at 517 kPa Weight Net: 
> 57 lb (26
> kg)
> Ship: 60 lb (27 kg)
> 
> Kevin
>  
> 
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