Robert Bodell wrote:

I built a homemade AC/DC welder. I used some big 400 amp 250 volt
diodes for the full wave bridge to get the DC.
http://www.geocities.com/robert_bodell/welder.html

It welds with a 1/16 to 5/32 rod fine and does stainless great too

I heard that there was plans someplace that you could use an arc to
get the HF necessary to weld aluminum with.

You really need AC to weld aluminum. Do you have a TIG torch? There's
no way to weld aluminum without it, unless you do it in a glove box
filled with argon.


I am not sure of this is before the transformer, after the transformer
and before the diodes or after the diodes and in the welding leads.


There are ways to add an HF system to a stick welder. Basically, you build
a heavy-duty Tesla coil, with a neon sign transformer, spark gaps and an
air-core resonant transformer. The secondary of the transformer is just
a few
turns of welding cable around the Tesla coil. There should be plans
somewhere
on the net for such a thing. If you are not very competent with REALLY
dangerous electrical gear, this could be a real hazard. It also will
likely wipe
out any TV or radio reception for blocks.

Jon

In article , Robert Bodell
wrote:

I built a homemade AC/DC welder. I used some big 400 amp 250 volt
diodes for the full wave bridge to get the DC.
http://www.geocities.com/robert_bodell/welder.html

It welds with a 1/16 to 5/32 rod fine and does stainless great too

I heard that there was plans someplace that you could use an arc to
get the HF necessary to weld aluminum with.

I am not sure of this is before the transformer, after the transformer
and before the diodes or after the diodes and in the welding leads.

Is there somebody here that could explain how that is built or guide
me to the plans?

thanks a bunch in advance.

Please reply to the group and send a copy to rbodell AT tampabay DOT
rr DOT com so I am sure to get it. I don't want to miss this.
Bob


Just hook up a readywelder spoolgun to your buzzbox to MIG weld
aluminum easily.

www.readywelder.com

The model 10250 is the one you want.

Jon Elson wrote in message ...
Robert Bodell wrote:

I built a homemade AC/DC welder. I used some big 400 amp 250 volt
diodes for the full wave bridge to get the DC.
http://www.geocities.com/robert_bodell/welder.html

It welds with a 1/16 to 5/32 rod fine and does stainless great too

I heard that there was plans someplace that you could use an arc to
get the HF necessary to weld aluminum with.

You really need AC to weld aluminum. Do you have a TIG torch? There's
no way to weld aluminum without it, unless you do it in a glove box
filled with argon.


I am not sure of this is before the transformer, after the transformer
and before the diodes or after the diodes and in the welding leads.


There is a forum attached to www.diywelder.com. Several posters have
built these things. In fact, there is a recent post with a neon sign
transformer shown in photos (you have to register to see the photos).

The HF setup is after the transformer and after the diodes. It is
also after the DC welder choke. These kind of help with the arc
stability. A capacitor is placed across the leads, and a large coil
of heavy wire is placed in series after the capacitor. This coil is
coupled to a coil of thinner wire, which is excited with a resonant
spark gap oscillator. The oscillator is powered by a low frequency AC
or a DC power source, and looks a lot like the primary circuit of a
Tesla coil.


There are ways to add an HF system to a stick welder. Basically, you build
a heavy-duty Tesla coil, with a neon sign transformer, spark gaps and an
air-core resonant transformer. The secondary of the transformer is just
a few
turns of welding cable around the Tesla coil. There should be plans
somewhere
on the net for such a thing. If you are not very competent with REALLY
dangerous electrical gear, this could be a real hazard. It also will
likely wipe
out any TV or radio reception for blocks.


Not too bad. I can think of a lot more dangerous electrical gear.
There have been some recent posts on the above mentioned group by
someone who claimed to get a working stabilizer with several
milliwatts of HF. Commercial units like the Miller use about 100
watts, and as a result, the primary circuit poses a shock hazard.
Microwave ovens, large capacitor banks used for pumping ruby rod or
NdYAG lasers, and high voltage powerline thyristor converters seem
much more dangerous.

As for the RF emissions, as long as the Q of these circuits is fairly
high, their interference is narrow band. Most homebuilders shoot for
about 1 MHz. The claims of TV interference are usually caused by
backflow along the power lines, and can easily be dealt with by means
of HV side chokes, or AC line filters in reverse. In fact, if you are
backfeeding that much power, you will probably burn out the gate
driver resistor on the FET (if you are using a DC supply). Mine has
two iron cored pye wound RF chokes in the HVDC bus to stop
backfeeding. It seems to work. There is a small AC line filter as
well.

Jon Elson wrote in message ...
Robert Bodell wrote:

I built a homemade AC/DC welder. I used some big 400 amp 250 volt
diodes for the full wave bridge to get the DC.
http://www.geocities.com/robert_bodell/welder.html

It welds with a 1/16 to 5/32 rod fine and does stainless great too

I heard that there was plans someplace that you could use an arc to
get the HF necessary to weld aluminum with.

You really need AC to weld aluminum. Do you have a TIG torch? There's
no way to weld aluminum without it, unless you do it in a glove box
filled with argon.


I am not sure of this is before the transformer, after the transformer
and before the diodes or after the diodes and in the welding leads.


There is a forum attached to www.diywelder.com. Several posters have
built these things. In fact, there is a recent post with a neon sign
transformer shown in photos (you have to register to see the photos).

The HF setup is after the transformer and after the diodes. It is
also after the DC welder choke. These kind of help with the arc
stability. A capacitor is placed across the leads, and a large coil
of heavy wire is placed in series after the capacitor. This coil is
coupled to a coil of thinner wire, which is excited with a resonant
spark gap oscillator. The oscillator is powered by a low frequency AC
or a DC power source, and looks a lot like the primary circuit of a
Tesla coil.


There are ways to add an HF system to a stick welder. Basically, you build
a heavy-duty Tesla coil, with a neon sign transformer, spark gaps and an
air-core resonant transformer. The secondary of the transformer is just
a few
turns of welding cable around the Tesla coil. There should be plans
somewhere
on the net for such a thing. If you are not very competent with REALLY
dangerous electrical gear, this could be a real hazard. It also will
likely wipe
out any TV or radio reception for blocks.


Not too bad. I can think of a lot more dangerous electrical gear.
There have been some recent posts on the above mentioned group by
someone who claimed to get a working stabilizer with several
milliwatts of HF. Commercial units like the Miller use about 100
watts, and as a result, the primary circuit poses a shock hazard.
Microwave ovens, large capacitor banks used for pumping ruby rod or
NdYAG lasers, and high voltage powerline thyristor converters seem
much more dangerous.

As for the RF emissions, as long as the Q of these circuits is fairly
high, their interference is narrow band. Most homebuilders shoot for
about 1 MHz. The claims of TV interference are usually caused by
backflow along the power lines, and can easily be dealt with by means
of HV side chokes, or AC line filters in reverse. In fact, if you are
backfeeding that much power, you will probably burn out the gate
driver resistor on the FET (if you are using a DC supply). Mine has
two iron cored pye wound RF chokes in the HVDC bus to stop
backfeeding. It seems to work. There is a small AC line filter as
well.

On Sat, 07 Aug 2004 16:49:33 GMT, Robert Bodell wrote:
I did like that attachment for a DC machine. I might look into that.
Does the gas take the place of the HF? Or do you still need the HF?

Gas is always needed when TIG welding, argon, helium, or an
argon/helium mix. You can TIG weld steel with DC- and without HF,
but you want to use AC to TIG weld aluminum, and you need HF
to stabilize the arc when using AC.

It is possible to TIG weld thin aluminum using DC+ and no HF,
but the torch will get very hot very quickly since the majority of
the heat goes to the tungsten when using DC+. You'd need to
use a large tungsten, and preferably a water cooled torch, if
you try DC+ welding aluminum.

Gary