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Posted by Jon Danniken on May 4, 2008, 10:09 pm
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Howdy,
The design of my footpedal current-controlled DC TIG welder is coming along
smoothly, but it has brought me to a crossroads.
It has come to my attention that welding aluminum with DC is best to be
avoided (I am guessing due to the need to get through the oxide layer), and
so far I am only designing a provision for foot control of DC current (the
current control is via a thyristor bridge after the AC transformer).
Here's my question: this project will have a (low current) HF/HV arc
starting module. If I leave this on while welding with DC, will that,
superimposed on top of the DC current, be of any significant help with
welding aluminum?
Thanks for any insight into this issue,
Jon
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Posted by Mechanical Magic on May 4, 2008, 11:32 pm
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Jon,
For ultra thin materials, DC/HF may work, reverse polarity IIRC.
But for sheet metal on up, nope.
There is a VERY significant swirl on the puddle caused by the AC, that
moves crap to the edge. On many settings, it is almost invisible,
depending on the machine.
Dave
wrote:
> Howdy,
>
> The design of my footpedal current-controlled DC TIG welder is coming along
> smoothly, but it has brought me to a crossroads.
>
> It has come to my attention that welding aluminum with DC is best to be
> avoided (I am guessing due to the need to get through the oxide layer), and
> so far I am only designing a provision for foot control of DC current (the
> current control is via a thyristor bridge after the AC transformer).
>
> Here's my question: this project will have a (low current) HF/HV arc
> starting module. If I leave this on while welding with DC, will that,
> superimposed on top of the DC current, be of any significant help with
> welding aluminum?
>
> Thanks for any insight into this issue,
>
> Jon
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Posted by Jon Danniken on May 5, 2008, 12:04 am
Please log in for more thread options "Mechanical Magic" wrote:
>
> Jon,
> For ultra thin materials, DC/HF may work, reverse polarity IIRC.
>
> But for sheet metal on up, nope.
>
> There is a VERY significant swirl on the puddle caused by the AC, that
> moves crap to the edge. On many settings, it is almost invisible,
> depending on the machine.
Thanks, Dave, I appreciate that. Didn't know that about the puddle, either,
so I'll watch for that.
Alrighty then, so a squarewave would be the easiest waveform to make, would
that be a sufficient enough selection of waveforms, and what frequency range
would be most useful?
Jon
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Posted by Ignoramus11115 on May 5, 2008, 12:12 am
Please log in for more thread options > "Mechanical Magic" wrote:
>>
>> Jon,
>> For ultra thin materials, DC/HF may work, reverse polarity IIRC.
>>
>> But for sheet metal on up, nope.
>>
>> There is a VERY significant swirl on the puddle caused by the AC, that
>> moves crap to the edge. On many settings, it is almost invisible,
>> depending on the machine.
>
> Thanks, Dave, I appreciate that. Didn't know that about the puddle, either,
> so I'll watch for that.
>
> Alrighty then, so a squarewave would be the easiest waveform to make, would
> that be a sufficient enough selection of waveforms, and what frequency range
> would be most useful?
>
I would say 20-200 Hz
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Posted by Jon Danniken on May 5, 2008, 12:34 am
Please log in for more thread options "Ignoramus11115" wrote:
> Jon Danniken wrote:
>
>> Alrighty then, so a squarewave would be the easiest waveform to make,
>> would
>> that be a sufficient enough selection of waveforms, and what frequency
>> range
>> would be most useful?
>>
>
> I would say 20-200 Hz
Thanks for that, Iggy. That's a nice approachable range. I'm smelling a
555 chip in this thing.
Jon
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>
> The design of my footpedal current-controlled DC TIG welder is coming along
> smoothly, but it has brought me to a crossroads.
>
> It has come to my attention that welding aluminum with DC is best to be
> avoided (I am guessing due to the need to get through the oxide layer), and
> so far I am only designing a provision for foot control of DC current (the
> current control is via a thyristor bridge after the AC transformer).
>
> Here's my question: this project will have a (low current) HF/HV arc
> starting module. If I leave this on while welding with DC, will that,
> superimposed on top of the DC current, be of any significant help with
> welding aluminum?
>
> Thanks for any insight into this issue,
>
> Jon