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Posted by Jon Danniken on April 23, 2008, 3:54 pm
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Howdy,
I was recently looking at an older TIG supply, transformer based, and am
wondering about it's performance compared with more modern machines. A
machine very similar to this one:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330226477870
On an older machine like that one, there is no foot pedal to control the
current output. Not being familiar with TIG, how important is a foot switch
to control current? What improvements/abilities does such a feature add to
welding?
What I am looking to do is to expand my abilities beyond what I am currently
capable of with my AC buzzbox, and allow me to do some welding on stainless,
aluminum, and thinner material than I can do on my AC unit.
Thanks for any insight into this,
Jon
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Posted by Don Foreman on April 23, 2008, 7:01 pm
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On Wed, 23 Apr 2008 12:54:30 -0700, "Jon Danniken"
>Howdy,
>
>I was recently looking at an older TIG supply, transformer based, and am
>wondering about it's performance compared with more modern machines. A
>machine very similar to this one:
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330226477870
>
>On an older machine like that one, there is no foot pedal to control the
>current output. Not being familiar with TIG, how important is a foot switch
>to control current? What improvements/abilities does such a feature add to
>welding?
>
>What I am looking to do is to expand my abilities beyond what I am currently
>capable of with my AC buzzbox, and allow me to do some welding on stainless,
>aluminum, and thinner material than I can do on my AC unit.
>
>Thanks for any insight into this,
>
>Jon
A significant advantage to TIG is the ability to control heat
independently from rate of addition of filler metal.
Inability to control heat with a foot control would be a major
compromise. I wouldn't consider a TIG without foot control. I have no
problem with older transformer-based machines that do have foot
control. That's what mine is. (Miller Dialarc 250HF)
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Posted by Rob Fraser on April 23, 2008, 7:09 pm
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> On Wed, 23 Apr 2008 12:54:30 -0700, "Jon Danniken"
>
>>Howdy,
>>
>>I was recently looking at an older TIG supply, transformer based, and am
>>wondering about it's performance compared with more modern machines. A
>>machine very similar to this one:
>>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330226477870
>>
>>On an older machine like that one, there is no foot pedal to control the
>>current output. Not being familiar with TIG, how important is a foot
>>switch
>>to control current? What improvements/abilities does such a feature add
>>to
>>welding?
>>
>>What I am looking to do is to expand my abilities beyond what I am
>>currently
>>capable of with my AC buzzbox, and allow me to do some welding on
>>stainless,
>>aluminum, and thinner material than I can do on my AC unit.
>>
>>Thanks for any insight into this,
>>
>>Jon
Jon,
Best analogy I could think of is sort of like computers.... A 286 vs. a
Pentium 4 .... And the foot control is a must unless you have three hands.
Rob
Fraser Competition Engines
Chicago, IL.
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Posted by Jon Danniken on April 23, 2008, 7:35 pm
Please log in for more thread options "Don Foreman" wrote:
>
> A significant advantage to TIG is the ability to control heat
> independently from rate of addition of filler metal.
>
> Inability to control heat with a foot control would be a major
> compromise. I wouldn't consider a TIG without foot control. I have no
> problem with older transformer-based machines that do have foot
> control. That's what mine is. (Miller Dialarc 250HF)
Thanks Don, that is what I was hoping to know.
It also brings up a desire to know what methodology is used to externally
control the current output of an inductive type machine (as in with a foot
switch) I wouldn't imagine it's done with servo's on the shunt, maybe a PWM
at some stage?
Jon
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Posted by BobH on April 23, 2008, 8:03 pm
Please log in for more thread options Jon Danniken wrote:
> "Don Foreman" wrote:
>> A significant advantage to TIG is the ability to control heat
>> independently from rate of addition of filler metal.
>>
>> Inability to control heat with a foot control would be a major
>> compromise. I wouldn't consider a TIG without foot control. I have no
>> problem with older transformer-based machines that do have foot
>> control. That's what mine is. (Miller Dialarc 250HF)
>
> Thanks Don, that is what I was hoping to know.
>
> It also brings up a desire to know what methodology is used to externally
> control the current output of an inductive type machine (as in with a foot
> switch) I wouldn't imagine it's done with servo's on the shunt, maybe a PWM
> at some stage?
There are a couple of ways of controlling the current. The newer
machines use PWM on the output of the transformer. The older machines
used a thing called a MagAmp that played games with controlling the
current coupling of the AC power by saturating the core with variable DC
levels. Sorry I can't give a better description, it's been a long time
since I sort of understood it.
Bob
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>
>I was recently looking at an older TIG supply, transformer based, and am
>wondering about it's performance compared with more modern machines. A
>machine very similar to this one:
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330226477870
>
>On an older machine like that one, there is no foot pedal to control the
>current output. Not being familiar with TIG, how important is a foot switch
>to control current? What improvements/abilities does such a feature add to
>welding?
>
>What I am looking to do is to expand my abilities beyond what I am currently
>capable of with my AC buzzbox, and allow me to do some welding on stainless,
>aluminum, and thinner material than I can do on my AC unit.
>
>Thanks for any insight into this,
>
>Jon