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gas for tig brazing and fusion tacks

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gas for tig brazing and fusion tacks

Postby LILarry » Tue Jan 09, 2018 12:48 am

I am a beginner. Retired, did some gas welding in the service a very long time ago, but brand new to TIG. When doing fusion tacks, do you need the argon to be on? I ask because my first project is a welding cart and I will probably be doing a few hundred tacks....a lot of gas...

Similarly, when I do tig brazing with Si-Bronze, is the gas level the same as with mild steel (15-25 CFH)

Thanks.
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Re: gas for tig brazing and fusion tacks

Postby LtBadd » Tue Jan 09, 2018 5:43 am

Hello Larry and welcome to the forum
Anytime an arc is established you need the argon shielding gas, and the gas flow would (probably) be within the range you specified.
Let us know what machine and TIG torch you have.
Richard

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Re: gas for tig brazing and fusion tacks

Postby cj737 » Tue Jan 09, 2018 6:34 am

As the LT said, always have to have Argon on for TIG. Depending upon your machine, the amount of gas flow will be under your control (if you have a gas valved torch) or it is set by the machine with an automatic post flow determined by the amperage you use (generally these machines use 1 sec post flow for 10 amps). It sounds like a lot of wasted gas, but in actuality it is not. It serves 2 purposes: first is to cool your tungsten and protect it from atmospheric contamination while cooling, and the second is to allow you to shield your weld (in this case tack) with argon while it cools for the same reason above.

Depending upon what size cup you use, 12 CFH is about right, all the way up to maybe 25 CFH with a large "Fupa" style cup. I mostly run in the 15-18CFH range with a #8 cup, 3/32 tungsten. It takes some discipline, but holding your cup over your weld while post flow runs, DOES help your welds. You just gotta remain in position after the arc is shut off, and gently wash the weld backwards or stay still over the tack.

For all the tacks on your cart, if you're mostly doing fusion tacks, the post flow will also help limit distortion as the post flow will slow you down from over-heating the tubing ;)
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Re: gas for tig brazing and fusion tacks

Postby LILarry » Tue Jan 09, 2018 1:39 pm

Thank you so much, guys. I thought when I registered that my equipment would show. Maybe I did something wrong in my profile.

In any event, I have a brand new dynasty 210dx and a 210MP, a 150amp gas cooled CK torch with a stubby gas lens. and lots of "coupons" to practice on before I start my welding cart. I'll set the gas as you suggested, with a post flow of 5 seconds for those quick fusion tacks and 10 seconds for the Si-Bronze. Are those sufficient numbers?

I've been looking forward to doing this for quite sometime and I've spent probably the better part of year studying and watching youtube videos before going out and buying. I was lucky that when I was ready Miller was offering a rebate on the dynasty and i got an additional good deal on the Lincoln 210MP. Everyone told me to at least start out with the MIG process, so that's the plan. And now that I've joined the forum, I will spend time reading all the info here as well.

Again, thanks for the quick response
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Re: gas for tig brazing and fusion tacks

Postby Lightning » Tue Jan 09, 2018 1:53 pm

If you do zillions of tacks, it might be worthwhile to put a Smith flow restrictor on your gas line (I put mine in between the flowmeter and the welder).

Image

It's basically just a small hole drilled in a fitting, but it tempers the "surge" of gas that you would otherwise get when the solenoid opens, due to there being a "reservoir" of 50psi gas stored in the lines between the regulator/flowmeter and the solenoid in the welder. People also use them in MIG machines.

About $15

https://weldingsupply.com/cgi-bin/einst ... X:15001-20
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Re: gas for tig brazing and fusion tacks

Postby LILarry » Tue Jan 09, 2018 9:33 pm

thank you, lightening....older I get, the harder it is to move stuff around...especially a 150 CF gas bottle....will order one
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