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TIG rod size

architect

Super User
From what I understand, the general rule of welding mild steel is to have filler rode size smaller than material thickness. Is it possible to use rod that's much smaller and just do several passes? For example, welding 1/4" mild steel using 1/16" rods and just layering it on. Is it just a matter of taking more time/passes or are there other advantages/disadvantages?
 
Yes, but too small and you are just creating a lot of extra work, and introducing the possibility of porosity in the weld pool just due to the number of passes. I'm no expert, but I know for certain operations it is recommended to make multiple passes. TIG is a world where craftsman exist more than others. What I always learned is the same as you WRT rod size. The calculators out there are just guidelines. For example the Miller one recommends 3/16" filler for your operation (fillet) on 1/4" plate.

Personally I don't use TIG for thick plate anymore, but that's just a convenience thing for me, as it is my favourite process. As I got older my hands aren't as steady and I need a table I can sit at to TIG. Since most of my work is fabrication, it's hard to sit at a 2 foot square TIG table and work on a 12' length of 2' inch tubing.
 
It is possible, but it not terribly efficient because you'll also be using more gas to make multiple passes. And as Pete mentioned, each pass has the potential for porosity.
 
The problem with using a thick rod to weld is that your TIG machine may not have enough power to easily melt it. I have some thick rod I think its 3/16 and even at 200 amps max it is not that easy to weld with as thinner rod (I think 1/8).
 
What about when dealing with solid round or square rods that are 1/2" or even 3/4"?

Solid 1/2" or 3/4" is small - certainly I would use my thinner rod. Even with that it will quickly turn red and then glowing red if you go a bit aggressive. If you are joining two 1/2" rods the proper procedure is to do a root pass over heavily ground down pieces and do successive passes to fill in the void with weld material. Your welder can deliver a lot of power & it may feel like this can be done quickly BUT the rod will glow red and may distort so thinner filler with more passes is safer.

I am no expert in TIG by any means.
 
i have a lot of years tig welding commercially, 99% of steel or stainless can be done with 1/16 filler, and 99% of aluminum with 3/32 rod, dont get to excited about the filler size, its not all that important

if you find yourself doing very thin gauge material .035 mig wire is the way go to

more importantly than the size of the filler is the size of your tungsten electrode, larger tungstens will not hold a steady arc at very low amperages, and conversely not be able to handle large amperages (garage shops doing steel are served well by 1/16 and 3/32 tungsten, and 1/8 for aluminum)

large weld profiles with tig are done in multiple passes, walking the cup, etc

if you are welding 1/4 steel plate often, tig is not the process really, its slow, costly (gas) and produces a ridiculous amount of warpage (due to the slow speed and large heat affected zone)
 
i have a lot of years tig welding commercially, 99% of steel or stainless can be done with 1/16 filler, and 99% of aluminum with 3/32 rod, dont get to excited about the filler size, its not all that important

if you find yourself doing very thin gauge material .035 mig wire is the way go to

more importantly than the size of the filler is the size of your tungsten electrode, larger tungstens will not hold a steady arc at very low amperages, and conversely not be able to handle large amperages (garage shops doing steel are served well by 1/16 and 3/32 tungsten, and 1/8 for aluminum)

large weld profiles with tig are done in multiple passes, walking the cup, etc

if you are welding 1/4 steel plate often, tig is not the process really, its slow, costly (gas) and produces a ridiculous amount of warpage (due to the slow speed and large heat affected zone)
This is bang on with my non-professional experience. Just wish I had heard this 20 years ago. I can't agree more. I only weld steel now, but settled on 1/16" rod and electrode for almost everything now. The exception is thin sheet, 22 to 16 gauge for box and pan work. Your recommendation of .035 MIG wire is exactly what I discovered as well through trial and error.

Great advice‚ glad to hear a pro mention this. Thanks.
 
My first tig was a PA special one of those 100 amp scratch start things that I used for some rust repair on a S10 wheelwell that’s when I used mig wire for the first time it made all the difference.
 
Yeah, me too. I remember like it was yesterday: the ah-ha moment. I kept blowing out corners on a steel box I was welding. I remember thinking "this would be easier with MIG because I don't need to heat up this darn filler rod so much." My eyes went to the bit of wire hanging out the end of the MIG gun as I held the TIG rod and I thought, "Hey. Wait a minute."

One of those experiences if you had had a pro teaching you from the get go, life would be much easier.
 
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I read that 3/32 can be sharpened to perform like a 1/16 but also be versatile for thicker steel? Well I bought 3/32 before people chimed. But I've been side tracked from being in the garage lately so haven't tried yet.
 
I read that 3/32 can be sharpened to perform like a 1/16 but also be versatile for thicker steel? Well I bought 3/32 before people chimed. But I've been side tracked from being in the garage lately so haven't tried yet.

your good, 3/32 is the most versatile tungsten size for steel/stainless, it starts to be a poor choice when your down in the 5-50a range, real light gauge work, i only swap out to 1/16 when fabbing or repairing things like stainless food service equipotent, otherwise the 3/32 lives in the torch
 
Interesting....just started Tig and love it (got rid on the Mig to get it). Guess I'll be using (learning) stick for bigger jobs (specially since my machine does it too).
 
Interesting....just started Tig and love it (got rid on the Mig to get it). Guess I'll be using (learning) stick for bigger jobs (specially since my machine does it too).
Did you keep some .035 MIG wire before you sold it?

As you improve with TIG, there's nothing better than MIG wire on 16 gauge or thinner sheet metal. I struggled with 1/16" rod on thin sheet metal. Then I looked over at my MIG and went, "Wait a minute here...".
 
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No all I had was flux core. The thinnest I've done so far is 0.060 sheet metal, easy enough to flow together, dab of 1/16 wire when needed at about 70amps (set) max pedal.

Went up in Rod size with a sharper point, seems to have a better feel.

Still learning.
 
In a pinch you can always twist two filler rods together, or twist up some mig wire. Cinch one end down in a vise, and chuck the other end in a drill. Spin clockwise for steel and counter clockwise for aluminum..
 
In a pinch you can always twist two filler rods together, or twist up some mig wire. Cinch one end down in a vise, and chuck the other end in a drill. Spin clockwise for steel and counter clockwise for aluminum..
I never heard the clockwise vs counter clockwise approach. What’s the reasoning here? :)
 
@Degen - when you say "rod" are you referring to the tungsten electrode?

What size tungsten are you running? Colour/electrode type? I always grind my tungsten to a point - I have a transformer machine so the point tends to "blunt" or round a little when it gets a little heat in it. Inverter machines tend to hold the point a little better. (AC/aluminum will ball the end)
 
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