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Old 07-30-2017, 04:49 PM
Rufus Rufus is offline
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Default Rod Size

Hi all:
I have always heard that when you weld up a particular thickness of steel, you want at least a rod that is half that size. Example...for 3/16" thick piece of steel you want a rod that is at least 3/32", for a 1/4" thick steel piece, you a rod that is at least 1/8" and of course for a 1/2" thick steel piece you want a rod that is at least 1/4". Now is this just an estimation or does this pretty much hold true? I can see maybe these sizes of rods holding to the size of thickness of steel for a single pass of weld bead, but if you use 1/8" rod for 1/2" plate, then you will need multiple passes. So...what are your thoughts?

Thanks
Tim
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Old 07-30-2017, 05:15 PM
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WOW! just think if you had to weld 1" plate
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Old 07-30-2017, 05:19 PM
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I think that you heard wrong, that statement would hold true about the size of the weld on a given thickness of plate if welded on both sides such as in a tee joint. A 1/2" plate would have a 1/4" weld on each side and so on.
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Old 07-30-2017, 06:27 PM
Rufus Rufus is offline
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Originally Posted by digr View Post
WOW! just think if you had to weld 1" plate
I remember that back in 2001 (maybe 2002) I took an adult welding class through Great Oaks in Sharonville (suburb of Cincinnati) and the instructor was a welder for Trinity Heads (I think the name was changed to Brighton Tru-Edge Heads) that was up the street from the school and he brought in an electrode that was about 1 inch in diameter and about 2 feet long and it looked just like a regular electrode and he said the stinger that was used for that electrode was shaped like bicycle handle bars. Talk about a big electrode

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Tim
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Old 07-30-2017, 06:40 PM
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I think that you heard wrong, that statement would hold true about the size of the weld on a given thickness of plate if welded on both sides such as in a tee joint. A 1/2" plate would have a 1/4" weld on each side and so on.

It is very possible that I heard wrong. Lots of stories floating around that are nothing more than myths.

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Tim
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Old 09-09-2017, 03:55 AM
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Originally Posted by Rufus View Post
I remember that back in 2001 (maybe 2002) I took an adult welding class through Great Oaks in Sharonville (suburb of Cincinnati) and the instructor was a welder for Trinity Heads (I think the name was changed to Brighton Tru-Edge Heads) that was up the street from the school and he brought in an electrode that was about 1 inch in diameter and about 2 feet long and it looked just like a regular electrode and he said the stinger that was used for that electrode was shaped like bicycle handle bars. Talk about a big electrode

Thanks
Tim
Those electrodes were common in ship building before sub arc realy got going. From memory the last place they were used regularly was Japanese navy yards during WW2.

As for electrode size.......
Use as big as you can control and still put down an acceptable weld. For the home shop or small job shop that doesn't do much welding, (please excuse the metric) 7016 - 2.5mm and 7018 - 2.5mm and 3.2mm are all most people will need. Steer clear or Rutile electrodes (XX13), they put down a really poor metallurgical composition, and there a bastard for porosity to boot. Same for Cellulose electrodes, very difficult to control and not necessary if you can do the prep work properly.

You cant really do V-down with a LH rod, which makes very thin material difficult if your technique needs some work. Anything <3mm is too thin to stick anyway (IMO).

All that being said, if it gets a job done, it has served its purpose.
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Old 09-09-2017, 07:45 AM
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Originally Posted by AussieTom View Post
Those electrodes were common in ship building before sub arc realy got going. From memory the last place they were used regularly was Japanese navy yards during WW2.

As for electrode size.......
Use as big as you can control and still put down an acceptable weld. For the home shop or small job shop that doesn't do much welding, (please excuse the metric) 7016 - 2.5mm and 7018 - 2.5mm and 3.2mm are all most people will need. Steer clear or Rutile electrodes (XX13), they put down a really poor metallurgical composition, and there a bastard for porosity to boot. Same for Cellulose electrodes, very difficult to control and not necessary if you can do the prep work properly.

You cant really do V-down with a LH rod, which makes very thin material difficult if your technique needs some work. Anything <3mm is too thin to stick anyway (IMO).

All that being said, if it gets a job done, it has served its purpose.
Passed my first plate test with a rutile 6013, Weldcraft, BOC product, still love them 50 years later.
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Old 09-09-2017, 08:39 AM
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Passed my first plate test with a rutile 6013, Weldcraft, BOC product, still love them 50 years later.
6013 does have its fans. I learned how to weld using 6013 on a cobbled up AC aircraft generator. Flange jockey aboard here has posted some amazing work done with that rod.

I have gone away from it for 2 reasons. The first being that it is not allowed by code for much of the stuff I have worked with. Second, I find 7018 on DC is far easier to see details of how the puddle is behaving. The slag does not cover the pool and hide thing like wagon tracks and slag trapping.

A lot of work is done with smaller electrodes (1/8/3.2 mm and smaller) due to welder limitations on current and duty cycle. I have rarely seen electrodes bigger than 1/8 on any mobile. Heavy stuff is done with multiple passes and lighter stuff can easily be done. This saves expensive storage space on a mobile rig.

My 0.02$ can. YMMV
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Old 09-09-2017, 08:55 AM
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Originally Posted by Rufus View Post
Hi all:
I have always heard that when you weld up a particular thickness of steel, you want at least a rod that is half that size. Example...for 3/16" thick piece of steel you want a rod that is at least 3/32", for a 1/4" thick steel piece, you a rod that is at least 1/8" and of course for a 1/2" thick steel piece you want a rod that is at least 1/4". Now is this just an estimation or does this pretty much hold true? I can see maybe these sizes of rods holding to the size of thickness of steel for a single pass of weld bead, but if you use 1/8" rod for 1/2" plate, then you will need multiple passes. So...what are your thoughts?

Thanks
Tim
I don't know if you can easily buy any rod bigger than 1/4" nowadays, not stocked that's for sure.
I have used 1/4-7018 at 300 amps when welding cutting edges to a bucket. The cutting edges are half spear 3" thick at the widest part, but the weld is where it is 1.5" thick welded to 1.5" bucket lip.

You will always run into something thick enough that multiple passes are needed.
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Old 09-09-2017, 06:07 PM
AussieTom AussieTom is offline
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Originally Posted by clive View Post
Passed my first plate test with a rutile 6013, Weldcraft, BOC product, still love them 50 years later.
There will always be people with different preferences, and if it works for you, then go for it.
I develop weld procedures for the company i work for, all the processes we use, stick, tig, mig, most of the mig variants, sub arc. First choice in consumables will always be Low Hydrogen. Working to code will always be a more complicated process, and i assumed (probably shouldnt assume anything, but i did), that the OP isnt working to code. His rule of thumb of electrode diam= 1/2 material thickness, is not correct, as most others seem to agree.
If i had to give a rule of thumb, it would be as i stated, use the biggest electrode(high deposition rate) that you can control(quality fusion) in any given situation. That goes for all the processes i can think of. Some common sense needs to be applied to that, your not going to change mig wire size for each joint, but if you need to put down roll after roll of a certan weld, it makes sense to select the best size.

It always makes me laugh when i see advertising on hobby machines the say things like "...will weld up to 1/2" plate". Why only 1/2"? Just add more passes untill the weld is big enough!

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