Arc welding 'mathematics'

[Welly]

Hi,

I'm fairly new to welding, and to this forum (although I have been reading it for a while).

I did a course at the end of last year at my local college, and althogh it was great at getting to grips with the logistical side (striking the arc, moving the electrode, etc), it was a fairly 'well trodden' course - in other words, the workpieces, electrode sizes, current settings, etc were all chosen for us and not a lot of information was provided about how they were selected.

Near the end of the course, I picked up a Pickhill 180a AC Arc welder from a farm sale, it has been sitting in the steading for a while waiting to be used. Finally, last week I had a crack at it and stuck a few small pieces of box section together. Not fantastic work, but good fun and enough to get me interested again.

My question is, how do you go about selecting what size of rod to use, what the current setting should be, and what depth of penetration you can expect from them?

I know it is probably down to experience (which I don't have), how you weld as an individual, what make of rods/machine you're using, etc, but I'd be interested to know what factors the more experienced folks consider. This kind of stuff just wasn't covered on the course I did.

Is it really just a case of having a go to see what happens, or is there some logic to it?

Cheers

Welly

 

[gordon stephenson]

Hello Welly,
Google the "miller stick welding calculator" this will give you some idea about amps for different rods and materials.

P.S also use 1 amp per thou thickness of work piece as a rough guide.
Cheers Gordon.

 

[TechnicAl]

Rods as a rule of thumb 40A per mm. So 2.0mm 80 amps, 2.5mm 100 amps, 3.2mm 130 amps etc etc.

 

[Tony]

Welding Calculator

Hi Welly,
If you go to the Miller website you can buy the welding calculator from them. One for each, Mig, Tig and Arc for $4 inc carriage, Ordered 2 lastTuesday, received on Saturday. They are worth having for anyone learning to weld. I bought them for two lads who have asked me to teach them to weld.

Tony

 

[Welly]

Thanks for the replies, chaps.

That calculator looks handy (I might even invest in a paper one) and 40a per mm of rod was about where I was working, so I was at least getting something right!

I think I need to concentrate a bit more on the angles, and try some larger rods to see what the 13a fuse will take. I was just playing with some 2mm ones to get started, and I've seen suggestions on this forum that I might get a couple of seconds of 3.2mm before it goes pop. We'll see.

Cheers

Welly

 

[cookie munsta]

just run a line in, if its too cold then turn it up if it too wet try turning wire feed up try to get a good combination of smmooth weld metal good burn in 'peno' and if it is too hot and you get undercut than turn up wire speed or leave w.s. and turn down fine and coarse etc until you find its ' happy place'
experience helps imennsly but they say there is only one way to get it, happy hunting

 

[Woody.v8]

just run a line in, if its too cold then turn it up if it too wet try turning wire feed up try to get a good combination of smmooth weld metal good burn in 'peno' and if it is too hot and you get undercut than turn up wire speed or leave w.s. and turn down fine and coarse etc until you find its ' happy place'
experience helps imennsly but they say there is only one way to get it, happy hunting

They are discussing stick (mma) CM

 

[cookie munsta]

well in that case it just got all the more simple, adjust one control, thanks woody