Arc Welding for Beginners

Got a small DIYer Arc welder years ago and never mastered the art. Got some 3mm steel and thought I'll conquer this tonight !
So played around got a pack of asstd 1.5mm, 2.0mm and 2.5mm rods from Halfords (!).

Experimented and found the 2.5mm rods and about 80amp at least got a couple of cms in an unbroken line and not all those big splattery bits which is what usually happens (or holes because trying to weld stupidly thin squre section tube from B+Q !!!)

So to my questions for tips / help !

1. Are the settings about right rod size / current for 3mm mild steel plate
2. when I get a nice weld going is it Ok to go over that again, or is it best to stop, get rid of all the crappy 'slaggy' bits (dont know what the right term is) with me little hammer and then weld over ?
3. Allright to angle grind the weld to make it look pretty and then touch it in with the welder again ? or best to angle grind off the weld completely and start again.

Only if I get to Brentwood and the new front falls of Maelstrom next week, Will's not ging to be too happy !
Thanks for any advise.
Cheers, Ian

Ok, the only thing I've every arc welded was some cast iron which is quite hard to do. But yes remove the slag before welding over the top again. Assuming you are welding the edge of two plate together always grind a 45 degree chamfer probably about halfway into both plates before welding, then fill the gap. This way if you grind the weld down after to tidy up it will still be strong without you grinding all the strength off. With practise you will get to the point where you won't need a grinder, well thats the theory I will yet you know when I get there. I will be the first to say I can't weld very well so your probably better off listening to someone else anyway.

When we first started building Turb years ago we arc'd the lower chassis, before getting a MIG which was better. Personally i've done more TIG so thats what Im best at, experience says just practice and you will get better.

hi, im regularly welding box section with a thickness of about 1.6mm or thicker but i've found im happy using 1.6mm rods at about 55 amps and i used those to weld most thicknesses apart from the really thick stuff where a better and hotter weld is needed. i would also advise using 1.6mm rods for your thin tube. also don't weld for ages in one go as the metal gets very hot and then start to melt etc, i weld for about 4-5 secs at a time and then have a rest to allow the metal to cool before carrying on again

you can go over a weld as much as you like, within reason to the point of it ending up massive.

when you say getting rid of the crappy saggy bits what do you mean exactly?- do you mean the covering of slag which needs to be chiped or knocked off the weld after you've finished? or do you mean after you chiped off the slag theres gaps in the weld which looks messy and mankey?

basically you gotta chip off the slag because it is formed when the weld is being made and it protects the weld as its forming etc, so when the weld is cool it needs to be chiped off. you can't weld over the slag because you will end up with a new weld being made over a load of easyily detachable slag and the weld would most likley fail or just be not very strong.

or if you mean theres gaps in the weld that look messy and mankey then its either your rod angle or your changing your speed as you weld, move the rod at a stedy speed and tilt the rod at about 45 degrees away from the vertical in the same direction that you are going in.

and yes you can grind part of a weld off and weld over it again if you want.

and the 2.5 rods work best at about 80-90 amps but it all depends on your speed. if your getting alot of spatter during the weld then that means your amps are too high compared to the speed you move your rod at so you would have to try turning your amps down. its all about finding the settings that work for you.

man this has taken ages to write

hope ive been of some help

Hi there, while matching your welding current to the rod size is important your own welding stlye will have an impact on your finished weld.
The angle that you hold the rod to the metal, the speed that you weld at and the distance that the rod tip is from the metal will all make a differance.
The further the tip of the rod is from the metal the more it will spray spatter everywhere!
As regards going over and over a weld, remember that as a weld cools it shrinks!
This bends and distorts your metal, weldind in long, continuous runs will increase this distortion. Weld both sides of the metal, if it is possible, making stitches every so often until the seam is complete.
Finally; practice, practice, practice!
Mike.

To ride a bike sit on saddle scoot away to give you forward motion, and then with your feet on the pedals continue to power yourself forward use the handlebars to steer and the break to stop.
Sounds easy but the first time you try it, you realise it is harder than any instructions will sound. Remember welding is a job that people get paid to do, because not all people can do it well. so don't be too sad if things don't look nice. :uhoh:

But here are some golden rules :idea:

Clean the weld area till you have shiny metal.
There should be a gap between the weld plates for better penetration, less distortion.
You €œdrag the rods along the weld€ About 70 deg to the horizontal but this always varies.
Gap between the rod tip and the weld is approximately 3-5mm
Try to weld on a horizontal plane so move the robot,
Make sure the welder cable will not snag as you traverse the welding portion.
Dry rods are important!
But like riding a bike it is practice. :mrgreen: :mrgreen: