Weld Thickness Question

[Krunch]

Another new guy question.

I have a Hobart AC235/DC160 stick welder and the Hobart website says the max thickness for welding is 1/2" for AC and 1/4" for DC.

I was scavenging scrap steel from the railroad trestle and found some cast steel plates that normally are spiked down under the track, and they are maybe 5/8" thick.

My question is, I could weld together two plates of steel that were thicker than the maximum 1/2" for AC or 1/4" for DC ... it would just require more layers or passes with the stick...right?

I mean, I could run one bead, then chip off the slag, then run another bead, then chip off the slag, then run another bead, then chip off the slag, and eventually weld together ANY size metal...right?

Or is it a deal where you just can't do it because you can't apply enough heat to metal thicker than 1/2" for it to fuse properly?

Sorry for all the dumb questions, and thanks for any answers.

[FWI]

Yes by applying more passes, stringer beads, to your weld you increase the legs and the throat, weld schedule, of the weld which in a "general" increases strength. If you were to weld thicker regardless I would weld with DCEP I'm not much for AC welding unless it's tig for aluminum..

[Sberry]

In theory you could weld unlimited thickness with that machine.

[usmcpop]

Some tie plates may have a fairly high carbon content (.2 - .5% ?), so keep that in mind when welding.

[rdneckhntr]

The maximum thickness they say you can weld with a machine is based on 1 pass...

[hankj]

Remeber that preparation of the weld joint is required for multi-pass welds.

You need to bevel the joint on both faces, leaving a small square face at the bottom of each bevel (the "root"), and leave a gap between the pieces. This allows subsequent passes to have a place to fuse to the workpieces.

The first pass, called the root pass, is intended to fuse the entire face of the root gap at the base of your bevel. Each susequent pass must fuse to the last, etc.

If you are not at all familiar with joint preparation, a little reading on any of the major manufacturers web sites in the education section will give you some help. ESAB at esab.com and Lincoln at liconelectric.com and Miller at millerwelds.com all have good tutorials.

Hank

[Krunch]

Thanks everyone for the replies. This site is a huge help.

[thingy]

Yep,all soild answers,,,what do you all think about how these machine manufactors advertize their mig machines[this one will weld 1/4 inch,,this one will weld 3/8th inch etc],,,yeah,,probably those little 110 volt mig machines are useless on most things ,,but they kinda keep it up,,,many newbies confused,,and will even argrue with you about it,,thingy

[Sberry]

I built up a rock crusher jaw with one,,, ha

[thingy]

These marketing genuises,,!,,,don't know a ****ed thing about welding evidently,,they advertise migs like this like it was a fact or something,,,kinda hard to explain,[if you don't know anything about it like some of these brochure writers],,but lets give it a small try,,,if you got a machine that will weld 1/8 inch plate together,,,you can weld 50 inch thick plate together,,,,you just gotta know the details,,,thingy

[Brianstick]

Hey, what's up with all the extra commas?

[Rocky D]

Hey, what's up with all the extra commas?
Thingy uses the commas like I use dot, or ellipsis...to change a thought or make the typing read more like one was actually speaking...a pause, so to speak. It works for me.;)

[smyrna5]

In theory you could weld unlimited thickness with that machine.


I never have fully understood why a 230v stick can "theoretically" weld unlimited thickness, but a small wire feeder can't, unless there is some physical crossover point between the power output of a 230v stick welder and a 110v small wire feeder where the heat transfer characteristics of steel just overcome the heat input of the small wife feeder. Once a piece of metal gets to a certain thckness, the heat transfer should radiate out in a series of half sphere isotherms (a bit oversimplified on the shape due to the surface affecting it) and the transfer will be directly related to the temperature at the heat source and the thermal conductivity constant of the metal. You will have to excuse the crude drawing this early in the morning.

http://www.atlantamusclecars.com/DeltaWolf/isotherms.JPG

You can do the same joint design for both welders, and make as many multiple passes as you want. It is an interesting physical coincidence that this crossover point occurs between the output of a 120v wire feeder and a 230v stick, given all the infinite power input points where it could have occured.

You guys will have to excuse my musings. I am like the old econonmist joke about an economist who sees something happen in real life and wonders if it will work in theory [g]. I believe the voices of experience here about what really happens in the real world, but I always wonder how that would work in theory! I guess I need to break out my old heat transfer text and get to figuring. Thirty years of inactivity makes one's heat transfer theory rusty to say the least.

What is the thickest two pieces of steel you guys have welded together with good fusion and a basic 230v buzzbox?

[usmcpop]

See post #39 here regarding penetration: http://www.hobartwelders.com/weldtalk/showthread.php?t=30226&page=3

[smyrna5]

See post #39 here regarding penetration: http://www.hobartwelders.com/weldtalk/showthread.php?t=30226&page=3

I did. Doesn't answer my questions.

[Rocky D]

I never have fully understood why a 230v stick can "theoretically" weld unlimited thickness, but a small wire feeder can't, ...
I think this sums up your question...fact is the small wire feeder can...just like stick, and like Cary said, unlimited thicknesses.

This is 1 1/2" rebar welded with a 90 amp wire feeder.
http://img.photobucket.com/albums/v252/RockyD/Stuff%20I%20built/Mantel/MVC-843F.jpg