Keep plate flate when welding?

northeastconfederate · Dec 22, 2018

I am welding two 12" squares of 1" thick steel plate together at their edges, and trying to keep them flat. Desired result is a 1' x 2' plate relatively flat. I am sure I started this all wrong: I beveled one side, hoping to keep a "finished" side without grinding. So far, this hasn't worked out very well:

I am using a Hobart Handler 175 with .030 steel wire. I made a couple of passes, not continuous, to try to limit the amount of heat at one time, and still ended up with a "V". I then flipped the piece over and grooved the "finished" side - the side I didn't want to weld or geind on - and ran a heavy bead on that side, which pulled the plate flat again. Then laboriously ground that weld flat. Now working on filling the "back" side again but I'm sure it's going to curl up again. So far, I've run a couple of short beads, letting the piece cool off significantly between welds, and already see movement.

How can I keep this flat? If I clamp it securely to the table until cool, will it just "spring" when I release the clamps? Am I going to have to keep welding on the opposite side to pull it back again?

This is will ultimately be a top for a mobile table (I have a total of four 12" square plates which will be welded into a single 24' square plate). It is also serving as a skill development exercise.

Any help?

DMF_TomB · Dec 22, 2018

northeastconfederate said:
I am welding two 12" squares of 1" thick steel plate together at their edges, and trying to keep them flat. Desired result is a 1' x 2' plate relatively flat. I am sure I started this all wrong: I beveled one side, hoping to keep a "finished" side without grinding. So far, this hasn't worked out very well:

I am using a Hobart Handler 175 with .030 steel wire. I made a couple of passes, not continuous, to try to limit the amount of heat at one time, and still ended up with a "V". I then flipped the piece over and grooved the "finished" side - the side I didn't want to weld or geind on - and ran a heavy bead on that side, which pulled the plate flat again. Then laboriously ground that weld flat. Now working on filling the "back" side again but I'm sure it's going to curl up again. So far, I've run a couple of short beads, letting the piece cool off significantly between welds, and already see movement.

How can I keep this flat? If I clamp it securely to the table until cool, will it just "spring" when I release the clamps? Am I going to have to keep welding on the opposite side to pull it back again?

This is will ultimately be a top for a mobile table (I have a total of four 12" square plates which will be welded into a single 24' square plate). It is also serving as a skill development exercise.

Any help?

.
its rare to get it perfectly flat after welding. many tack plates opposite direction it will warp to (not tacked flat).
.
you have to keep same amount of passes as extra passes in general it will warp more. the bigger the welds the more warpage in general. that is you often dont always need big full size welds with 100% penetration that cause a lot of warpage.
.
sheetmetal welding often is making the smallest and fewest welds with no gap to joints to limit the warpage. often only weld a inch with many inches space between welds. takes skill not to warp sheetmetal

northeastconfederate · Dec 22, 2018

DMF_TomB said:
.
its rare to get it perfectly flat after welding. many tack plates opposite direction it will warp to (not tacked flat).
.
you have to keep same amount of passes as extra passes in general it will warp more. the bigger the welds the more warpage in general. that is you often dont always need big full size welds with 100% penetration that cause a lot of warpage.
.
sheetmetal welding often is making the smallest and fewest welds with no gap to joints to limit the warpage. often only weld a inch with many inches space between welds. takes skill not to warp sheetmetal

Thanks for your feedback. So, maybe best thing is to tack it in a "V" shape to begin with; then weld the opposite side which will pull it the other direction. Meanwhile, multiple short welds to limit heat.

I'm at it again this morning. It's chilly, so the plate is cooling off fast. And I'm doing other things as well, so plenty of time between welds.

Next pair of plates I'll try the reverse tack method.

The other thing I figured I could do is bevel both sides and alternate welding one side, then the other. If I do this, as well as make multiple short welds with cooling time between, will this help?

DMF_TomB · Dec 22, 2018

northeastconfederate said:
Thanks for your feedback. So, maybe best thing is to tack it in a "V" shape to begin with; then weld the opposite side which will pull it the other direction. Meanwhile, multiple short welds to limit heat.

I'm at it again this morning. It's chilly, so the plate is cooling off fast. And I'm doing other things as well, so plenty of time between welds.

Next pair of plates I'll try the reverse tack method.

The other thing I figured I could do is bevel both sides and alternate welding one side, then the other. If I do this, as well as make multiple short welds with cooling time between, will this help?

.
even if you weld both sides it often will warp length wise or 90 degree to main warpage in a curl or slight curve. hard to describe. usually best to limit amount of welds especially if 100% weld not needed

idacal · Dec 22, 2018

When im dealing with thicker plate. you cant do it on this one but on the other 2 pieces. i give it some bend in the opposite direction before welding then some heat and a hammer to true it up. Research flame straightening,After fighting with it for few hours and a bunch of gas and oxegen i go buy piece of plate that is one piece and flat. Unless you grind it on a table machine it will always have some wave in it.

cyanidekid · Dec 22, 2018

1) it’s a fools errand to even try to get such a thing flat(you just learned that).

2) what it your spec for “flat”? Even a new piece of 1” plate is not going to be flat.

3) it’s generally best to start out with an accommodation for weld shrinkage in advance. I’d probably stick a strip of 1/16 X 1/2 or 3/4 under the joint, to gap it a bit, before welding

jamscal · Dec 22, 2018

I hate to tell anyone to give up....but give up.

It's not practical practice for anything really. (Well, I guess you're going to learn something

) I'd say the 4 pcs of plate are going to be more useful as 4 and not one.

Get some 1/4" plate or thinner, esp with .030 wire and practice running beads. Or get some thicker bar stock scraps to bevel and pc together if you want to do thicker stuff.

plastikdreams · Dec 22, 2018

Probably coulda called RS Phillips up in Sussex and got a 24x24x1 piece all ready to go.

030 is rather small for 1". 035 or 045(if you can burn it) would be my choice. More weld material laid down quicker = less heat.

DDoug · Dec 22, 2018

plastikdreams said:
More weld material laid down quicker = less heat.

THIS ^^^^^

Hotter makes less total heat input.

Get on it hot, and get off it.

and yes, just buy the plate you need, your welding table needs to be very flat.
How is everything you make on it supposed to be flat ?

Also, with only 2' sq. you should be able to get it blanchard ground.

PlasmaOnTheBrain · Dec 22, 2018

Prevention and Control of Distortion in Arc Welding - YouTube
Watch this video, it has most of the above answers in it + a few more.
Flame straightening would work well in your case too. You might need a rosebud torch to get the heat input needed on plate that thick.
Also, your welder is a bit undersized for the task at hand... It will do it but not without the issues you are running into. If you could rent a gas powered stick welder with about 200 amps your life would be a lot easier...

gbent · Dec 22, 2018

Beveling both sides results in less total weld metal. It also allows you to balance the weld deposition about the neutral axis to minimize distortion.

You will have more money in consumables and electricity than it should cost to buy what you need. A store bought piece will be much flatter than what an expert could produce, let alone a beginner.

Save practice for practice. If you need arc time to practice muscle memory, get a stick welder.

northeastconfederate · Dec 22, 2018

Well.... I have a 225A stick welder. Which I just got. It blows the 30A breker after running a 1-1/2" bead with 5/32" 7018 rod at 175A. Hence the use of my MIG welder.

I learned today while talking to a friend of mine who is a Lincoln Electric sales engineer, that the reason the stick welder pops the breaker and the MIG welder does not is that the stick machine is current driven, while the MIG is voltage driven.

I picked up a larger breaker for the garage subpanel this afternoon. That should solve the stick welder's breaker issues.

I do realize plate isn't "flat" like a surface plate. Of course it isn't. But I don't think anybody has their backyard welding table surface ground or scraped for flatness.... But it's become apparent that this project is not going to result in even a relatively flat surface.

DDoug · Dec 22, 2018

northeastconfederate said:
Well.... I have a 225A stick welder. Which I just got. It blows the 30A breker after running a 1-1/2" bead with 5/32" 7018 rod at 175A. Hence the use of my MIG welder.

I learned today while talking to a friend of mine who is a Lincoln Electric sales engineer, that the reason the stick welder pops the breaker and the MIG welder does not is that the stick machine is current driven, while the MIG is voltage driven.

I picked up a larger breaker for the garage subpanel this afternoon. That should solve the stick welder's breaker issues.

I do realize plate isn't "flat" like a surface plate. Of course it isn't. But I don't think anybody has their backyard welding table surface ground or scraped for flatness.... But it's become apparent that this project is not going to result in even a relatively flat surface.

Let's just leave the Lincoln electric salesman out of this o.k. ?

First you said the welding table will be for "mobile" use.

Now it's "Backyard" ?

make up your mind please, and stay with it.

Many welding tables are ground. Acorn welding tables are ground, as are several others.

northeastconfederate · Dec 22, 2018

PlasmaOnTheBrain said:
Prevention and Control of Distortion in Arc Welding - YouTube
Watch this video, it has most of the above answers in it + a few more.
Flame straightening would work well in your case too. You might need a rosebud torch to get the heat input needed on plate that thick.
Also, your welder is a bit undersized for the task at hand... It will do it but not without the issues you are running into. If you could rent a gas powered stick welder with about 200 amps your life would be a lot easier...

Thanks for posting that video. Entertaining as well as informative. Not to mention "old timey".

I also have a rosebud tip and may attempt to flame straighten it.

But ultimately, it sounds like my best move is going to be to just get a piece of plate the size I want. I really didn't expect 1" plate to distort so much!

northeastconfederate · Dec 22, 2018

digger doug said:
Let's just leave the Lincoln electric salesman out of this o.k. ?

First you said the welding table will be for "mobile" use.

Now it's "Backyard" ?

make up your mind please, and stay with it.

Many welding tables are ground. Acorn welding tables are ground, as are several others.

Give me a break, will you? My garage is in my backbyard, OK???? Have you ever heard of an "expression"? And it will be mobile: the top will be welded to a pipe, which in turn will be welded to the center hole of an old 8-lug Chevy wheel. Which then will have a couple of casters welded to it, so that the whole thing can be tipped up on its wheels and moved from one corner of the garage to the center of it, and back again. Or maybe to a different corner. Or maybe even into the yard. As long as the ground is dry so it won't sink. See? "Mobile".

There. Does that satisfy your need for literal interpretation? Or do you care to try to belittle me for whatever dumb shit inconsistencies you think you see???

plastikdreams · Dec 22, 2018

Heat plate up enough and it'll warp, no matter the thickness. Different metals distort differently though. 316ss will potato chip if you look at it wrong, 17-4ss barely moves even in heat treating.

northeastconfederate · Dec 22, 2018

plastikdreams said:
Heat plate up enough and it'll warp, no matter the thickness. Different metals distort differently though. 316ss will potato chip if you look at it wrong, 17-4ss barely moves even in heat treating.

"Potato chip" Lol... Huh. I figured, Big plate = pretty stable. Obviously I was wrong.

Cycle1000 · Dec 23, 2018

Sometimes you have to use what you have. With thick plate and small machine you want to V bevel to a small point and leave a gap for welding. First tack would be dead center, then a small one on each end. Then flip ans skip until done.
No matter how you do it there will be some warp so heat and beat will be the order of the day
Gary

plastikdreams · Dec 23, 2018

northeastconfederate said:
"Potato chip" Lol... Huh. I figured, Big plate = pretty stable. Obviously I was wrong.

It's an industry term

northeastconfederate · Dec 23, 2018

Cycle1000 said:
Sometimes you have to use what you have. With thick plate and small machine you want to V bevel to a small point and leave a gap for welding. First tack would be dead center, then a small one on each end. Then flip ans skip until done.
No matter how you do it there will be some warp so heat and beat will be the order of the day
Gary

I hear you. I think my next move is going to be installing the 60A breaker and put the stick machine in service. Among other things, it will give me some practice with it. Then heat and beat. I do have an anvil, which will come in handy for this.

The next pair of plates I will bevel on both sides and alternate, following the advice in this thread to tack it with a "V" at the joint to begin with and let the weld pull it; then alternate sides. Hopefully, it will end up "sort of" flat. Again, I am not expecting surface plate flatness here. I'll do a better job beveling, using a grinder. First go-round I used a torch, having seen the local welder do that with great success. He is very good at what he does and has been doing it for many years. Decades, in fact. I have dabbled with all of this for 25 years or more but never have been any good at it, really. Never any consistent practice, and only a small amount of instruction here and there from a handful of welder friends and acquaintances. Anyway, my torch beveling did make a bevel, but way too much of one and not all that even, despite the use of a straightedge to guide the torch.

So, a 30 or sondegree bevel with a grinder on both sides and we'll see what happens.

Keep plate flate when welding?

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