# Welding - WTH?



## Duke (Dec 23, 2019)

I am busy upgrading my mini mill - part of which involved welding a structure from 10mm steel plates.

The base plate is about 12" by 25" and is 10mm thick.

I decided to add a couple of steel bars to the bottom of the base plate for additional support.


After welding, I discovered that the whole plate has been bent out of shape along both it's width and length.

I knew that stuff will bend while it is welded, but did not think this will happen on 10mm steel.....


Fortunately I did manage to get it bent back to within about 95% of what it was.


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## savarin (Dec 23, 2019)

Nothing to do with welding or machining but many years ago when we first came to australia virtually every back yard (in North Queensland) had a wood fired barbequem
Ours didnt have a plate to cook on so I used a steel plate 36x24 inches.
It was dead flat when it went on but after the first bbq the bow in the centre was around 3 inches higher than the edges.
I left it as it was so all the fat drained off.
It is amazing how much metal will distort with a little heat on one side.


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## FOMOGO (Dec 23, 2019)

Stitch welding, plug welding, and moving from side to side, will help to minimize distortion. Any size metal will distort from welding. 10mm, at under 1/2" is in no way immune. Like most things, a little more experience will help you in this area. Mike


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## MrWhoopee (Dec 23, 2019)

As the weld puddle cools, it shrinks, SIGNIFICANTLY! You have just learned one of the most important lessons for any weldor, very similar to the first time you mill off one side of a piece of cold-rolled. In exactly the same way, you learn to anticipate and plan accordingly. No matter how firmly you clamp the parts, they are going to move.


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## MrWhoopee (Dec 23, 2019)

savarin said:


> Nothing to do with welding or machining but many years ago when we first came to australia virtually every back yard (in North Queensland) had a wood fired barbequem
> Ours didnt have a plate to cook on so I used a steel plate 36x24 inches.
> It was dead flat when it went on but after the first bbq the bow in the centre was around 3 inches higher than the edges.
> I left it as it was so all the fat drained off.
> It is amazing how much metal will distort with a little heat on one side.



In the same vein, my friend built a large wood stove from the end of an explosion-proof conveyor housing that had to be shortened. He made the top plate from 12 ga. 304 S/S. When the stove was hot, that plate would dish down almost 2 in., returning to flat (more or less) when it cooled. I suggested he weld a ring in the middle and attach linkage to a needle on the mantle, creating a large temp gauge.

Four decades ago, I built a heavy stainless steel fire grate for the cave I used to live in. I designed it to allow the 1/2 diameter rungs to expand and contract by only welding them at one spot in the middle. It is still flat, and sufficiently heavy that no one has bothered to steal it.

All steel moves with heat, stainless moves even more.


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## DavidR8 (Dec 23, 2019)

Slightly on topic, are there tables available with expansion rates for various metals?


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## Mitch Alsup (Dec 23, 2019)

You have just discovered why I like brazing--there is way less distortion after things cool down.


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## RobertB (Dec 23, 2019)

DavidR8 said:


> Slightly on topic, are there tables available with expansion rates for various metals?







__





						Thermal Expansion - Linear Expansion Coefficients
					

Linear temperature expansion coefficients for common materials like aluminum, copper, glass, iron and many more.




					www.engineeringtoolbox.com
				




also has a calculator.

Google "coefficient of thermal expansion" and you will find many versions.


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## DavidR8 (Dec 23, 2019)

Thanks @RobertB


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## benmychree (Dec 23, 2019)

savarin said:


> Nothing to do with welding or machining but many years ago when we first came to australia virtually every back yard (in North Queensland) had a wood fired barbequem
> Ours didnt have a plate to cook on so I used a steel plate 36x24 inches.
> It was dead flat when it went on but after the first bbq the bow in the centre was around 3 inches higher than the edges.
> I left it as it was so all the fat drained off.
> It is amazing how much metal will distort with a little heat on one side.


Did you slip a shrimp on the Barbie?


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## matthewsx (Dec 23, 2019)

benmychree said:


> Did you slip a shrimp on the Barbie?


 Oh, they don't like that one mate....


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## benmychree (Dec 23, 2019)

matthewsx said:


> Oh, they don't like that one mate....


And we do?  So much for TV ads!


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## matthewsx (Dec 23, 2019)

Definitely visit Australia if you have the chance, fantastic country with very friendly people. 

John


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## benmychree (Dec 23, 2019)

matthewsx said:


> Definitely visit Australia if you have the chance, fantastic country with very friendly people.
> 
> John


Were I the traveling type, I would do that; Were I the traveling type, I'd first visit the Isle of Man and Britain, land of (most of) my ancestors.


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## savarin (Dec 23, 2019)

benmychree said:


> Did you slip a shrimp on the Barbie?


Nope! because we call them prawns. 
Have a good one guys.
Not a good Christmas here this year, 7.4 million acres burnt out, nearly a thousand homes wiped out, 180 deaths so far and it still going strong.


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## brino (Dec 23, 2019)

savarin said:


> Not a good Christmas here this year, 7.4 million acres burnt out, nearly a thousand homes wiped out, 180 deaths so far and it still going strong.



I heard you set new all time record high temperatures -----ON TWO CONSECUTIVE DAYS!

Stay safe, Charles!


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## benmychree (Dec 23, 2019)

savarin said:


> Nope! because we call them prawns.
> Have a good one guys.
> Not a good Christmas here this year, 7.4 million acres burnt out, nearly a thousand homes wiped out, 180 deaths so far and it still going strong.


In California, we can relate to that, with our fires, maybe not the gross acreage, but with loss of life and property; scary times!


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## MrWhoopee (Dec 23, 2019)

savarin said:


> Not a good Christmas here this year, 7.4 million acres burnt out, nearly a thousand homes wiped out, 180 deaths so far and it still going strong.


I'm feeling your pain, welcome to the new normal. We were evacuated for 5 days in '12, the fire got within 1/2 mile. I still have flashbacks when I see the convoys of fire trucks. Fire season just ended a month ago and we're finally able to relax a little. 
Stay safe & ready.


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## savarin (Dec 24, 2019)

Thanks guys, I am safe up here on NQ but my sons are close down in victoria
Whatever, have an awesome Christmas everyone.


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## Janderso (Dec 24, 2019)

As I was reading through this, I was wondering how you are making out Savarin?
Terrible what is happening down there!
Glad to hear you are ok.
All of us in California can relate to the fire storms.
 7 million acres?


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## Aaron_W (Dec 24, 2019)

Janderso said:


> 7 million acres?



For some perspective in the US the 10 year average number of acres burnt annually is 6.9 million, with about 1/4 to 1/3 of that total occurring in Alaska. To date in 2019 the US has burnt 4.6 million acres, with 1/2 of that occurring in Alaska. 

So far in 2019 Australia has burnt a combined 12 million acres and they are only in the middle of their fire season. By landmass Australia is roughly 2/3  the size of the USA and they are only in the middle of their fire season.

Australia is no stranger to fire, but 2019 is set to make several new records, it has been a very bad year for fires.


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## welderr (Dec 26, 2019)

I used to be a volunteer firefighter here in Northern New Jersey and we had the occasional brush fire but they were always pretty manageable, but down in the pine lands they have huge fires because of all the needles that the trees drop there is natural kindling spread all over the ground. And once it gets going and hot enough even the live trees burn. My late cousin used to work in Georgia on a large timber plantation of pine trees a couple months out of the year, he was always clearing the fire roads with a large dozer, and the fire breaks. They would do a controlled burn every year of a  third of the property to keep the fuel load on the ground manageable. Fires unfortunately are a natural thing , it is amazing to see how quickly nature regenerates after a fire but unfortunately that doesn't include the people or a lot of the animals who perished in it. I have a good friend in Australia right now, he is safe so far but wild fire is a scary thing it can change direction in an instant and the wind can carry embers pretty far, I pray for all involved. TJ


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## ericc (Dec 26, 2019)

I recommend reading a good welding text with an emphasis on engineering, such as the Lincoln Procedure Handbook of Arc Welding, or something like that.  It has been referred to as the "bible".  I don't know how you did the welding, but the book stresses on calculating the amount of weld length based on the strength requirement, and not welding too much more than that.  This will go a long way to help avoid warping.  No full coverage welds unless you are welding up an anvil.


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## epanzella (Dec 26, 2019)

A long weld starting from one end will warp just about anything. Tack weld the whole structure if it can support itself and then alternate seam welding (1" max at a time) from one side to the other so the shrinking welds fight each other.  On parts that have to remain true I often weld or clamp  extra braces and cross pieces, only removing them when  welding is done and cooled. As mentioned in previous posts only full seam weld if you absolutely need it.


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## Chips O'Toole (Jan 1, 2020)

Look into flame-straightening. It doesn't mean you heat your project and bend it while it's hot. It's a completely different thing.


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## crazybrit (Jan 11, 2020)

Duke said:


> After welding, I discovered that the whole plate has been bent out of shape along both it's width and length.
> 
> I knew that stuff will bend while it is welded, but did not think this will happen on 10mm steel.....
> 
> ...



Obviously anything will warp with enough heat but I'm a bit surprised too on the 10mm .

There are some useful videos on YouTube if you search for "weld sequencing". 

Glad you were able to get it mostly square.






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## RYAN S (Jan 11, 2020)

Here is a setup that we recently used to resist / work with warpage due to the heat of welding. The plate was pre flexed by placing a washer in the middle and then bolting down the edges. After welding it came out flat.


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