Metal warpage Q's

[Daddy454]

Not even sure if that's the right term,but how do you account for/prevent it?Been working on a welding cart for a machine I've had for years,although I haven't used it much.Lincoln Electric flux core rig the wife bought when I thought I was gonna stretch a tank for my bike years ago.Inspired by the "welding projects" thread,I started the cart.Using 1" square tubing,and angle,and the more I tack it together,the worse it's getting.Luckily it's mostly done as far as the frame,but I was just curious how you avoid twisting the steel?I'm really starting to get into it and want to build some more projects,but wondered what the experts do to make their stuff straight/square/whatever?

 

[A_Pmech]

The Lincoln Electric "Procedure Handbook of Arc Welding" has a good section on weldment distortion and designing around it.

http://www.amazon.com/dp/B000K6O6PE/?tag=atomicindus08-20

 

[Daddy454]

The Lincoln Electric "Procedure Handbook of Arc Welding" has a good section on weldment distortion and designing around it.

http://www.amazon.com/dp/B000K6O6PE/?tag=atomicindus08-20

Thanks,I may have to look into that.I was just wondering if there were any general "rule of thumb" guidelines that most often get used,or is every situation different.

 

[AMCguy]

That book is the Bible of welding and is well worth every penny.

In general terms, it is primarily caused by the cooling of the filler metal. It went in as a liquid but contracts when it cools to a solid. The contraction pulls the material out of position. The work has to be either completely supported in a fixture stronger than what you are welding (that little magnet can't do that) or pre distorted a calculated amount so the welding pulls it back into position.

It's a science and takes a good understanding of it to be a good fabricator.

Best advice I can give is get that book.

 

[AMCguy]

I'll add a little more.

Looking at what you are doing there, It looks like you have tried to tack the whole assembly and then fully weld it. You can't.

Try welding the complete front laying flat. Then weld the complete back laying flat. Then weld in the short pieces in to create the sides.

If you have more of that melamine lying around cut a square of it to fit into the four square openings you are creating in your frame. Arrange the four pieces around the melamine and clamp them. Do all of the outside corner welds. You can also arrange a couple of square pieces to form a 90 degree angle and screw them down well to that big piece you have.

 

[Daddy454]

I'll add a little more.

Looking at what you are doing there, It looks like you have tried to tack the whole assembly and then fully weld it. You can't.

Try welding the complete front laying flat. Then weld the complete back laying flat. Then weld in the short pieces in to create the sides.

If you have more of that melamine lying around cut a square of it to fit into the four square openings you are creating in your frame. Arrange the four pieces around the melamine and clamp them. Do all of the outside corner welds. You can also arrange a couple of square pieces to form a 90 degree angle and screw them down well to that big piece you have.

Looks like I may have to invest in that book if I'm gonna keep this up.I did in fact weld this up as you suggested,doing the side pieces first,then the short end pieces.I just found that once I got to the last short piece-not pictured here-I was almost 1/4-3/8" too tight(?).I had to pry it open just to get the piece in.As I'm no engineer,the pre-distortion is probably way over my head.Guess I'll be buying alot more clamps now too.

 

[GarageEnvy]

I would consider A Pmech the authority on this topic as he's the pro and I'm the "Joe" with a home hobby setup. I'd only add that a corner clamp like the one below has worked wonders for me in keeping things relatively square. The other photos are of a mailbox project I'm working on right now. It's 1" square tubing (.083 wall) and I welded it up using the method described by AMCguy. It's very similar in construction to what you're trying to do. There was very little warpage. Keep in mind that when I say it's pretty square, that means by tape measure standards. When A Pmech says it's square that means down to the .0000001" usually.

 

[mjb]

I second getting the Lincoln book. This video might help until the book arrives.

 

[Daddy454]

GarageEnvy-I have seen those corner clamps on some of the projects in here.I just recently grabbed my little magnets,thinking that would be enough.They do help a little but those clamps look pretty helpful too.Like you mine is mostly tape measure square,but certainly not within any sort of "spec"As I said earlier,look like I'll be buying alot more clamps.I'll add those to the list.Thanks man.

 

[Daddy454]

I second getting the Lincoln book. This video might help until the book arrives.

Thanks man,I'll give it a look.