.120 Mild Steel Tubing Help

[PLWeld]

Push or Pull as apposed to burn through

KarateBoy,
I wanted to try and help clarify this burn through discussion. If you think about burn through, at what point of the weld bead does burn through take place? At the puddle, right? So, Sundowner is right. If you are using a pull technique in an already molten puddle and already extremely heated material, as you move along you are creating more heat and thus more molten temps than the thin wall can handle.......unless, of course, you stop welding and let it cool. With a pushing technique, you would essentially be pushing the filler metal into still solid material, which has not reached the temp of weld bead or puddle yet. does that help?

Also, on the issue about weaving your weld bead, especially when welding tubing. The claim is that when weaving while welding this tubing is it generates even more heat than necessary and can cause undercutting at the shoulders of your weld bead. Make sense? I never weave when I'm welding thin wall tubing, just a nice, even straight bead and has always worked well for me.

[nocheepgas]

Also, on the issue about weaving your weld bead, especially when welding tubing. The claim is that when weaving while welding this tubing is it generates even more heat than necessary and can cause undercutting at the shoulders of your weld bead. Make sense? I never weave when I'm welding thin wall tubing, just a nice, even straight bead and has always worked well for me.

I wouldn't consider .120 as "thin wall" and always weave, making sure I get a goot tie in on both metals and fill any undercutting. Welding a buggy frame, I'd definitely weave! On thin stuff like 14 gauge or higher, then weaving does put too much heat into the metal and also creates severe warpage problems.

[On fire most of the time]

Im not so sure I'd call .120 wall thin tubing either...

Most of the roll cage material I work with is thinner than that, at .095.

My best advice to you is to stay 90' to the joint at all times, and when fitting the two pieces of tubing together, make sure that you eliminate the feathered edge of the tubing...a quick once over with a sander will fix that. Ive seen several cages crack when the fabricator didnt fit the tubes very well.

If you stay 90' to the joint, and you have the welder (and weldor) set up right, shouldnt have any issue.

[Craig in Denver]

Not going to retype the whole passage, but if you're interested, I refer you to page 46 of the Miller GMAW handbook. This section deals with Direction of Travel-Type of Technique.

Since you made me look, I'll type it.

Quoted from the Miller GMAW handbook:

"There are some distinct advantages of a push technique. One advantage is when relatively thin materials are to be welded, or when doing a process such as hardfacing. Low penetration would be required, and a push technique along with a faster travel speed can help achieve this in certain applications. The concentrated heat and arc force are now directed away from the weld puddle (and its thermal heat). This generally results in less penetration and a flatter, wider bead."

This manual can be downloaded or ordered in hardcopy as part of the Miller Student Pack ($25 including postage). The student pack, not only includes the GMAW handbook, but also an excellent TIG Handbook, along with a bunch of other goodies. Best $25 you can spend in welding.

I agree about the best spent $25 in welding, along with Lincoln's Procedure Handbook of Arc Welding, also $25.

I use both techniques, just depends on what I'm trying to accomplish.

Worth learning both directions, someday you may need it.

[Vicegrip]

To much Stick Out? More stick out the taller the bead among other things.

[SundownIII]

Craig,

First off, appreciate your taking the time to type that.

Second. It's sorta funny. If the majority of the posters on this board had and used the two references you mentioned, a good 60% of the repetitious questions would not have to be asked.

Not only would the answer be right there before their very eyes, but it would be a "detailed" and "verifiable" response, not like some of the responses I see coming from some posters on this board.

There's a wealth of information to be obtained from these boards, but there's also a lot of "bad" information put out also. I guess, what I'm saying here, is a message board is no substitute for self study and real research.

[PLWeld]

Hey guys, I guess I should pay attention the the previous posts before opening my big mouth. Somewhere in here........... I lost the part where we were talking about .120 wall thickness, oops. Sorry bout that. I'll pay more attention next time before I open mouth, insert foot. I really thought we were discussing thin wall tubing I guess if I had've payed attention to the title, I wouldn't be looking silly right now

[KarateBoy]

KarateBoy,
I wanted to try and help clarify this burn through discussion. If you think about burn through, at what point of the weld bead does burn through take place? At the puddle, right? So, Sundowner is right. If you are using a pull technique in an already molten puddle and already extremely heated material, as you move along you are creating more heat and thus more molten temps than the thin wall can handle.......unless, of course, you stop welding and let it cool. With a pushing technique, you would essentially be pushing the filler metal into still solid material, which has not reached the temp of weld bead or puddle yet. does that help?

Also, on the issue about weaving your weld bead, especially when welding tubing. The claim is that when weaving while welding this tubing is it generates even more heat than necessary and can cause undercutting at the shoulders of your weld bead. Make sense? I never weave when I'm welding thin wall tubing, just a nice, even straight bead and has always worked well for me.

Make sense to me. I really prefer pulling the torch because its so much easier to see the puddle but maybe I'll need to learn to push too.

[On fire most of the time]

Hey guys, I guess I should pay attention the the previous posts before opening my big mouth. Somewhere in here........... I lost the part where we were talking about .120 wall thickness, oops. Sorry bout that. I'll pay more attention next time before I open mouth, insert foot. I really thought we were discussing thin wall tubing I guess if I had've payed attention to the title, I wouldn't be looking silly right now

I forgive you,

Ive misread things and responded to them that way before...not on this board yet though.

[TS-Off-Road]

I build roll cages every day. .120 DOM. Pull the gun while weaving or making small circles. Not weaving the gun will pile up the bead on a tight joint.