Ask your WELDING questions here.

[David R]

LexLeroy, those are some beautiful had made parts.

Nitro Acres, nice welds. I got no rhythm......

My son and I have a job shop. We tig as much as we can.

David

[JAFO]

So you remember those oxy-fuel cylinders I came across a couple months ago? Yeah- I also scored two sets of portables, cheap.

I hae been an oxy-acetylene cutting FOOL over the last month. Trying to figure out brazing now- I blew through an oilpan I was trying to braze a fitting onto. I think I should have used a welding tip, not the cutting head (duh!). To my credit, I didn't activate the cutting jet.

I still have to go get the big bottles filled. That's going to be a pain in the ass- local shops won't fill them if you don't have a pickup bed to put them in.

Did the gent that was trying to use a pressure reg on a Lincoln 3200HD ever get the code broken on settings and such? I would like to give gas-MIG another shot.

[DiabloADV]

I've got a Hobart 110v wire feed welder (with gas). I'm looking to weld up some exhaust pipes. I am NOT a highly skilled welder.

I'm looking for technique tips on welding mild steel pipes together. I found this YouTube vid that seems to make a lot of sense to me, at my skill level. Rather than try to lay a bead, the guy makes a series of tack welds around the tube. This strikes me as a way to really control what I'm doing.

http://www.youtube.com/watch?v=_v_6j...eature=related

Thoughts on this approach? Better suggestions...?

[LexLeroy]

Originally Posted by JAFO

I hae been an oxy-acetylene cutting FOOL over the last month. Trying to figure out brazing now- I blew through an oilpan I was trying to braze a fitting onto. I think I should have used a welding tip, not the cutting head (duh!). To my credit, I didn't activate the cutting jet.

Flux is your friend. When it turns glassy w/ no bubbles then it's hot enough to melt the filler metal - too much heat and you roach your flux. Use a flux that wets out at the right temp for your filler. For bronze or nickel silver I use Gasflux type "B" - similar to Harris #17 (that blue paste stuff).

[David R]

Originally Posted by DiabloADV

I've got a Hobart 110v wire feed welder (with gas). I'm looking to weld up some exhaust pipes. I am NOT a highly skilled welder.

I'm looking for technique tips on welding mild steel pipes together. I found this YouTube vid that seems to make a lot of sense to me, at my skill level. Rather than try to lay a bead, the guy makes a series of tack welds around the tube. This strikes me as a way to really control what I'm doing.

http://www.youtube.com/watch?v=_v_6j...eature=related

Thoughts on this approach? Better suggestions...?

A true tack weld is made to break off if needed or hold things in position to be welded.

A series of tacks would be a series of welds made to break off.

I weld exhaust with an SP100 turned down C 3 .
I start at the top and make my way down. One pass each side.
Make a dry pass to see where the gun will fit if its on the car.

David

[fxstbiluigi]

Originally Posted by David R

A true tack weld is made to break off if needed or hold things in position to be welded.

A series of tacks would be a series of welds made to break off.

I weld exhaust with an SP100 turned down C 3 .
I start at the top and make my way down. One pass each side.
Make a dry pass to see where the gun will fit if its on the car.

David

David:
A 'tack' also needs to be strong enough to hold the parts in alignment and withstand the pressure of coaxing the rest of the weldment into alignment. And withstand the stresses of welding once the fit-up is complete.

[DiabloADV]

What I mean is to use a series of short welds rather than a long bead.

[JAFO]

This will work fine, it's how I built the exhaust on my Jeep. Butt-welded tubes and short tacks. It's been bounced off of rocks and, while the tube has been squashed in areas, the welds have NOT failed.

Sent from my MB886 using Xparent Green Tapatalk 2

[David R]

What I am trying to say is learn the machine. Set it so you can run a bead. It is the right welder for the job. .023 ER70S-6 wire and c/25 gas. I do a lot of exhaust.
If its too hot and you continually have to stop then turn the machine down. If you are almost blowing through then the heat is right.

Have fun and enjoy the machine.

Sent from the phone in my shoe. Maxwell Smart.

[BobbySands]

Originally Posted by fxstbiluigi

David:
A 'tack' also needs to be strong enough to hold the parts in alignment and withstand the pressure of coaxing the rest of the weldment into alignment. And withstand the stresses of welding once the fit-up is complete.

eh, don't confuse the two. You tack pieces together and give them a smack, maybe too. But a third or fourth time or too much movement and your pieces are going to be laying on the ground.

In other words, tacks hold together only when subjected to a small force. And when the gap isn't right, the fitter will simply break the tack and have the welder start over.

[larryboy]

Originally Posted by DiabloADV

Thoughts on this approach? Better suggestions...?

It's fine for exhaust, don't weld a roll cage like that or anything your life depends on. We call that WyoWelding(Wyotech teaches that and it's technically wrong), the weakest part of a weld is the start when it's the coldest and that technique gives you a full weld of cold starts...wrong, but fine for exhaust.

[NitroAcres]

If a Tack was a Weld, it wouldn't be called a Tack....Tacks are to hold stuff together till you Weld it....a bunch of tacks stacked ontop of each other is Not a Weld.

[fxstbiluigi]

It all comes down to what you are welding.
A tack can be anything from a quick zap from a wire machine, think exhaust system, to hold the parts together. Or an actual weld such as needed to hold two pieces of pipe in alignment for welding. Or a short weld to keep two pieces of sheetmetal from warping so far apart that they can't be welded. Or heavy (1") Plate from warping from the heat input.
Some tacks can be small and light and some need to be considerably more substancial it all depends on the application and circumstances.

[dmaxmike]

Originally Posted by larryboy

It's fine for exhaust, don't weld a roll cage like that or anything your life depends on. We call that WyoWelding(Wyotech teaches that and it's technically wrong), the weakest part of a weld is the start when it's the coldest and that technique gives you a full weld of cold starts...wrong, but fine for exhaust.

I never learned that there? Must be that west coast wyotech. Then again i only used a MIG machine long enough to pass the requirements for it then all I used was TIG because that’s what i wanted to learn and be good at. Most high end race shops don’t even have a MIG in the building. Its real fun tacking together a full class one car with a TIG torch, talk about sun burn!

[Strong Bad]

Originally Posted by dmaxmike

Most high end race shops don’t even have a MIG in the building.

Most (if not all) NASCAR chassis are MIG welded. A quality MIG weld is more than strong enough for roll cage work as well as suspension components. I've seen my share of crappy TIG welds in offroad racing. Multiple pass welds where the root pass is cold and fills gaps in poorly notched/fitted tube and then a "sic Bro weave" washed over the top. Total crap strength wise, but looks like a million bucks.