I bought an unwelded collector from a very good reputable place. I basically tacked two of the pieces together and welded it. I'm afraid of it cracking so I weld on the inside as well. When I let the peice cool, I tried the fitment to the other two peices that are left and the collector no longer lines up!

Did I just warp the entire piece? Should I have tacked the entire collector up and then welded it together?

 

i wouldve tacked the entire thing first.

 

I noticed after I finished...

Oh well you live, you learn. What settings are you guys using to weld this stuff together?

 

what welder are you using.

 

Thermal Arc 185TSW.

 

what material, what thickness.

more info please.

 

Schedule 10 304L Stainless. .065

 

John, I see you're welding now, eh? I use a Miller 180SD and I weld that stuff at about 80-85 amps. Generally if your welds are grey and dull in color you're using too much heat. Practice on some scrap and try to get a nice rainbow-looking color.

PS I gotta come over once I finish my car. I need a street tune!

Steve

 

Yea, I've been practicing quite a bit. I called up the guys at Thermal Arc and they sent me a sheet because the machine runs hotter than the Millers and what not. Like you run 80amps. I run 70amps and I don't floor it or anything. My welds come out rainbow colored. I'm actually worried about penetration and stuff though. How can you tell from the back of the weld? How should it look if there's good penetration?

Steve, do you backpurge? I actually do it. People aren't willing to part with their setups. I have a seperate regulator with line and I use aluminum foil to keep the argon inside the collector while i weld.

There's one thing I cannot figure out. When I tail off the weld, there's a dark blue spot that shows up. I turn down the post flow and it goes away. Do you know what that is? Come by the shop anytime. Maybe show me something I haven't tried yet!

-John

 

I generally don't backpurge. You'll notice that you have good penetration if the welds bleed through and since you backpurge you shouldn't get the "sugaring" that occurs when you don't. About the blue spot, I honestly don't know what that is.

We'll definitely hook up over the summer.

 

I don't get the bleed thru but I get the sugaring if I don't backpurge. I gotta show you some of my welds. Maybe I need to turn it up to 80amps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Pikachu &raquo;</TD></TR><TR><TD CLASS="quote">I don't get the bleed thru but I get the sugaring if I don't backpurge. I gotta show you some of my welds. Maybe I need to turn it up to 80amps.</TD></TR></TABLE>

Usually when you backpurge, the backside of the weld has better cooling because of the argon flowing past it so the weld stays cooler than if you didn't backpurge. I usually turn up my machine an extra 5-10 amps when I backpurge.

And yeah, definetly have to have everything tacked up before final welding, that goes for just about anything, not only collectors.

 

Should I check for that bleed thru? The weld looks strong but I didn't see the bleed thru. What I'm really trying to do is to make sure the weld is strong so it does not crack.

Backpurge: Can you tell me what are the characteristics of a good strong weld that will resist cracking? TIA!

 

Ideally the backside of a weld will look similar to the topside of the weld if you have 100% penetration. On thicker materials you either bevel the weld joints or leave a small gap (1/16" or so) or a combination of both to achieve 100% penetration.

Stealing this from SMSP -



That's the backside of the weld.

 

Ahh bevel. Ok that sounds good! Gonna give that a try. Thanks for the help!

 

If you are welding the pieces of the collector together don't worry about penetrating 100% since the 4 into 1 section never really cracks and isn't under too much stress. Try to penetrate about 80% or so and if you've got a small enough torch do a fusion weld on the inside to get the 100% if you are that worried about it. I would suggest backpurging and trying to get 100% on the butt welds of the runners though.

 

I beveled all the runner pieces. I will be backpurging it so it will be looking nice on the inside.

 

Ill be there Sunday John. I lay down some beads and we can take a look at what you are doing. By the way, I'll set up your saw too.

 

Woohoo! I can't wait. I was about to toss the saw too cuz all the blade would do is jump off the wheel.