Pie Cut Tubing Opinions

[Mike T]

 

[ijames]

Looks very nice, and an amazing job getting all the way around all of those beads. I wonder at what point assembling a bend it would be worth rigging up a glove bag or glove box, where you could jig up a small bend, seal it in the bag and purge with argon, and then make all the welds. You would get shielding on the backside, as well, so cleaner on the inside, and it would save gas.

 

[Mike T]

I have jumped around a bit trying to figure the best way to complete each stage of the project with the tools that I have. Purging is at the top of my list right now and I have begun machining my purge plugs out of some square plate that I had laying around and testing ways to get complete argon coverage.

 

[turbodave231]

Nice purge plates!!!

I usually tape the ends and stick a purge hose in through the tape. That wouldn't work if you are welding small pieces............ You could use aluminum foil and a hose clamp, but that wouldn't be as cool looking.

 

[ijames]

On long pieces with few joints that works well. I figured on a tight bend with lots of very short slices there would just be too much leakage and you would be forever peeling and retaping to keep the tape far enough away to not melt or burn. I've never actually used a glove bag arrangement, but something like this seems like a good place to try it. Just put the workpiece in a clear plastic bag, stick in the torch, ground clamp, and purge hose, squeeze out all the air you can, tape off the end around the lines, and grab the torch through the bag. Purge for a bit, then weld. Just try not to let the bag touch hot metal . A clear wastebasket sized garbage bag should work for this. Wrap the bag around the lines for at least six inches, a foot if you can, with a ring of tape every few inches, so the linear velocity of the escaping argon will best fight air trying to diffuse in, and the diffusion path is as long as possible. Work as far away from this as you can, again to minimize the effect of any air infiltration. If you have a small plate you can attach the ground lead to that and weld with the bend sitting on the plate (just like a big welding table), and it will protect the bottom of the bag. Anyway, something I've read about and seen pictures of, but never had the need to try myself.

 

[20psiofevil]

A lot of work imo. I'd guess 2 hr's worth of welding alone.

 

[Jerryl]

Lol.

 

[Mike T]

View attachment 233054 View attachment 233055 View attachment 233056 Nice purge plates!!!

I usually tape the ends and stick a purge hose in through the tape. That wouldn't work if you are welding small pieces............ You could use aluminum foil and a hose clamp, but that wouldn't be as cool looking.

That's a great looking pipe Dave. Is that 3.0 or 3.5 tubing ? From what I read most of the guys seem to be purging the same way your and have had no problems with it. My problem will be with the small pieces but the aluminum foil idea will work for sure in some areas. I have a milling vise similar to yours that really comes in handy for holding stuff at odd angles. BTW since you are a machinist you probably caught that I was using a milling bit in the lathe .

 

[Mike T]

A lot of work imo. I'd guess 2 hr's worth of welding alone.

I would like to think it would only take me 2 hours but I wouldn't be surprised if it takes the good part of a day. There will be a lot of welding when the cuts around the air box area are included.

 

[Mike T]

On long pieces with few joints that works well. I figured on a tight bend with lots of very short slices there would just be too much leakage and you would be forever peeling and retaping to keep the tape far enough away to not melt or burn. I've never actually used a glove bag arrangement, but something like this seems like a good place to try it. Just put the workpiece in a clear plastic bag, stick in the torch, ground clamp, and purge hose, squeeze out all the air you can, tape off the end around the lines, and grab the torch through the bag. Purge for a bit, then weld. Just try not to let the bag touch hot metal . A clear wastebasket sized garbage bag should work for this. Wrap the bag around the lines for at least six inches, a foot if you can, with a ring of tape every few inches, so the linear velocity of the escaping argon will best fight air trying to diffuse in, and the diffusion path is as long as possible. Work as far away from this as you can, again to minimize the effect of any air infiltration. If you have a small plate you can attach the ground lead to that and weld with the bend sitting on the plate (just like a big welding table), and it will protect the bottom of the bag. Anyway, something I've read about and seen pictures of, but never had the need to try myself.

I hear what you are saying and I have though about doing sections in some sort of controlled environment. If you have ever watched welding tips & tricks he has a good idea for making a cheap argon chamber out of a Harbor Freight bead blaster cabinet. This sounds like a good idea but for myself by the time I look through glasses, cheater lens, welding helmet and a bag or chamber it might be a little hard for me to see the weld.

 

[turbodave231]

Mike,
Thanks! That DP is 3.5. Fits a 1970 Lesabre project. End mills are handy in more than just a mill!




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[20psiofevil]

I would like to think it would only take me 2 hours but I wouldn't be surprised if it takes the good part of a day. There will be a lot of welding when the cuts around the air box area are included.

I was being generous on that time frame. 3 welds on 3.5" mandrel tube take me about 30min. I like to weld personally but do it for a living (mainly stick with 7018 and 6013) for the past 8 years and I'm burnt out with my last hot side pipe set to mount the new turbo.

 

[Mike T]

I was being generous on that time frame. 3 welds on 3.5" mandrel tube take me about 30min. I like to weld personally but do it for a living (mainly stick with 7018 and 6013) for the past 8 years and I'm burnt out with my last hot side pipe set to mount the new turbo.

Maybe it won't take as long as I expect . I will have about 24 seams to weld at just under 9.5 inches each (about 19 feet of welding). I can weld at probably 4 inches per minute and at that rate non stop it should take about 1 hour. Including all of the other steps needed I would be very please to have it finished in even 3 hours.

 

[John Larkin]

Obviously you'll allow for some cooling time. I bought cheater lenses also, 2.0; made a world of difference for me but I still have to be around 12" from the torch to get the best view. The idea of a purge box sounds great but I would be too far away as well.

 

[ijames]

Obviously you'll allow for some cooling time. I bought cheater lenses also, 2.0; made a world of difference for me but I still have to be around 12" from the torch to get the best view. The idea of a purge box sounds great but I would be too far away as well.

I've heard of using a blast cabinet, but a clear plastic bag gives you a closer view and makes it almost free to try. Good beads are a result of a comfortable setup and good vision, so do what makes your welds the best.

 

[Mike T]

Not the best welds... just finding the right temperature and testing my purge on two scrap pieces.

 

[Mike T]

Purge side of weld.

 

[Jerryl]

Looks great! You can weld my projects anytime!

 

[Mike T]

Looks great! You can weld my projects anytime!

Thanks for the complement Jerryl but it really should have looked a little better because it's just a fusion weld. I see that there is going to be a very fine line between good penetration on the inside and cooking the outside a bit. I will probably beat these pieces with a hammer to see how the fusion weld will hold up.

 

[turbodave231]

I've been fusion welding (also called "Scotch" welding) 304 for years and I've never seen a failure. Your purge side looks great.