05snopro440
Well-known member
Holy! I just saw the last page of the thread and at first thought you were making 39-46 Chevy fenders. Great work on the fenders and even the buck! I wish I had a quarter of your skill and half of your ambition! 
HD trike
- Thread starter dutch
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Dr Crankenstein
Rocket Surgeon
Your photo below... how do you avoid distortion while welding a joint of this length?
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bob w
Still crazy after all these years!
Hopefully Dutch will explain. However, I did watch a video tape by an English metal man who gas welds without filler rod too. He states that by moving at a constant pace distortion is minimized. Notice the consistent width of the heat discoloration in the pic above.
I've tried it on flat test pieces and it works.
I've tried it on flat test pieces and it works.
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I`ll try to explain how I work...
there`s always some distortion, but real problems occur when the distortion is uneven. Single most important thing is to cut the panels to a seamless fit so when placing the tack welds you wont need any filler rod and you`re able to steer the panel and hold the torch in the other hand. Tacking takes every bit of focus I can find. Correct level on both, heat/tack, check and correct height for next tack, look at gap closing, set next tack before panels start to overlay etc... I dont use clamps since I already know the panel fits seamless to the other so it will end up in the right position anyway. I place a tack at the edge of the blue of the tack before, so about every 3/4".
After that, it`s hammering the seam flat and the panel to the shape it should be. Wirebrush the seam clean on both sides and weld in one pass. Takes some practice to get the penetration right, but what you get is a crater on the top side and bead hanging on the other side of the weld. Work that flat and 90% of the shrink/distortion will be gone.
By welding in a single pass the discoloration is very even, so the shrink is very even ,so the distortion is minimal.
You do need to understand the reason why sheetmetal will distort after heat.
When heated it expands, when cooled down after heat, the surface area has shrunk more than it was before heat. So uneven heat = uneven shrink = distortion = very hard to correct.
Hammering these a/o welds is no problem because they are as soft as the surrounding metal. I can cut them with snips no problem and I can use the e-wheel to stretch larger area`s.
hope this makes any sense and / or helps
there`s always some distortion, but real problems occur when the distortion is uneven. Single most important thing is to cut the panels to a seamless fit so when placing the tack welds you wont need any filler rod and you`re able to steer the panel and hold the torch in the other hand. Tacking takes every bit of focus I can find. Correct level on both, heat/tack, check and correct height for next tack, look at gap closing, set next tack before panels start to overlay etc... I dont use clamps since I already know the panel fits seamless to the other so it will end up in the right position anyway. I place a tack at the edge of the blue of the tack before, so about every 3/4".
After that, it`s hammering the seam flat and the panel to the shape it should be. Wirebrush the seam clean on both sides and weld in one pass. Takes some practice to get the penetration right, but what you get is a crater on the top side and bead hanging on the other side of the weld. Work that flat and 90% of the shrink/distortion will be gone.
By welding in a single pass the discoloration is very even, so the shrink is very even ,so the distortion is minimal.
You do need to understand the reason why sheetmetal will distort after heat.
When heated it expands, when cooled down after heat, the surface area has shrunk more than it was before heat. So uneven heat = uneven shrink = distortion = very hard to correct.
Hammering these a/o welds is no problem because they are as soft as the surrounding metal. I can cut them with snips no problem and I can use the e-wheel to stretch larger area`s.
hope this makes any sense and / or helps
BillM
Well-known member
Thanks for the explanation Dutch. I presume you use a small brazing tip?
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Usually I use a #1 welding tip. #0 also works fine for 19gauge but is too small for 16gauge . I use 16gauge for fuel tanks and I dont have to switch tips that way.
Neutral flame always.
Old Iron
Well-known member
Thanks for the details.
I never knew why this process worked so well either.
[P[P[P
I never knew why this process worked so well either.
[P[P[P
Very nice explanation. Thanks. If I tried it, it would look like Swiss cheese.
MercuryMac
Builder Junky!
Thank you for the explanation, Dutch.
Dr Crankenstein
Rocket Surgeon
Thanks, dutch! [cl
I'm a "heavy metal" fabricator and welder, with an early (abbreviated) career in collision repair. I can iron out some damage, but I'm nobody's "coach builder".
Unfortunately, I never learned how to do what you do, but I hope to learn before I die. (Little demand for custom work in my corner of the world.)
Another question:
- Have you tried TIG welding the same joints? I don't see a huge difference between the two processes, especially when performing a fusion weld with no filler rod... I'd appreciate your opinion on the subject...
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I'm a "heavy metal" fabricator and welder, with an early (abbreviated) career in collision repair. I can iron out some damage, but I'm nobody's "coach builder".
Unfortunately, I never learned how to do what you do, but I hope to learn before I die. (Little demand for custom work in my corner of the world.)
Another question:
- Have you tried TIG welding the same joints? I don't see a huge difference between the two processes, especially when performing a fusion weld with no filler rod... I'd appreciate your opinion on the subject...
.
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Thanks, dutch! [cl
I'm a "heavy metal" fabricator and welder, with an early (abbreviated) career in collision repair. I can iron out some damage, but I'm nobody's "coach builder".
Unfortunately, I never learned how to do what you do, but I hope to learn before I die. (Little demand for custom work in my corner of the world.)
Another question:
- Have you tried TIG welding the same joints? I don't see a huge difference between the two processes, especially when performing a fusion weld with no filler rod... I'd appreciate your opinion on the subject...
.
I came from heavy metal myself Doc... I`m a farrier and blacksmith by trade and after I quit shoeing horses I worked as fabricator welder building bike frames ,sidecars, trikes and race quads... but I also had my share of H-beams.
about the tig welding...Should work I guess but I suck at tig welding...
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Old Iron
Well-known member
Doc, I tig fusion welded a set of quarter panels that I stretched on a 74 Javilen and they came out just like Dutch's welds.
Dr Crankenstein
Rocket Surgeon
I came from heavy metal myself Doc... I`m a farrier and blacksmith by trade and after I quit shoeing horses I worked as fabricator welder building bike frames ,sidecars, trikes and race quads... but I also had my share of H-beams.
about the tig welding...Should work I guess but I suck at tig welding...
Thanks for your reply, dutch. I don't have an oxy/acetylene setup anymore. (I still have torches, but no bottles. Since I acquired a plasma cutter and discovered zip-cut discs, my torches are busy collecting dust.) I like to think I'm handy with my TIG, though I've never tried a long, continuous run on light gauge material. [S
Thanks again for your explanation(s) dutch, much appreciated!
Thanks for chiming in, OI. I respect your opinion and I (now) feel confident I can attempt a delicate butt weld with my TIG.
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there`s one thing I really dont like about tig welding vs o/a. Its sooo sensitive on pollution. The slow pace and high temps of a/o welding clear out most crap before fusion is there.
Dr Crankenstein
Rocket Surgeon
I hear you loud and clear, dutch. I've TIG welded miles of CLEAN aluminum, some chromoly, some stainless and some mild steel... like you said, TIG does not play well with contamination, period!
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that said... contamination is the word I`ve been trying to find....
Why 2 words in english while 1 word in dutch for the same thing...?
So what happens when tig welding sheet, at least when I weld; I end up with crappy welds which need a lot of repairs which causes uneven heat, uneven shrinkage and a lot of distortion.
Hey Doc... thanks for cleaing up why I dont like tig on sheet ...
Why 2 words in english while 1 word in dutch for the same thing...?
So what happens when tig welding sheet, at least when I weld; I end up with crappy welds which need a lot of repairs which causes uneven heat, uneven shrinkage and a lot of distortion.
Hey Doc... thanks for cleaing up why I dont like tig on sheet ...
Old Iron
Well-known member
The metal definitely needs to be clean and have a the smallest diameter wire in hand just in case you need to dob that blowout.
Low amps, 1/16" or smaller tungsten and keep moving.
Low amps, 1/16" or smaller tungsten and keep moving.
Dr Crankenstein
Rocket Surgeon
Thanks for the tips and advice, guys.
dutch: You write English very well... call it pollution or call it contamination, welders know exactly what you're saying. [cl
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dutch: You write English very well... call it pollution or call it contamination, welders know exactly what you're saying. [cl
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I had to wait a bit on the muffler, as the owner had it custom built by the best exhaust shop in the country and I needed it to get measurements for the floor. I wont bore you guys with the $900 pos muffler, unless you make me. I think I will make a pan to cover it in case someone looks underneath...
anyway, I made a start with the trunk lid and the first part of the floor.
I pre stretched for the 3/4" beads on the e-wheel , but still a bunch of distortion and after rolling the step I had a lot of shrinking to do. Turned out just fine, fits and its strong... it needs to carry the pos muffler...
anyway, I made a start with the trunk lid and the first part of the floor.
I pre stretched for the 3/4" beads on the e-wheel , but still a bunch of distortion and after rolling the step I had a lot of shrinking to do. Turned out just fine, fits and its strong... it needs to carry the pos muffler...
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DozerII
Well-known member
Your workmanship is incredible Dutch. [cl[cl[cl[dr[dr[dr[P[P[P
