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TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Wed Aug 18, 2010 9:34 am
by Tim
I just got a lincoln tig and it came with a -17 torch and one 3/32 "red" tungsten electrode and a jug of argon but no setup documentation.

What is the setup to weld a bandsaw blade? Do I need a 1/16" or an 040 or 020 setup?

I have an '97 import car fender that needs a repair. I can only say that it is pretty thin. I haven't measured it. I removed them to bang out some dents and creases. When I hammer and dollied the dents and creases, it was incredible just how light of a tap was needed to move the metal. It's maybe ... 1/32" ??? How do I go about selecting an electrode diameter and amp setting?

I read that the "magnum" torch is compatible with the torch that lincoln uses. I was looking for a -9 torch sans cable that I could swap in. Can someone tell me what to look for? I'm just looking the lincoln pta-9 brand.

Thanks

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Thu Oct 28, 2010 12:31 pm
by dustelf
i see nobody wants to answer your questions, i will try to do that.

1 , band saw blades, i've done it a few times with 1,6mm tungsten , would use a smaller one if availble, i can also say if a bandsaw will brake, it will have more cracks along so the weld might hold up but it will brake soon somewhere else.

2. tig welding fenders.. i ve done that also, not the best proces for welding fenders, it can be done thou.

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Thu Oct 28, 2010 1:09 pm
by jakeru
I TIG welded an old Chevy truck panel. I measured the metal thickness at .050", which if you look at the sheetmetal thickness charts, is 22 gage. Almost certainly a modern car will be made of even thinner material.

If you are butt welding, do yourself a favor and spend lots of time working to get a real nice joint fit-up. So tight that you can autogenously tack weld fuse the pieces together is ideal. It will reduce the amount of heat input you'll need. Then you just add a dab of filler (MIG wire works well) to bring the puddle up to, or slightly above the surface. Scribe your cut line for a real tight fit-up, and finish off with a file or sander to finalize the fit-up.

I followed the "tack weld a million times until you can't stand it anymore, then fill in between the tacks with skip weld seams" routine. Skipped around and waited for the panel to be cool enough to touch before welding. Still ended up with some panel distortion. Holding a copper spoon on the back side helped reduce heat input and makes filling in any holes a breeze. But that probably requires a second person to hold it. For machine settings, I developed a real aggressive, slow speed pulse that was great for reducing heat input. Maybe 100 amps peak current with pedal all the way down, minimum (maybe 10%) pulse duty cycle, minimum (maybe 10%) base current, and minimum (maybe 1.5) pulses per second. That was for an Everlast Super200P at least. I really liked that setting for reducing heat input. I used some .030" or so 70k psi MIG wire (pulling lengths at a time off the roll) for filler, just added where needed. Ended up with a real narrow weld bead, and low heat input.

If I do it again, I'd like to try finding a low tensile strength, small diameter filler wire. I know low strength steel alloys are available in oxy acetylene welding filler rods, in 45k psi and 60k psi strengths. I was thinking the lower tensile strength filler might shoulder more of the metal stretching duties, and let the parent metals remain more distortion free. I am quite sure that 70k psi tensile strength is overkill. However I'd need it real small diameter (like MIG wire size) so not sure how readily available that would be.

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Thu Oct 28, 2010 5:40 pm
by kermdawg
Just a question-Would oxyfuel welding produce less distortion on sheet metal like that?

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Fri Oct 29, 2010 7:15 am
by ogorir
I weld automotive sheet at 35A, 1/16th tungsten, #4 cup. use as little amperage as possible to get a puddle on both sides. a little pre-heat helps even your penetration out. if you're not getting full penetration to the back side, just weld the back side. use as little rod as possible. I use .035 Er70S2 for everything but filling holes, which I use .045" ER70S6 rod or .030 ER70S6 from the mig spool. standard sheetmetal practices apply. lots of tacks, only weld 3/4" at a time, move around, let the fender cool, ect.

most automotive sheetmetal until the 80s was 19ga, and even past there it was mostly 19ga, they just started making it out of shit metal. the high-draw sheet metal they use in modern cars doesn't weld worth a flying pile of dicks, which is why no one does it. you CAN weld it, but it just sucks. also, a lot of parts are now galvanized. make sure you grind all that off both sides near your weld as it will weld like shit if there's any zinc in your puddle. and I'd advise wearing a respirator.


I have no experience welding band saw blades, but the 1A per thousandth rule usually applies. I'd err on the side of less heat, but experiment until you can get full penetration with one pass. you might also try clamping your joint to a block of copper, lighting up on the copper, and moving the arc onto the piece so the arc start doesn't blow a hole in the edge of the blade. works on razor blades.

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Fri Oct 29, 2010 5:10 pm
by jime46
Just a comment on the band saw blades. Many, many years ago, before the days of resistance welders on the saw, I welded lots of blades with silver solder. Need a fixture to hold the blade in position. Grind the blade with a 15-30 degree angle to get a longer weld. Easy to grind flat and really strong.

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Fri Oct 29, 2010 10:22 pm
by kermdawg
Next time my bandsaw blade breaks I'mma try that :) Got buttloads of silver solder layin around, but its for brazin copper. Same stuff? I know theres 20 differant kinds.

Re: TIG WELDING - BANDSAW BLADES, IMPORT CAR FENDERS

Posted: Fri Oct 29, 2010 11:02 pm
by ogorir
nope, not the same stuff. silver solder is mostly silver, other solder is mostly tin or lead. silver solder is expensive, but very handy. you can pick it up from most jewlers supply places. ottofrie.com has decent prices, but they'll only sell to you if you have a sales tax #. I'm sure you can pick it up local, too, though.