bentwings
03-10-2008, 11:38 PM
Hi,
I'm a long time hot rodder, streetrod builder, toolmaker, engineer, welder and a few others.
I have a Lincoln 175 that is ok I guess. Not the old Miller that I learned TIG on many years ago and doen't have the very latest adjustability that I'm thinking I need now.
So here goes:
I do a lot of fuel tank repair and make a few new tanks for the streetrod and racers. Almost all of my aluminum welding is done on 14 ga or less, usuallly .050 and .040 5052.
I have a tank in for repair that has probably the best welds I've ever seen. They look the same inside and outside. I don't see how it could have been machine welded as there are various turns that would have prevented it. It almost looks gas welded except for the TIG like beads. It is .050 and I think it is 5052 judging by the hardness and stiffness of the material. Near the welds it is considerably softer however.
I don't know how it would have been possible to use a backing in this tank. I have been able to look at every weld and they are flawless inside and out. This tank is at least 15 years old and was anodized. I had them strip it so it is clean now.
I had to cut a sizable section out of this so I tried some practice welds on the cut out..
When I weld this stuff no matter how hard I try I still get the butt crack or closed butt crack on the back side. At very best I can get a full weld on the inside but you can clearly see a dark line down the middle of it on the back side. To date I haven't had any problems with the welds cracking even on some really old stuff I did back in my shop work days. You can clearly see the oxide layer on the inside weld.
I have a good double flow regulator so I can back purge. This doesn't seem to help much except for stainless.
I have a number of stainless wire brushes that are used just for aluminum. I also have some stainless wool. It is supposed to be 304 but I can't verify it. I can't say it is bad or good either. I have brushed hard and immediately began welding, I've stopped and brushed again, I've even gone so far as to brush the filler rods. I still get the same thing. Outside welds are ok, it's just the inside that doesn't pass muster. I also have some de-oxidized copper sheet that I use for backing occasionally. It works when I can use it.
Being old school I have a hard time converting to the auto dark lens. I still habitually flip the helmut up. I still on occasion use the old flip down helmut. I normally use a #8 shade for this welding this thin stuff. Interesting enough I see better welds with the old lens. It definitely is a different color. I use several reading glasses for help with my eyesight. The welds appear magnified so I can control the puddle better.
For this I use both green and red 1/16 tungstens with new gas lens and ceramic, no real difference I also removed the gas lens and used the standard collet and gas cups. I balled both and tried both pointed. I see some difference but the balled green seems better. At least the welds look better.
I got fresh 1/16 5356 rod as the tank will be re-anodized. I have also gone over the welder for gas leaks from the regulator to the electrode. Nothing. I have grounded directly to the tank, no difference. The pedal works very well. I set the welder at about 60 amps and I have plenty of range with the pedal.
Fit up on some of these repairs leaves a lot to be desired as the tanks are usually banged up a bit. I usually make a lap fit rather than a butt fitt as it is simply easier.
I think I have some technic problem that maybe you guys can help with. Any suggestions??? Sorry I just don't have a good camera.
Also is there some kind of water soluble backing tape that I could use??
thanks
I'm a long time hot rodder, streetrod builder, toolmaker, engineer, welder and a few others.
I have a Lincoln 175 that is ok I guess. Not the old Miller that I learned TIG on many years ago and doen't have the very latest adjustability that I'm thinking I need now.
So here goes:
I do a lot of fuel tank repair and make a few new tanks for the streetrod and racers. Almost all of my aluminum welding is done on 14 ga or less, usuallly .050 and .040 5052.
I have a tank in for repair that has probably the best welds I've ever seen. They look the same inside and outside. I don't see how it could have been machine welded as there are various turns that would have prevented it. It almost looks gas welded except for the TIG like beads. It is .050 and I think it is 5052 judging by the hardness and stiffness of the material. Near the welds it is considerably softer however.
I don't know how it would have been possible to use a backing in this tank. I have been able to look at every weld and they are flawless inside and out. This tank is at least 15 years old and was anodized. I had them strip it so it is clean now.
I had to cut a sizable section out of this so I tried some practice welds on the cut out..
When I weld this stuff no matter how hard I try I still get the butt crack or closed butt crack on the back side. At very best I can get a full weld on the inside but you can clearly see a dark line down the middle of it on the back side. To date I haven't had any problems with the welds cracking even on some really old stuff I did back in my shop work days. You can clearly see the oxide layer on the inside weld.
I have a good double flow regulator so I can back purge. This doesn't seem to help much except for stainless.
I have a number of stainless wire brushes that are used just for aluminum. I also have some stainless wool. It is supposed to be 304 but I can't verify it. I can't say it is bad or good either. I have brushed hard and immediately began welding, I've stopped and brushed again, I've even gone so far as to brush the filler rods. I still get the same thing. Outside welds are ok, it's just the inside that doesn't pass muster. I also have some de-oxidized copper sheet that I use for backing occasionally. It works when I can use it.
Being old school I have a hard time converting to the auto dark lens. I still habitually flip the helmut up. I still on occasion use the old flip down helmut. I normally use a #8 shade for this welding this thin stuff. Interesting enough I see better welds with the old lens. It definitely is a different color. I use several reading glasses for help with my eyesight. The welds appear magnified so I can control the puddle better.
For this I use both green and red 1/16 tungstens with new gas lens and ceramic, no real difference I also removed the gas lens and used the standard collet and gas cups. I balled both and tried both pointed. I see some difference but the balled green seems better. At least the welds look better.
I got fresh 1/16 5356 rod as the tank will be re-anodized. I have also gone over the welder for gas leaks from the regulator to the electrode. Nothing. I have grounded directly to the tank, no difference. The pedal works very well. I set the welder at about 60 amps and I have plenty of range with the pedal.
Fit up on some of these repairs leaves a lot to be desired as the tanks are usually banged up a bit. I usually make a lap fit rather than a butt fitt as it is simply easier.
I think I have some technic problem that maybe you guys can help with. Any suggestions??? Sorry I just don't have a good camera.
Also is there some kind of water soluble backing tape that I could use??
thanks