How do you guys weld patch panels - butt or lap?

Yeah I'm kinda new to the welding game so please don't hate when I ask basic questions . These Howells bun panels come with a flange. I'll be MIGing them with .023 wire. Should I cut off the flange and butt weld or leave the flange and lap weld? Any help is greatly appreciated!

 

I lap weld, but the guys who know what they're doing butt weld them....and they don't use MIG either.

 

It would really be worth your time to learn oxy/acetelene welding. Weld an inch, hammer on dolly while it's still glowing red, weld an inch, etc. A "gas" set up is much less expensive than MIG or TIG, and for body work provides superior results.
Nobody does it any more cause it's too much like work.
Butt weld.
That's how I do it anyway.

 

Use the method that YOU get the best results with. A good lap weld might be better than a bad butt weld. Do a few tests on some scrap. If you use lap welds make sure to seal the back side to keep out moisture. I did some years ago & sealed the back with penetrating epoxy from a boat shop. 20+ years & rust free. I have also butt "hammer welded" stuff with a torch. Very slow but good results. You might use a combination of techniques depending on the part.

 

Here's a good read...
Nothing To Exciting 30 Ford Sheetmetal Work!

And here's another...
Welding in patch panels

 

Butt joints, whether oxy-acetylene or MIG

 

Yes MIG butt is the better for fit and finish. However, for a beginner I would use a lap weld, joggle the patch under the old skin. Drill small holes in the top skin and plug weld. Butt welds if you don't have many hours with a Mig will create more burn thur holes and more grinding. That's my 2 cents.

 

Butt weld works best for me.

 

That's usually where guys go wrong, they forget to seal the back side of the lap. Patience is a virtue. Gas weld and hammer on scrap for a while, you'll find it more fulfilling in the long run. And it's more traditional

 

Depends on what you're trying to attain, really. I don't care for a lap joint because it leaves a space where rust can form on the inside if it isn't sealed properly. And unless you're gonna take the lazy route and just use some seam sealer, then it's going to take twice as long to weld. You're not really saving yourself any time either because now you're welding both sides of the panel so even though you have a thicker joint, you're putting that much more heat into it.

I don't know how that panel is supposed to look when finished. Are we looking at a body line? It almost looks like you could cut away the existing metal and tuck that flange behind if you prefer a lap joint, but if that's a body line then I would say that's a bad idea because once you weld, your body line will almost disappear.

That's not to say there isn't a time and a place for a lap joint either, where panels have to overlap like a seat re-enforcement or where a floor pan meets a rocker. The factory often spot welds places like this, but most places won't have the equipment to duplicate that. Then I say plug weld and lap weld and seal both sides. And use a weld thru primer before you start welding. It's not the best solution but it's better than nothing and paint will just burn off and make your welds that much uglier.

Mathius

 

Lap welds are for quicky body shop jobs, overlapping metal is just an invitation for rust. However if two pieces of metal must be overlapped both sides of the seam should be protected from the elements either by paint, seam sealer or undercoating.
Butt welding is the way to go, but its harder to fit the patch and has a tendancy to warp panels easier if done to fast.

 

Hey guys,
butt welding is the way to go. Tig is also the way to go because it doesn't warp panels like other methods. If the panel lasted 80 years the patch panel should last as long.
just my 2 cents worth.
thanks
Dale

 

On a panel like that I would butt weld, using a what ever method of welding mig, tig, etc. But being that your new to the welding go with lap. Drill out the top panel and plug weld the two panels together. After that you can weld the seam. Be sure to take your time, weld one plug weld and let it cool and repeat till your finished. If you weld the seem I wouldn't weld more than 1/4'' at a time, same here let it cool between welds to reduce warping. Most important thing is patients and keeping trying not to warp the area. Good luck and enjoy yourself it will get easier with time.

 

Also, if you're going to lap weld go pick up a good weld through primer... this will prevent mother nature from trying to claim your ride again. On another note if you burn through get a piece of flat copper and stick it behind the burn through then weld the hole shut... makes it easier to close up the hole.

 

Everytime I try to butt weld I burn through at some point no matter what I do.

Lap weld city for me...

Besides, the "bad" side is out of the weather inside the panel anyway. You can use a bead of seam sealer and then prime or paint over it to make it weather proof.

 

Last tip I swear... when have to lap weld things on I will use self-tapping screws to hold the panel on. The advantage of doing that is tighter panel to panel fit, saves time looking and messing with claps, and you can fit the doors and deck lid on the car making sure of the proper gaps.

 

Butt weld. TIG when ever possible, else MIG. Haven't had a warped panel in years. This is a patience game. Tack in a few places, far apart, and then wait until the panel is cool to the touch. Tack again, splitting the difference between the previous tacks, then wait again until the panel is cool to the touch. Correct any misalignment as you go. Repeat until the tacks collide. If you are burning through, your welder is set too high. If it can't be set lower, turn up your shielding gas flow, and SLOW DOWN.

 

there are some cool little panel holders that help with root gap for butt weld...worth the money if you are doing a fair amount of welding.

 

On panels like that I would use panel adhesive and skip the welding. You already have a flange, cut your body to match and use 3M 08115 or comparable panel bonding adhesive, you'll never regret it. The biggest drawback to traditional flange joinery is that when welded they leave a gap in which moisture can collect and soon rust. With panel adhesive there is no gap...the entire flange is filled with adhesive. Better bond an NO warping due to welding heat.

 

Well said! I was about to write something similar but you've got everything covered.....

For all you guys burning holes, go read the last couple lines over and over....

I swear that 50% of welding is understanding your equipment and how to use it.

 

x 2

 

You can make your own:

http://www.jalopyjournal.com/forum/showthread.php?t=11673&showall=1
http://www.garagejournal.com/forum/showthread.php?t=92220




And just for the record, those aren't my welds.

Mathius

 

laps work faster, but encourage rust, also if the vehicle sits in the sun for any length the metal will expand at a differant rate due to the added thickness and can cause a ripple look when you sight down the lines.... but if you're new to welding,,,,,,,go with the lap

 

I think it's a combination of all the hollywood bs over the last 10 years that discovery channel's put out and just a lot of bad information out there. I had welding instructors telling me it isn't possible to gas weld aluminum, and there are countless certified welders out there who believe you have to have the "frying bacon" sound to make a good weld. And my absolute favorite is people who honestly believe a TIG welder gives the strongest weld or a superior weld.

Welders are pretty simple, you have one setting for heat, and some way of controlling the filler. If that's a stick welder... you get out of the puddle, if it's a tig, you add less filler, if it's a mig, you turn your wire feed down.

volts/amps = heat, wire feed = how much metal.

It's pretty basic, but there are so many people out there getting bad information.

I passed a mig certification with the welder sounding like it was sputtering. I was welding on 3/8" plate, v-groove, uphill. I turned my amperage way up to get proper heat, and I turned my wire feed way down so I didn't have to race up hill to keep the puddle from dripping on me. As long as you stay in one spot long enough to fill you can move back and forth nice and slow and get a gorgeous bead that's got 100% penetration.

It's all about controlling the machine and watching the puddle. It has nothing to do with a sound, or a certain technique, or anything like that.

Mathius

 

Very well said Mathius!

 

Ditto!! I use small 7/16 metal framing screws. Get them at Home Depot real cheap. This way, you can set the panel and make sure its where you want, then make sure you spot weld at 3" apart. Have an air gun to blow the spot welds cool while you go along. Do not weld more than just a small spot. Grind as you go. Main thing is "HEAT IS YOUR ENEMY". Don't use water to cool it as it tempers the metal, only use air. Once you start getting all the seam done, remove the screws and welt the holes. You basically end up connecting all the dots of weld and have very minimal warping.

 

Thanks for all the replies! I think I'm gonna whack the flange and butt weld it. I butt welded the patch panels (washing machine top) on my turtle deck quarters and they came out OK. Still need some work though.



I also made a bunch of butt weld clamps, so I'll use those.

 

Ok, I admit I didn't read the whole post.....but the "Proper" way would be to butt weld, the lap weld would leaves an area that will collect and hold moisture and possible rust down the road. The Lap weld on the other hand makes it easy to fit the panels, gives you a backing for welding and probably wouldn't be as prone to warping as a butt weld would be. In the end of the day, what do you feel the most comfortable with?

 

Oh, and don't forget, proper fitment and cleanliness of your material are the most important steps in the welding processs. Without them, you are guaranteed to fail.

 

I second that notion. The first body panel repair I did was on my floor pans for my Malibu and I didn't have very good cutting tools. I ordered factory replacement sections from the paddock. All I had at the time was a small die grinder, and a saw zaw. I couldn't get good clean cuts with the saw zaw on the patch panel because it vibrated like hell. Cutting the floor pan in the car worked out ok. On top of that the repair panels didn't cover the whole area where I had rust.

Long story short I had some big gaps. You can weld them, but it takes forever and when you're done you have a lot of weld to knock down to make it look factory.

If you're doing a panel like you showed where it's an outter panel that's cosmetic and will be seen, take extra extra care.

I'd knock that flange down like you want to, then refit the panel to the car and trace it out with a sharpie or something, then make your final cut. If you're not sure on an area, take small cuts until you get it right. Offset aviation snips work nice for making smaller precise cuts up to 18 ga. Anything over that and they're not much good for anything. 18ga is tough, but you can do it.

Mathius