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Panel paching, splicing and welding questions

Hemirunner

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I’ve seen some of you guys post pictures of welded patches and spliced panels where you can’t even tell any work was done. Lots of examples in Pat’s Bullet Charger build thread. My question is do you grind each set of spot welds before making the next series of welds? I have a gap so the panels don’t but and warp but I’m wanting some suggestions to improve my rather mediocre metal skills.
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You can do whatever your comfortable with. I'll usually do a section and then grind. If I keep welding I get carried away and start getting stuff too hot. You can also warp just from grinding.
 
You can do whatever your comfortable with. I'll usually do a section and then grind. If I keep welding I get carried away and start getting stuff too hot. You can also warp just from grinding.
What do you grind with and what grit abrasive? Do you knock it down with a course and finish with a couple different finer grit abrasives? Using 2,3 or 4”? Air grinder, electric? This fender is a total piece of **** so anything I do can’t hurt it. I’m just looking for ideas on techniques and equipment.
 
What do you grind with and what grit abrasive? Do you knock it down with a course and finish with a couple different finer grit abrasives? Using 2,3 or 4”? Air grinder, electric? This fender is a total piece of **** so anything I do can’t hurt it. I’m just looking for ideas on techniques and equipment.
Usually start with a 36 or 80 grit Rolock (sp?), small disc. Once it's down just about the entire way I'll go to a bigger wheel to metal finish. The small disc is good for quick knock down of the weld but you'll struggle to get a straight panel since it's so concentrated. 80 is all the finer you need for metal work IMO. I have all air stuff.

I ruined a ton of stuff trying different things. You just gotta dig in and practice.
 
I use these and generally knock the majority of the weld down as I go then finish them off once done. I see you using TIG a lot, TIG welds are softer and much friendlier to hammer and dolly work which can be helpful. Given your skills I have no doubt you'll knock it out.

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I use these and generally knock the majority of the weld down as I go then finish them off once done. I see you using TIG a lot, TIG welds are softer and much friendlier to hammer and dolly work which can be helpful. Given your skills I have no doubt you'll knock it out.

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I have those in 2” and 3” that I use in the air grinder.
I do a lot of TIG welding and have gotten pretty decent results with it. One of my big faults is that I need to slow down to keep things from getting too hot.
I cut a 1/16” gap in this panel and I’m using the mig since it’s a horizontal joint and I need to improve my MIG welding game on sheet metal. If it was a vertical joint, I’d have a much tighter fit up, run a vertical down with the TIG and knock it out.
 
Weld in random spots. Cool down. Weld again. Cool. Repeat process till seam is welded. Grind with 36 on small 2" rolock till weld is close to flush. Watch the heat build from grinding. Cool when it starts to get warm. Grind flush with 80 on larger 3" rolock or disc till flush. Cool as grinding. DA with 180 grit. Try to keep the discs as flat as possible on the surface. Dont use flapper wheels on a 4 1/2" disc grinder. They induce too much heat. I have seen them used with good results but it takes a light touch.
 
I'm not as good as some of these guys but to me the #1 thing is to tinker with the settings until a short spot weld penetrates through but doesn't melt away the metal. From there it's keeping the temps down by jumping around, on problematic spots I've I've even laid a damp towel along the weld area but that was a long joint on a flat panel.
 
I'm not as good as some of these guys but to me the #1 thing is to tinker with the settings until a short spot weld penetrates through but doesn't melt away the metal. From there it's keeping the temps down by jumping around, on problematic spots I've I've even laid a damp towel along the weld area but that was a long joint on a flat panel.
I’m using a copper paddle behind it for the same effect as the damp towel. It pulls some heat out, not near as well, though.
Weld in random spots. Cool down. Weld again. Cool. Repeat process till seam is welded. Grind with 36 on small 2" rolock till weld is close to flush. Watch the heat build from grinding. Cool when it starts to get warm. Grind flush with 80 on larger 3" rolock or disc till flush. Cool as grinding. DA with 180 grit. Try to keep the discs as flat as possible on the surface. Dont use flapper wheels on a 4 1/2" disc grinder. They induce too much heat. I have seen them used with good results but it takes a light touch.
I’ll try this tomorrow. Sounds like sound advice. Never thought about using the DA.
 
There are several ways to skin this cat as mentioned above.
I like to jump around and make tiny welds then quench with compressed air after each weld.
Grind off the tops of the welds with the edge of a cut off wheel on a 4 1/2 grinder, only touching the weld, not the panel, then finishing off with a 60 grit flap wheel.
Never had a problem with warping.
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I guess I’ll have to try the cutoff wheel on the grinder trick. Bad things usually happen when I have a cutoff wheel, lol.
 
I like the rotolok 60-80 grit myself, I feel I can control the pressure applied to the panel as well as the speed better than a 4 in.
A 4" can heat a panel in a couple of seconds if not careful....
 
You can also use the welders mud as I call it.....comes in a container and you spread it above and below your weld area.

As you stated earlier just go slow....
 
You can also use the welders mud as I call it.....comes in a container and you spread it above and below your weld area.

As you stated earlier just go slow....
As others have mentioned, the key is to take..........your..........time.
Careful handling with the edge of the cut off wheel will focus the heat on the weld and not the panel. It chews up discs pretty fast but they're cheap.
Long fast strokes with the finish grinder and don't fall into the trap of focusing on a single spot.
:thumbsup:
 
I mentioned the die grinder.....I find it much easier to control (you can kinda "throttle" it), and the wheel is half the size
I like using die grinders for allot of stuff too but when I have a ton of grinding to do as in the pics above I'll use the 4 1/2".
I like to rock out when I work and I can't hear the stereo very good over the compressor but I can over an electric grinder.:drinks:
 
I use arcabrasives 2" Predator quick lock discs on angle grinder. Best I've found are the arc discs. They last a long time, and also do the cut off wheel trick
 
Ok guys, I tried the cut off wheel trick and I have to say it’s not for me. I started practicing by patching the antenna hole. Not bad, went slow and found the compressed air nozzle worked the best for keeping heat out. Another thing I learned is to clip the wire before each pull of the trigger no matter how much of a pain it was. That gave me clean, consistent welds each time. Here’s the antenna hole after I shot it with self etch from a rattle can.
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I went on to do the lower fender patch. That went ok. I knocked it all down with 36grit on a 3” roloc and then 80 in the DA. The area above the seam is going to need a skimcoat of filler, but I knew that going in. These fenders probably weren’t worth salvaging.
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I don’t hate it and I know the next one will probably look better. Now, for the next question... how do I fix these thin areas where it blew holes when blasted?
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You can see this thin area ‘blistered’ from the abrasive it was so thin. Should I cut out and weld in a patch?
 
I hate to say it but that looks pretty thin to me. Have you priced a new AMD fender?
I do not like body work and many times it's worth it just throw in the towel and replace it.
 
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I hate to say it but that looks pretty thin to me. Have you priced a new AMD fender?
I do not like body work and many times it's worth it just through in the towel and replace it.
It’s a 70 coronet fender on a Superbird clone. AMD doesn’t make them and mint originals fetch $1500 each... unfortunately, I have to make chicken salad out of chicken ****.
 
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