BODY, a patch panel from start to finish

[Tinbender]

I see that some good information on patch panels has been posted. This piece is kinda long, so I thought I’d start another thread. First, understand there are many ways to do this. This is one of the procedures I use for simple panels like this 63 Impala fender. It’s what works well for me.

In the first picture the area to be replaced is marked. There is a brace behind the rust out that is still in good condition. I marked my cut lines in areas where I could get to the back of most of the weld to hammer it. I also like to use curved corners, rather than 90 degree corners in the open areas of the panel. This seems to help keep distortion down.

[Tinbender]

I cut the 2 spot welds along the edge with a spotle tool. Any spot weld drill could be used, or you can grind thru the top layer of metal at the weld to remove the piece.

[Tinbender]

After removing the section, the brace should be cleaned up. I wire brushed this area, and treated it with conversion coating after the metal work was done.

[Tinbender]

I started the patch by braking a 90 degree edge in a piece of 18 ga.

[Tinbender]

I used a shrinker to pull the crown in the patch. If you don’t have one you can cut and weld the flange. The important thing is that you take the time to fit the patch well. It should lay flat without clamping.

[Tinbender]

Once the crown is correct, then the patch is trimmed to fit. I like a slight gap, about 1/6” and even all around the patch. Again, take the time to fit your patch and the job will go easier, and you finished product will come out better.

[Tinbender]

I held the patch with magnets for the first tacks.

[Tinbender]

In this picture the patch is tacked in place, and I’ve started skip welding the seam. I use gas welding for all my sheet metal work. This way the tacks and the welds can be stretched by hammering them over a dolly to compensate for the shrinking caused by the heating and cooling of the metal during welding. It’s a common misconception that warpage is caused by heating. The real damage comes from the shrinkage of the surface area when the metal cools. I use compressed air to cool. Never water. (Unless I’m using a shrinking disc). Even when I’m using air, I cool the weld slowly, and only use the air after the weld has been hammered.

[Tinbender]

More hammer welding.

[Tinbender]

Welded.

[Tinbender]

After some hammer and dolly work, and the first filing, you can see the highs and lows.
Guide coat will help identify high and low spots for more hammer work

[Tinbender]

Here’s the fender after more pick and file work. How far you go depends on the amount of time your willing to spend. This repair will not be a metal finish. Nothing wrong with a little filler.

[Tinbender]

This last shot shows the fender ready for filler. I finish metal in 40 grit for filler work. That’s plenty course enough for adhesion, and fine enough that you don’t loose too much metal in the grinding process.
Thanks for looking, Tin.

[kentucky]

Nice tech! So do you hammer each weld as soon as you tack it? I'm trying to get my nerve up to try http://www.jalopyjournal.com/ubbthreads/images/graemlins/smile.gif

[Tinbender]

Yep, hammer each tack, and hammer each stitch weld. (I weld 1/2" to 1" each time) Don't make the next weld till the metal is cool enough to touch. Correct the metal with hammer and dolly between each weld. This is not as hard as it looks! I'll never weld sheet metal with a mig again

[kentucky]

Thanks for the advice. I plan to practice on something less cool before tearing in to the 46 http://www.jalopyjournal.com/ubbthreads/images/graemlins/smile.gif

[Morrisman]

[ QUOTE ]
I finish metal in 40 grit for filler work. That’s plenty course enough for adhesion,

[/ QUOTE ]

Do you throw filler onto bare metal, or spray some primer first? I always heard to use a primer coat. I shall be coming to this filling and finishing stage on my Morris very soon.

[Tinbender]

Bare metal.

[Tman]

Great post.

Hey guys, hop over to the TECHOMATIC, overspray covers the Bondo part pretty well.

Also, kudos on CLEANING YOUR METAL!!!!! It drives me nuts to see guys welding a rusty piece onto a part slathered in old paint!!! You metal sinners know who you are! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[kustombuilder]

EXCELENT demenstration!

pay attention boys and girls THIS is the RIGHT way to do sheetmetal work. BEAUTIFUL!!!

[NoSurf]

Man, if it only was a '64 fender you fixed, then I would be SET!

What do you do with the torch when you do the hammer and dolly work? Do you have a "holder"? And what kind of torch head is that you're using?

[palepainter]

Hey Tin Bender,
Which gas welder unit are you using? I have seen a couple out there, notknowing which one to get.

Mike

[kustombuilder]

looks like he is using a HENROB torch. AWESOME setup but they run about $400 for the unit itself. it offers super fine flame adjustability. i used Fab32's once and it was awesome!! it's on my wish list.

[jay]

Okay dont yell to loudly but i have to know the answer..I know i messed up trying to weld to much of the panel at one time so thats where i got alot of bad wrinkles..i also didnt leave any gap so i'm learning here..but do you weld your stitch and hammer it right away? I was going back and getting it red hot and hitting it which i guess is a bad thing also i was using a rag with water.

[Tinbender]

Thanks guys!
Yep, using a Henrob. Very nice torch, worth every penny they cost. But you can still get good results with a standard o/a torch. Try turning your pressures down some and using a small tip. (Make sure your O/A set up has anti-backfire valves)
I have a stand that I put the torch in while I hammer the welds. I leave it lit. I hammer each weld stitch while it's still hot. If you don't stretch an area enough, you can re heat, and hammer again. You can hammer cold too, It just adds some work hardening.
If you stretch too much, you can heat the area again, and cool it to shrink, or use a shrinking disc.

[Plowboy]

Cool post, I guess I need to figure out how to weld with my Henrob instead of just cutting shit with it, now that I have a plasma cutter on semi-permanent loan in the garage.

[slammed]

You prefer the O/A over mig. Why? Less grinding and a more uniform penetration of the weld? This step-by-step can not get any better.....unless we were right over your shoulder in person.

[Tman]

Henrob (OA in general)makes for a "softer" weld. It is easier to work and grind since it matches the parent metals properties closely

[NoSurf]

Thanks Tin!

Can you explain more about the hammering and dolly part? As you do this you are stretching the metal back out, so do you hammer around the spot the dolly is heeled against?

[Satinblack]

What type welding rod do you use?

[Dan]

another important tip he gave is to use round corners on the patch panel rather than square corners - the round corners take up less area and thus you are doing less welding - less welding = less heat = less warpage
Very good post!

[Tinbender]

What Tman said about MIG vs. O/A is correct. MIG is very hot and concentrated. It cools fast and thermal shocks the steel, causing the weld to harden too much for sheet metal(if you plan on working the metal after welding). With O/A even though your causing a much larger heat effect zone, it cools slower and remains softer. It will grind easier, and most important, can be worked with hammer and dolly with out cracking.

More on hammer welding. You want to hammer the weld as fast as you can. The hotter the metal the easier it stretches, and the less it work hardens. You use "hammer on dolly". The weld is sandwiched between the hammer and dolly so that it is forced to thin, which increases the surface area.
You are trying to compensate for the shrinking that happens when the metal cools. How close you match the stretch to the shrink will dictate how close the metal will be to it's intended shape when your done.

BTW, I use 1/16" mild steel rod for most work, once in a while I'll use 1/8" if I have a wide gap to fill.

[v8minor]

Very nice work ,I have a set of o/a bottles ,have not used them in years. The price of gas over here is wild . Seeing this I will have to get them filled..

[LoungeLife]

For all you guys wnating more info on that Henrob torch setup, there's some great how to info on their website - I couldn't pull myself away. I found it a couple of days ago and had to "work late"

lounge

http://www.cut-like-plasma.com/

[Paul]

bttt

[topdeadcenter]

I will bttt this one!

TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!TECH-O-MATIC!!!!http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

Mike

[banzaitoyota]

Tinbender, have you ever tried the Mecco Midget and compared it to the Henrob?

[4t64rd]

Tech-O-Matic! BTTT

Already in my favorites

[hatch]

Here's some more thoughts on patching....After I weld in a patch, I turn off the shop lights, and hold a spotlight behind the panel to check for pinholes. I also prefer to use a very thin coat of "all metal", front and back, before finishing with bondo. I used to lead the repaired area for insurance, but now feel that we have some modern alternatives that are less of a health issue. One other thing....when you are repairing a "sandwiched" area, weld-thru primer is a good idea...available either as a spray or brush on application. Some of these ideas are from ICAR training on unibody...good course if you ever get a chance.

[superbell]

Top Tech!!!

[hammeredabone]

Great tech, very well organized and informative!

[Tinbender]

Thanks for the nice words guys!
Banzai, nevr tried the Mecco, but I've heard nothing but good about it.

Hatch good tip on the light, I check my welds all the time with a strong flash light. As for the All Metal, I don't use it, and I strongly recommend against it. It's unnessary and prone to cracking and leaveing ghost lines, all the things you avoid by gas welding.

[hatch]

I agree on "all metal" cracking. No flexibility at all. I only use it over the weld and almost thin enough to see through. The one advantage is moisture can't get through it, where with bondo will absorb moisture.....Great post and pics...hatch

[Hip]

For all you guys wnating more info on that Henrob torch setup, there's some great how to info on their website - I couldn't pull myself away. I found it a couple of days ago and had to "work late"

lounge

http://www.cut-like-plasma.com/
(http://www.cut-like-plasma.com/)
I just went to to the sight, AWSOME!!! Its a "MIRACLE TORCH"! I gotta have one when i save up my pennies. Thanks for a very cool tech! Iv been doing bodywork and patch panels for years!, but i certainly learned a thing or two off this post. Thanks