Panel replacement technique

[Gary Schulz]

I have been replacing a lot of bodywork on my latest project and I was wondering if any of you use the technique I have tried to diagram below?

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In this technique you place the repair panel on top of the original bodywork and then draw an outline of the shape of the repair you want to make. Instead of trying to cut the repair panel to size first and then trying to accurately scribe that same shape onto the existing bodywork you just make a cut through both panels at once making sure you angle the grinder as shown. This way when the two panels are brought together they line up "perfectly" with no gaps. That is the theory....

Up until now I have just cut the repair panel to the desired size and then worked very hard to very accurately cut the panel underneath to match. That is a very tedious process on large repairs so I was wondering if this other technique is useful?

Any experience with this?

EDIT: Doing a little quick Trigonometry, the angle you need is very much sharper than what is shown in the picture (assuming the cutting blade is a bit thinner than both panels). Even with the thinest blade you will still have a small gap to contend with but perhaps this is still practical?

[minibitz]

That should work in theory.

In reality it takes a lot of experience to cut accurately enough for the new panel to match exactly. In most cases there will always be some clean up and fine tuning required. You also run the risk of ending up with a gap. Even when using a 1mm cutting disc the cut will be wider. Probably OK for MIG but you would want a tighter gap if TIG welding.

What I prefer to do is cut the old panel or portion of panel out, then clamp the new panel in place overlapping the retained portion of panel work. From there you can scribe onto the new panel. I cut the new panel slightly to the outside of the scribe line then linish the edge back gradually doing plenty of test fits until I get a desirable fit for butt welding.

[OGW 1082]

Hello Guys,
I've come across a YouTube Channel called Fitzee's Fabrications.
He does something similar to what Gary is trying....very good at what he does and worth a watch.
Most of his work is rust repairs.
Merry Christmas to all,
Regards
Glen

[Andrew1967]

That's an interesting technique.

Personally I just use a 1mm slitting disc to cut through both panels at once and then use some home fabricated panel clamps hold the two perfectly aligned.

Having the 1mm gap allows for weld penetration.

[Gary Schulz]

That's an interesting technique.

Personally I just use a 1mm slitting disc to cut through both panels at once and then use some home fabricated panel clamps hold the two perfectly aligned.

Having the 1mm gap allows for weld penetration.

So having the gap doesn't just blow away the edges when welding? I spend a lot of time trying to eliminate the gap but in all fairness it makes panel replacement an incredibly tedious process.

Do you back up the gap with a piece of copper while welding?

[Andrew1967]

You have to be careful when welding and continuous weld would result in blowing the metal away. I usually do a small weld, then go to another piece section, small weld, then another and go around like that until fully welded.

I use a piece of aluminium flat bar to take the heat out.

Practice on some off cuts to get the technique right

[360gts]

You have to be careful when welding and continuous weld would result in blowing the metal away. I usually do a small weld, then go to another piece section, small weld, then another and go around until fully welded.

I use a piece of aluminium flat bar to take the heat out.

Gary, I use the same technique that Andrew mentioned above.....small weld about two inches apart....with a thick piece of aluminum attached behind the joint using magnets. Heat is a big enemy when doing butt welding....getting rid of it will prevent distortion.

BTW, the alloy bar is attached with two U shaped steel straps with strong magnets one each end.
Merry Christmas and happy welding.

[360gts]

"You have to be careful when welding and continuous weld would result in blowing the metal away. I usually do a small weld, then go to another piece section, small weld, then another and go around until fully welded.

I use a piece of aluminium flat bar to take the heat out"

Gary, I use the same technique that Andrew mentioned above.....small weld about two inches apart....with a thick piece of aluminum attached behind the joint using magnets. Heat is a big enemy when doing butt welding....getting rid of it will prevent distortion.

BTW, the alloy bar is attached with two U shaped steel straps with strong magnets one each end.
Merry Christmas and happy welding.
[/quote]

[360gts]

"You have to be careful when welding and continuous weld would result in blowing the metal away. I usually do a small weld, then go to another piece section, small weld, then another and go around until fully welded.

I use a piece of aluminium flat bar to take the heat out"

Gary, I use the same technique that Andrew mentioned above.....small weld about two inches apart....with a thick piece of aluminum attached behind the joint using magnets. Heat is a big enemy when doing butt welding....getting rid of it will prevent distortion.

BTW, the alloy bar is attached with two U shaped steel straps with strong magnets one each end.
Merry Christmas and happy welding.

[360gts]

"You have to be careful when welding and continuous weld would result in blowing the metal away. I usually do a small weld, then go to another piece section, small weld, then another and go around until fully welded.

I use a piece of aluminium flat bar to take the heat out"



Gary, I use the same technique that Andrew mentioned above.....small weld about two inches apart....with a thick piece of aluminum attached behind the joint using magnets. Heat is a big enemy when doing butt welding....getting rid of it will prevent distortion.

BTW, the alloy bar is attached with two U shaped steel straps with strong magnets one each end.
Merry Christmas and happy welding.
[/quote]

[Tupers]

Gary I think that technique may work on thicker pieces but on the 0.8mm steel of most Mini panels you’re going to loose much hope of accuracy to movement in the cutting disc and the steadiness of your hand.


As mentioned above I opt for laying the new pieces over the old, scribing and line in and trimming to the line with either aviation shears or a pneumatic body saw.

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[Gary Schulz]

Yes, in fact I use blue layout fluid (Dykem) and a carbide scribe to get accurate cut lines as my preferred method. That is how I replaced the rear panel and a couple other repair sections. It is however very tedious so I was wondering if others had tried this method. Sounds like Andrew's method is pretty close but manages to deal with the 1mm gap.

I guess I will stick with my layout marking dye and scribe then. I don't want to be experimenting with the central tunnel replacement since there is too much at risk if it goes badly!

You can see the layout blue in this shot along with the final result. You are all correct. Keeping the heat down is key to a good result

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[Peter Laidler]

I always think that a lot of the methods used by you 'tinnies' or metalsmiths are those you've picked up over many, many years and are most comfortable with. Even if to others, they look awkward, they're the methods you feel suit you.

I have to admit that I am in awe to the skills you mostly amateur, self taught (?) tinnies display here - no matter whatever methods you use!!!

[Old English White]

As they say - there's more than one way to skin a rabbit
Yes, whichever way works for you. Many of us are too old to learn anything new now

[Peter Laidler]

You're right OEW! My old, late dad was a self taught carpenter, probably to cabinet making standards. But he refused to use modern aero standard wood glue. Nope....., just old boil-in-the-pot smelly animal glue. I think that I'm becoming like him by the day..........

[Andrew1967]

Some great repair work there Gary.

[Dearg1275]

Gary,

Echo Andrew’s comments. Oh it must be wonderful to work with a shell fully stripped of rust and paint. I just dare not do that here. Salt wind from the sea would wreck things in days, even in doors.

D