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Fri Nov 07, 2008 7:59 am

Finally I found some rust on my 70 Ghia vert. I've ordered replacement panels from Cip1 and KGPR. Having read some posts here, I know better than to cut before the parts are in my hands. I understand that there should be about 1 mm space between the new and old before butt-welding. Having welded only once (and certainly not body parts) I'd like to know what the best tool is for cutting the rusted parts out and trimming the replacement parts to fit. Scissors will most likely warp the metal (I also doubt that it's even possible to cut this thickness with hand shears). A Dremmel tool will go through disks like there's no tomorrow. So what's the best tool for medium sized areas (i.e. rocker panels, lower fender areas...)?

Also, what's the best way to get the correct shape of the cut? I was going to cut out a paper or cardboard template and trace the outline onto the repair panel as well as the car. Any better ideas?

The repair panels come with a gray primer. Should this primer be removed prior to welding? What's the best way to remove it?

A tutorial on cutting, prepping and welding would be greatly appreciated by amateur metal workers like myself.':?'
Thanks.

Fri Nov 07, 2008 8:07 am

I use a sawzall with a long metal blade and a 4.5" grinder. Use the grinder to grind a slot to get the sawzall blade in to start.

Fri Nov 07, 2008 8:17 am

If you have an air compressor that is good run a cut off wheel. I use this and it is fast and will not warp the metal. I also have an air hammer and you can get a bit that is made for cutting metal with it. I have one of these and it works fast and cuts very clean on straight cuts. This will not warp the metal either.

On replacement body panels I always cut the metal that is bad from the car and then cut the replacement up to fit the portion that i cut out.

I know a lot of people butt weld their metal in but I really like to use a crimper tool (I have an air one) that bends the edge of the metal and then you slide it in behind the OG metal. This is nice and easy welding.

Fri Nov 07, 2008 9:06 am

I would cut the areas that have to be replaced with a angle grinder. Take a thin grinding disk (1mm) and it will be really easy.
First cut out the bad areas and then prepare the replacement part.
I would butt weld, but do it very slowly, with time for cooling down after each spot. Otherwise you will have lots of distortion. This isn't that easy as to spot weld crimped material, but if you do it properly you won't see anything afterwards, and humidity can't get into the seam

Fri Nov 07, 2008 10:56 am

What I do about the seam is it is all bare metal before welding and then it gets POR 15 in the seam and then seam sealed. No problems. Either way you have to do something to the back side after welding for rust prevention.

Sun Nov 09, 2008 8:45 am

A 4 1/2" grinder with a Dewalt metal cutting disc (they are the thinnest and hold up) will work for most. I also use an airsaw, can use a sawzall as stated earlier. Definitely clean the edges of the old and new metal prior to spot welding, biggest failure point is here. Use a brass wire wheel on a drill.
I copy the new metal on to carboard and overlay it, get out the Sharpie then the saw. Sounds odd, but once you get started you will lose most fear of under/over cutting. You can always cut some out or weld more in. Just take your time.
JW

Sun Nov 09, 2008 9:32 am

thanks for the tips. that was very helpful.
I do have a Bosch electric reciprocating saw. I don't have a MIG welder, but I can borrow an Oxy-Acetylene setup from a friend. I hear that this is very difficult to use on body panels, but is the preferred procedure by the VW shop manual downloadable at http://www.karmannghia.com/links.asp (coupe body repair) and John Kellie. Can some of you "newbies" at welding tell me your experiences with gas welding?
Thanks.

Sun Nov 09, 2008 2:35 pm

As already mentioned, we always use a "pizza cutter" (cutoff discs) to section quarters, or whatever we need to cut. Always lay down a piece of tape so you can have a nice straight cut.

When you do lap welds, or even weld in places where you cant get some type of rust inhibitor on the backside, use a Weld thru primer. You can put a coat on all of your bare metal, even where you are welding...I believe I use SEM brand.

Do you mean gas welding as in Oxy/acetylene? Personally, I wouldnt just because you want to control/contain the heat as much as possible to avoid warping the panel and creating more work for yourself.

Sun Nov 09, 2008 5:09 pm

This works very nicely for me:

Cut the replacement panel to size first, lay it over the area it should replace and mark the edge with a marker. Then lay painter's tape over it such that the marker is in the middle of the tape.
Put the replacement panel back over the area and use sheetmetal stud screws to hold it in place (holes are easy to mig closed anyway). Scratch a line onto the painter's tape and steel using a sharp hobby knife.
Take the sheetmetal screws out and peel one side of the painter's tape off (obviously on the side that you intend to cut out). Then cut it out using a cutoff disk or dremel tool, carefully following the other edge of the left over painter's tape.

The painter's tape works well for me because it makes a nice, clear demarcation as to what should be cut.

Mon Nov 10, 2008 12:35 am

if your not really experienced in welding, leave your hands off gas welding. You will destroy your sheet metal by melting away. Gas welding is the most difficult way of welding. MIG welding is the easiet way for newbies.

Mon Nov 10, 2008 3:11 pm

Thanks for all the tips.
I guess that I'll have to find a MIG, at least for the outside panels.

Mon Nov 10, 2008 4:34 pm

zehbeh wrote: . Gas welding is the most difficult way of welding. :?

Tue Nov 11, 2008 7:40 am

Another trick where access permits:

Lay the patch on and around the damaged area, as tight as you can, maybe holding with self-tappers. I'm assuming you have a little too much repair panel available.

Cut through both good and bad metal at the same time with a 1/16" Walter air die grinder disc. Yes, these are expensive and break if you twist them. But 1/16" leaves a 1/16" gap which is perfect for MIG butt welding. Try getting a box of 50, and count on using 20 or so and selling the rest to friends. You actually need an "angled" mini air die grinder.

Cutting through both panels at once removes the need to measure and removes any hand error. Possible downside is when you have a third dimension to the piece (like a bus rear corner) and the extra layover introduces an error the thickness of the body metal back at the first two dimensions. You can figure out a correct order of tasks to get around this.

IMO you have to be pretty good to use gas on sheet metal, and you need a tiny tip like a #0.

Tue Nov 11, 2008 12:33 pm

Another great tool is an auto body panel saw. They are like a miniature sawzall that is airpowered. I bought one at harbor freight for 20 bucks to see if I liked it. I am going to get a cp or craftsman after this one dies. Wish I would have had this during my younger years when I was butchering dashes to put in a radio or doors for speakers. For welding you might want to find someboby that is proficient with a welder. I have done it several times and my results are varied. i can tell you that my first one was UGLY. If this is a one time thing you might save yourself a bunch of anger. If however you are going to do more in the future he best way to learn is by doing it. Best of luck to you on your project

Tue Nov 11, 2008 3:24 pm

I am very anxious about welding and working the metal myself. But, I'm a guy who has the attitude of "I can learn to do anything, all I have to do is stay persistent". So far, I've learned to paint, bake, fly, practice medicine, speak 5 languages, etc. I love to work with my hands, learn traditional crafts going extinct, and solve problems. All I need is (a) good teacher(s) and a good attitude.
Now, I want to learn how to weld and work the metal with a hammer and dolly. That's why I have all these questions.
You guys have been great so far in giving me guidance.
Thanks allot! :)

Fri Nov 14, 2008 3:45 pm

I use a 4/12 inch grinder without the guard and have for many years. The one thing that you don`t what to do is buy the cheap made in china cut off wheels they will come apart and hurt you. I like Norton wheel and the thinner the better and have never had one come apart. So get the good ones or use the guard you`ll need it with the junk blades.

Sat Nov 15, 2008 7:22 am

anybody have feedback on this type of cutter.
I saw it in one of the thousands of catalogs MAMW has sent me and just curious if it works well.
http://www.mamotorworks.com/acvw?frame=1.8051

Tue Nov 18, 2008 11:14 am

fluxcap wrote: anybody have feedback on this type of cutter.
I saw it in one of the thousands of catalogs MAMW has sent me and just curious if it works well.
http://www.mamotorworks.com/acvw?frame=1.8051

I wouldn't waste your money on this thing. You can get a true nibbler at harbor freight for $30. Even then I don't use it much. My favorite is still a dremel with the thin sandstone discs and my sawzall with a metal cutting blade. I've also found a jigsaw with metal saw is also useful.

Tue Nov 18, 2008 2:24 pm

Thanks for the feedback Nor_Al!

Tue Nov 18, 2008 2:41 pm

That Mid-America tool (link above) is a nibbler attachment. Ive owned a nibbler for years. When I bought it, I thought it was the ticket. One problem is that its hard to cut straight with it. You can use a fence to make a straighter cut, but freehand isnt so good. The biggest problem is that it makes a mess. A big mess, of little crescent shaped pieces of metal that are sharp, and love to stick to the bottom of your shoes or poke your fingers if you try to sweep them up in your hand. Its so bad that I made a vacuum attachment to suck out the pieces as their cut.

In the long run, I think its easier to use a 3" cuttoff wheel. I use my plasma cutter first, cutoff wheel second or for trimming a final fit.