I have a 35 buick sedan with a large opening in the roof. I am attempting to fill the roof with a top I cut off of a honda (power sun roof). I have the top cut fitted and tacked into place. It looks pretty good but when I am trying to weld it in I am getting warpage in the panel. I have my mig heat set as low as it will go and I am welding about 1 inch then going to another area and welding an inch. Is it normal to get warpage. Don't worry about it and fill it? Or is there a trick? Also this car has rectangular slots all along the roof opening. Should I weld all of these up or fill them?

Welding shrinks the weld area. Another thing you are up against is how well the crown front to back and side to side matches between the two panels. You may have it fitting well side to side but not front to back or vice versa.

If you must mig-weld, be sure to weld hot and briefly. One hot zap, weld somewhere else, and don't come back to the area until it is cool to the touch. You will still get shrinking, but perhaps it will be a more controllable.

Check out the flow strip in my flare album:

http://allshops.org/cgi-bin/communi...d=9980138836765

This tool will allow you to see the curve in the roof so you will know where to stretch or shrink. If you expect to be able to weld without doing metal-work, you should also expect to use a ton of filler.

I have some ideas about stretching and shrinking on roofs if you are interested. Do you have any pictures?

John www.ghiaspecialties.com

This may give you a little more info on how to control the warpage.

http://www.metalmeet.com/forum/show...thin+sheetmetal

Randy Ferguson

Something that will help is to weld from the old (thick) metal to the new (thin) in a stitching pattern. Try backing the tip away some as this will (cool) the weld temp of the wire the further away you go.You can use a copper welding spoon behind the weld as a back-up with a helper or strong magnets if possiable to help prevent burning thru.
One last thing, Be SURE the metals in the weld area are CLEAN.....PERIOD...

Old paint & crud are the worst thing in the world for screwing your welds.

The last roof fill I did was on a 32 two door sedan with a fairly large opening. I used a donor piece of roof that matched the contour I needed, The piece was rough trimmed untill it was about an eigth of an inch larger than the opening. I set the panel on the roof and centered it in the opening, then I put one tack weld in the front along the center line to hold it from shifting left and right. The I started in the center rear and trimmed and welded as I went from the center rear jumping left to right all the way down the sides untill I hit the corners in the front. At this point I broke the temporary tack weld loose from the center front and started trimming and welding from there to the front corners. There were about three places along the sides that needed to be stretched as I went along and one spot on the front center that needed to be shrunk. There wasn't a defect deeper than a 32nd of an inch when done, perfectly metalfinished would have been nice but Oh well. I think tack welding all the way around the perimeter and continuing to weld untill full is going to require alot of stretching when your done.- I did a 36 Ford this way 16 years ago that ended up needing more filler than I care to admit-(but it is holding up just fine). Bob

Thanks for the info. Especially the link to the metal forum Randy. I am going to need to read up on metal shrinking and stretching before I continue on. This roof looks so good in this car I don't want to screw it up. I will attempt to attach some pics so you can see shere I am. This is my first rod so I am looking for any help I can get. .......Thanks

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Nice old Buick. Really like the big rods.

Randy just finished installing a roof insert in a '30 model A sedan we wheeled out on the english wheel. Randy is the brains and the talent, I was just one of the "help hold the panel up guys." If he hasn't already I am hoping he will post pictures. Using slapper, hammer, dolly and a shrinking disk Randy has the roof ready for paint using no filler.

The information on MetalMeet will provide good guidance.

Read alot, maybe go to a MetalMeet event, ask lots of questions,and take your time.

Good Luck!

Can I UPS this thing to Randy and have him do the roof for me?

Well, you would have to get in his customer line.