Thread: welding question

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Okay what I am tring to do is weld a donor roof on my 1929 ford model A .... since it is sheet metal I would guess I need do spot weld all over the place thousands of them so I don't distort the roof or can I do some small welds just moving around? anyway I have a snap on welder I had the heat at 7 and the feed at 7 with the gas at 20 inches... it does have settings for spot, stitch and continous weld.. with spot with settings upto 4 seconds... I had it on contious weld and was able on practice sheet metal get it to get good penetration where if i bent the sheet metal back and forth it would break behind my spot welds... there is a lot of extra weld on top is this normal or is there a way to cut down on the extra metal and have a more of a flat spot weld? also sometimes the spots would look like "puter" very rough and pourus what causes that? any help on setting this welder up and getting a better weld would be appriciated.... I don't want to touch the welder to the car till my welds look a lot better! but I don't want to use a whole spool of wire and tank of argon co2 tring to get this right....

thanks,
simon

Bad looking spots,IE holes in the weld are from bad airflow, or dirt or paint in that spot.

On sheet i just do about a half of an inch at a time, jumping from side to side like torquing down a head. Some guys will have a buddy with them and do a good small bead then follow it up with a hammer and dolly while the bead is still hot.

Okay well the hammer and dolly Idea won't work since there won't be any room on the inside to put the dolly ... the wood will be in the way... I saw a good video on setting the welder up.. it said to use what would be a good heat setting then turn the feed all the way down pull the trigger and turn the feed up till you get a good sizzle, then check to see if the penitration is good ... adjust heat if needed then the feed to get the good sizzle.. which I did and the welds came out much better.. I also found if h two pieces are butted up together you need more heat than if there is a little gap between the pieces... is this true? I feel a lot more comfortable about welding now... so If I do 1/2 welds and cool with a wet rag right away and move from side to side the warpage should be minimal? or should I just use thousands of tack welds? I am using a ribbed roof I hope that it will help with keeping the warpage down... any more pointers would be great !!!!

thanks
simon

Originally Posted by Evolvo

Do not cool with a wet rag, this will make the welds brittle. Let them air cool. It's a pain in the azz but thousands of tack welds will be best, IMHO.
Good luck,
Alan

i have to agree many many many tack welds all the way around till the tacks are connected. you can use an air hose and a blow gun to cool the welds. after you lay a tack then you can blow air over the weld and that will cool it with out that shock of cold water. hope that helps.

Have you considered gluing the top on? I welded on 2 tops on my 32 sedan and warped them both. The third time I glued the top on and it look good and is strong. I talked to a 3M rep and said as long as I tacked the corners and glued the rest, they would stand behind the job. First I dry fitted the piece and secured with sheet metal screws every 2". Then I took apart and ground off the burrs and then roughed up the mating surfaces with 30 grit grinding wheel. Then I applied the glue ,except for the corners, and reapplied the top using the screws back in the holes. Snugged them up untill the glue started to ooze out and let cure.Next day I removed all screws and ground off the excess dried glue. Then I used a bevel bit in my 90 degreein each screw hole. then dabbed a little glue in the beveled ho;es and let it set. Then grind off smooth and do the body work. Been on there for 3-4 years now without any failure. Just a thought. Later

Don't be afraid to spend some $$ on materials for training/practice. It is way cheaper than cutting the top off and digging up another.

I hear lots of panels on todays cars are just glued on. I'm not sold on it. If the panels are not falling off in thirty or forty years, then I'll buy in. Till then, I'd rather pop rivet and bondo over it if I can't weld.