Need some help here peeps.
I am suiciding the doors on my El Camino this weekend. House of Kolor is supplying all products for the paint job, an upholstery shop wants to demo the car and want to put a free full custom interior in it. I just need to buy 2 hides and 6 yards of suede at cost, to be surrounded in leather. I spend all my time building other peoples cars and own the perfect canidate for the show Overhaulin lol.
I designed some suicide door hinges with AutoCAD and while building them, the heat keeps pulling them out of square. The door pins have to be perfectly in line, so the hinges don't bind, when the door is opened. I am tying 3" box, .188 wall, with a 1" square tube .125 wall, 8" long,. In opposite corners I have welded 3/4 OD .188 wall pipe. I slid a 3/8 " rod through the pipe peices, leveled and squared it all and began welding. After I tacked the top I welded both seams with alot of heat. Turned the box over and repeated, when I was done I noticed the rod was bent, after yanking the rod out, it's about 3/16" out of straight.
How do real welders, do this right? More tacks? Out of time to build a jig. So anyone with some welding background, please help me out.
Insom

I’ve got some engineering/welding background, so I gave this some thought …

For a start, what you’re trying to do is pretty ambitious for a home welder, you only really get the sort of fine tolerances you’re talking about on a production line with proper jigs & precisely controlled welds …

That said, I’ve got a few ideas:

I'm assuming you've got the door pins in situ while welding just to get the alignment correct? If not, think about a redesign with removable pins;

Don’t use the door pins while welding - cut a length of 3/8 rod, thread the ends & use that to clamp it all up, weld & then bin the rod;

You might also want to think about using a slightly thinner pin, slightly fatter tubes & fill the gap with 3/4" or so long bushes (4 per door if I'm visualising what you've doing correctly).
Finding some nylon 66 bar & a lathe _sounds_ like extra hassle (you might find something suitable off the shelf, but it’s unlikely), but it does give you some room for fettling before the final fit, & you could bevel the ends of the bushes to ease getting the pins in. If you’ve got the space, you could leave a cut-out in the tubes & drill & tap the bushes & fit grease nipples.

what exactly are you useing to weld with? stick and torch? You can hang it up if you are. you need a tig or mig welder. Now that being said I use a tig welder for what I do and thats some prety then tolerant stuff @ times. with the tig make sure to turn on the gas (unimix) and don't be scared to use the gas...pour it on or you will just get "grape globs" you have to be sure to melt both peices that are to be wleder together, but do it like this. Jig everything up for your weld, get it all lined up. the more area you have in the clamp the better. Often I find it best to have as much area as close to my weld clamped up as possible. As the thinkness of my metal clamps/vise will absorb alot of heat. Then wehn you go to weld use very short strokes. In your case I would try do do several tacs and wait between the tacs in order to cool. you could even spray it down with something like cutting oil/coolant, but this will have to be cleaned before you can make your next weld. simpler to just wait. DON'T USE WATER! water cooling will change the makeup of the metals hardning and just make it soft. good luck man ...BTW I seen someplace where you can buy hinges premade...was on pimp rides on MTV...they were rediculously high though...was made to open the doors up instead of out?

Quote: Originally Posted by FizzledFiend ...BTW I seen someplace where you can buy hinges premade...was on pimp rides on MTV...they were rediculously high though...was made to open the doors up instead of out?

you are thinking of the "Lambo-Hinges"...they make the doors open like a lamborghini-out,then up.
what insom is doing is"suicidng"the doors......making them open in reverse fashon(instead of the rear of the door opening,the front of the door pulls outward)

insom,as well as the other good ideas presented,when going to weld,tack all peices first.
every place you are going to weld,tack first.
it will reduce the "pulling"effect of the heat from the opposite side weld.

another thing to consider is heatsinking to draw the heat out.

One thing ya'll havent mentioned is to tack in oppisite corners. You tack one corner then go diagonaly and tack the other, then check to see if its still square. If so then go diagonally then tack another corner. So on until your finished, this way takes the longest but produces the best results.

Thank you all.
What I ended up doing is clamping all pieces, after aligning the bushings, tack the he77 out of it with medium heat, diagonally around the piece. After all three sides where very well tacked, checked the bushings again and they where dead on, so I cranked up the mig and burned it. After a couple cigarettes, the assembly was cool enough to handle, so I unclamped it and rechecked it, still on the money, so I burned the last side and it worked GREAT!
Pretty simple with all your input and some common sense. For one it seems that tack welds not only hold your pieces, but helps transfer the heat generated when welding. Not quenching it to speed up the cooling process, that only warps it and of course having the pieces in a 'make up jig' assembly to keep it all square while welding and cooling. Sounds pretty simple once you think about it, but in my line of work, I only work with sheetmetal. When dealing with larger stock....the higher heat causes those parts to move all over the place.
The hinge geometry, bracing, and the door pockets has proven to be nothing short of mental masturbation and I am worn out.
Thanks again,
Insom

and as payment for all this fine and expert help we want pictures of the car when completed, incl. your welding.

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