I did a search and got some good info, but would like to follow up. When welding in the boxing plates on an A frame, is there a particular weld sequence? Most of the info looks like tack it, weld a short section, then skip around the perimeter, alternating side to side. I have front and rear plates and plan to start in the middle and work towards the ends. The edges are bevelled on the plates and frame. Thanks for your help. RB
Good advise , I also had my A's frame jiged and secured so it wouldnt move, on a steel table. It came out very flat, straight and square.
And I boxed my A's frame while supported on four jackstands on the garage floor, with a tape measure and a four foot level. It came out pretty flat, straight and square. Just weld no more than about three inches at a time and move around, left to right and top to bottom. Check often for square and level and don't get it too hot... Of course if you have a steel table, use it...
I would limit welds to one inch and be sure to mirror every move on the top to the bottom and from the right side to the left. The longer you heat a spot on the frame, the more it will shrink as it cools. Don't linger on one weld too long and don't come back to that area until it cools down.
I disagree with the skipping around method. You have to get the metal molten, a short molten metal isn;t a cooler and safer than just starting at one end and going to the other. If you think about it, starting at one end and just buzzing to the other is likely less stressful than welding up to a certain point, letting that point cool and then returning to taht point to continue the weld. I do know for a fact that if you do that technique (start, stop, skip etc) on 18ga sheetmetal body panels you will have one hell of a mess trying to metal finish because it;ll have more waves and gullies than a golf course. It is a physical fact that metal shrinks at a higher rate than it expands when heated, to minimize distortion you heat uniform and consistant. Start at one end and don't stop until you get to the other - well, thats kinda hard to do with 10' of frame rail but you get the idea. To illustrate the point, if you were welding a door skin and you welded 3", skipped and then came back for another 3" weld when complete the HAZ (heat affected zone) will look like a bunch of catapillers walking in a crazy line. Where each catapillar joined the next there will be a pucker in the metal. This is where you stopped one weld, allowed it to cool and then heated the spot back to molten and continued the weld. So, that one spot - say an 1/8th inch - was heated to molten, allowed to cool and shrink, then heated to molten and allowed to cool an shrink again. It has gone thru two heating/cooling cycles when the metal adjacent has gone thru one cycle, in short that spot has shrunk twice as much as the metal befor and after it. To be honest, i haven't been able to go from one end to the other of a frame rail. But that would be the best way.
I do it pretty much as scottybaccus describes but run about three inch welds I clamp it firmly to a jig and check with tape and square after every weld or two
Chopt Top Kid said, "Check often for square and level" Paul said, "check with tape and square after every weld or two." How do you fix it if it's not square? I plan on boxing a frame on jack stands like Chopt did but I'm not sure how to fix it if it does happen to warp. Do you just figure out where it bent, heat it up with a torch and bend it back with a lever or a hammer? Or can you weld a longer stretch on the opposite side and hope it pulls it back into shape?
Hopefully, if you check it often enough, it will not get so far out of square or twist so much that you have to take drastic measures to make it straight again. The warpage is being caused by too much heat in one area. As soon as you notice one rail trying to move on you, throw some weld opposite of where you just put the weld that caused it to bow. Hopefully It will pull back in shape. Some times you can use a length of chain, a turnbuckle or come-a-long and a piece of 2X4 to help pull a badly twisted frame back into shape. Use your level as a straight edge and you can usually see exactly where you need to put the heat to pull it back in line. Jump around, go slow, check often and don't let one area get too hot. The trick is to not let it get away from you in the first place, then you won't have to fix it. Hope this makes sense...
Thanks for the help. This project is on jackstands since I have no table. I have angle iron "tacked" to the frame to hold it in place as best possible and I'm starting with a square and flat frame. We seen enough build threads and I'm moving so slow on it right now that I haven't started one, although I'm taking pics as I go. I think I'll be opting for the 1-3" welds to start and see how it goes, but have to make the m/m's first to see where they go, weld them in and cut the plates to go around (but welded to) them. RB
We used to set engine blocks on 2x4's across the frame over the jack stands to hold it down tight. Frame stayed flat and straight. I must have been stronger back then. Stick welded and overhead on lower edge, wire welders sure make stuff easier now.
If you are going to box your frame on jack stands keep a close eye on square and level and load it up with bags of concrete, heavy anvils or whatever else you have around that is heavy. I had some 90# bags go bad on me but kept them around just for that purpose.
do it like SB said. you need to make sure to weld the exact opposite part of the frame each time, that counteracts any warping, and if there is, both sides will at least be the same! that sounds good in theory, but would end up on craigslist as a pretzeled wreck!
I do it often enough that i earn a living at it - have been for about 30 years. I don't build pretzels.
Doesnt mean you are right, just lucky Most of us prefer to give solid answers that a newcomer won't get into trouble with.
Then, since you seem to do it different than anyone else, please do a thread on your technique. I am not being a smartass here, just curious. Learning is a good thing.
I have been welding since 1978, and am certified to weld everything from .010" to in excess of 6", from upside-down, to under water. I can weld with whatever heat source is available, including a car alternator, or three batteries hooked together in series. 100+ frames and miles of metal-finished body seams later, I can honestly say, do as ScottuBaccus says. On a frame rail, or thinner, a straight weld, all the way across, is the short-track to building a pretzel.
Oh? Thats interesting - and i have a great respect for both you and scotty. Techniques are as individual as the people that do them. As far as a tech thread, they have been done over and again - David Gardiner has a very good one. If you are more curious go to AllMetalShaping.com and subjects of this nature are common. Or go to the welding sites and ask how they skip around welding plates of steel for a ship. You'll raise an eyebrow or two.
Sorry guys, it is just in my nature to be contrary at times. I guess skipping is ok as long as you are trying to even out the heat.
My first pro welding job was welding in ballast tanks for nuclear submarines. There was no skipping around on any of the welds there. Shipbuilding a building and car building are miles apart. It is all about balancing the heat. That is the key. I have seen 4" thick plate, beveled on both sides to a 1" root, set perpendicular to more 4" plate, get pulled out of position, after 30 passes on each side, due to unbalanced heat, applied by those who do not understand it. It took nearly a fist-fight to get the foreman to allow me to save the piece, by having them CONTINUE to weld it, at my instruction. The piece was was saved and passed inspection, visual, and x-ray.
OK, I'm wondering if the frame is going to be completely boxed..If so, frames go through lots of stress and without empty areas the stress can't get relieved, no place to go..I recommend at least a 2" empty space, four to each side of frame.. That is my thinking..If no place for stress relief the welds can crack.. What ever that worth... Duane.
No. That is the fast-track to a cracked frame. It is all or nothing. Leaving gaps in the weld will create a stress riser at where the welds border the the un-welded portion. All of the flex will be focused there, causing a failure, in short order.
Strombergs97 -- I'm interested in what you said, but I'm not sure I understand what you meant by "empty space." Does that mean spaces between the boxing plates or does it mean not welding every inch on of a boxing plate?
I've heard of fully boxing a frame and partially boxing a frame, but never heard anyone say you should leave gaps between the boxing plates. If done right a fully boxed and crossmembered frame will have no flexing or cracking issues. The model A frame under my 27 was fully boxed with an arc welder well over 20 years ago and has never had any signs of stress or cracks. Don
I would try and size my boxing plates so they are inside corner to inside corner. That way there is no need to bevel the plates. Peter
Yep, and one way to hold the backing plate in the right position, until it is welded, is to first tack weld in some little "stops" made from scrap strap steel so that the backing plate has something to rest against. Then you can clamp down the backing plate tightly against these stops to not only hold it a uniform distance from the rails all around, but also to help minimize warpage. These stops can be as simple as some 1/8 x 2" strap steel, cut into pieces as long as the distance between the top rail and the bottom rail, and spaced a foot or more apart. Once they are tacked inset the proper amount there is no way the real backing plate can slide too far into the rail until fully welded. Makes for a nice straight inside wall when done. Don
Thats a good idea. I get my backing plates from a guy that cuts them for tig welding, they'll almost drop inside the pocket of the 'c' channel and that gives room for a nice fillet. The biggest problem i encounter is taht those old frames are far from the perfect laser cut of the boxing plates. I generally spend a day or more just getting them into shape to weld.
OK, I understand your thinking. I will add a little, at the end of each plate, (where the weld ends) should have a radius, no a 90 degree angle. A round grinding stone would make the radius.. I was a shipfitter/welder in the Navy and maybe my thinking is old way.. Duane.
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