Welding Question

[PTS Kustoms]

On the front of my 72 frame where the bumper bolts up I have a crack about 1" long. When fixing a crack I was told to drill a hole at the end to releive the stress point. Can someone shed some light on this for me. I definitely do not want it to show back up. I plan on using a mig to fix the problem. Please help!


Thanks...

[Mike C]

The reason you drill a hole is to stop the crack from expanding. If you drill a hole, you no longer have a focused point for the stress to travel down. This is usually done to stop a crack from getting any worse, and not to repair. If you are going to weld the crack up, I see no reason to drill the hole. But if wouldn't take very long if you wanted to, then you would just weld it back up.

[walker]

I say drill the hole. It will get you 100% penetration in the stressed portion of the crack, giving it no place to restart. Also, turn the heat up on your mig for this process, you really want to burn this in there if it is a high stress portion of the frame.

[PTS Kustoms]

Thanks for the replies...

[Blue Beard]

When you weld it....be sure to grind a v in the crack and weld it up for complete penetration.....

[Stepsides 4Ever]

Good advice from all!

Definitely drill the end of the crack and vee it out about 75%-90% (deep enough to ensure good penetration but not so thin that you burn through), and weld both sides if you can. CLEAN the area surrounding the weld zone before you weld...remove all rust and paint with a grinder or sander. If you weld both sides you can grind it down flush and make that crack disappear...

[PTS Kustoms]

When you say v do you close the gap of the crack and grind a v along the crack? This really helps!

[Stepsides 4Ever]

Generally, yes.

The idea is to pull the piece back into alignment, keeping in mind that, after you finish welding it, even if it was aligned perfectly before you started the welding process will have deformed it some. If you have a gap in the piece after aligning, all the better for the penetration. If the metal is stretched, then you might have to create a gap between the pieces to bring them into alignment. If you end up with a gap, turn the heat down a little and weld smaller sections.

So you drill the end of the crack, then align the pieces and vee it out along the crack...take your 4.5" angle grinder and run the disc edgewise along the crack ought to do it. Clean an area about 1/2" on either side of the crack of paint and rust, on both sides if you can. Next prop/pry/jack/clamp the pieces in question into position...then, depending on the length of the crack, tack weld the crack every inch or so. Start at the end opposite the drilled end first, tack weld, then alternate from each end of the crack so as not to heat one area too much longer than necessary. After it's all tacked up, when you weld, weld a short section (from tack to tack), then alternate to an opposing section, to avoid concentrating the heat in any one area. You have to heat it to weld it, and heat causes distortion, so try to even out the distortion...the purpose of the tack welding is to try to hold the pieces in alignment while they are being welded. PRACTICE is the name of the game here...practice your tack welds and short stringers on some scrap until you get the welder set right. Hot and fast is better than slow and cool. Get in, do what you have to do, then get out. Let the piece cool down some between welds. If you think you are going to burn through, stop and let it cool...check it out from the other side and see what the penetration looks like. If you do it right, the side that has been vee'd will need very little grinding to make it flush...if you then weld it once more from the back side, the weld area will be thicker (and stronger) than the surrounding area.

And remember, in welding position is everything...can you weld it flat, or is it overhead or vertical? Your chance of success, especially if you don't have a lot of experience, is much greater if you can weld it flat.