I'm repairing my dash mess from the PO. (for context, here's an older post: https://www.ford-trucks.com/forums/1...ow-to-fix.html)

I ended up just cutting out the old "repair" in order to start "clean" as much as possible. I machined an 1/2" radius on a solid steel bar and welded that in along the bottom edge of the dash. The radius matches the stock bottom edge. I then machined a step on the left and right edges of the 0.100 patch plate, so that the edge of the patch slid behind (overlaps, from behind) the original dash sheetmetal. The idea of the step was to try to give me some extra thickness for welding and to prevent blow-through (at least that was the plan).

When I welded in the patch, the right side came out pretty well. The bottom edge (along the solid, radiused bar) is tacked.

However, the left edge put up a horrible fight. I was able to TIG some of it, but the original material is so thin (about 0.037"), the weld is just cracking along ~80% of the seam. There's very little original metal to work with (and is mostly cracked as well).

Here are some pictures of the general repair, front (visible) side, and backside (under the dash).

Anyone have any ideas how to get a decent (structural) weld along this edge? I've been trying to make a scab plate to span the weld between the new patch and the old dash metal (from behind), but so far that's not working out very well. The step between the new and old metal isn't consistent. The backside of the seam isn't flat either.

Any ideas how to bridge the crack and get a weld onto it that will hold up to steering column loads?

(I have no idea why the PO thought it was a good idea to remove this whole section of the dash and braze in (badly) a patch that also cracked along the bottom edge.)

Thanks!

 

I would tackle this by leaving a 1/16" gap between the patch and the parent material
Back it with a backing piece 16 gauge and bridge them all when you weld.


This may also be Liquid Metal Embrittlement (LME) this happens when certain metals experience a drastic decrease in tensile strenght, or embrittlement when exposed to certain liquid metals. Who knows what kind of flux or braze was used back in the day or the quality of the sheet steel. You may want to try to anneal the parent metal first. Some of these old sheet steels work harden and then if you braze them you can get LME in the parent material.
Heat the parent material up to just above cherry and let cool slowly not air cool just gradually reduce the heat input to the metal till it loses colour then let air cool.

I would give that a try first if that does not work back it with a backing patch using a gap between the parent material and the filler patch.

 

I have the question why is the metal so thin? And if it's that thin should you think about putting something a bit thicker in it's place. AS in cut back to thicker metal?

My thoughts behind that is you'll be mounting the steering column right below that. That's gonna be a good amount of force and torque over the years. And if the metal is that thin you for sure are gonna get waves and cracking in your metal and welds.

Perhaps you can make a backer piece that you can weld in behind the dash. Something that extends to the thicker metal area. Then drill some holes in the dash and do some plug welds to attache it? Make sure to do a weld through primer to avoid rust.

 

Interesting - embrittlement/hardening never occurred to me. Can't hurt to try to anneal the thin area. I've been thinking of something similar to the back patch - though I like your idea of opening the gap a bit and then welding the edges/building it back. That will be a PITA, but I might be able to do it in 2 sections, after looking at it a bit more.

 

The original dash metal only appears to be about 0.037" or so thick in that area - presumably the parent sheet was thicker before stamping, but this area is ended up pretty thin - even when it was new. That, plus the fact that I had to grind off the old braze material to (hopefully) avoid weld contamination (see the pix in the original post), so the metal got even thinner (maybe 0.030"). I did cut back from the old braze seam on both sides to try to get to thicker/better metal, but the braze filler did cover some of this area that I'm now struggling to weld. Matthewq4b suggested that maybe the brazing has changed the metallic chemistry / made it more brittle / work hardened it.

I agree about the steering column loads - that's why I'm trying to repair this "right" in the sense of putting back some real structure. The good news is that I'm putting in a power steering system (that's how I got here...) so the wheel/column loads should be a whole lot lower than with the original manual steering box.

It seems like I'm going to have to find a way to back this up with more metal one way or another. Plug welds seem like a good approach, though with the thinness of the metal, I'm guessing that I will be chasing the weld as the dash metal vaporizes under the torch. This repair seems a bit beyond my (already) mediocre TIG abilities...

 

The idea of backing up with a patch and plug welding is a good one. But first you might want to try clamping a flattened piece of copper pipe behind the area to be welded. And using TIG is a good idea but it is easy to overheat if you have too heavy a foot. You might want to try using MIG in short bursts of about one second. You can adjust the amperage to control burn through. Make sure that the copper is in contact with the back of the weld spot. It will absorb some of the heat. Also I would suggest using Easygrind .023 wire.

I just finished welding a stress crack on my hood with this method. It works great.

 

Definitely backup the weld with copper to try and dissipate some of the heat you will generate.. I would cut back father and build a larger patch, maybe place a large strip behind the entire area and rosette weld it in to give you a backing as well as additional strength in the joint.


Don't you just love fixing other peoples screw ups! lol

 

Hey all, I used a backing steel piece, plug-welded into place from the front. I then discovered that my TIG setup has a pulsing setup so I tried that - which made a huge difference. The pulser drives high current, then steps it down, the back up, etc. It seemed to give me much more control over the puddle and fusion than if I just blasted it with the normal peak current. It still put up a bit of a fight, but allowed me to add a whole bunch of tacks over the cracking. Eventually I was able to stitch it all back together. I wouldn't call it pretty by any means, but it seems structurally solid now. I did get some warping, so it will still take a bit of bondo to level it back out, but overall it seems like the repair is good.

Thanks to everyone for the tips and suggestions.

 

Good. Glad you got it fixed. Copper backing would have prevented warping.

 

Good to know! I've got plenty of thin sheetmetal to weld on this project, so I'll give it a try next time. I had my hands full just trying to get everything positioned and clamped to begin with!

 

This is a fantastic idea. I have had issues with burn through and never thought to do the copper pipe thing - thank you so much for sharing this petemcl, that's actually a bit of a revelation for me! Now I can't wait to get out and try it!!!

 

Using copper backing made me appear to be a much better welder than I am!!!!

 

Here is a 54 dash that I did some time ago. I used a dash repair panel that I bought from Midfifty. The OEM dash was all hacked up so I covered all the miscellaneous holes and ash tray all with one panel. The 56 panel is even easier since there is no lower gauge cluster lip to deal with. This panel is held in place with 3M-08115 panel adhesive...no welding, no warpage, no cracks, no grief. Every time I see/read an account of folks having difficulty bonding thin metal I think of how much simpler and cleaner the job would have been had they used structural adhesive.

 

this is really helpful after paint when you forgot a captured nut(tack weld it to a washer and glue it on) or broke this off and need too stick it back on