Monday, 26 June 2017

Stud patch process

Remember a couple of posts back when I was patching the stud line and had made a replacement captive nut section but opted not to weld it in for some vague reason? I didn't admit it at the time, but the truth is that I made a complete mess of the rear of that patch panel whilst attempting to weld the captive nut into position. Originally I drilled the 4 corners of the weld nut and tried to plug weld through them. However, the intense heat actually melted away edges of the nut and left a less than desirable outcome. It looked like crap, so forgive me for not sharing a photo of that abomination! After some contemplation, I decided to remake that patch taking a different approach to affix the nut. Essentially, I would start out with an oversized off-cut of steel and plug weld the captive nut in place neatly before spending the time trimming it down to the exact shape required. Less time wasted if I happened to balls it up again...

I used a scribe to trace round the shape of the old piece (on the other side) and locate the position of the main nut hole (10mm). I then drilled out 4 smaller holes that I would plug weld through:

As you have probably gathered, for this method I welded from the front side into the captive nut, rather than from the back through the nut.

M8 captive nut (Hooky's) camped into position and perfectly aligned ready for plug welding through the four holes:

Welded and ground flush to a tidy finish:

Good penetration on the underside and most importantly, no edges burnt away:

Now that I was content with the outcome I took my time carefully shaping the patch:

Positioned on the wheel arch:

Welded, finished n' linished:

Moving on around the arch I deemed that the next captive nut was saveable as the steel still appeared thick and the surrounding area was not sunken or protruding. So, I welded up the slits (left over from my previous patch repairs) and smoothed everything back:

The next captive nut, complete with the partial remains of an old seized bolt, was completely shot and promptly chopped out :

This revealed quite a bit of surface rust behind it on the inner (soon to be inaccessible) panel. I shotblast the area the best I could to get it back to clean steel:

Then sprayed a couple of coats of zinc primer to keep it protected:

Whilst that was drying I knocked up another repair patch using the above approach. Fabricated this one in literally half the time now that I know what I am doing:

Couple of tacks to hold it in place:

After waving the magic wand:

This wing mounting area is becoming a lot more solid now. A lot of work has gone into it (with more to come!), but I think the results are worth it:

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