Wednesday, 24 June 2015

Napoleon fix-up (part 1)

A turning point has been reached as things are now very slowing starting to go back together! Because this blog post documents the first significant metalwork repair on the car, I have opted to covered it in step-by-step detail (don't worry, im not going to be as obsessive about describing every single minor repair in the future!). I shall publish this task in several parts as I progress, just to make it more digestible. 

Enough of the intro, lets jump into the action.... 

Repairing the Naps hat from the previous 'balls-up' has been weighing on my mind ever since the incident. You may recall from this previous post that I had ended up with a rather large gap between the old metalwork and the repair section due to poor judgment on my part. Since that time I have attempted to make various repair sections, but the arbitrary angles have caused nothing but frustration and poor alignment. I needed to simply things and approach this from a different angle (pun not intended). So, I decided to recut the remaining naps hat at a 90 degree angle to the diagonally sloping top edge. Here is the proposed angle marked with gaffer tape:

Checking for accuracy using a set square;

Once cut and neatened up I was confident that I had an angle that I could trust. It was a known quantity:

The main reason that I failed initially was that I had not focused on keeping the bottom edge of the repair straight and true. So, I figured that making a jig was the way to go this time. Essentially, I joined 2 pieces of scrap box section together using spot welds on one side and beads on the other. With the beads ground down and a lick of primer added I had a nice flat area:

I then made a paper template stencil with the bolt holes carefully mapped out to match the factory dimensions (with additional cross-hairs to visually assist with alignment). Also marked out some guides for aligning the jig with the chassis tunnel:

A quick spray of red primer to contrast against the grey:

....and the jig was good to go:

With the jig clamped into place on the chassis, I was provided with a solid foundation to work from. I trimmed up the end of the repro panel (again at 90 degrees to the sloping diagonal) and positioned it on the jig, clamping it into place. This allowed me to accurately assess the missing gap that I needed to fabricate:

Once measured up I cut out the repair section from fresh 2mm thick steel. Before bending the patch into shape, I knocked up a diy former to ensure that the outer profile of the piece would accurately match the original. I then put the whole lot into a vice and when I was sure everything was lined up correctly I proceeded to progressively tap the piece over with a rubber mallet:

 This created a good 90 degree bend with a suitable bend radius:

The fabricated piece all clamped up, aligned and ready for the welding to commence:

After countless hours playing with the settings on my new welder to ensure adequate penetration, I was finally confident to make the first tack weld of this resto - a significant milestone:

All of the tacks in place just prior to filling in the spaces in-between with a series of stich welds. To mitigate any heat warping, I filled up my compressors and used the air gun to blast a jet of cool air onto the hot welds:

Once it was all fully welded up I carefully ground the welds down dressed the area to make the new section blend seamlessly. Also rough cut the excess away from the bottom edge of the new piece:

Lining up the end section cut from the repro panel:

and here it is all welded in:

....and ground down nice & flush:

Seeing this section coming together has been really motivating and has boosted my confidence no end. You know, I reckon I can do this! 

Coming up in Part 2: I shall be cutting the bottom sections flush with the jig ready to accept newly fabricated flanges, drilling a few holes and more... Oooooh, the suspense!