Volvo 120 Boot (Trunk) Floor Fabrication: Part 1- Making a 'Form'

With the spare wheel well removed and the rear panel replaced, I have initiated attempts to fabricate the boot floor. This represents a significant challenge for me as I  am lacking in both skills and resources. The pieces that I need to make are those that constitute the main part of the boot floor and although largely flat, they are complicated by the fact that the edge that meets the rear panel is curved. (There is also the big issue of the rolled lip recess where the fuel tank sits, but more on that later.) My strategy was to try and make a 'form'.

I assembled the following materials:

• Large carboard box
• Sheet of thin ply (reclaimed from an old sideboard)
• Two sheets of 18mm ply, 1.2m x .25m (from the 'offcuts' bin in B&Q, £1 each - bargain!)

I began by making a template with the card from the box. (I use corrugated card as it was more ridged than paper or thin card, and I found that I could refine it with a sanding block.)

I  placed the template onto the thin ply and marked out the curve

Then, after cutting out with a jigsaw, I offered up this ply template to the rear panel inside the boot.

Although this seemed to be a good fit, I realised early on in this process that I had made a bit of an error. This task would have been much easier if I had made the template using the new rear panel before it was attached to the car! Hindsight is a wonderful thing...too late now.

I used the ply template to mark the curve onto the first sheet of 18mm ply and again cut with the jigsaw. I then refined the form using a surform file, repeatedly offering it up to the floor/rear panel.

Once I was happy with the shape, I marked up the second piece of 18mm ply and cut that to match.

Starting on the repair section itself, I made another card template this time including a larger area of the floor. I also incorporated an additional 15mm to allow for the lip to the rear panel and the rear spare wheel well repair section.

I had already acquired a 1m sq sheet of 20 gauge (0.9mm) 'Zinctec' steel, so using this template I marked and cut out the panel with an air nibbler. 

This is my preferred tool for large pieces it cuts through the sheet steel with ease, can handle tight curves and corners, and doesn't bend or distort the edge.

Next, I carefully clamped the repair piece in place between the two halves of the plywood form, ready to begin the hammer forming.

At this point I decided to finish for the day. I am having some misgivings about the gauge of sheet metal I'm using as it feels a little thin. I had been led to believe that the original panels were pressed from 20 gauge (16 for the 'chassis' sections) and whilst I know that some of the strength in the panel will come from the folding and forming, I am not confident that this stuff is thick enough, is going to be strong enough. I need to investigate.

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