WoodSkills Issue 02 - Page 69

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A former can be made from any material which will take the compression forces applied by the vacuum without deforming. There are companies which can manufacture these to your specification from dense form or MDF by using a hot wire or CNC machine. Or it may suit your design to turn one on a lathe and cut down to the section required. The method chosen for use here is one which can be made easily enough in the workshop and adapted to many different designs.

The first step is to create a side view template of the former from sheet material. Use a sheet thickness that the bearing of a router trimming cutter can run along – I find that 9mm MDF is perfect for this job. Lay aside enough decorative veneer to skin the former later. This can be any veneer you have at hand. Measure the thickness of this veneer.

The rest of the former will follow this template so it is worth spending the time here to make sure that it is as accurate to the inner curve of the piece being made as is practicable. Subtract the thickness of the skinning veneer from the curve.

Add at least 75mm to the base of the former to allow the vacuum bag to pull into the edge and around 10mm each side to the width. Once this is ready the template can be traced around and transferred to the sheet material that will be used to construct the former. This could be MDF or chipboard, whatever is cheapest or closest at hand – the last few formers I made were repurposed from a Swedish flat pack wardrobe that had fallen apart and which I had cannibalized for parts. This had the advantage of being free, close at hand and saved me throwing it on the rubbish heap.

Once the layers have been roughly band sawn out, the template can be fixed to the first layer using panel pins and trimmed to size. The template is removed, the “prime” layer is then screwed to the next roughed out layer and the trimming is repeated. Successive layers are added and trimmed until the requisite width has been reached. If the width is considerable, every second layer can be a hollow “edge only” layer made from lumber or sheet material offcuts. This will lighten the former and save on materials whilst maintaining adequate strength in the structure.

Constructing the Former