12″ Ported Bass Cabinet. Basic cabinet construction.

The B&Q laser-guided cutter never did get fixed. In the end, I searched around until I could find a local timber merchant who would supply a full sheet of ply, and also make the cuts for me. Step up William Frances Timber in Herne Bay. The timber has now been cut and collected – so I have six sheets of Malaysian, hardwood ply to make up my cabinet, (and another six to make up another project).

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My first job will be to construct the basic walls of the cabinet – with the front and back panels left un-fixed, and un-glued, at this stage. These two pieces will, however, be used as supports during the joining – in order to make sure everything is square and true, at the corners. It’s vital that the dimensions of the cut sheets are accurate.

The basic construction consists of the top, bottom and side panels. I find it’s always a good idea to identify and mark them up. The top and bottom panels will be routed at the edges, where the side panels join – so a small, 5mm deep and 18mm wide rebate is cut for each side panel to sit into. It helps to take your time setting up the router – working out how to clamp down the wood with a suitable straight edge in place, to run the router along. I used a 16mm wide cutter to rout the channels – so it requires two passes for each rebate. Doing it this way allows you to check that the cut is straight and equal along its’ full length, and gives a chance to make critical adjustments for the final pass. I usually do a test run on a waste piece of timber, as well – just to make sure the initial setup is exactly what I’m after.

Once the router is properly set up – the top and bottom panels are routed at each edge. It’s sometimes easy to cut the wrong edge – especially if pieces are almost square. Check. Measure twice – cut once – and all that sort of thing.

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With the top and bottom panels ready to receive the side panels – I always do a test assembly without glue. The rebates are exactly 5mm deep, and the front and back panels have been cut 10mm smaller in height – to accommodate this. It’s important, therefore, that the rebates are accurately cut, and square – or else the corners won’t go together properly. Too shallow, or too deep – and the edge joints might not be tight, and will be weak. The box is going to have to vibrate to do it’s job properly. I don’t need bad joints, or a wonky box.

I fit the panels together, and use a strap clamp to pull everything in on itself. Using the front panel fitted inside the box as a support – I can tighten up the panels, and check the joints and alignment. I’m pleased to see that the front panels sits snugly inside the surrounding frame, and that all the edges look to meet squarely, and fit well. I back off the clamp, dis-assemble everything again – and then run a couple of beads of wood glue along each of the rebates – top and bottom. The box is then brought together again, and the strap clamp tightened. This time, however – I move the strap clamp over to one side, and fit a second clamp around the other opening. After cleaning off any glue seeping out of the joints, with a damp cloth – I push the supporting front panel through, to fit under one of the strap clamps. I can then push the back panel in, under the second strap clamp.

I test the corners for square with a set-square, and make sure all of the panels are properly aligned at the ends. Once everything looks good – I give everything a final wipe over, to get rid of any surplus glue – and then fully tighten up the strap clamps. I set the box up on a workbench, and then put a heavy toolbox on the top. It’s hot and humid in the workshop today. With weather like this – the glue will soon be dry enough to handle.

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After an hour or so – the glued joints seem pretty secure – but I don’t want to risk pulling anything apart, so I have to move on carefully. If I’d had a third strap clamp – I would have strapped up the middle of the box. But I don’t – so I want to get some securing dowels in to the middle of each joint as soon as I can. I loosen the strap from one side, slide it over so it’s roughly in the middle, and then tighten it up again. Then – using a dowel jig, set to place an 8mm dowel exactly in the middle of the 18mm ply – I drill a hole sufficiently deep enough to take a dowel pin. The dowel holes are drilled through the top and bottom panels – and into the side panels, so there are four centre pins to locate. One opposite the one I’ve just tapped – and then spinning the box 180 degrees for the two on the bottom panel. Once the four holes are drilled, a drop of wood glue goes into each, and then glued dowel pins are hammered home.

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Now that the centres of the panels are securely pinned, I move the strap clamp to the outside edge again, and then drill similar dowel holes every inch or so, along the side edges of the top and bottom panels. As the holes are drilled, the dowel pins are glued and hammered home – until each edge is securely glued and dowelled into place.

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After cleaning off any surplus glue with a damp cloth, the cabinet is set up on the workbench again – with the heaviest toolbox I have, placed on top. The front and back faces are left inserted, but unfixed – to help keep things true, and to check everything is square. With the edges securely joined and dowelled, and with the corners square and true – I leave the cabinet in the workshop overnight, for the glue to fully cure.

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