Monday 9 July 2018
The motivation for this project came from a Strathclyde Woodturners' monthly competition. This called for something out of the ordinary, or even downright bizarre. After racking my brains for the best part of a month, I was still without inspiration. In the past, I have made several wall plaques where a squared piece of wood is turned with a series of grooves on one or both faces, then sliced into strips which are then offset and glued up again, giving a rather bizarre appearance. This, I thought, might be a suitable item for the competition. Then with less than a week to go, I had a vague recollection of having seen a picture of a four-sided vase, turned on each face, but at the time I could not recall where I had seen it. This seemed to be a development of my first idea which I thought might be even more bizarre. I later discovered that the vase had been made by Derek Andrews of Seafoam Woodturning in Nova Scotia, and thanks are due to him for inspiring me.
Tools used: Thin 1.5mm (1/16in) parting tool, 12mm (1/2in) swept-back bowl gouge, Continental spindle gouge, 10mm (3/8in) swept-back spindle gouge
I used a piece of mahogany (Khaya ivorensis) for this project, about 230mm (9in) wide by 255mm (10in), 250mm (9 3/4in) long and 63mm (2 1/2in) thick. To secure it in place you will need a second piece of wood, roughly the same size – which will serve as a faceplate. In the centre of one face, drill a 50mm (2in) diameter hole approximately 15mm (5/8in) deep – this will allow your chuck to expand into it. The piece can now be split into three, or, as in this case, I decided to turn the front and back faces before splitting it. Mount the faceplate on the lathe, roughly flatten the face, and then find the centre. Working from the centre, mark the positions of six mounting holes, mark out two on the longitudinal centre line, about 200mm (8in) apart, and another two pairs 65mm (2 1/2in) on either side
Drill four holes corresponding with the four corner pilots on the faceplate. These holes need to be deeply countersunk on each face, and the mahogany then needs to be screwed to the faceplate, using 75mm (3in) screws
Set the toolrest in place, spin the work by hand to make sure everything is clear, and start the lathe at about 500rpm. Then, use a ground back bowl gouge to flatten the face of the wood. If the spinning mass is reasonably in balance, increase the speed to about 750rpm, or even a bit higher if you can. Be careful here
When the surface is flat, start again at the centre and form a series of grooves, right out to the edges. Slow the lathe down and sand the finished face, if required. But be very wary of the corners. In fact it is not necessary to sand right into the corners as they will disappear later in the process. That's the first axis done
Next, unscrew the wood, flip it over, screw it back on the faceplate, and flatten the other face. Form another series of grooves and beads from the centre out, but use a different pattern from the first face, and sand if necessary. That's the second axis done
Remove the wood from the faceplate, and saw it into three pieces. The width of each piece should be equal to the thickness. Drill mounting holes through the cut faces at each end of each block. Make sure the new holes line up with the holes in the faceplate. Again, countersink the holes
Screw the three blocks in place, but be very careful about their position and make sure that the outer ones are correctly orientated to give the correct finished result. You may just be able to see the marks L, C, R. The importance of this will become clearer later but also mark 'top' and 'bottom.' Mount the assembly back on the lathe and turn another pattern on that face, and repeat the process for the fourth and last face
Remove the three blocks from the faceplate, and remove the faceplate and chuck from the lathe. Mark the centres of each end of each block, and mount the first of them between centres. Set the toolrest just below centre height
With the lathe running at about 2000rpm, use a spindle gouge to form the bottom end into a cylinder. This cylinder should extend up beyond the screw fixing holes, and should be blended into the main body
Check the diameter to make sure all three blocks have the same diameter
Replace the drive centre with a chuck and remount the block, making sure it is properly centred. Replace the tailcentre with a 10-12mm (3/8-1/2in) twist drill and, with the lathe running at about 500rpm, drill as far down into the block as you can. Then, once again back to the tailcentre, speed up to about 2000rpm, and start to shape the neck end to a pleasing profile. Remember to cut 'downhill,' from each end of the neck. At this stage you can sand the neck and the bottom
Set the toolrest across the end and use a pull cut with a swept-back spindle gouge to shape the inside of the neck to a pleasing flare, which will match the outside. Blend the inner part to the centre hole, and fine down the mouth of the flare. Be very careful when shaping the inner flare – a catch here is all too easy – and can shatter the top, or even knock the piece out of the chuck. Sand as necessary, and after sanding take a very fine push cut at 45° across the mouth of the flare. Do not sand this part again, as you want to retain the crisp edge. Apply a finish to the ends, if this is required. Finally, part off just above the screw fixing holes, after putting a couple of little decorative grooves just above the part line. Angle the parting tool to give a concave bottom. Do not try to part off fully, take it down to about 6mm (1/4in) then stop the lathe and saw the last little bit off. Then tidy up the bottom with a carving gouge or skew, and abrasive.
One of the four-sided bud vases is now complete, but you have the other two to do. Try to get them all looking alike at the tops and bottoms. Individually these bud vases look a bit bizarre, but set them up on a diagonal and they present four different but homogeneous patterns when viewed on the four faces. This is why care has to be taken when mounting the individual vases on the faceplate