Four Part Bowl archive
Friday 17 October 2008
Tracy Owen turns four bowls that can fit together like a jigsaw
Gallery
The finished article
Draw on the circles using a compass
The piece with the circles drawn on where the bowls will be cut and three lines dividing the bowls where the wood will be cut
Cut the wood with a 12mm (1/2in) 3tpi blade. The narrow blade helps cut the tight curves
The block of wood divided into the four sections
Drill a 25mm (1in) centre hole into the piece using a saw tooth cutter. This will be used to mount the piece on to the lathe
Mount the first piece onto the spigot jaws. These jaws open out into the hole for a very secure way of mounting each of the four out of balance pieces of wood
With the piece held firmly onto the chuck and with the aid of indexing to hold the spindle stationary, use a bobbin sander to remove the bandsaw blade marks from the flat surfaces
Through the door of the sandblast cabinet. It is difficult to take a photo of sandblasting in operation, as the system will not work with the door open. Sandblast the natural side underneath the bark and the sides that were cut by the bandsaw
Close up of the surface underneath the bark after sandblasting, before applying a finish
The sawn edge after sandblasting, before a finish
Use a 10mm (3/8in) bowl gouge to flatten off the bottom of this first piece. Use the tip of the tool with bevel contact. This is a difficult cut to make because of the irregular shape. Lathe speed is about 700rpm. The speed is low as it was way out of balance
Cut the dovetail using a 10mm (3/8in) spindle gouge. Lathe speed is still 700rpm
Put a small dot in the centre of the dovetail for tailstock alignment when the dovetail is removed
The flat bottom and dovetail ready for mounting into the jaws of the chuck
Cut the top face flat using the 10mm (3/8in) bowl gouge. At this stage, I still encountered the same sort of problems as before because of the irregular shape
Close-up of the 10mm (3/8in) bowl gouge beginning to cut out the bowl form. Lathe speed still about 700rpm
Start the cut to flatten off the top face. In the picture it almost looks as though the tool is missing the wood completely, but there are shavings coming off the gouge where it is cutting the wood
Keeping the piece stationary, check the top face is nice and flat
Apart from sanding, the piece is just about finished. This picture shows how much the tool is missing the wood with the irregular shape
With the spindle lock on to hold and the piece stationary, power sand the top face using grits 120, 180, 240, 320 and 400. Sanding this way helps to keep the piece flat and all the edges nice and crisp. If the piece is sanded when rotating they would be rounded off
Power sand the bowl form with the piece rotating using 120, 180, 240, 320 and 400 grits. Lathe speed is about 500rpm
Re-chuck to remove the earlier cut dovetail using a wooden disc to fit the bowl form and a piece of anti -slip mat to protect the bowl. The anti-slip mat adds grip to drive the bowl and is supported with the aid of the tailstock
Due to the shape of the base, I still made a cut across the whole of the bottom face using a 10mm (3/8in) bowl gouge. This gives this piece a larger stable base to sit on. This quarter has a large chamfered area on one side making the piece unbalanced. The wider base helps it to sit straight. Lathe speed is about 500rpm
Cut away the dovetail using a 10mm (3/8in) bowl gouge
Check that the surface is slightly concave. This photo also shows the uneven base - the extra couple of cuts just taken off this base have made it a little bit wider, thus making it more stable
Introducing the vacuum chuck. I did not want to use this right at the beginning for re-chucking because of the piece being out of balance but with hindsight I am sure it would have been all right. Place the piece of wood on the vacuum chuck and use the tailstock to centre it
With the tailstock out of the way, remove the centre pip using a 10mm (3/8in) spindle gouge
With the piece still sucked onto the vacuum chuck and using the spindle lock to hold the piece stationary, power sand the bottom using grits 120, 180, 240, 320 and 400
Fill in any small faults over the four pieces with brass powder and then fix with thin superglue
Give all four pieces three or four coats of Danish oil, with sufficient drying time between coats. Use a toothbrush on the textured areas
Over the past several years I have been making off-centre pieces of work - turning more than one bowl form out of the same piece of wood. These have mainly been two bowls, but have been as many as four, which usually run into one another. This type of work is normally made from very irregular shaped pieces of wood.
The piece of ash (Fraxinus sp) for this project had been kicking around for five or six years and because of its unusual shape I had been unsure how to cut it, let alone what to make from it so it was put on one side until I could find the best use for it. Recently I decided it was about time I got the saw to it. With it being such an unusual shape it had to be cut using my chainsaw rather than the bandsaw. It was cut it into four slices, the smallest of which had some splits and cracks in it and went straight into the fire pile.
I chose the centre slab of the remaining three for this project, as it was the best overall shaped piece for it. My first thought was to make this as one piece with four bowls forms. Then I had the idea of cutting it into four separate pieces so that it fit together like a jigsaw. It could then be used together or as individual bowls.
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