Monday 9 July 2018
I call these pieces butterfly bowls. They have the benefit of giving you a substantially sized piece from a relatively small piece of branch wood. They are not difficult to make but they do need care in the making.
Actually, they are not really like a conventional bowl at all. They would not be very useful to hold things, but then they are meant to be more decorative than useful. However, from some angles they do look somewhat like a butterfly in flight, so – butterfly bowls they are.
Made from a yew (Taxus baccata) branch as this one was, or laburnum (Laburnum anagyroides), the contrast between the dark heartwood, the pale outer, and the dark bark – if you can keep it on – can make for a very striking piece.
As with any bowl, apart from the obvious fact that it is going to be long and narrow, you have a choice of shapes which you can make. Viewed from the front, you can make a conventional convex bowl, or cup shape. You can make a concave shape, flaring out from the base. Or, you can do – as I have done here – and make an ogee shape. Normally you would opt to make both wings the same length, but if you choose, or if you are not careful, it is possible to make an asymmetrical piece with one wing longer than the other.
12mm bowl gouge
Start with a piece of branch wood about 100mm diameter by about 400mm long. It should be relatively straight in order to produce a relatively symmetrical end result. When you drill the hole for the screw, or expanding pin chuck, make sure that it is in the centre of the length and width of the log, and also make sure that the upper extreme ends, which will form the wing tips, are at the same height above the drill table. This is not so critical if you have opted for the cup shaped piece, but for a flared or ogee piece, it is important
Mount the log securely on the lathe, making sure that the 'wing tips' are in the same plane of rotation, and, if possible, that the log has two points of contact, or support on the faceplate behind the screw or pin chuck. If you are nervous about the mounting, you could bring up the tailstock for some added support. Here you can see the position with the handle of the gouge well down and tucked against the body. The tool used is a 12mm bowl gouge with the wings swept back. The cutting action is that of drawing the tool back from the centre, keeping the cutting edge presented at approximately 45° to the direction of the cut
Here is the shape of the underside in its early stages. Take light cuts, stopping frequently to adjust the toolrest nearer to the wood. Lathe speed should initially be around 600rpm
Here is the underside about half way done, and the foot beginning to be formed. Bring your speed up to around 750rpm, making the cuts in the centre a little heavier. Continue to take light cuts as you move towards the periphery of the bowl shape
Keep an eye on the ghost image to see how the shape is progressing, continuing to adjust the toolrest. You may have to use a glove, as the speed increases to about 850rpm
Here is the underside, complete except for sanding. Re-sharpen the gouge and take very light finishing cuts at about 1,000rpm. DO NOT ATTEMPT TO SAND WITH THE LATHE RUNNING, except perhaps for the foot itself. Power sanding of the wings can be done with the lathe stopped, although the shape of this piece lends itself to hand sanding with the grain. You can sand the underside of the wings at this stage, or wait until the inside has been finish turned
Here is the shape of the underside, and the big knot which was still causing some unbalance at this stage. This photograph also shows the small foot which will be gripped in O'Donnell jaws to enable the inside to be turned. Re-mount the piece ready for forming the inside
Here you can see the beginning of the inside forming, with the large knotty lump being removed. This time use a push cut towards the centre. The tool is the same 12mm (1/2in) bowl gouge as was used for the outside. Indeed, this is the only tool used for this project. Again light cuts are necessary, to avoid catastrophic catches, and a sharp tool is essential. Speed is still around 1,000rpm
Here is a piece of tape on the toolrest which corresponds with the outer periphery of the bowl, as a reminder of the invisible sharp edges of the bowl. Do not let any part of your body or clothing stray over the top of the toolrest
Here is the interior progressing toward the centre. From this point on it is simply a case of refining the interior shape to match the exterior. Take the thickness down to about 7mm. Finishing cuts should be light with a freshly sharpened gouge, and as steady a hand as possible to get the best finish off the tool, and thereby minimising sanding. This again is best done by hand in the direction of the grain
Here is the bowl still mounted on the lathe, and a foam rubber or plastic backing pad, which will support the abrasive and help to remove any residual ripples left by the tool. As the wings will be relatively flexible, support the back of the wing with one hand whilst sanding with the other. Depending on the finish you can achieve off the gouge, start with about 120 grit and work through the grits to 320. If you want, you can apply a coat of sanding sealer, although in this case, I did not do so
If you have buffing mops, this is an ideal way to finish off with a light application of Carnauba wax. Keep a good grip on the bowl and be very careful not to allow the mop to catch an edge, or the bowl will be snatched out of your hands and thrown violently across the workshop. If you do not have a buffing mop, a perfectly good finish can be achieved by applying a light coat of wax and buffing with a brush
Here is the finished butterfly bowl which was turned from yew branch wood
And here are a variety of other examples of butterfly bowl you can make