I finished this bowl this morning and was greatly relieved to have completed it with only a grazed knuckle.
I have had this piece of spalted beech lying around in the workshop since about last October. It was originally ordered to make a yarn bowl and was advertised as an 8 x 4 round of spalted beech. When it arrived, it was certainly 4 inches deep on one side, but barely 2 inches on the other, so there was no way I could have made a yarn bowl from it. I resigned myself to having bought a useless piece and stuck it under my bench. Nonetheless, it kept nagging at me and every time I thought of trying to do something with it I became very conscious of the fact that it was going to be severely unbalanced and would thrash about on the lathe, with the potential to at least injure me in interesting ways. It got put back under the bench several times.
Last week I decided that I couldn't leave it there any longer and that I would have to face up to tackling it. I explored several ways of mounting it on the lathe, none of which would have had any effect on the balance. Eventually, I just drove a steb drive centre into the curved face as close to the middle as it was possible to judge, then set the lathe to a medium speed. Bear in mind that this lump of wood weighed 2.7kg, so predictably the whole setup started jumping around like a caged and angry lion; I reduced the speed to the minimum, made sure my tools were as sharp as they could be and started work. Despite being supported by a live tailstock there was always a chance that it would break away from the steb drive and become a missile.
This was tough. My lathe spindle speed is governed by shifting the drive belt from the motor to any of three different pulley settings. A bit crude by modern standards but it does work, provided that the motor is firmly clamped in place at each change. The immediate problem I had was that the shaking was so violent that it was loosening the motor clamp every few seconds, which meant that the belt slackened and the workpiece stalled on the gouge. At this point I was only trying to create a rebate in what would become the base so that the bowl could be mounted more securely in the 100mm chuck jaws. The lathe had to be stopped around every 30 seconds just to retighten the clamp. I was re-sharpening the gouges about every 2-3 minutes. Eventually I got the rebate cut and was able to reverse the piece onto my standard chuck and 100mm jaws; it would at least be more secure. Time for a cup of tea.
I came back to the lathe and started turning the wood into a more round. Up until now it still was very much as it had been when cut from the tree. Getting into a more circular form certainly helped to reduce the shaking, though it was still heavily weighted on one side. However, as I stared cutting into the bowl the weight became more evenly distributed and it became a much less difficult job. Nonetheless, I was now forming a rim, one side of which would be higher than the other. Obviously, it was inevitable that I would catch my knuckles on this at some point. Blood was drawn, but nothing more serious than this.
The job became progressively less risky as more wood was taken out. At long last I reached what I had decided would be the base at about 5mm thickness at the centre. Another two or three hours were put into sanding the bowl, taking out any unevenness left by the gouges, and then sanding to to 3000 grit for a really smooth base ready for oiling. The bowl had 5 coats of Tung oil over a 24 hour period and was then left to dry. Once it was cured more polishing was done with a fine steel wool as various layers of wax were applied: t coats of microcrystalline, followed by 2 coats of gold enhancing wax, followed by two further coats of microcrystalline gloss wax for a deep shine.
The finished bowl is now for sale in my Numonday shop .
By the way, the bowl now weighs 400gms!
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