The tool used throughout this sequence is the BCT 1/2" Supercut. Although many think, on first sight, that this is scraper-type tool, they couldn't be more wrong. What the originator
of this tool has done is study the effective profile of the bowl gouge and replicated this using a circular cutter with a very specific cross-section machined into it.  This is mounted onto a square shank through a novel
head which allows the cutting edge to be positioned to give near-perfect cutting regardless of the location of the cut surface. (Back)
The first photo shows the cutter head oriented in the straight-ahead position, aligned parallel to the lathe's axis, with the bevel of the tool running on the timber
surface (note the "skid mark"). The tool is initially presented with the shank in a horizontal position and with its square surface flat on the toolrest. Note that in
this position, no cutting takes place and the tool can be held in this position in complete safety. ( The tool was originally devised to aid in the teaching of turning to those of more
nervous disposition!) (Back) To commence cutting the tool handle is drawn gently
toward the operator, still with the shank horizontal, until the edge starts to cut. The aggressiveness of the cut can be varied somewhat by the degree to which the
handle is drawn toward the operator. To cut across the surface of the workpiece, the front hand is used to draw the tool towards the operator, keeping the angle between the shank and the lathe axis roughly constant by moving both hands in tandem. (Back) The cut can be made more aggressive by altering the cutter presentation angle using the key supplied, as
shown on the full, illustrated instructions supplied with the tool. Even with a heavy cut, as illustrated, the surface finish left by the cutting action is
exceptionally smooth, subject to steady tool control.. (Back)  The centre of bowl surfaces can be the bane of the
turner's life with a small raised nub, or nipple, of timber left in the centre with an alarming tendency for this to tear out when approached with a gouge. The Supercut
provides you with a whole new way to address this feature. Simply by rotating the tool away from the operator (clockwise viewed from the handle) through ninety degrees - or one flat on the square shank - the
tool is re-oriented for cutting towards the centre. In this alignment the tool cuts just as readily, allowing the centre feature to be removed simply by working the tool away from the operator, as
illustrated. (Back)
 Normal cutting is resumed simply by rotating the tool
back through ninety degrees to the original orientation. As the photograph shows, the amount of material which can be removed in a single pass is impressive, yet the timber surface is not torn and sub-surface
damage, as seen when using scraping tools for this operation, simply does not occur. The cutting tip lasts many times longer than the edge on a bowl gouge and
thus the time lost to sharpening operations is minimised and the rhythm of working is not disturbed. Note that the removed timber is in the form of substantial shavings, without the predominance of dust  and "woolly" shavings which would indicate a scraping action. (Back)
Hollowing continues to deepen the bowl section of the workpiece with occasional forays in the opposite direction to maintain a flat surface across the centre of the
bowl. Even though the tool is being used to create a deep hollow it can be used right up to, and even out along, the bounding wall without risk of catching or grabbing.
The Supercut is almost eerily well-behaved in these circumstances! (Back)
The hollowing is now complete and the tool is being used to refine the inside bottom  surface of the bowl, taking progressively finer cuts as
we approach the finished dimension and to refine the surface further. (Back)
The final shaping concerns the slight undercutting of the edge immediately beneath the rim area to create that defined shadow which does so much to make bowl designs which stand out as classics from those which are merely containers. (Back) Final finishing for a decorative piece will probably be carried out using abrasives in the normal manner.
However this process can start with a much finer grit than is usually the case with the internal surfaces of deeply-hollowed bowls, simply because the surface
off-the-tool is so much better than is normally the case - for most of us "mortal" turners, at least. (Back)
For everyday treen (tableware) of a utility nature, no further finishing should be required at all, as indicated by the  final photograph which shows the finish obtained directly off-the-tool. It can also
be seen in this shot that the test piece was not exactly an easy and forgiving piece of timber: this example contained knots, voids, spalting and some decidedly "pecky", or soft, grain
areas. The rim area has been left in its original state, for comparison: this surface had been cut with a bowl gouge prior to the commencement of work with the Supercut. And yes, the torn
grain is in the rim area turned with the gouge, not in the bowl where the Supercut was used. What more can one say. You'll never believe it until you've used it - and when you've
used it you'll never understand why you didn't try it out a long time ago! (Back) |
