I recently began wood turning having acquired and restored a ‘90s vintage Record DML-24 lathe. One of my first projects was, rather ambitiously, a tulip bowl which presented my first real challenge. Centring the lathe’s faceplate on the bowl blank, which most turners would accomplish by eye.
In truth you can do it by feel too, but by eye or feel it’s never 100% accurate. Inspired by a tool shown by fellow blind turner Chris Fisher in his recent ‘becoming a blind wood turner’ series, I set out to make a device that would make accurately centring the faceplate a snap. I had a couple of ideas – use a threaded bar to match the thread of the faceplate and turn it down to a point at 1 end, or make a simple cylinder to fit snugly in the faceplate hole.
I opted for the latter solution as I don’t yet own a metal lathe and
freehand grinding a precise point on a threaded bar 3/4 inches in diameter would be difficult if not impossible. Besides threaded bars aren’t themselves precision stock, so the ideal solution would be to turn the complete tool, thread and all, from a single piece of round stock – or hexagonal stock, so that the tool could be removed with a spanner. This simply isn’t possible on a wood lathe no matter how skilled you are.
Instead I turned a cylinder in Delrin rod to 3/4 inches in diameter using a sharpened scraper at 950 RPM. Turning the Delrin on the lathe was tricky as it is a slippery material and the chisel had a tendency to skate if not held with an iron grip.
I refined it by sanding with 120-grit paper to fit snugly in the hole of my faceplate. I cut the head off of a nail and used its 3.6 mm shaft, with the pre-formed point, as a central pin for the centring device. Thus the device fits into the plate, its point is located into the central hole of the bowl blank, and the plate is held perfectly centred while you screw it in place.
Having made mine I proceeded to make one for my father, who owns a high-end modern Record lathe with a larger M33 x 3.5 mm thread. The Delrin rod I had was 32 mm in diameter and try as I might I couldn’t turn it freehand to fit this thread. There’s a very fine line between a piece that doesn’t fit at all and a piece that fits with too much play and without the facility to control the depth of the cut to a thousandth of an inch skimming a tiny amount from a rod is nigh-on impossible. Instead I turned his from an oak cylinder roughly 40 mm in diameter, with a slightly tapered end and a decorated handle. The same size nail was used to provide the centre point.
These devices make the process of mounting a faceplate to a bowl blank quick and easy, and I’m surprised they don’t exist on the market. If (when) I have a metal lathe at my disposal I will produce some aluminium versions with much better accuracy and a revised design, but as a concept these work really well.