Part 3: The Water Wheel

In Part 1, we looked at sandpaper and in Part 2, stones and wheels. Here, we look at a water wheel.

The water wheel sharpening machine in the photo (made by Tormek – there are others) is eight or ten years old and has a new stone fitted.

The stone is, of course, on the right and runs in a water trough that's lifted into position when in use. The bar shown at the front has a cut-off toolrest fitted (cut off to allow sharpening of short tools – the real one is about twice that depth front-to-back).
The bar is set at a distance from the wheel to suit current purpose. In the photo it's as close to the wheel as reasonably possible and the toolrest is set to about 20 degrees to the wheel and doesn't quite catch the bow-wave dragged around by the wheel. You will have surmised that it revolves slowly (90 revs/minute)... You may not have surmised that the top rotates away from you which, in my configuration, causes a problem with short tools – they tend to be pulled upwards by friction … but currently only one tool, and the problem is minor compared to the convenience of the other jig, at the top.

The bits of perspex lower right are set for the protrusion of bowl gouges and spindle gouges from the front of a jig which slides on the bar. The tools are then wiped on the stone, swung back and forth from side to side to sharpen and preserve their swept-back 'wings'. The two types of gouges, though set up similarly, have different spacings from the stone, set by another piece of perspex suitably cut to shape.

That other jig, at the top (by Mick O'Donnell … there are others...) has a sliding, pegged toolrest, easily set-up with a spacer at 20 degrees to the stone and subsequently allowing easy and accurate settings for angles, in 5 degree steps, from 15 to 45. Judicious use of a ruler, a few sums and a triangular file has extended that range to (about) 50 & 55 degrees.

On the other side of the machine are leather honing wheels, requiring fine paste as an abrasive – a flat top about 8 inch diameter and a smaller profiled wheel for appropriately curved tools – concave, small to medium convex and sharply 'veed' tools.

In use, the grinding wheel forms a bevel on the back of the tool shaft, matching (of course) the wheel diameter, while the honing side refines it – particularly towards and at the edge. The grit size of the honing paste is probably towards p10,000 – very fine, extra smooth, extra sharp for carving.

Woodturning chisel bevels vary according to type from between 45/50 degrees down to both sides at 15 (ie overall about 30) and are not honed, while the carving counterparts are usually about 20 degrees and most definitely are honed. It's a good idea to give the heel ridge of the bevel a wipe across the stone after sharpening, in order to soften the ridge thus reducing any scraping/bruising of your workpiece, especially for carving, where the heel of the bevel is often used as a pivot.

Articles by Rod

18.11.13 Front Page

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