During the years that I’ve been turning some of my tools have got shorter. Each grinding takes off just a little bit of metal and it adds up. I have never yet got to the end of a gouge or scraper. But there comes a time when grinding short gouges with a jig gets difficult.
Different jigs have different ways of clamping a gouge. Some have a peg that fits in the flute and some have a flat plate that bears on the sides of the flute. Either way, the jig has to lock the gouge in place and align it properly.
Modern gouges tend to have short flutes. This is a good thing, because it makes the tool more rigid. But if the jig clamp acts on the flute itself, how do you use it when there is not enough flute left to give the proper projection in front of the jig? When the flute gets short, the tool may have plenty of life left in it. But the jig clamp begins to bear on the up-sweep at the end of the flute, and then later on the round surface of the shank. It no longer grips securely or aligns the flute properly.
There are several ways to overcome the difficulty of grinding short gouges. You can reduce the projection of the gouge from the jig, but this changes the bevel angle. You can learn to sharpen freehand – a nearly worn-out gouge is a good tool to practice with. Or you can re-shape the shank to suit the clamp. This is what I did today on two of my favorite bowl gouges. They were originally shallow fluted spindle gouges that I ground with a short bevel and round nose. They work really well for making small wooden bowls that aren’t too deep.
I ground down the upper surface of the shanks, leaving them flat and at the same level as the top of the flute sides. This would be enough for some types of jig, but mine is a Tormek jig that I use on the high-speed grinder. It has a small projecting peg under its clamping plate. So I mounted a metal-cutting wheel from an angle grinder in the lathe and carefully ground a groove along the middle of the flat part. I can now carry on sharpening the gouge as before, getting a lot more use from these two tools.
When scrapers get short, the handle starts to foul the platform rest at the grinder. To overcome this, you can make the platform smaller and cut off its corners so the tool can swivel for sharpening. Another option is to make a secondary platform that clips on the main one. Make it smaller, and thick enough for the tool handle to pass over the lower platform unobstructed. The secondary platform should be easily removed. If the lower one is steel, you might be able to use magnets, but they would attract the grinding dust. I use a bit of plywood with a length of perforated steel strapping as used by builders. This slides over the main platform. You have to alter the platform angle to allow for the extra height.