by Jon Siegel

This article first appeared in The Old Saw, the journal of the Guild of New Hampshire Woodworkers (www.gnhw.org) June 2005.

Just looking at the vast array of turning chisels that appear on the pages of modern tool catalogs can be overwhelming.

Even general woodworking tool companies, such as Woodworker’s Supply have over 100 different turning chisels. Suppliers which specialize in turning tools, such as Packard Woodworks, or Craft Supplies each have over 300 different chisels! Why are there so many types of chisels? Which ones do you really need?

Last time, I wrote about tools for getting started in spindle turning. I mentioned that there are five chisels that you need. Remember that in spindle turning, the grain of the wood is always parallel to the axis, and its orientation does not change as the work turns. The attack is always downhill, and the cutting action is always across the grain. This dictates that we use shallow gouges to scoop out material across the grain, and skew chisels to slice the end grain off cleanly.

On the other hand, bowl turnings are mounted on a faceplate or chuck. They are usually oriented so that the grain of the wood is perpendicular to the turning axis. To avoid end grain, the attack is from the face whenever possible (axial). The grain direction is variable and continuously changing as the work turns. Therefore some tear-out is inevitable. To minimize this and deal with tough end grain, we use narrower gouges which possess a smaller nose radius, and finish with a freshly sharpened scraper.

Types of Chisels

You will need at least one bowl gouge for bowl turning. The difference between a bowl gouge and a spindle gouge is the shape and depth of the flute. The flute of a spindle gouge is circular and shallow, while the flute of a bowl gouge is parabolic and deeper. A 1/2˝ bowl gouge is a good place to start, but if you are turning green (wet) wood you might want a larger one. This is because wet wood is softer and you can take wider chips. If you are doing smaller work in dry wood, you might also want a 3/8˝ bowl gouge.

Please note there are two different ways of measuring the size of a gouge. Some dealers specify the size to be the diameter of the round stock from which the gouge is made – all modern bowl gouges are machined from round bars of tool steel. But some dealers measure the width of the flute, which is somewhat smaller.
You will also need some scrapers for bowl turning – remember that scrapers are almost never used for spindle turning. There are two main categories of scrapers – round nose and spear point. Both of these have many variations. It is useful to have several round nose scrapers with different radii of curvature, because the round nose scraper is the most versatile type of scraper. Spear point scrapers can have a variety of point angles, but about 75° is best for going into square corners. Another useful type of scraper is the square nose, which is simply straight across.
At first you can operate with only a few scrapers, but inevitably your collection will grow over time. The extra thick scrapers which have been offered in recent years are definitely an improvement over the older types, especially when you need to extend the chisel some distance beyond the tool rest.

Metallurgy

Until about twenty years ago, woodturning chisels were invariably made from carbon tool steel. This type of steel has remained almost unchanged for hundreds of years. Suddenly, chisels made from High Speed Steel (HSS) appeared. These have gradually become the standard. Why this transition occurred in the 1980s is somewhat of a mystery, since HSS was invented around 1920. In recent years, chisels made from high alloy and powder metallurgy have come on the market, and the choices can be dizzying. My advice is to beware of advertisements which exaggerate the benefits of these expensive tools, and while they definitely do hold an edge longer than HSS, they are not five to ten times better as advertisers so often claim. If you are looking for a chisel that will stay sharp forever, there is no such thing. You would be better off spending your money on a good sharpening system. If the time and effort you need to invest in sharpening is thus reduced, then the length of time the tool stays sharp becomes less of an issue. The subject of sharpening woodturning chisels will be discussed in detail on these pages in upcoming issues of The Old Saw.
The tools described above are the ones you will need for general work. If you want to specialize, you may need chisels designed for a single purpose. For example there are mini chisels for very small detailed work. Or, if you want to make hollow vessels, you will find an amazing variety of tools designed for reaching into the small opening of a vessel for hollowing the inside. Some of these hollowing devices are equipped with a laser beam to gage the thickness of the wall of the vessel while you are turning.

What You Need

Five chisels you need for spindle turning – 3/4˝ roughing gouge, 1/2˝ spindle gouge, 3/8˝ spindle gouge, 1/2˝ skew chisel, and a parting tool (diamond pattern).

Four additional chisels you need for bowl turning – 1/2˝  bowl gouge, 1/2˝ round nose scraper, 3/4˝ round nose scraper, and 3/4˝ spear point scraper.