Dieter Schmid's Fine Tools


Some notes on the bevel angle of chisels

As a rule western chisels are supplied with an angle of 25°, Japanese chisels with an angle of 30°. Mortise chisels may already have a blunter angle when you buy them. When sharpening a chisel it is generally advisable to stick to the original bevel angle of the product. For special applications, however, a case can be made for changing the bevel angle.

Softwood: if you are working only with softwoods, such as spruce, pine or similar, especially if you're touching up some previous work without a hammer – ie, using only the pressure of the ball of your hand – the bevel angle can be slightly reduced, to 23° for western chisels and to 28° for Japanese chisels. Finishing is easier at this angle, but be aware that the cutting edge is immediately far more sensitive. Do not use a hammer or any levering motions (which should anyway be avoided at all times). And furthermore, don’t discount the effort required to create a sharper angle: you will always need to grind the whole bevel.

You’ll find you need a sharper angle only in exceptional cases and the altered chisel should then be reserved exclusively for these specific tasks. For softwood the standard angle is nearly always good enough! It may even happen that even for a softwood you will need a blunter angle. This could happen if you are working spruce with a pronounced pattern of knotholes that has the effect of hardwood on the cutting edge, or if you decide to give the chisel a real pummeling with a hammer.

Hardwood: by all means increase the bevel angle when working with hardwood such as beech and oak. This makes the cutting edge less sensitive and you avoid the frequent notching on your chisel that is caused by the higher stresses that occur while processing hardwoods. A blunter angle also permits occasional levering, which especially in the case of deep mortises is hard to avoid. In contrast to a sharper angle it is actually quite easy to produce a blunt angle. You don’t have to grind the whole bevel, instead it is enough to grind the first 1 to 2 mm behind the cutting edge. Don't forget, if you want to return the chisel to a sharper angle you’ll need to grind the whole bevel angle. You can increase the 25° standard angle of European chisels to 30°, and the 30° standard angle of Japanese chisels to 35°. By all means experiment with intermediate values! The optimal cutting performance may well lie at some angle between the two extremes!

A few tips on buying chisels

A good chisel can only show how good it is if it is used for the purpose it was intended for. The building site is the wrong place for an expensive chisel, for there the wood there will be spattered with concrete and the danger of theft will be high. It is delicate work should be done with fine tools, in the workshop.

The finest work can only be achieved if the chisel is sharp. One should never use dry grinding wheels on fine chisels, because they cause the steel to soften and the cutting edge will last hardly any time at all. And, beware of the marketing from manufacturers who practically promote their chisels with the slogan, "Sharpened and ready for use – just unpack and start carving!" Always sharpen and hone your new chisels first. You need to flatten the back of the chisel to absolute flatness; if you don’t, you cannot expect to finish it properly after sharpening the cutting edge. Then sharpen the bevel, and finally hone both the bevel and the flat face. Do not be afraid of using a sharpening guide. There is nothing more frustrating than re-sharpening or re-grinding a bevel because you were simply holding the chisel in your hand while working it on the stone.

Perhaps you have heard a story like this- someone found Grandfather’s ancient chisel in a corner of the attic. It still worked, after being sharpened up brilliantly to an edge that lasted for ages, and became the tool of preference for every job. Stories like this are actually true, and not some miracle, because of the properties of carbon steel. Carbon steel is excellent to sharpen and has high hardness. In the 19th century, virtually every cutting tool was made of carbon steel, the name given to steel unalloyed with any other substance. It is allowed to contain up to 1.7 % carbon. However, it has some disadvantages - it is brittle, can be denatured if heated, and it is not stainless.

Many of today's manufacturers avoid these disadvantages by using steel alloys. Adding chromium and nickel makes the steel stainless, adding tungsten and molybdenum makes it resistant to heat, and adding titanium toughens it. Foundries will mix the additives to obtain the best combination for their product.

However, these advantages in turn bring their own disadvantages. Stainless steel tools are less easy to sharpen, readily clog grindstones, and the cutting edge dull more quickly.

As the disadvantages of carbon steel used in handheld cutting tools are more than outweighed by its advantages, we declare a preference in the case of chisels made of high-carbon steel over those made of alloyed steels.

Japanese chisels are made of plain high-carbon steel. Two Cherries and MHG chisels are made of alloyed steel.

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