Chisel Basics

When it comes to chisels, you have a number of options, for example consider the following partial list:

  1. Paring Chisel — For removing thin shavings (e.g. Cleaning up the bottom of a grooved slot).
  2. Beveled Edge Bench Chisel — Functions as a general purpose chisel.
  3. Mortise Chisel — A heavy duty chisel with square sides, made for chopping & prying out wood for a mortise joint.
  4. Registered Chisel — A chisel with sides square to the blade’s back. Used for general chopping. Sometimes used for mortising although the blade is not as thick as a mortising chisel and therefore will not hold up as well as a mortising chisel, for chopping and prying out a mortise joint.

Chisel handles come in two flavors, socket & tang. The chisel on the left in the photo below shows a chisel with a socket type handle (the wood or plastic handle would be tapered to fit inside the metal socket). The chisel on the right in the photo below shows a chisel with a tang type handle (the metal tang would fit inside a wooden or plastic handle).

Whatever chisel you are using, the importance of keeping your chisel razor sharp cannot be over emphasized. This will help to insure you successfully accomplish the chiseling task your working on.

Chisels are sized according to blade width, which ranges generally from 1/8″ to 2″. The typical range of sizes available are as follows:

  • 1/8″ 5/8″ 1-1/4″
  • 1/4″ 3/4″ 1-1/2″
  • 3/8″ 7/8″ 2″
  • 1/2″ 1″

Odds are having just a 1/4″, 1/2″, 3/4″, & 1″ chisel sizes would meet most of your chisel needs. Then add on to this set as the need for other sizes arises.

Safety Pointers:

  1. Move sharp edge of blade away from you.
  2. Keep both hands behind the cutting edge.

For controlled shaping of your work piece with a chisel, light taps with your mallet work better than heavy whacks with a mallet on the chisel.

For paring cuts, which consists of taking thin cuts, work with the back of the blade against the work piece being cut. Push the chisel with one hand and use the other hand to keep downward pressure on the chisel blade.

For rough cuts, work with the beveled side of the blade against the work piece being cut. Instead of trying to hog all the wood to be removed with one rough cut, better to remove the wood with several more controllable rough cuts.

Chisel Angles:

  1. A common angle for chisels is 25 degrees.
  2. For cutting thin shavings, such as for paring, people generally use an angle somewhere between 15 and 25 degrees. The 15* camp wants a razor sharp edge & their willing to live with a fragile edge that requires more sharpening maintenance. The camp trending toward or at 25* wants a physically stronger edge that requires less sharpening maintenance.
  3. For more physically demanding cutting and chopping of wood, trend is to use 30*, in order to hold a stronger edge (less sharpening maintenance req’d). Mortising chisels would for example tend to use the 30* angle.
  4. Regarding all the angles mentioned above, some sharpen to those angles and stop, and then there is another school that includes a second bevel angle of around 5* greater than the 1st bevel angle. This second bevel angle is generally referred to as a micro-bevel. Logic behind using this micro-bevel is that its easier to maintain the sharpness of this edge since its face surface area is considerably less than the face area of the primary bevel. Personally, I am in the micro-bevel camp.

The image below consists of two Sketches, the upper Sketch showing a chisel with a 25* bevel. The lower Sketch shows a chisel with a 25* primary bevel and a 30* micro-bevel. The two Sketches were drawn to scale and then enlarged by a factor of 16, in order to make the sketches more readable. The linear dimensions shown represent full scale values (the multiplying factor of 16 has been accounted for). A blade thickness of 1/8″ was used for the chisel.

The image below is best viewed by clicking on the image to enlarge it, and then return to article by clicking on arrow in top left corner of your monitor.

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Until Next Time, Take Care
AL

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