How to Use a Mortising Attachment on a Drill Press

Written by wade shaddy
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How to Use a Mortising Attachment on a Drill Press
Use a mortising attachment on a drill press for clean mortise cuts. (Jupiterimages/ Images)

A mortise is a square cut in wood that corresponds to a tenon in a traditional mortise and tenon woodworking joint. A mortise needs to be cut to almost perfect dimensions to work properly. A mortising attachment is a drill bit inside a square housing with a sharp edge. Drill press mortising is an accurate, efficient way to cut a mortise into almost any wood.

Skill level:
Moderately Easy

Things you need

  • Mortising attachment, 1/2 inch
  • Tape measure
  • Masking tape
  • Board, 3/4-inch by 2-inch by 24-inch

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  1. 1

    Install the mortising attachment on the drill press just as you would a drill bit. Measure up from the bottom of the mortising attachment 3/4 inch and wrap a piece of masking tape around it.

  2. 2

    Stand a board on its edge under the mortising attachment. Make two marks on the edge of the board, perpendicular to the grain centred on the edge 2 inches apart.

  3. 3

    Slide the board under the attachment. Turn on the drill press and grab the handle to lower the attachment just as if you were drilling a hole. Line up the attachment inside the lines that you made. Bring the handle down and drill the attachment into the wood up to the tape mark and pull it back up. As you drill down, the sides of the attachment will cut square corners on the wood.

  4. 4

    Slide the board over 1/2 inch and drill down again overlapping the first hole by 1/32 inch. Pull the attachment back up.

  5. 5

    Drill down again making successive holes adjoining each other until you have spanned across the pencil marks. You should have a mortise in the edge of the board 2 inches long and 1/2 inch wide.

Tips and warnings

  • The measurements here are for examples. You can make a mortise any length you desire. You can purchase mortising attachments in varying widths.
  • Wear safety glasses when using a mortising attachment.

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