Cake Knife

This knife, with its customized inlay, makes a wonderful wedding gift and keepsake.

Several months before her wedding, my daughter asked me to make a decorative knife with which her and her husband could cut their wedding cake on their special day. They had also asked his father, an avid woodturner, to turn the pen that they would use to sign the register.

Both he and I had a bit of a chuckle when we finally got together to examine each other’s work, and realized that we had both chosen to work with cocobolo without any prior consultation.

This project can be constructed from any hardwood that you like. I chose cocobolo because it is a relatively dark wood, which makes installing the inlay easier. I also happened to have some leftover pieces perfect for this project.

The center of the handle contains two birch veneers which sandwich the knife blade. The birch was chosen for its stark colour contrast to the cocobolo. Since this knife was ceremonial in nature, to be used once and then put on display, my wife selected an inexpensive cake knife with a plastic handle that was purchased for a few dollars from our local hardware store.

Prepare the Material

I chose to make the handle slightly longer than a standard knife handle; select a handle length that you are comfortable with.

• Mill stock for the handle (A) and veneer (B). The pieces are fairly small, so be careful when cutting them on the table saw. Remember not to run stock shorter than about 12″ through your thickness planer; best to mill a wider and longer piece of stock, and then cut the handle pieces to size. For the veneer, start with a piece of birch about ¾” x 2″ x 8″. Joint one face and edge, and then rip a piece on the table saw just slightly thicker than 1⁄16″. Use a featherboard and push block. Use a sanding block or hand plane to remove any milling marks.

• Carefully remove the handle from the store bought knife blade. Take special care not to scratch or mar the finish on the blade.

• With a hacksaw, cut a piece of ⅛” steel rod, about ¼” long. The rod will be inserted through the hole in the knife blade and pin the blade into the new handle. Steel rod is available from most building supply stores or automotive supply shops.

• Plan the desired inlay and make sure that you have enough material on hand to complete it. I used gold mother-of-pearl for the text and white for the interlocking hearts.

Inset the Knife Blade

The knife blade is inset into the two thin birch center plies. You need to cut a shallow relief in each veneer to accommodate the blade. The fit must be precise so that when assembled, the veneers don’t bulge or have excessive play around the knife blade. Cutting the relief for the blade is carried out in the same manner as cutting the cavity to inset the inlay. Decide how much of the knife blade will be inside the handle. Also, pay attention to the angle that the blade enters the handle. You want the handle and exposed portion of the blade to be well proportioned.

• Cut the handle end of the blank square.

• Place the pieces of birch veneer on each side of the blade in the desired position, making sure the edges line up. With a small clamp, press the veneers tightly in place on each side of the blade. The birch is soft enough that the steel blade will leave an impression and perfectly mark the cavity that the blade will fit into.

• Remove the clamp, and use a very sharp X-Acto knife to etch the line around the blade.

Do this to both veneers. Then, using a rotary tool, dremel.com, with a 1⁄16″ burr, rout the cavity to exactly one half the thickness of the knife blade. Be sure that the blade fits snugly in the cavity and that the birch does not bulge where the blade is inserted.

Install Pin and Handle

• Drill a ¼” hole through both veneers. Be sure the hole in the blade lines up perfectly with the holes you drill.

• This hole also needs to be transferred into the cocobolo. Be sure not to drill any deeper than necessary into the cocobolo.

• Install the piece of ⅛” x ¼” steel rod to anchor the blade to the handle.

• Test fit the parts before applying glue. I used G-2 epoxy, but any waterproof glue will work. Apply the glue as per directions and clamp with three clamps, and allow it to dry overnight.

• Make a template of the handle shape from ⅛” MDF. Place the template on the assembled handle and trace carefully around the pattern.

• Cut the shape out using a scroll saw or bandsaw, and then sand the edges.

Install the Inlay

For this project you will need two pieces of mother-of-pearl shell for the inlay, rescuepearl.com.

• Select the font and size of the text for the inlay. Print the text in the desired size and attach the paper to the cocobolo stock in the proper place with cyanoacrylate (CA) glue. Attach another copy of the pattern to the shells with CA glue.

• Use a jeweller’s saw with a 2 – 0 blade and carefully cut the shell.

• Debur the shell with a small file when the cutting is done.

• Attach the shell to the paper pattern on the cocobolo with balsa wood cement and allow to dry.

• With a very sharp X-Acto knife etch the cocobolo at the edge of the shell. The pattern helps you stay accurate.

• Using a rotary tool with a 1⁄16″ bit, rout the cavity. You want to set the inlay slightly proud of the surface. Make sure the inlay fits in the cavity. Do not force the inlay into place. When the inlay fits the cavity, insert it and flood the area with CA glue.

• After the glue has dried sand with a block and 80 grit paper.

• Using the X-Acto knife, clean out all the air bubbles. These show up as light spots in the glue. Re-flood these areas with glue, and then allow it to dry again. When the glue is dry re-sand with progressively finer paper, finishing with 220 grit.

Final Tasks

• Shape the handle using a rotary tool with a ½” sanding drum on the flex shaft, being careful not to sand through the inlay. Once shaping is done, sand the handle to 220 grit.

• Apply a water resistant finish. I use Tru-Oil, which you can buy at most sporting goods stores, though you could use polyurethane. Allow plenty of time for the finish to dry as any oil finish on dense tropical hardwood dries slowly. Once the finish is dry, buff it out with a soft cloth.

This is a fun project that can be completed over a long weekend or a week of long nights.