To Float Your Mortise (Part 1)

Not that long ago I read a blog post or an article in a magazine about motise floats, I don’t remember who wrote it but it did remind me that I needed to make some. Sure you can buy them from Lie-Nielsen, but one can make them too as they are not that complex.

I happened to have some 1/4″ x 3/8″ O-1 precision stock sitting around for the past 5 years that I purchased for this exact project but never got around to starting. So let’s get started!

Here I have cut the bar stock to approximate length. It’s long enough to get into most motises that I make, and has enough non-toothed area for holding in a handle. I’m making two at the same time as you will see later that I can gang cut most of the teeth making the second one very time efficient. I have applied some layout fluid to help see where I scribe my lines, they are spaced 1/8″ apart.

O-1 1/4" x 3/8" bar stock cut to approximate length and 8tpi layed out.
O-1 1/4″ x 3/8″ bar stock cut to approximate length and 8tpi layed out.

Next I use a small triangle file to cut start the edge of the teeth. A fine toothed file is easy to get started and make a clean starting point for each tooth. Note this is only one of the two floats that I am making.

Small triangle file used to cut an initial groove.
Small triangle file used to cut an initial groove.

Still with a single piece of bar stock I use a hack saw to extend the groove I previously started well across the width. I keep the saw parallel to the scribe lines and perpendicular to the edge the best I can. Counting the number of strokes with the saw and being consistent on the length of the stoke helps keep them consistent in depth.

Hacksaw was used to extend the groove.
Hacksaw was used to extend the groove.

Now I take both pieces of bar stock and put them into the vise. I tried to make the top faces flush and the tips even. Then with the hack saw I extended the cuts across both faces, again being consistent with the number and length of the saw strokes.

Hack saw used to extend the cut onto the second piece of bar stock.
Hack saw used to extend the cut onto the second piece of bar stock.

At this stage I have used the hack saw to deepen the cut to near full tooth depth. Note the scuff marks on the surface between the teeth are not critical at this point as that material will be removed later. Consistent depth of cut is the most important at this stage.

Hack saw was used to get consistent depth of cut on each tooth.
Hack saw was used to get consistent depth of cut on each tooth.

Layout fluid was applied to all the saw kerfs and the faces of the teeth.

Layout fluid applied to the surface.
Layout fluid applied to the surface.

Here I am using the largest flat file that I own. The goal is quick removal of material. The large teeth cut fast and leave a nice surface. The layout fluid is used to help with consistency, you want to remove the same amount of material from each tooth. This is the step that typically takes the most amount of time, be patient and consistent.

Large file used to remove material quickly.
Large file used to remove material quickly.

Unfortunately I didn’t get the faces of the bar stock exactly flush when putting them into the vise and you can see it here. I have removed most of the material with the large file for the teeth and have made them reasonably consistent.

The teeth are near full depth and made consistent at each step in the process.
The teeth are near full depth and made consistent at each step in the process.

Next I have taken the saw and layed it flat on the teeth to undercut the gullet of the tooth slightly. This is a quick method of removing the bulk of the material to help establish the rake of the tooth. Once that’s complete I use a large triangle file to help define the rake angle a bit more. Layout fluid was used once again to help with my consistency. Note there is a small amount of layout fluid still remaining on the flat tip of each tooth.

Hack saw and large triangle file were used to establish the rake angle of each tooth.
Hack saw and large triangle file were used to establish the rake angle of each tooth.

At this point I like working with only one float as we are starting to get close. I progress through several sizes of files, the larger ones cut quicker, the smaller ones cut deeper into the gullet and produce a smoother cut. I continue to use consistent amounts of pressure, length and number of strokes are also important. The goal is to make each tooth as close to the same as practical.

The teeth are very near completion. They still have a small amount of flat face on them that shows the layout fluid. All the heavy metal work has been done.

There are quite a few steps left to do such as: grind front tooth, heat treating, attaching a handle, jointing the teeth, and the final sharpening.

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