Wood’n Bits Workshop

First let me apologize for the “pre-release” of his blog post.  It was just me screwing up posting dates.  Anyways, here it is…with words and pictures.

I’ve been distracted from the shop, playing Mr. Fix-It, and my woodworking time has been spent  navel gazing and some doing some sketching as my aged brain grapples with what a good-looking bathroom vanity looks like.

But I’m like a violinist between concerts; I still have to fiddle.  Quite a while ago I bought a marking knife “kit” from Czeck Edge Hand Tool.   The kit comes with a blade, several tip covers for the blade, and a ferrule – the assumption being that you will use a lathe to turn a typical marking knife handle.

The problem with round knives is that they roll off benches and the laws of Mr. Murphy require that such knives always hit the ground, or foot, point first.  So, I thought I’d follow a method I first saw on the Woodworker’s Zone and produce a knife that will stay put on my bench and includes a matching tip cover.  The only materials required are:

1) a central core piece that is just a teensy bit (technical term dating back to the 18th Century I think) thicker than the blade.  I used maple.

2) two side pieces that, when added together with the center piece make up 1/2″ or so (another 18th Century qualifying term used mostly while holding your thumb up next to the wood and saying “That looks about right.”

The length of these pieces is determined by how long you want the handle plus the blade length.  Width should be “some” wider than the blade width.  My pieces were 6 1/2″ x 3/4″.

Making the blade cavity

This is the key to this sort of construction.  You cut a cavity in the center section that will eventually hold the blade shank and provide a slot in the cap into which you can stick the blade.  Trace around the blade to get the cavity shape but leave a bit of space around the blade itself rather than tracing tightly to the blade sides and blade end.  When you trace the shank, however, trace close to the sides but leave a bit of space in the bottom.  These accommodations will cause fitting the shank to the knife to go well and allow the cap to work without problem.

If you have one, a scroll saw makes quick work of this job.  Otherwise, use a fret saw.  You can probably get away with cutting it with a sharp knife, using multiple passes with the knife.

Gluing Up Time

Once it is cut out, a very important thing is to mark, on the sides of the piece, the location of the blade base.  You have to know where this is and this mark will be the only evidence after the glue up.   Use your favorite glue and build a 3-layer sandwich.  I recommend that you apply glue to both sides of the center piece rather than to the side pieces so that a minimum of glue fills the cavity.  Too much filling and you’ll have a hard time when it comes to fitting the blade.

Once the glue is dry, mark, on all sides, the location of the blade base.  I cut all four sides with a carcase saw, ensuring that I didn’t cut too deeply and separate the cap from the handle.  Ultimately, though, you will cut through the two pieces here so the saw marks work very well.

Removing Non-Marking Knife Material

At this point the woodworker in me trumped the blogger in me and I forgot to take photos as I shaped the knife.  Oops!  So, I posed this photo to show you some of the tools I used.  I started with a hand plane, removing edges and squaring up the sides.  Then I used a carving knife to shape the ends and to cut the curved ‘notch’ that will become the interface between the handle and the cap.  I finished up with a “bit of the rasp” and then some sandpaper.

Assembly

Assembly starts with a bit dis-assembly.  I used my carcase saw to separate the cap from the handle.  I made sure the blade fit in the handle slot, mixed up a bit of epoxy and glued it in place.  If you did the tracing right, it should register itself straight relative to the handle but check it anyways.

Once the glue is dry, test fit the blade into cap.  Mine was a bit tight and so I used a thin file to clean up the slot where the blade was binding.  I suspect it was due to excess glue.  It could be that you can get the wood/metal fit close enough that the cap will stay on but there’s too much silicone caulk in the world to worry about that.  I took a bit of clear caulk and filled the opening to about 1/16″ deep and let it dry.  Once dry you can shove the blade through it a couple times and you’ll have a nice tight fit and the cap is easy to remove but it’ll stay put when you want it to stay put.

Finishing/Finished

It’s fashionable to put high-gloss, bulletproof finishes on marking knives.  That’s smart cuz you can sell them for a bunch of money.  Maybe I’m a “traditionalist” or maybe just a luddite but I like my tools to have softer, easier to revitalize, finishes and so I applied a couple thin coats of boiled linseed oil and followed those up with two coats of 2lb-cut blonde shellac.   I’m happy with how it turned out and the long, thin blade will be great for marking dovetail pins…or tails.  You choose.

Cheers — Larry

larry@woodnbits.com

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This entry was posted by Larry on Monday, February 8th, 2010 at 4:30 pm and is filed under Carving, Hand Tools, Layout/Measuring, Techniques, Tools, Woodworking. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.