Making an Awl and a Marking Knife
Two of the most basic tools in a joiner’s toolbox are the lowly awl and marking knife - yet they are often two of the poorest tools, too. I know - I've been suffering with a pair of cheap hardware store awls for years - they are truly useless for marking, though. Thick and heavy, and don't hold a point worth squat. My main marking knife has been a utility knife, too - a poor substitute. Yet these are some of the most important tools to have for fine joinery. I decided it was time for an upgrade...
The first thing you will need for an awl is some round steel of some sort. It has to be hard enough to hold a point, but not so hard as for that point to break off easily. An old screwdriver (a good quality one) is one source - I had some 1/8" O1 steel drill rod laying around though, so thought I could use that. However, the drill rod I had was annealed - and needed to be hardened, a simple process. So, after cutting a piece of rod to the length I wanted, I grabbed the propane torch and heated it to cherry red:
A propane torch works, but you won't heat much more than an inch or so to red-hot. It's enough for an awl, but you would need a mapp gas torch to do any more. Once heated to cherry red (just past the curie point where the steel loses it's magnetic attraction) it's time to dunk it in some oil to cool it quickly:
I used just plain old motor oil - 10w30. Dunk the rod straight down into the oil and swish it (using vertical movement, not horizontal) until it cools. Now the end of the rod is hardened - too hard as it is, and the tip will break off easily when I use it, so I need to temper it. So, I throw it in my shop oven (a toaster oven I got for $5) at 350 degrees for about 45 - 50 minutes:
You need to use an oven thermometer with these things - the dial for it doesn't reflect any sort of reality. This should get the rod to a Rockwell hardness of around R58 - 60 or so.
Followed by a little time with the 3M magic wheel and a leather strop. I square the end of the rod that's going into the handle on the anvil with a hammer, to distort it slightly so it grabs the wood in the handle better, then jamb the thing into the handle I made for it out of scrap cocobolo:
The handle was turned on the lathe, using methods similar to what I used in the Tanged Tool Handles article elsewhere on this website - though for these small tools, I didn't heat up the ferrule or steel, just jammed it into place. It's a 1/8" rod, into a 1/8" hole, and with the slightly bashed end it goes into the cocobolo tightly, so I don't need to epoxy it into place, though I can always do that later if it does come loose.
The result is a much finer awl (compare to the ghastly hardware store clunker in the photo above) for use in fine work. There are many times when a marking knife just won't do, such as when scribing the pattern shown on the paper in the foreground... Now I should be able to do that with much more accuracy...
Cleaning up while waiting for some glue to dry, I was wondering what to do with the "disposable" planer blades that I had just swapped out of my lunchbox planer. It looked to be the proper size for a marking knife, so cut and ground a blade to shape out of it, including a ‘tang’ that is about the same length as the portion you see in the photo below. The tang should be roughly 1/3 to 1/2 as wide as the blade, or better yet, about 1/3 the width of the handle it is going in. I this case, it's the same - the blade and the ferrule I used on the handle are both 1/2", so the resulting tang was tapered from around 3/16" to 1/4" wide nearest the blade.
I then dug up some scrap cocobolo, donned the necessary gear and turned a quick handle. I then fit a 1/2" ferrule to it, drilled the hole for the blade, and epoxied in the blade:
The angle of the marking knife is also personal preference - the one I did above is a little more than 60 degrees, give or take - sharp enough of an angle to get into a corner that is 90 degrees. The length of the exposed blade is about 1-1/2" to 2" or so:
I ground about a 35 - 45 degree bevel on the edge. Don't worry about getting it razor sharp - just plain old sharp will do. Too sharp, and the line left behind will be too fine to be useful, at least IMO.
Because of the thinness of the blade (something between 1/16" and 3/32"), not to mention that it was sharp - I found it easier just to epoxy the blade into place. The steel from the planer blade seems to be the perfect width and thickness for this purpose... It is high-speed steel, and should hold its edge well. Other sources of blades include O1 tool steel (which will require hardening, the same as the drill rod for the awl above), and used up or disposable jointer blades.
The length and size of each is up to you - just make sure the blade is deep enough to reach past whatever you are marking - such as through the tails when you mark the pins for dovetails.
When turning the handles, it's also a good idea to leave a little flat spot on each side, to keep the tool from wanting to roll off of the bench while you are using it.
These two small projects were both done in less than an hour, and because they were done with scraps, leftovers, and inexpensive parts, cost less than the utility knife I had been using as a marking knife.
They were fun, too!
Thanks for reading!