Re: Scratch Awl
William R. Duffield, on the Cohansey
>Well done, John. I like it.
The first question has to be, "How does it work?" As Tom Sweeney pointed out in responding to my post, form must follow function, at least when you are making a tool.
It does look a little "wasp-waisted." Knowing that the drill rod extends through the waist and well into the larger part of the handle means that is it still plenty strong enough, of course. It would look better with a less massive ferrule. It's curious that we didn't even discuss the ferrule size when we anayzed mine. I just used the smallest nut I had in stock.
I will have to look "farther afield" for more options for ferrules. The shape of the one you used is interesting, and should also have significant structural benefits, especially for small rasps, files, and carving tools, where the handle seems to get in the way of the work.
Is your bushing threaded on the inside, or did you need epoxy to hold it in place? I sometimes find I need to use epoxy even with threaded nuts, because I strip the threads off the wood if I get too much taper on the tenon or use wood that is too brittle. (That should be less of a problem with ash than with some of the woods we like to turn.)
If you know you are going to epoxy the ferrule in place, you can start with a short section of thick walled brass pipe. I find it at the Borg in the same place in Plumbing as the brass compression nuts. Cut it to length with a hacksaw, flatten one end on a file, and smooth and shape the other end after you have glued it to the tennon.
When turning tool handles, the order I follow when I most often get good results is as follows: Sometimes I get lucky, and it works.
1. Start with a blank that is long enough and large enough in diameter. Rough turn it. Stop the lathe and grab hold of it and imagine how it will feel in use when you are done. I have lots of rough turned blanks laying around that I abandoned at this point because I found out they were already too small for the tool I had in mind. Eventually, I'll find something else to use them for.
2. Turn the tenon and mount the ferrule. If necessary, turn off the facets. Now you have one end of the final shape defined.
3. Turn the waist behind the ferrule, to fit your thumb and fingers. Leave room between the waist and the ferrule for a "hilt" if it is a tool you are going to push.
4. Rough turn the remainder to the proper diameter. If you don't know already by measuring a successful handle, the diameter that gives you the maximum strength grip is just large enough to allow you to wrap your fingers around it in a firm grip with your finger tips not quite touching the ball of your thumb. You can check this without removing it from the lathe.
5. Figure out how long it should be, and define the butt end. This varies a lot, depending on what type of tool it is. For example, scratch awls like ours are often very short, optimized used for tracing around irregularly shaped objects; A brad awl, screw driver, rasp, file or carving gouge handle needs to be about as long as the width of your hand; Turning tool handles need to be much longer, because you hold them between your arm and your ribs; There are all sorts of subtle variations in chisel lengths, depending on how they are used.
6. Now you can start working on fairing the curves to get you between the critically defined functional points. I've grown luckier since I started following these procedures.
I didn't harden and temper the tip mine, but probably should have. We'll see how it holds up. I started with hardened steel rod from a pin punch, and sharpening it didn't change the color, so maybe I'll get away with it. I did have a problem due to starting with salvaged material. The rod was not perfectly straight. Therefore, the point is not absolutely centered on the metal shaft (it's more like a Concorde's nose), and the shaft is not absolutely centered in the handle (since I used the shaft as the live center to turn the handle). If you look at the awls in the Lee Valley catalog, you will find some ideas for alternate grinds.
What kind of spray lacquer do you use? I have some problems with durability of walnut oil and shellac for the tool handle application, and was considering a coat of lacquer over it, but I would have to find one that will stick to the wax and oil. I know that Deft brushing lacquer will stick, but I haven't tried padding it on, even on a rapidly spinning lathe.
