I love these quick little projects. I need another screwdriver (say “trunscrew” while holding your lower jaw stiff for the proper effect) like I need a root cannal. But it was fun to make. Now I need to make a smaller one for #4 screws (this is for #6).
I picked up today where I left off last night – flattening and smoothing out the sides of the blade. Clamping it to a piece of scrap wood by the tang like this is pretty handy, you can really focus your sanding without chasing the part all over the workbench.
Next I needed to cut a slot in the copper pipe plug for the tang. I scribed a center line and broke out my trusty cut off wheel. The copper is so soft that you could do this with a file or hacksaw, but to get the ball rolling this is what I did. I’m pretty comfortable using this tool, so it’s not uncommon for me to reach for it first for this sort of operation. I’m not a big hacksaw fan.
After cutting the initial slot I went to work with some small files, it didn’t take any time at all to clean up the slot and open it up to fit the tang of the blade.
I traced the shape of the screwdriver blade onto some scrap paper, and doodled some ideas for the filework design.
Once I had something that I liked I applied a fresh coat of dykem, and laid out some guidelines for the design. After that it was just a matter of filing and grinding until I had something that looked decent.
I didn’t take any pictures of heat treating this — the hardness isn’t critical, and I think you want something closer to a spring temper in the end (or a “floor temper” – heat it up to a dull red and let it cool laying on the shop floor). I heated it up to a dull red, plunged it into my pail of quenching oil (an ancient mixture of motor oil and transmission fluid). That get’s it hard, which you can confirm by running a file over it – a dull file should just skate across the surface. It’s also brittle and needs to be tempered to reduce the hardness and increase the toughness.
Since I wanted a flame-blued finish I tempered it as part of that process. I played my propane torch along the part and watched the oxidation colors carefully. I worked it up to a dull purplish-blue, and then re-quenched it.
This picture is a little fuzzy, but you can see the straw color near the tang. That is the sign that it’s about to turn purple, so go slowly.
It’s all downhill from here. I shaved down two lengths of 3/8″ dowel rod to take up the extra space around the tang in the handle. I tapered them slightly so they got tighter as the turnscrew was assembled. I mixed up some epoxy (remember to put the copper ferrule on first!) and put the whole thing together finally. I coated the inside of the handle, both dowel pieces, the tang and the end of the handle that fits inside the ferule. I had to tap it with a soft faced mallet to get everything to seat properly, and there was just enough squeeze out to tell me that there was enough glue on all the parts.