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.
Smoothing out the Grind Marks
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.
Ready to Slot the Cap
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.
Filework Design Ideas
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.
Guidelines for Filework
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.
Tempered and Heat Blued
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.