Hi Charles,
I have co-incidentally just been re-looking at mine - bought it exactly 42 years ago, but in those days inventions took a while to get to these latitudes.
It was called the Stanley Electrichisel - I still have the original instruction sheet. Mine is for a 3/4 inch dado - I remember that the packaging came with a small piece of beechwood, with the dado cut for reference. The collar was used to set the depth of cut, and the tool was advanced along a straight-edge. The relatively long length meant that most of the time, the depth of cut was set from the upper surface of the straight-edge, I.e. the collar rode on top of the straight-edge, and the cutting tool race against the side of the straight-edge.
Worked reasonably well on solid wood, got blunt quickly on particle-board 9the days before met).
As you say, routers were not common - I did not have one, and what was available was the Stanley fixed-base type - very expensive for the time, with limited hss bit availability - no carbide.
Someone still has a cabinet I made at the time, with the shelves dadoed into the particle-board sides - saved me a lot of work cutting dados by hand in chipboard, but blunted the tool and I could never quite crack the sharpening (did not have a Dremel at the time, either). Then I acquired an Hitachi plunge router, and never needed it again. But I tend to hoard tools, “just in case”.
I was going to toss it out last month, then happened to see that Arbortech has a Turboshaft tool for a small angle grinder, which has a similar cutting configuration (but with replaceable carbide cutters). So I have been thinking about whether to modify it for use with an angle-grinder, but probably will land up tossing it. I don’t do freehand carving, anyway.
Stick, it was not designed for vertical use, and so would not be ideal for screw removal - also the gap between the internal edges of the cutting blades would be tight - less than 1/4 inch on my 3/4 inch model. It was more akin to a straight router bit than a plunge bit, and was hard to control in vertical use (tended to bounce away from the straight-edge), and would have left a vertical column of wood. Vertical use was for final smoothing of the floor of the dado.
It was also pretty heavy on a hobby drill at the time. My Millers Falls 500rpm 1/2hp drill did not cut it, and I put some serious mileage on my brother’s small Metabo. But when I acquired a 1hp 3000 rpm Metabo, it worked much better, but burned the cutting edges on the chipboard -we used to make serious chipboard locally in those days.
Charles, I can scan and post the user leaflet, if you require it.
Interesting, not only am I becoming a fossil, I may be a tool museum soon.
