Slot mortising machine
This is Kurt's slot mortising machine. The machine has a few features that I found rather neat.
The motor on it is a 50 Hz three phase motor that can be switched between 3000 RPM and 1500 RPM.
It isn't a particularly powerful motor. I never quite understood why a slot mortiser needs
to have a three horsepower motor on it. Being able to switch speeds is nice, especially if
the machine is used as a horizontal boring machine.
Kurt mostly uses the machine as a horizontal boring machine. He uses it to make precisely
spaced holes in stock for dowel joinery. The bit in the chuck here is just a regular 12 mm
brad point drill bit.
A really cool feature of the machine is this bar with holes in it. A locking pin can be used
to lock the side-to-side motion of the machine to the hole positions. The shaft with the holes
in it in turn can be turned to have various differently spaced series of holes facing the locking pin.
This feature is very handy for making a precisely spaced series of holes without having
to fuss. My biggest beef with dowel joinery is that it's so hard to get the holes all aligned
precisely enough, but with this machine, that becomes a non-problem. Kurt really likes
dowel joints, we even argued at some point whether tenon joints or dowel joints are stronger,
which led me to try this experiment. When I
built my own horizontal boring machine, I integrated
a similar feature into it.
The vertical adjustment wheel is also very cool. Each turn of the wheel raises or lowers
the motor assembly by 2 mm. The dial and counter in the middle of the crank
makes it easy to repeatably set the right interval. So if you want to join something with
two rows of dowels, this dial and counter can be used to space them precisely.
It's sort of a more sophisticated version of my counter wheel
on my own slot mortiser design.
The mechanism is just stuck in the middle of the crank, and the dial mechanism internally
has a weight to keep it facing up. It would be nice to have indicator dials like that -
I could think of a bunch of places where I would use one!
The slot mortiser is made by a German company called KÖLLE. I couldn't find a website for the company, but they are still in business as far as I can tell. The machine is not that old - I think it was built in the 1980s.
Where I was boatbuilding on the bavarian lakes some different Kölle jointers and thicknessers (usually the heaviest machines by far in the machine-shops) were in use, together with some pretty weird combination machines like bandsaws with integrated horizontal bore-units under the table for example.
Absolutely undestroyable machines, even ten years outside in the rain was easily undone with abut one or two days of work on the unvarnished tables and slides, something I learned while working with a dealer of used woodworking machinery; multipe over-dimensionised bearings, very accurate casting throughout, no frills, only quality down to the last handle.
See also:
My own slot mortising machine
and horizontal boring machine
