Easy Mortises, Dowels, and More.

So I’ve used the router/table saw combination of doing mortise and tenon joinery, but for a kitchen island/table build I was looking at 32 mortises to cut on the six legs of the piece, plus 222 dowel holes for the slotted shelving and cross braces. Given the design, everything had to be very precise, so my setups had to be highly repeatable.

I looked into mortise machines, and as much as I wanted that Powermatic, I had a hard time justifying the $400 (with accessories) price tag for 32 mortise cuts, and it still didn’t solve my dowel problem. If I used floating tenons, I could get more use of the Powermatic, but there was no way to get the long apron pieces on the tool to cut the mortise. I also test drove the Festool Domino Joining System, and that was really nice, but impossible to justify the cost.

Enter the JessEm Zip Slot Mortise Mill. This unique tool uses a ‘special’ 3/8” drill bit and steel guide bushing that is pressed into a large bearing. The guide and bearing is installed into a carriage assembly on the tool. The carriage slides back and forth on two shafts via the long lever. Using your own high speed drill, simply use the guide bushing to guide the drill bit while you oscillate the bit back-and-forth with the lever system. In many ways this is a semi manual version of the Domino. An added benefit was if you lock the carriage assembly down to one side, you now have a precision doweling jig.

Like all JessEm products, this thing is built to last with quality materials, precision engineering, and tight manufacturing. With various adjustable stops, adjustable scales, and a vacuum port, it seemed every detail was thought of. Almost.

After spending a month with Mortise Mill I have to say it does a really great job of cutting tight slots with little mess. The same for all my dowel holes. Setup takes minutes, and you can really get excellent, repeatable results. Where the tool fails the most is around clamping and supporting your work. You need two hands—one to guide the drill the other to oscillate the lever, so you need to rely on clamps to attach you work to the mill. Put simply, they just don’t provide enough clamping surfaces on the mill, especially for larger pieces that need more support. I had several instances (okay about eight out of over 200 cuts) where the work slipped slightly. All recoverable errors, but getting a piece aligned with all the clamps, blocks, etc., to ensure no movement was more time consuming than it needed to be. But that was really my only concern, and if I was to approach another large job on the mill, I’d probably take the time to hack out a quick stand to mount the mill to and provide support to the pieces I’m mortising.

A few other things to consider. You need a fast drill and I ended up using my corded Bosch. The shear size of the drill and the long bit made the operation a bit unwieldy, but mounting the mill on a lower table would have helped. Also, it is best to apply gentle pressure on the drill as you move back and fourth until you at least started the slot across the full range of motion. Otherwise you get a bit of surface ‘fuzziness’ around one end of the mortise. Lastly, the 3/8” bit and bearing sleeve is a bit ‘sticky’ when withdrawing from the cut, although this may be due to my purchase of the floor model at my local Woodcraft.

So for about $250 (minus 20% for taking the floor model), I got a precision tool that solved my multiple needs. As I advance more into furniture pieces I can see the mill getting a lot in future projects. I already purchased a spare 3/8” bit as well as a 1/4” bit and guide/bearing assembly for smaller work.

I know I probably didn’t do the mill justice in describing its operation, so I embedded a Youtube video below so you can see it in action. The video is accurate, in that my results were as described.

-- Thomas, Marblehead, MA