Safety notes

Although cutting mortises with this machine is generally safer than cutting them with a plunge router, careless use of this machine can still lead to injury. It is the reader's responsibility to ensure that the machine is solidly constructed, that stock is always well secured to the machine, and that hands are kept well clear of the cutter during operation.

It is assumed that the builder is skilled in woodworking. This should not be your first woodworking project. It is also assumed that the builder is already familiar with the safe operation of routers. cannot be held liable for injuries that you may incur with your slot mortiser.

Some safety tips

  • The greatest risk that I can think of is that the stock being cut is not sufficiently secured. Such a scenario could be particularly dangerous when cutting hinge mortises, or any cut where the axis of the router bit is above the stock. The work piece, if it becomes loose, could get pulled under the router bit and shot out at high speed. Worse yet, such a scenario could cause the router bit to snap, resulting in a second flying projectile. The use of safety glasses is highly recommended.
  • Ensure that your router is rigidly attached to its mount. Periodically check the hose clamps holding the router to ensure that they have not come loose or begun to fail. Seasonal changes in humidity, as well as router vibration may cause the hose clamps to become loose over time.
  • The control lever mechanism gives a four to one mechanical advantage from the handle to the cutter head. Excessive force on the lever may router into the stock faster or harder than it is meant to go, possibly resulting in the failure of the router mount, router bit, or work piece clamping.
  • Use of the slot mortiser as a horizontal router where stock is pushed across it manually is not recommended. Horizontal router tables usually have the axis of the router bit below the table surface, which is something that is not possible with this machine. Pushing stock below the router bit may result in the work piece either lifting into the bit, or getting pulled under the bit, depending on the direction of cut. The only times I have used my machine as a horizontal router table is using a very large work piece and cutting away only about 5 mm of material.