Cutting CAHinge Slots

When those #11 hobby blades get dull we often chunk them in the trash.  Some people are talented enough to sharpen them and can reuse them several times.  I, however, am not one of those people.  I keep the dull blades in an old aspirin bottle for those times when you need a special tool.  One way I use them is to make a jig for cutting hinge slots for CA hinges.  I used to try to freehand the slots, which needless to say, was less than successful. Several commercially-available hinge slotters can be found, but this system also seems to work pretty well.

For ailerons or elevators that have square leading edges (as shown in the figures), insert 3 or 4 used blades in the center line of the leading edge.  See Figure 1.  Then place a thin metal ruler against the edge of the hobby blades. Place the edge of your hobby knife against the edge of the ruler. This aligns the blade exactly in the middle of the center line.  Then very carefully begin cutting the hinge slot by cutting a very shallow slot slightly longer than the width of the hinge.  See Figure 2.  Don’t try to make this initial cut too deep.  All you need to do is start the slot and then you can go back and make several more passes to cut the slot to the desired depth.  Don’t get in a hurry – otherwise your hobby knife may skew and cut outside of the slot.

To make hinge slots in rounded control surfaces or in the trailing edge of the wing or horizontal stab, simply draw the center line and you normally would.  Then follow the steps above, inserting the used hobby blades exactly in the middle of the center line.

Please remember that you are dealing with extremely sharp tools.  In fact, it’s not a bad idea to dull the edges of the used blades to the point where they will not cut.  Make sure the piece you are slotting is secure and cannot shift.  Cut the wood – not yourself!

Figure 1

Figure 2