Setting Up For Perfect Dovetails!
The dovetail joint has many applications for producing strong efficient wood joinery. We use it often on “the Router Workshop” with the Mitre Gauge System from our sponsor Oak Park. Many times people ask us questions about making dovetails. Here we will cover some helpful hints on setting up for dovetails using the Mitre Gauge. This is only one of the many uses of the Mitre Guage.
A Successful Joint
To make a perfect dovetail we need the following:
A. Correct Bit Height
B. Centered Bit
C. Correct Wood Thickness
A. Correct Bit Height
An important note to always remember is NEVER change the height of the bit for cutting both the slot and the pins. The bit height must remain EXACTLY the same.
Getting the correct height is probably the most difficult part of this operation. We use a 14 degree 1/2” dovetail cutter. Set the height slightly less than 3/8” (use a brass measuring bar to make this easy.) This however may not be the exact height you need. (The grind of the angle on your bit can affect this setup.) Cut the slot and the pin on scrap pieces and check the fit.
"Heighten To Tighten and Lower To Loosen" is a rule of thumb to remember. If the fit is loose simply raise the cutter. If the fit is tight lower the cutter. After each bit adjustment you will need to run another test cut. Once you have the exact fit, cut a slot sample and keep this as a setup block for future use (be sure to mark it as such and keep in a safe place.)
B. Centering The Bit:
If the router bit is properly centered in the 1” guide, then the ends of the dovetail pin will come to a sharp point. However if the guide is not centered then one of the points will have a square shoulder.
C. Correct Wood Thickness:
The preset holes in the Oak Park Mitre Gauge are for centering pins on ½” and ¾” thick wood.
You can make dovetail pins on thicker wood (as shown below) but they will not be centered.
Dovetail On Thick Stock
Dovetail On Thick Stock In Slot
You can not use undersized wood to make a dovetail joint because a square shoulder will appear on both points of the dovetail pin (as shown below)and it will not fit in the slot.
Dovetails With A Table Fence
You can also cut this type of dovetails using a table mounted router and a simple table fence.
Step 1 is set the bit height as with the Mitre Gauge (use sample block you made with the Mitre Gauge) and cut the slot. You must use a table fence for support when cutting the slot.
Step 2 Position the back side of the table fence (so the guard is away from the cutter) over the bit so that only the angle of the cutter is exposed. Place your 1/2” material on edge and run both sides. This creates the pin.
Check the fit, if you have a square shoulder on the pin, tap the table fence to the right. You can use the same scrap peice, run it again and check the fit.