Porter-Cable 4216 Instruction Manual page 15

Some items to consider when purchasing alternate bits for half-blind dovetails are:
1. A shallow angle of the bit requires a deeper cut. A steeper angle requires a shallower cut.
2. The diameter of the bit should be slightly greater than 1/2". The greater the diameter, the deeper the cut.
3. The bit should have a cutting length at least as long as the cutting depth.
NOTE: When using alternate bits, ensure that the pin board (drawer front) is thicker than the depth of cut.
NOTE: When using alternate bits, ensure that the bit will not cut into the base of the jig. For deep cuts, take out
most of the material with a straight bit, then follow up with the half-blind dovetail bit.
HALF-BLIND DOVETAIL BITS WITH THE TAILS AND PINS CUT SEPARATELY
Using two different-sized dovetail bits to make half-blind dovetails
requires separate cuts, similar to cutting the rabbeted half-blind
dovetail. This method provides a more hand-cut look and is an
important step in creating inlayed half-blind dovetails.
Some items to consider:
1. The two bits must have the same angle.
2. A shallower angle requires a deeper cut, while a steeper angle requires a shallower cut.
3. When the diameters of the two bits are added together, the sum must be slightly greater than 1". The closer
the sum is to 1", the shallower the depth of cut will be. The larger the sum, the deeper the cut.
BIT COMBINATIONS FOR SEPARATE HALF-BLIND CUTS (READILY AVAILABLE)
LARGER BIT
3/4", 14°
5/8", 14°
5/8", 7°
5/8", 7°
9/16", 7°
SETUP
The only difference between cutting this joint and cutting the
standard half-blind is the use of two router bits. If you use one
router, you will have to set the depth-of-cut for each router bit. You
can make a simple depth guide as illustrated in Fig. 21A.
If you have two routers, you will not have to go through the process
of changing the bit each time you make a different cut. This method
requires, however, two 3/4" OD template guides and two template
guide locknuts, available from Porter-Cable.
HALF-BLIND DOVETAIL BIT (READILY AVAILABLE)
DOVETAIL BIT
17/32", 7°
17/32", 14°
9/16", 7°
5/8", 14°
SMALLER BIT
APP. DEPTH OF CUT
13/32"
3/16"
9/16"
APPROX. DEPTH-OF-CUT
1/2" 14°
1/2" 14°
17/32",7°
9/16", 7°
17/32", 7°
15
3/4"
Fig. 20A
9/16"
3/8"
7/8"
1"
5/8"
Fig. 21A