Taper tang drilling is good practice for a better fit and finish, feel, and sleeker aesthetics. Tapered tangs offer reduced weight and better balance in the finished knife.
This process may not be necessarily essential when using small diameter pins (<2mm) which can bend. When using thicker pin stock, Corby bolts or blind rivets that are threaded, then it is certainly advisable as the small thread is easily sheared off whilst tightening down the handle scales and becomes worse as the offset angle increases.
Three different methods are covered in this post.
- Drilling clamps (As pictured below)
- The Manual method with calculations and shim/hinged plate.
- Tapered Tang Drilling Jig
Method 1: The first thing to do is to position the handle scales on the tang and secure them in place using what I call “tapered tang clamps”.
Drilling Clamps are available for purchase from Rausch Engineering.
The wood has to be well secured, and you should use a small piece of brass or other hard material to protect the handle material from bruising from the securing screw.
Due to the varying thickness of the steel and handle materials, the securing screw may protrude from the base of the clamp. To overcome this so that the tang clamps sit horizontally for drilling, I use a PVC plate with a groove milled into it to allow the clamp screw not to interfere with the flat stand section of the clamp.
An alternative option is to grind down the head of the cap head screw.
Method 2: If you do not have Tapered Tang Clamps, you can calculate the offset of the tang in the clamp by using the following formula.
Half the thickness of the blade – Half the thickness of the tang end
= (0.5 * 3.2) – (0.5 * 1) = 1.1mm
To accommodate this offset, I use a hinged device into which I can clamp a spacer i.e. a drill bit or shim. This angles the tang section so that I will be drilling through the tang and into the handle scale at right angles to the centerline of the knife.
The rule here is to raise the blade side when drilling through the tang,
and raise the tang side when drilling the counter borehole in the handle side.
With the clamped assembly secured, on top of the PVC spacer and the hinged plate, the drill will be at right angles to the centerline of the knife.
The final result shows the gap at the bottom of the thread and touching the square at the top. The gap at the bottom should be the offset used to level the tang centerline.
A third option is to use Tapered Tang Drilling Jig.
Clamp the knife blade into the clamp on the top of the block and screw up the tang support post/rod until it rests on the underside of the handle. The centerline of the knife is horizontal and the hole will be at right angles to it.