This instructable will show you how to make custom wooden knobs for a fraction of the cost of ugly, plastic store-bought ones. I recently had a need for a few knobs for an adjustable miter fence for my table saw. Rather than buy the plastic ones, I thought I'd make my own - always a better choice!
For each knob, you will need:
- A scrap of wood - preferably a hardwood like maple, oak,
mahogany, cherry, hickory, etc.
- A threaded insert
- A screw that fits the threaded insert (cut the head off
- Sanding/shaping tools like a belt sander, wood rasps,
- A drill press helps, but is not necessary
Step 1: Find a Blank & Lay Out the Shape
The first step is to identify the blank of wood you will be using. Things to take into consideration are aesthetic quality, grain direction, species, or any blemishes you want to either include or avoid. For a really hard hardwood like maple, the grain direction will not be critical - assuming you won't be really reefing on the knob with all your might. For this Instructable, I am using maple.
Step 2: Drill a Hole For The Threaded Insert
It is easier to install the threaded insert while the blank has square and parallel edges, so next we will drill a hole that will receive the threaded insert. With a hardwood, it is important to size the hole properly for the insert. You can probably look it up, but the hardware store where I got mine has the drill size listed in the bin with the inserts. Carefully lay out the location of the hole and clamp the blank into a drill press vise. Set the depth of the hole based on the dimension of the threaded insert. Just turn on the machine and drill away.
Step 3: Screw in the Threaded Insert
This is where a drill press will really pay off. It is important to get the threaded insert screwed in straight. Otherwise, every time you tighten your knob, it will wobble and remind you that you need to buy a drill press. Many threaded inserts have a slot at one end that are for using a straight bladed screwdriver to screw in. Do not use these. Years ago, I learned the hard way that those slots were designed by someone who never intended on ever using a threaded insert. They simply break off. The way to do it is to thread a screw (with the head cut off) into the insert and using the drill press, turn the drill's mandrel by hand. But to keep the screw from just turning in the insert, screw on 2 nuts and jam them together - this will provide a 'stop' for the insert. Unplug the drill press!! Then with the screw chucked into the press and the blank carefully positioned and clamped under the mandrel, turn the drill's handle with one hand, and with the other hand, rotate the mandrel clockwise. This will apply downward pressure and screw the insert right into the blank nice and straight. One thing to note: I apply paste wax to the threads of the insert - this provides lubrication which can be very helpful with a hard wood like maple.
Step 4: Start Shaping
With the insert installed, now it is time to start shaping your knob. I used a chop saw and a table saw to cut the blank down to rough size, but you can use whatever tools you have. Then I turned to my stationary belt sander for the majority of the final shaping. Sneak up on the lines and then slightly round over the corners.
Step 5: Lay Out Your Wings
Now we mark some layout lines on the surfaces we just created in the last step. This will outline the tapered wings of the knob. I just made some tick marks that were measured, then free-handed lines to connect them. I didn't spend much time on making them precise - it's just a knob!
Step 6: Shape Your Wings
Now its back to the sander to sneak up on the layout lines we just made. After that, I made the top slightly concave using the top drum of my sander. After sanding to the lines, take a few minutes with sandpaper (150 grit, then 220) to hand sand the entire knob, smoothing out the roughness of the belt sander, and easing the sharp edges. Now finish with 2 coats of a quality water-based polyurethane (I like Varathane); sanding between coats with 220 grit sandpaper.
You can be creative with your design - the knob shown here is just 1 of many possibilities. You can make a star knob by drilling a series of 3/8" diameter holes in a circular pattern, then cutting between them, or a taller knob if that is what you need - the possibilities are endless!
I am entering this in the 'Woodworking' contest, so please vote early and often! Thanks!