Wooden Guitar Knobs With a Drill

I really like wooden guitar knobs, and I really like making stuff. I don't have a lathe or any fancy workshop gear, so I thought I'd try my power drill instead.
Drill sanders are easy enough, so how about switching it round and mounting the workpiece in the drill instead?
For this experiment I used scrap pieces of ash and ebony left over from my guitar and ukulele builds, but use what you have.
I don't have a drill press, I have a drill stand and I would not recommend using your drill without a secure mounting, be that a stand or mounted horizontally.

Power drill, or drill press if you have one
Drill stand
6mm x 50mm bolt and matching nut
Rasp
File
Sandpaper
Wood glue
15mm forstner or spade bit (or whatever you have that will work)
Scrap wood

I'm making these knobs to be 20mm diameter and 20mm high. Due to the nature of manufacture I need two pieces per knob; a big one for the main body and a thin slice for the top. I'm using ash for the main body and a 5mm slice of ebony from a botched fretboard I ruined several years ago in the ukulele build. Use whatever woods you like, even make the whole thing out of slices or whatever you have kicking about in the scrap pile.

As long as the wood will give a 20mm diameter cylinder, it doesn't matter how it starts out

Mark the centre of the knob. The first cut is for the recess at the bottom that sits over the pot nut. Do this first as it's much easier to use the centre hole of the forstner for the wood bit rather than try and centre the forstner bit in a 6mm hole.

Plunge the forstner in about 10mm, then change to the 6mm wood bit and take the drill fully through the wood.

I've used a 6mm bit as the pot shafts I'll be fitting to are 6mm and this will fit on the pot nicely.

Take the 6mm bolt and insert into the wood and do the nut up really tight. The shaft of the bolt will be held in the drill chuck and spun really fast, so it needs to be tight. If you have a reverse thread bolt that might be better, or reverse the drill direction.

Before you mount the workpiece, you'll want to file off those corners to make the the shaping easier and safer. I used a sanding drum, but use whatever you have to round the edges.

Mount the bolt into the chuck and set it spinning. Use the rasp to take down the wood to close to the final size. You see now why we rounded the corners off first. I didn't the first time and I may have induced vibration white finger in the process.

Anyway, rasp it down to about 21mm diameter, leave enough for filing and sanding in the next round of rounding.

When the body is ready, take your topper and glue it to the main body. It needs to be glued to the flatter end, the non recessed one. Clamp it up and leave for a few hours. Or overnight.

Now the top is in place the bolt won't go through. Not to worry, a blob of pva in the hole will be enough to secure the bolt for the next round of shaping as we'll only be sanding and the stress on the bolt won't be as great this time.

Pop the bolt in and leave to go off.

Once it's all set, back to the drill.

OK, so it's all dry. Again, take the corners off the top and sand or file it back to close to the base diameter. Do this before you but it back in the drill to keep stresses on the bolt connection as low as possible.

When you're close, back in the drill and just use sandpaper to get to the final diameter. Start with 80 grit, and get progressively finer before finishing on wire wool. Slightly round over the top edge and there you go, a finished knob all ready for oil or varnish or whatever takes your fancy.

Finally, check the knobs are straight and true, trimming off the bottom if need be and checking they're as flat as can be. If you need to drill out more of the recess, then do so carefully and offer up to the guitar.

These will be fitted to my 51 frankenbass and I think the sapele control plate will compliment the wooden knobs nicely.

Thanks for reading, and happy building!