I’ve been hanging around Talk Bass for a long time and I figured it was about time that I post something of possible value. So I decided to do a tutorial.
Lately, my focus has been on making custom wooden control knobs. I borrowed a few tricks from my artwork by using some exotic materials and some cool inlays. So I thought I'd show everyone how I make a simple knob. No fancy stuff, just a good looking functional item that will dress up your favorite instrument.
I know most everyone doesn’t own an engine lathe, but with this lathe I can achieve some extreme accuracy.
This tutorial is picture heavy….Hopefully it isn’t too long.
Woolly Mammoth Ivory and Snakewood
Cocobolo with Sterling Silver and a Turquoise Cabachon Inlay
I first make a dowel of the Cocobolo. This is done on a wood lathe.
With enough material extending from the chuck, The Coco is shaped to the working diameter.
Most barrel style knobs tend to be about .750 inches, although they can be made upto @ 1.25 inches if you like the speed knob style. Here I want to leave it just a tad heavy to allow for sanding.
I bore a pilot hole in the base to help to keep bits from wandering around....Not totally necessary, but it is a habit of mine.
A 1/8 inch deep recess is bored with a 5/8 Forstner bit. This recess allows the knob to sit down very low to the "deck" and hide the nut and washer of the pots/electronics.
Next, a 1/4 inch bit bores a hole 3.5mm deep. This is the diameter of the pot shaft. Then bore another hole with a slightly smaller bit for the split of the shaft. I use an "A" bit (.2330) for this hole and you can see that I simply use a piece of tape for a depth guage....About 5/8 will do it.....If you are drilling for 6mm pots, I just make one bore with a "B" bit (.2355).
With my combination square set at 3/4 inch, Adjustments are made to part the partially finished knob from the stock material.
My first parting cut is made only partially into the Cocobolo.
This allows me to sand the knob and soften the edges of the knobs with sand paper....Starting with 120 to do the roundover, then proceeding up to 600 for final sanding. Then a quick buff with grey 3M pads.
The parting cut is then made.
This leaves us with a partially finished knob which is ready for inlay and set screw work.
For this tutorial, we’ll keep it simple and drill a 3/32 diameter about 1/8 inch deep for our position marker. Make yourself a jig so you can repeat your results on any matching knobs you may be making.
I’m using the 3/32 position marker material from Stew-Mac…..A touch of medium viscosity super-glue and you’re good to go.
With a pair of diagonals, snip off the excess plastic rod, being careful not to get too close to the top of the knob so you don’t deform the roundness of the plastic with the pressure from the cutter.
With the rod clipped, it is time to sand flush.
I sand the top down with 3M Stick-it sandpaper on Corian blocks. You won’t need to get very aggressive. The plastic sands down quickly. Here is where you’ll have to clean up the parting cut though. If you are careful, it should sand nicely without much effort. I like to use a circular motion with the head of the knob on the Corian/sandpaper. Obviously the picture is showing the sanding progress and not the actual sanding!
The finished top ready for the set screw procedure.
I drill the pilot hole for the set screw with a #30 bit @3/8 from the bottom skirt of the knob. This will allow the set screw to be able to grab the shaft and not the indented area of some shafts.
Next we’ll tap the set screw hole with a M4-0.70mm tap. Take your time here and make sure you are square and perpendicular. I use 4 and 6mm hex head set screws.
The finished threads! Extremely hard woods like Cocobolo and African Blackwood are great for tapping threads.
There you have it! A very cool exotic wooden control knob. With the finish of your choice and then a trip to the buffer and you are done!!!!
To make other types of knobs such as speed knobs, bells, capped knobs, and stacked sets, I have developed a few methods for holding the work piece onto the chuck. I can get into that at another time.
Well…There it is! I hope I didn’t put anyone to sleep.