Wood Knob tutorial (using a drill press)

[turindev]

A few days ago I posted a picture of some knobs I made in my build thread Build #2 & #3 - A modern single cut with a twist . A few folks asked for more details on how it was done, so I though I would post it in it's own thread.

There are probably a ton of ways to do this, but here is how I did it.

Step 1: cut squares from raw stock
I bought some pen blanks in Indian Rosewood to match the body top on my current build. The stock is roughly 3/4" square. I marked the height I wanted each knob (11/16" in my case), and cut 5 squares.

Step 2: Add center marks
Next I marked the center on each square. This is where the shaft hole will be drilled. I also added reference marks for the corners by measuring the distance from the center to the edges. Be precise or your knobs may be smaller than you want

Step 3: Drill center holes
It is important to know what kind of pots you will be using and the shaft diameter. In my case I will have 6mm shafts for an Audere preamp. I drilled slightly larger holes (6.3 mm). You can also use the exact size, but they will have a super tight fit, this is a personal preference.

Step 4: Sand corners & install set screws
I hit the corners with my belt sander. This gets it a little closer to round and will save time later.

Next I drilled the set screw holes. In my case I used M3 5mm set screws. After a little experimentation, I ended up using a 1/8" drill bit. I also inserted the set screws at this point by screwing them in. I have found that if I insert them after the knobs are done, it can cause the wood to flare out or chip.

Step 5: Rough Sanding
Put the knob back onto the drill bit you used in Step 3. Using a sanding block (make sure it's square!) Begin rough sanding with coarse sandpaper. (I used 80 grit). Take it slow, don't press too hard against the bit. Just let the sandpaper do the work. Keep sanding until all the flat spots are gone, and continue until you get to your desired diameter. This takes anywhere from 1-5 minutes depending on how square your raw stock is.

Step 6: Dot inlay
This step is optional. Remove the knob from the drill. I like to make a mark on the drill bit so I can put the knob back in the same alignment later. Drill a small hole for your inlay and insert side dot material with CA glue. Clip the inlay and put the knob back on the drill press.

Step 7: Sand the top of the knob
I usually start with 150 grit here, and just hold the sandpaper on the top of the knob. You will need to sand this until all of the tool marks are gone from when you cut the knobs to length in Step 1. If you don't get all the tool marks out, they will be obvious later. Also run the sandpaper on the edge to create a roundover (to your liking).

Finishing it up:
Continue sanding the sides and the top through the grits until you get to your desired smoothness. In my case I went 80-150-220-320-400-600-800-1000. Each grit should remove all the scratches from the previous grit. Once you get past rough sanding (80 grit), the grits go much faster, maybe 30-60 seconds each. Once youre done, you should be ready to finish them!

In my case I put on a few coats of sanding sealer, followed by a few coats of matte clear.

That's it! Hope this is useful to someone, feel free to ask any questions for clarification.

 

[Jisch]

I do something similar, but I clamp a piece of wood securely on the bed of my drillpress, then I drill a hole for the shaft. I leave the wood clamped in the same position and I put a big drill in the drill press and drill out the inside just a little for clearance of the nut that secures the pot. Finally I pull the drill out and put a hole saw with the center drill removed and drill the knob. I usually sand by hand after that, but I like your idea of using a set screw to put it in the drill press and sand it that way.

 

[Matt Liebenau]

Thanks. I have done something similar with a drill press and tenon cutter. I just was going to make black knobs from an acrylic pen blank and was trying to figure out how to turn it on my lathe because I don’t have a chuck for something square that will go small enough to clamp the pen blank in. After I read your post in the other thread I remembered that and cut and drilled the blank then installed the set screw and turned the knobs that way. Again, the scenic route to say thanks!

 

[turindev]

I do something similar, but I clamp a piece of wood securely on the bed of my drillpress, then I drill a hole for the shaft. I leave the wood clamped in the same position and I put a big drill in the drill press and drill out the inside just a little for clearance of the nut that secures the pot. Finally I pull the drill out and put a hole saw with the center drill removed and drill the knob. I usually sand by hand after that, but I like your idea of using a set screw to put it in the drill press and sand it that way.

I was actually just thinking about doing the same thing for nut clearance, sounds like I was on the right track! Hopefully my knobs are wide enough.

 

[TerribleTim68]

Really appreciate this thread. Thanks to both @turindev for the original post and @Jisch for expanding on it. I'll be using this knowledge in the future.

 

[Dean N]

I put a little bit of radius on the top of the knob by chucking it in the press and sanding it with a piece of PVC pipe cut lengthwise, with sandpaper attached to its concave side. 100 grit, maybe. Then I install the marker at the new "angle", or else it will end up being elliptical. Then hand sand in the press with finer grits.

 

[TerribleTim68]

I put a little bit of radius on the top of the knob by chucking it in the press and sanding it with a piece of PVC pipe cut lengthwise, with sandpaper attached to its concave side. 100 grit, maybe. Then I install the marker at the new "angle", or else it will end up being elliptical. Then hand sand in the press with finer grits.

That's a great tip too!

 

[james condino]

Nice work!

If I make them on my $150 drill press, I'll need a new excuse to justify my giant 2000 lb Oliver patternmaker's lathe....

 

[FretsAreFor]

Nice writeup!

A couple of quick additions on the set screw:

For some knobs I've used a plug cutter. This is great in some ways, not great in others. One way it's tricky is that you have to drill the set screw on a knob that's already round. I use a V-shaped jig with sandpaper inside the V to hold the knob in place. This also helps ensure that the set screw hole is perfectly on a radius.

Also, I prefer to cut the threads with a tap, instead of letting the set screw do the cutting. Either way, it's good to hit the interior thread with some CA glue, then re-cut the threads. This might be unnecessary, but belt & suspenders.

Oh, and I usually put my drill bit upside-down when sanding the knob. Makes for a solid connection with the set screw.

Lastly: I recommend keeping a set of calipers handy. If the knobs aren't exactly the same diameter, your fingers will feel it!

 

[Jisch]

Good additional comments, I also use a tap and CA glue on the threads. I struggle getting the set screw on radius, I'll be stealing that sandpaper idea.

 

[Scoops]

Good additional comments, I also use a tap and CA glue on the threads. I struggle getting the set screw on radius, I'll be stealing that sandpaper idea.

While ya got the CA out, you could do what the guys that make pens do and put a CA finish on the knobs

 

[pbass74]

Just found this almost three year old thread, but it's just what I'm looking for. Thought I'd try my hand at making some knobs to dress up a bass or two. Thanks for sharing your experience!