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How a CNC Volume Knob Is Made and What Drives Its Price

September 14, 2026

A volume knob is a small part with an outsized bill. Buyers who have just paid for a chassis are often surprised that 100 knobs cost a meaningful fraction of it. The reason is simple: almost nothing in a knob’s price is cutting time.

How a knob is actually made

Most machined knobs follow the same route:

1. Turn the profile from bar stock on a lathe: outside diameter, face, chamfers, the bore for the shaft.
2. Mill the features: knurl, flutes, a pointer slot, a set screw hole, a logo pocket.
3. Deburr by hand. Every knurl tooth and every flute edge has a burr on it. This is bench work, not machine work.
4. Finish: bead blast, brush or polish, then anodize, plate or lacquer.
5. Inspect under light, one at a time, on the faces the user sees.
6. Pack so no two knobs touch.

Steps 3 to 6 are where the money goes. On a plain aluminum knob they are often more than half the unit price.

Material

Material	Feel	Finish route	Notes
Aluminum 6061	Light, neutral	Bead blast or brush, then anodize	Cheapest to repeat, widest colour range
Aluminum 6063	Light	Anodize	Anodizes brighter than 6061, softer, marks easier
Brass C360	Heavy, warm	Polish then lacquer, or nickel or black plate	Machines beautifully, tarnishes if bare
Copper C110	Heavy	Polish then lacquer	Soft, marks in handling, tarnishes fastest
Stainless 304	Heavy, cold	Bead blast or brush	Hardest to finish evenly, most expensive
POM or acrylic	Light	As machined	Cheap, but reads as cheap next to metal

Weight is a design decision, not an accident. A 40 mm brass knob feels like a different product than the same knob in aluminum, and buyers of high end gear notice within a second of touching it.

Grip: knurl, flute or plain

Diamond knurl is rolled or cut into the outside diameter. Rolled knurling is fast and cheap, but it displaces material, so the finished diameter grows and the pattern can look uneven where the roll starts and stops. Cut knurling is slower, cleaner and costs more.

Flutes are milled slots around the circumference. Each flute is a separate toolpath, so cost scales with the count. Twelve flutes cost roughly twice what six cost. Flutes also create twelve sharp edges that somebody has to deburr.

Plain with a bead blast is the cheapest and, on a small knob, often the best looking. If the knob is 20 mm and the user turns it with two fingers, grip texture is decoration rather than function.

The shaft interface

This is where knobs fail in assembly, and it is worth getting right on the drawing.

• Set screw on a round shaft. Simple and cheap. Specify the bore tolerance, usually H8 or a slip fit a few hundredths over the shaft. A grub screw in brass or nylon tipped avoids marking the shaft.
• D shaft. The flat stops the knob rotating on the shaft. It needs a broach or a wire cut, which adds a setup.
• Split collet. The nicest feel and the most expensive. The knob clamps concentrically, so there is no wobble and no witness mark on the shaft.
• Press fit insert. A brass or steel insert pressed into an aluminum knob. Used when the knob is soft and the shaft is steel.

If a pointer or an indicator line has to align with the flat, say so on the drawing with an angular tolerance. Without it, half the batch will point slightly off and you will only notice once they are on the units.

Matched sets cost more than the parts

A preamp with a volume knob, a source selector and two smaller trim knobs is four different parts that have to look like one family. That means:

• Same alloy and same bar lot where possible
• Racked and anodized in the same load
• Approved against one reference, not four
• Rejected as a set if one is off

A shop that quotes the four knobs as four independent parts is quoting the wrong job. Say “these four are a matched set” in the RFQ and let the price reflect it.

Engrave before or after anodize

A marking on a knob, a pointer line, a channel number or a logo, can be made two ways:

• Engraved before anodize, then the anodize coats the groove. The mark is the same colour as the part, visible as a shadow. Subtle and durable.
• Laser marked after anodize, which burns through the dye. The mark is bright, often near white on black. Crisp and high contrast, but the burnt surface is slightly less corrosion resistant.

Neither is better. They look completely different, so pick one and put it on the drawing.

Realistic cost behaviour

There is no useful universal price for a knob, but the shape of the curve is predictable:

• 1 to 10 pieces: setup dominates. Per piece cost can be ten times the volume price.
• 20 to 100: the normal range for a boutique run. Deburr, finish and inspection dominate. The finisher will often charge a minimum for the load.
• 200 to 1,000: cutting time and material start to matter. Cost per piece drops sharply here.
• Above 1,000: worth asking whether a rolled knurl, a simpler profile or a cold formed blank changes the picture.

What to put in the RFQ

• Drawing with the bore tolerance and the shaft type
• Material and whether weight matters
• Finish, colour reference and which faces are cosmetic
• Grip type with the knurl or flute count
• Marking method, before or after anodize
• Whether this knob is part of a matched set
• Quantity for this order and per year

Frequently asked questions

Keep reading

• What a Turntable Platter Needs From the Shop That Machines It
• Machining Headphone Cups and Yokes That Match Left to Right
• Isolation Feet and Spikes: Threads, Materials and Finish

This guide is part of Knobs, Platters, Cups and Feet, one of four sections in the guide library.