A control knob with a D-shaft bore, grip flutes and a pointer

Knobs look simple, but they hide several small decisions: how tight the bore is on the shaft, how deep the flat goes, how many flutes, and where the pointer goes. We asked:

A control knob for a 6 mm D-shaft: Ø32, 18 mm tall, a rounded top, grip flutes around the side and a pointer mark.

What came out

• The bore fits the shaft: a D-shaped hole 13 mm deep with a Ø6.1 round wall, so 0.1 mm of clearance on the 6 mm shaft, and the flat 1.55 mm from the axis, so the D measures 4.6 mm against the shaft’s 4.5 mm.
• Grip flutes: 12 round grooves, Ø4, evenly spaced, running from the bottom up to 14 mm, which leaves a plain 4 mm band under the rounded top.
• A rounded top (a 3 mm fillet) and a pointer: a groove 1.2 mm wide and 0.6 mm deep running out to the edge.
• Measured by the kernel: 32 × 18 × 32 mm overall, the flute tops at 14 mm, and the bore wall at Ø6.100.

Genie also said what it didn’t check: the fillet’s radius, the pointer’s size, and which way the pointer faces relative to the D flat. That last one matters on a real front panel, and now you know to look.

Why it helps

• Fits are part of the answer. “A 6 mm D-shaft” becomes a bore with a sensible clearance, not a 6.000 mm hole that won’t go on.
• Ten editable features. Change the flute count or the knob’s diameter and the rest follows.
• Honest about the gaps. Every answer separates what was measured from what was assumed.

Try it: name the shaft (a 6 mm D-shaft, a 1/4 inch round shaft) and the look you want. Then ask Genie to “line the pointer up with the flat” if it matters for your panel.