From the Loftsmith Workshop
D-shaft replacement knob + fit gauge, 6 mm and 1/4 in
Brings back the knob that went missing from an amp, mixer or old radio. A small gauge with six D-shaped holes and dot marks lets you test a shaft before you print the knob. The grip is fluted, with a pointer line on top.
2 parts · 13 g · 74 × 69 × 23 mm
Ask for the sizes you want to tweak, e.g. “make the width adjustable”.
How to print it
Parts
- knob · PETG · Upright as used, open bore and nut slot on the bed; no supports
39.9 x 39.9 x 23 mm at the defaults, about 9 g and 18 min in the engine's per-part estimate. PETG because appliance panels get warm (softens around 75 °C, against about 55 °C for PLA). PLA is fine for audio gear.
- pointer · PETG (accent colour, filament 2) · Prints in place on top of the knob as one object
Raised 2.4 mm wide ridge on the crown. With one filament it prints in the knob colour and still reads as a raised line.
- fit-gauge · PETG or PLA · Flat on the bed
74 x 17 x 5 mm, about 4 g and 10 min. Six D-holes at 0.05 to 0.30 mm clearance in 0.05 mm steps; hole n has n dimples.
Print settings
- Layer height
- 0.2 mm
- Walls
- 3 (about 23 g and 47 min for knob, pointer and gauge at 3 walls, 15 % infill, including the colour change)
- Infill
- 15 %
- Supports
- None
- Notes
- The page's stats line uses 2 walls and 15 % infill: about 19 g and 39 min. Both figures include about 5.9 g and 11 min of purge for the pointer colour changes (an engine estimate; your slicer's flush settings decide). In one colour at 2 walls and 15 % it is about 13 g and 27 min. Three walls are rec
Hardware
- M3 hex nut (5.5 mm across flats, 2.4 mm thick) · Set-screw option only. Drops into the slot from the underside.
- M3 grub screw (set screw), M3x8 at the default shaft size · Set-screw option only. Across the shaft range the engine picks M3x6 to M3x10; the Set screw check on the Check tab names the length for your sliders.
- 1.5 mm hex key · Reaches the grub screw through the 5 mm side bore.
Assembly
- Measure your shaft with calipers: the round diameter and the distance across the flat (from the flat to the opposite round side). Set Shaft diameter and Across the flat. Measure how long the flat is and set Bore depth no longer than that.
- Print the fit-gauge and push each hole onto the shaft. Use the tightest hole that slides on without wobble (one dimple = 0.05 mm, six dimples = 0.30 mm) and set Clearance to that value.
- Pick the retention, knob diameter, height, flutes and skirt. Set Pointer angle: 0 puts the pointer directly over the flat. Then print the knob.
- Set-screw version: drop the M3 nut into the slot in the underside, thread the grub screw in through the side bore until it is held by the nut but not yet in the bore, push the knob onto the shaft, line up the pointer and tighten the screw onto the flat with a 1.5 mm hex key.
- Push-on version: press the knob straight onto the shaft with the flat lined up to the flex tongue. If it slides on loosely, your printer makes true-size holes and the tongue is not gripping; reprint with the set-screw option.
Good to know
- Not for gas hob, oven, heater or other heat- or gas-critical controls. Use the manufacturer's part for those.
- Fits D-shafts only. Splined, knurled and double-D shafts are not covered.
- The checks cover fit, walls and screw reach. Long-term durability and torque on a stiff appliance timer are not checked, so test the knob on your appliance.
- Push-on is modelled with zero clearance on the flat. It grips only if your printer makes holes slightly undersize, which is common but not certain. If the knob is loose, use the set screw for a sure fit. On a large knob over a nearly round shaft (a flat under about 0.2 mm deep) the push-on grip chec
- PETG softens around 75 °C. Keep it away from surfaces hotter than that.
- Knob diameter starts at 24 mm, because the captive nut needs that room. Smaller audio-style knobs are not covered.
Comments