# How to 3D print a knob for a bolt, nut or shaft

Knob Generator guide · NabiMakes Tools · Updated 3 November 2026 · https://nabimakes.com/tools/knob-generator/guide/

Knob Generator makes star, fluted, knurled, round and wing knobs for jigs, clamps, drawers and electronics. A clamping knob takes a hex nut, a bolt head or a heat-set insert in metric and inch sizes; a shaft knob fits a D shaft or a knurled shaft. The pocket takes your printer's press fit, the knob prints face down so nothing bridges, and a fit sample lets you try the nut or shaft first. It is free and downloads STL or 3MF.

[Open Knob Generator](https://nabimakes.com/tools/knob-generator/)

## What can you make with Knob Generator?

Knobs 10 to 100 mm across for M3 to M12 and #6 to 1/2 inch screws, and for 3 to 10 mm shafts. Makers print:

- A clamping knob for a jig, a fence or a router table.
- A thumb knob or a wing knob on a bolt you turn by hand.
- A replacement knob for a potentiometer or a rotary encoder.
- A drawer or cabinet knob on a heat-set insert.

## How do you make a knob, step by step?

Everything is in the panel beside the knob, which updates as you change it. Start from a preset, then change what you need.

### 1. Start from a preset

Pick M8 star knob, M6 wing knob, M4 thumb knob, Pot knob 6 mm D, Encoder knob 18 teeth or Drawer knob M4. A preset sets only the values it names; Surprise me tries another grip, diameter and height and keeps what the knob fits on.

![Knob Generator: the presets with Surprise me above the settings, beside the star knob on the print bed.](https://nabimakes.com/tools/assets/preset.light-fsENbcVn.webp)

### 2. Say what it fits on

A hex nut, a bolt head (hex or socket cap), a heat-set insert, a D shaft or a knurled shaft. For a nut, a head or an insert, pick metric or inch and the size; inserts are metric only. A nut knob lets the bolt go through its face, or stops the bore 1 mm short of it.

![The Fits on section of a nut knob: what it fits on, the sizes, the size and Bolt goes through.](https://nabimakes.com/tools/assets/fits.light-DUQrIYJu.webp)

### 3. Shape the grip

A star, fluted, knurled, round or wing grip, the lobes or flutes, the diameter and the height, a chamfer on both edges and a pointer: a line in the face or a notch down the rim.

![The Grip section: the grip, the lobes, the diameter, the height, the chamfer and the pointer.](https://nabimakes.com/tools/assets/grip.light-nbPHoS21.webp)

### 4. Fit a pot or encoder shaft

For a D shaft, set its diameter and the width from its round side to the flat. For a knurled shaft, its teeth, and whether they are cut in the bore or the bore is round at their tips. Bore depth is how far the shaft goes in.

![The Pot knob, 6 mm D preset: the shaft, the width across the flat and the bore depth.](https://nabimakes.com/tools/assets/shaft.light-DHTTsymS.webp)

### 5. Check it and download

The checks say whether the wall round the pocket is strong enough, whether the pocket fits in the knob and whether a shaft's teeth print with your nozzle. Turn on Fit sample to print a thin disc with just the pocket, set how many knobs, then download 3MF or STL.

![The checks, the print figures and Download · free at the end of the panel.](https://nabimakes.com/tools/assets/download.light-D40zAZmM.webp)

## Which knobs can you start from?

Each example opens in Knob Generator as a new design, beside your own.

- **M8 star knob** (M8 nut, Star, 5 lobes, 40 × 22 mm, Free): A clamping knob for jigs: an M8 nut presses in and the bolt goes through. [Open in Knob Generator](https://nabimakes.com/tools/knob-generator/#design=1.PY_BTsMwEET_Zc4LaqsWVXvuDSEOHDhv4nVsEduRvUFAlX9HjgS30bzd0cwdVsoMxkcuw8OkWatYqSA4MQHf8am1xZLBR8IiVVLrro_WXjMYeTUQ2nczTWAktRrH7sQfBePlCkJQcc8xOzCCfoFgoZZ1CmCrqxJaEG-3KElNK_iJ4Gex9-gsgM-PF4Kpdn28Uu9rQd3f71Cq3nTZ6YEw1biA0Uz6hrkM2sAXgvtPPx96oTgFA59OhDFI8h30fSXm_Qi5ZAVhLGu2Hflob5KWWcFe5qbbtv0C)
- **Pot knob, 6 mm D** (6 mm D shaft, 12 flutes, 20 × 16 mm, Free): A fluted knob with a pointer line for a potentiometer's D shaft. [Open in Knob Generator](https://nabimakes.com/tools/knob-generator/#design=1.PY_BTsQwDET_Zc5etF3BauXz3hDiwIFztnEaizSpEhcBq_47SiW4WfPsmfEdVkoC4yOX22GSLNVZqSB4Zw58x6fUpiWDB8LiqptbV4Nae81g-EOLLhgI7buZzGDMYlXHruiPgPFyASGK88-aPRhRvkCwWMs6RbDVVQi7y1XdLCYVfCaE5OxdvUXw48MTwUT6PFyod7Yo_u_2VqpcZdnpkTBVXcAIaTXxIKRykwYeTgT_H3A69k46RQMPZ8IY3Rw66G8WzfsSkmYBYSxrth0FtTc3L0nAwaUm27b9Ag)
- **Encoder knob, 18 teeth** (6 mm shaft, 18 teeth, 18 × 16 mm, Free): A knurled knob for a rotary encoder's 18-tooth shaft. [Open in Knob Generator](https://nabimakes.com/tools/knob-generator/#design=1.PY7NSsRAEITfpc6tGHCXpc97E_HgwXMn05MZnJ8w0xF1ybtLAuutqK-rq26wWhMYn6WOD7MWbWK1geDEBHzDl7YeawEPhEWa5L67Plp_K0dubQmE_tNNMxhZrcVpd-KvgvF6ASGouJdYHBhBv0Gw0Oo6B7C1VQk9iLdrlKymDXwm-CT2EZ0F8PPjiWCqux4utC-2oO6eHWvTqy4HfSLMLS73XepASHXUDj4R3H_B_iZonIOBhzNhCpL9AQhLjeU4QopFQZjqWuxAPtq75CUp2Evqum3bHw)
- **Drawer knob M4** (M4 insert, Round, 30 × 20 mm, Free): A round drawer knob on an M4 heat-set insert. [Open in Knob Generator](https://nabimakes.com/tools/knob-generator/#design=1.PY-xTsQwEET_ZeoF5eAOoa2vQycKCmonXscWsR2tNwg45d-RT4JuNG92NXOF1bqA8VHqeDdLEXVWFQTvzIGv-BRtqRbwgbA6dbl1NyRrrwWMVJqogdC-m0kGI4tpmrqTfgSMyxGEKM6_pOLBiPIFgkWt2xzBppsQWnTBzsllMVHwEyEszt6Ttwg-3p8IJtL14Zl6ZYvi_27HqnKW9UYHwqxpBUPrVjwISx2lgU8E___-ceiN0hwN_DAQpuhy6KBvrKncQii1CAhT3YrdUEj25vK6CDi4pcm-778)

## Which print settings work best for knobs?

Every knob prints face down, and the fit sample beside it: the pocket opens upwards, so nothing bridges and no supports are needed, and the face takes the bed's finish. The layer height is a starting point; the thinnest wall is the one the printer checks hold each filament to.

| Filament | Layer height to start | Thinnest wall | Supports | Notes |
| --- | --- | --- | --- | --- |
| PLA | 0.2 mm | 0.8 mm | None | Crisp grips for jigs, drawers and electronics. |
| PETG | 0.2 mm | 0.8 mm | None | Tougher, for a clamping knob you turn hard. |

## Tips for knobs that fit

- Print the fit sample first: a thin disc with just the pocket, to try your nut or shaft before the whole knob.
- Use a plain nut, not a self-locking one: the nut presses in from the clamping side, and the bolt's pull holds it.
- Count the teeth on a knurled shaft: most encoders have 18, many guitar pots 24, and the two do not mix.
- Measure a D shaft from its round side to the flat: 4.5 mm on a 6 mm encoder shaft.
- Before you print, check it on the view's bar: Dimensions shows its size, Measure the distance between two points, Section cuts it open and Layers steps through it as your printer will.

## What if the knob is loose, tight or its wall is thin?

- **The nut or the shaft is too tight or too loose.** The pocket takes your filament's press fit, and a bore your printer's measured hole offset. Print the fit sample, then set your printer's fits from its fit test and print the knob.
- **The checks say the wall round the pocket is thin.** Press Apply for the smallest diameter that leaves three nozzle lines round the pocket, or choose a round or fluted grip, whose narrowest point is wider than a star's or a wing's.
- **The checks say the pocket is deeper than the knob.** Press Apply for a taller knob: it needs the pocket's depth and a 1 mm face.
- **The teeth in the bore will not print.** They are finer than two nozzle lines. Press Apply for a round bore at the teeth's tips, which grips by pressing on.

## Is Knob Generator free?

Yes. Every knob, size and download is free; downloading needs a free NabiMakes account, which also keeps your projects.

Free:

- Nut, bolt head, insert, D shaft and knurled shaft knobs
- Every grip and pointer
- The fit sample
- 3MF and STL

## Every setting, with its range and default

Lengths are in millimetres. Each setting shows only where it applies: the sizes for a nut, a head or an insert, the shaft's settings for a D or knurled shaft.

| Setting | Range | Default | What it does |
| --- | --- | --- | --- |
| **Fits on** | | | |
| Fits on | A hex nut, A bolt head, A heat-set insert, A D shaft, A knurled shaft | A hex nut | A hex nut, a bolt head, a heat-set insert, a D shaft or a knurled shaft. |
| Sizes | Metric, Inch | Metric | Metric or inch screws; heat-set inserts are metric only. |
| Size | M3 to M12, #6 to 1/2 inch | M8 | The screw, from the size tables. |
| Head | Hex, Socket cap | Hex | A hex head or a socket cap head, where the table has it. |
| Bolt goes through | On, off | On | A nut knob: the bolt passes the knob's face, or stops 1 mm short of it. |
| Shaft | 3–10 mm | 6 mm | 6 mm on most pots and encoders; 6.35 for a 1/4 inch shaft. |
| Across the flat | 1.5–9.5 mm | 4.5 mm | A D shaft, from its round side to the flat. |
| Teeth | 12–36 | 18 | A knurled shaft's teeth: 18 on most encoders, 24 on guitar pots. |
| Teeth in the bore | On, off | On | Teeth cut in the bore, or a round bore at their tips that grips by pressing on. |
| Bore depth | 4–30 mm | 10 mm | How far the shaft goes into the knob. |
| **Grip** | | | |
| Grip | Star, Fluted, Knurled, Round, Wing | Star | The grip's shape. |
| Lobes | 2–24 | 5 | A star's lobes or a fluted grip's flutes. |
| Diameter | 10–100 mm | 40 mm | Across the grip. |
| Height | 6–60 mm | 22 mm | How tall the knob is. |
| Chamfer | 0–3 mm | 1 mm | 45° off both edges, at most a third of the height. |
| Pointer | None, Line, Notch | None | A line in the face, or a notch down the rim, at a lobe. |
| **Print** | | | |
| Knobs | 1–12 | 1 | How many knobs on the plate. |
| Fit sample | On, off | Off | A thin disc with just the pocket: try your nut or shaft before the whole knob. |