# Potentiometer panel-mount bushings and shafts: M7, M8, M9 and 3/8-32 bushings, 6 mm and 1/4 in shafts, knurl and flat (Bourns, Alps, Alpha, CTS)

> What thread and shaft does a panel-mount potentiometer have, and what hole does it need?

- Category: Electronic components › Panel cutouts
- Kind: Standard part
- Basis: Bourns PTV09, PDB18x and PDA24 data sheets, Alps Alpine RK09 and RK163 sheets, Taiwan Alpha RV24 and RVQ24 sheets and the CTS series 270 data sheet, as read; numbers only
- Page: https://xemstudio.com/objects/potentiometer-panel-mount-bushings-shafts/ · JSON: https://xemstudio.com/api/geometry?object=potentiometer-panel-mount-bushings-shafts · Plain text: https://xemstudio.com/objects/potentiometer-panel-mount-bushings-shafts/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no tolerance added.

## Notes

- Rows are what each maker prints for the bushing (the threaded neck that goes through the panel), the shaft and the supplied nut and washer. The bushing thread is not the same on every 'size': 9 mm Bourns PTV09A is M9 x 0.75, 16 mm Alps RK163 is M7 x 0.75, 17 mm Bourns PDB18x is 3/8-32 UNEF, and the 24 mm Alpha RV24 is M8 x 0.75 while the Alpha RVQ24 sheet prints M9 x 0.75. Both Alpha figures are shown because the two sheets differ. The body size in the family name (9, 16, 17, 24 mm) is the housing, not the thread.
- Panel hole: almost no maker prints one. The only panel-side numbers found are on the CTS 270X drawing (a 15.9 mm 'bushing clearance hole' and a 2.4 x 1.0 mm locating-lug clearance, two holes), which is a clearance for the control body behind the panel on that drawing, not a threaded-bushing hole. For the bushing hole, drill a hole at the thread's major diameter plus your own clearance: M7 = 7 mm, M8 = 8 mm, M9 = 9 mm, 3/8-32 = 9.525 mm. These are the nominal threads, not a maker's panel hole.
- Anti-rotation: the datasheets read show a locating lug or pin (CTS lug left / right / both / none; Bourns PDA24 'anti-rotation pins') but none gave a position as a labeled number, so the lug hole position is not on this page and no gauge is drawn. Panel thickness is also not printed on any of these sheets; the bushing length (CTS .250 in to 1.000 in in 1/8 in steps) sets what the nut can clamp.
- Shaft: 6.0 mm (Bourns PTV09A, PDB18x, Alps RK09 / RK163, CTS .236 in), 6.35 mm / 1/4 in (PDA24, CTS .250 in, RVQ24 unlabeled). Knurled shafts are 18-tooth (Bourns S, Alps RK163, Alpha RV24, Bourns PDB18x / PDA24 config 00), 24-tooth (PDA24 config 01, CTS T, PDB185) or 40-tooth (Bourns PTV09A 'U', Alps RK09). 'D' or flatted shafts use the CTS X / Y values above; their labels are not defined in the text read.
- Alps RK09K / RK09D is a snap-in part with a 6 mm bushing and no thread in the pages read, so it is not a nut-mount pot. Trimmer pots: trimmer-potentiometers. Rotary encoders and arcade parts: adafruit-buttons-joysticks-encoders. Toggle bushings: toggle-switch-bushings-panel-holes.
- No file: the pot body, the lug and the knurl profile are not published as complete numbers, so a drawing would be invented. Maker 3D models are linked from the maker (Bourns lists a model per part), not copied.

## Sizes

| family / series | feature | value (as printed) | source |
|---|---|---|---|
| Bourns PTV09A (9 mm) | metal threaded bushing (style 6) | thread M9 x 0.75 (printed 'M9 X 0.75 (.030)') | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | sleeve bushing (styles 1, 7, 8) | no thread printed; 6.8 mm DIA (.268) on the style 1 drawing | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | plastic plain bushing (style 5) | no thread printed | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | hardware | one flat washer and one hex nut supplied with the bushing version | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | shaft diameter | 6.0 +0 / -0.1 mm (.236 +.000 / -.004) | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | shaft length L (+/-0.5) | 15 (bushingless only), 20, 25, 30 mm | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | shaft types | F flat insulated; S insulated knurled, 18 teeth; U insulated knurled, 40 teeth (U not listed at 15 mm). The shaft-style table prints 6 / 7 / 12 mm for the F row and 6 / 7 mm for S by length; the column is not defined in the text read | Bourns PTV09 data sheet |
| Bourns PTV09A (9 mm) | mechanical angle | 280 deg +/-10 deg | Bourns PTV09 data sheet |
| Alps RK09K / RK09D (9.8 mm wide) | bushing | snap-in body; outline drawings show bushing diameter 6 (no thread printed, no panel hole printed) | Alps RK09K / RK09D outline pages |
| Alps RK09K / RK09D (9.8 mm wide) | shaft | diameter 6; length LM1 15, 20, 25, 30 mm (varies by model); flat 4.5 mm; 40-tooth knurl (driver and knob types) | Alps RK09K / RK09D outline pages |
| Alps RK163 (16 mm) | bushing | body diameter 16 mm; thread M7 x 0.75 (printed 'M7G0.75') | Alps RK163 data sheet |
| Alps RK163 (16 mm) | shaft | diameter 6 mm (knurled, flat, slotted); L1 15, 20, 25 mm recommended (30 mm also in the 16 mm ordering code); knurl 18 teeth, 0.7 mm high; flat 4.5 mm and slot 0.5 / 1.0 / 1.6 mm are printed unlabeled | Alps RK163 data sheet |
| Alps RK163 (16 mm) | hardware | hex nut M7 x 0.75; flat washer 12 mm OD, 7.2 mm ID, 0.5 mm thick (nut thickness 2 and size 11 are printed unlabeled) | Alps RK163 data sheet |
| Bourns PDB181 / PDB185 (17 mm) | bushing | thread 3/8-32 UNEF-2A (PDB185 sheet; PDB181 sheet prints '3/8 NEF'); bushing diameter and length not labeled | Bourns PDB18x-GTR sheets |
| Bourns PDB181 / PDB185 (17 mm) | shaft | 6.00 mm DIA (.236) knurled and plain; knurl 18 teeth (C0.5 chamfer) on the PDB181 sheet; PDB185 lists 18-tooth, 24-tooth and slotted styles; lengths are printed unlabeled | Bourns PDB18x-GTR sheets |
| Bourns PDB181 / PDB185 (17 mm) | hardware | two flat washers and two mounting nuts supplied per control | Bourns PDB18x-GTR sheets |
| Bourns PDA24 (24 mm) | bushing | thread 3/8 NEF | Bourns PDA24 sheet |
| Bourns PDA24 (24 mm) | shaft | 6.35 mm (.250) DIA plain (config 02) or knurled, 18 teeth (config 00) / 24 teeth (config 01); 19.00 mm (.748) printed on the knurled drawing, other lengths unlabeled | Bourns PDA24 sheet |
| Bourns PDA24 (24 mm) | hardware / angle | one flat washer and one mounting nut supplied; mechanical angle 300 deg +/-5 deg; anti-rotation pins listed as a feature, position not legible | Bourns PDA24 sheet |
| Alpha RV24AF / RV24BF (24 mm) | bushing | thread M8 x 0.75 standard ('Blank' code), bushing length 6.5 mm; option code D2 printed '3/8'' x 0.75', 6.5 mm | Taiwan Alpha RV24 sheet |
| Alpha RV24AF / RV24BF (24 mm) | shaft | length codes 15F, 20F, 25F, 30F (unit not printed); 18-tooth knurl; chamfer C0.5; shaft types K, F, R, R1 list 'A : 6.5 mm' (A not defined) | Taiwan Alpha RV24 sheet |
| Alpha RVQ24 (24 mm) | bushing | thread M9 x 0.75 (M9P0.75) on both drawings; 10 and 12.7 mm options printed without a label | Taiwan Alpha RVQ24 sheet |
| Alpha RVQ24 (24 mm) | shaft | 6.35 mm printed unlabeled (+1 / -0.5 on one drawing, +0.03 / -0.05 on the other); lengths 'various', not tabulated | Taiwan Alpha RVQ24 sheet |
| CTS 270 (panel control) | bushing thread | 3/8-32 UNEF-2A on 270X, 270U, 270V, 270T (brass bushing). Metal-shaft options by shaft size: .125 and .156 in shafts 1/4-32 UNEF-2A or M7 x .75; .187 in 3/8-32 UNEF-2A or M7 x .75; .236 in 3/8-32 or M8 x .75; .250 in 3/8-32 or M9 x .75. Molded-shaft bushings: 1/4-32 or M7 (.156 in), 3/8-32 or M7 (.187 in), 3/8-32 or M8 (.236 in), 3/8-32 or M9 (.250 in) | CTS series 270 data sheet |
| CTS 270 (panel control) | bushing length | .250 in (code 2), .375 in (3), up to 1.000 in (8) in 1/8 in steps | CTS series 270 data sheet |
| CTS 270 (panel control) | shaft diameters | metal: .125 in (3.20 mm; the shaft-type table prints 3.18), .156 in (4.00), .187 in (4.70), .236 in (6.00), .250 in (6.35); molded: .156 in (4.00), .187 in (4.70), .236 in (6.00), .250 in (6.35) | CTS series 270 data sheet |
| CTS 270 (panel control) | shaft length L | metal .500 in (code 16) to 1.000 in (code 32) in 1/32 in steps; molded .500 in (U and K trims), .875 in (V trim), .984 in (W trim); molded 'FMS' printed .875 in (22.2 mm), .984 in (25.0 mm), .500 in (12.7 mm) | CTS series 270 data sheet |
| CTS 270 (panel control) | flatted shafts: type, diameter, X, Y | B .125 in (3.18 mm), X .250 (6.35), Y .109 (2.77); D .250 (6.35), X .375 (9.52), Y .156 (3.96); H .187 (4.75), X .250 (6.35), Y .156 (3.96); F .156 (3.96), X .250 (6.35), Y .109 (2.77); L .236 (6.00), X .472 (12.0), Y .177 (4.50); V molded .187 (4.75), X .313 (7.95), Y .156 (3.96); W molded .236 (6.00), X .472 (12.0), Y .177 (4.50). X and Y are not defined in the text read | CTS series 270 data sheet |
| CTS 270 (panel control) | knurled and slotted shafts | metal N .236 in (6.00 mm), X .342 (8.70), Y .039 (1.00), 18 teeth; metal T .236 in (6.00), X .279 (7.10), Y .062 (1.57), 24 teeth; molded U .187 in (4.75), 18 teeth; molded K .236 in (6.00), 18 teeth; slotted (C, S, J, M, E) slot width .047 in (1.19 mm), depth .039 in (1.00 mm) | CTS series 270 data sheet |
| CTS 270 (panel control) | panel hole and locating lug (270X drawing) | 'bushing clearance hole' 15.9 mm (.626 in); locating lug clearance 2.4 x 1.0 mm (.094 x .039 in), 2 holes (270T-2 drawing: 2.39 / .094 x 1.0 / .040); lug options left, right, both (50 % detent) or none. An 11.13 mm (.438 in) dimension near the lug callout has no readable reference | CTS series 270 data sheet |

## Where the files are

- Bourns: [PTV09 series 9 mm potentiometer data sheet: bushing styles 1, 5, 6, 7, 8, shaft types F / S / U, shaft lengths, hardware (M9 x 0.75 metal bushing)](https://www.bourns.com/data/global/pdfs/PTV09.pdf) — web — Maker data sheet; numbers only
- Bourns: [PDB18x-GTR 17 mm panel control (guitar series): 3/8-32 UNEF-2A bushing, shaft styles, hardware](https://dtsheet.com/doc/1640599/pdb185-gtr) — web — Maker data sheet (mirror); numbers only
- Bourns: [PDA24 24 mm panel control: 3/8 NEF bushing, plain and knurled (18 / 24 teeth) shafts, 300 deg](https://dtsheet.com/doc/1640582/pda24) — web — Maker data sheet (mirror); numbers only
- Alps Alpine: [RK09K / RK09D 9 mm snap-in potentiometer (outline pages): shaft types, shaft length LM1 15 / 20 / 25 / 30 mm](https://static.chipdip.ru/lib/521/DOC059521048.pdf) — web — Maker data sheet (distributor copy); numbers only
- Alps Alpine: [RK163 series 16 mm metal-shaft potentiometer: M7 x 0.75 bushing, shaft, nut and washer](https://www.meditronik.com.pl/doc/plus/rk16.pdf) — web — Maker data sheet (distributor copy); numbers only
- Taiwan Alpha: [RV24AF / RV24BF 24 mm rotary type metal shaft series: bushing thread and length, shaft lengths, 18-tooth knurl](https://static.chipdip.ru/lib/165/DOC013165626.pdf) — web — Maker data sheet (distributor copy); numbers only
- Taiwan Alpha: [RVQ24 24 mm potentiometer: M9 x 0.75 thread (OCR-garbled drawing text)](https://www.meditronik.com.pl/doc/plusik/rvq24900.pdf) — web — Maker data sheet (distributor copy); numbers only
- CTS: [Series 270 panel control data sheet: bushing threads, shaft diameters and lengths, flatted / knurled / slotted shafts, locating lug options](https://dtsheet.com/doc/1396772/series-270-data-sheet) — web — Maker data sheet (mirror); numbers only
- Bourns: [Commercial panel controls: product pages with 3D models per part (PTV09, PDB18x, PDA24)](https://www.bourns.com/products/potentiometers/commercial-panel-controls) — web — Maker page; CAD per part from the maker

## Questions

**What thread does a 16 mm Alpha / Alps pot have?**

Alps RK163 (16 mm) is M7 x 0.75, with an M7 x 0.75 hex nut and a 12 mm OD, 7.2 mm ID, 0.5 mm washer.

**What thread does a guitar (17 mm Bourns) pot have?**

3/8-32 UNEF-2A on the PDB185-GTR sheet (3/8 NEF on PDB181), with two washers and two nuts per control; shaft 6.0 mm.

**What shaft does a 9 mm Bourns PTV09A have?**

6.0 mm (+0 / -0.1), lengths 20, 25, 30 mm (15 mm bushingless only); flat, 18-tooth knurled or 40-tooth knurled.

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