# Linear bushing (LM, LMF, LMK)

Linear ball bushing for round shafts in the common LM dimension series, shaft diameters 3 to 60 mm: straight
(LM…UU), round flange (LMF…UU) or square flange (LMK…UU).

## Geometry

Envelope for assemblies and housing design:

- outer sleeve, outside diameter **D**, length **L**, bore **dr** (the shaft diameter);
- straight type (LM): two retaining-ring grooves of width **L2** down to diameter **D0**, their outer edges **L1**
  apart, centred on the length (sizes 3 and 4 have none);
- flanged types: flange of width **H** at one end, round with diameter **D1** (LMF) or square **K** across flats
  with its corners on the D1 circle (LMK); four mounting holes **d1** on the **PCD** (on the axes for LMF, on the
  diagonals for LMK), counterbored **d2** × **h** from the flange face.

Balls, retainer and seals are not modelled. Axis along Z, from z = 0 (the flange face, or one end) to z = L.

## Parameters

| Parameter | Meaning |
|---|---|
| `size` | Size code = shaft diameter, mm: 3, 4, 5, 6, 8S (short 8 mm), 8, 10, 12, 13, 16, 20, 25, 30, 35, 40, 50, 60 |
| `style` | `LM` straight, `LMF` round flange, `LMK` square flange (flanged types from size 6) |

## Source

THK *General Catalog — Guide Ball Bushing / Linear Bushing* (515-1E): model LM, pages A4-42/A4-43
(<https://tech.thk.com/en/products/pdfs/en_a04_042.pdf>); model LMF, pages A4-52/A4-53
(<https://tech.thk.com/en/products/pdfs/en_a04_052.pdf>); model LMK, pages A4-60/A4-61
(<https://tech.thk.com/en/products/pdfs/en_a04_060.pdf>). Every value below was checked against these pages. Other makers' LM…UU / LMF…UU / LMK…UU bushings share these main
dimensions.

| Size | dr | D | L | L1 | L2 | D0 | D1 | K | H | PCD | d1 × d2 × h |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 3 | 3 | 7 | 10 | | | | | | | | |
| 4 | 4 | 8 | 12 | | | | | | | | |
| 5 | 5 | 10 | 15 | 10.2 | 1.1 | 9.6 | | | | | |
| 6 | 6 | 12 | 19 | 13.5 | 1.1 | 11.5 | 28 | 22 | 5 | 20 | 3.4 × 6.5 × 3.3 |
| 8S | 8 | 15 | 17 | 11.5 | 1.1 | 14.3 | 32 | 25 | 5 | 24 | 3.4 × 6.5 × 3.3 |
| 8 | 8 | 15 | 24 | 17.5 | 1.1 | 14.3 | 32 | 25 | 5 | 24 | 3.4 × 6.5 × 3.3 |
| 10 | 10 | 19 | 29 | 22 | 1.3 | 18 | 39 | 30 | 6 | 29 | 4.5 × 8 × 4.4 |
| 12 | 12 | 21 | 30 | 23 | 1.3 | 20 | 42 | 32 | 6 | 32 | 4.5 × 8 × 4.4 |
| 13 | 13 | 23 | 32 | 23 | 1.3 | 22 | 43 | 34 | 6 | 33 | 4.5 × 8 × 4.4 |
| 16 | 16 | 28 | 37 | 26.5 | 1.6 | 27 | 48 | 37 | 6 | 38 | 4.5 × 8 × 4.4 |
| 20 | 20 | 32 | 42 | 30.5 | 1.6 | 30.5 | 54 | 42 | 8 | 43 | 5.5 × 9.2 × 5.4 |
| 25 | 25 | 40 | 59 | 41 | 1.85 | 38 | 62 | 50 | 8 | 51 | 5.5 × 9.2 × 5.4 |
| 30 | 30 | 45 | 64 | 44.5 | 1.85 | 43 | 74 | 58 | 10 | 60 | 6.6 × 11 × 6.5 |
| 35 | 35 | 52 | 70 | 49.5 | 2.1 | 49 | 82 | 64 | 10 | 67 | 6.6 × 11 × 6.5 |
| 40 | 40 | 60 | 80 | 60.5 | 2.1 | 57 | 96 | 75 | 13 | 78 | 9 × 14 × 8.6 |
| 50 | 50 | 80 | 100 | 74 | 2.6 | 76.5 | 116 | 92 | 13 | 98 | 9 × 14 × 8.6 |
| 60 | 60 | 90 | 110 | 85 | 3.15 | 86.5 | 134 | 106 | 18 | 112 | 11 × 17.5 × 10.8 |

Not offered: the long types (LM…L, LMK…L) and pillow-block units, which these catalogue pages don't define.

Preset list: designations of the step.parts catalogue (MIT), see `library/NOTICE.md`.