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Pilot Bore Sprockets – 1/2” Pitch Roller Chain Sprockets

At Bolton Engineering Products Ltd, we stock a full range of pilot bore sprockets designed for reliable, efficient power transmission in machinery, conveyors, automation systems, and chain-driven equipment.

These plain bore sprockets (Type A) have an unprepared bore and require a keyway and set screw for installation, allowing them to be fully customized to fit any shaft size and meet your specific needs.

BEP Ltd have you covered – whether it be a light-duty sprocket or an item designed for continuous use, all our parts are made from high-strength materials and custom machined to tight tolerances at very competitive prices.

What Is a Pilot Bore Sprocket?

A pilot bore sprocket is a chain sprocket supplied with a basic, oversized bore, allowing engineers or machinists to finish-machine it to the exact shaft diameter or keyway required.

These sprockets are popular in:

  • Manufacturing & processing equipment
  • Agricultural and industrial machinery
  • Conveyors and material handling systems
  • Motorcycles, bicycles & chain-driven vehicles
  • General engineering and fabrication workshops

Their flexibility makes them a go-to choice for custom drive systems and OEM applications.

Technical Specifications

Specification

Details

Product Type

Pilot Bore / Plain Bore Sprocket

Chain Pitch

1/2” Pitch (BS Standard Roller Chain)

Tooth Count Options

8T to 50T+

Material

C45 Steel / Hardened Steel

Bore Type

Pilot Bore (Machinable to Required Shaft Size)

Mounting Style

Direct Shaft, Hub, or Bushing Mount

Tooth Profile

British Standard (BS / ISO Chain)

Applications

Industrial, Agricultural, Conveyor, Mechanical Drives

Finish

Untreated / Phosphate / Black Oxide (model dependent)

Key Features & Benefits

  • Customizable Bore: Machine the bore and keyway exactly as required.
  • Smooth Power Transfer: Precisely machined teeth ensure accurate chain engagement.
  • High-quality Steel made: Any types of metal work, 5” Heavy Duty.
  • Large Size Range: Will work small equipment all the way up to large industrial machinery.
  • Also compatible with BS standard: Suits all 1/2" pitch standard roller chains.
  • Bulk order discount: Great for OEMs, garages and maintenance facilities.

Why Choose Bolton Engineering Products Ltd?

As one of the UK’s trusted suppliers of pilot bore sprockets, BEP Ltd offers:

  • Large inventory of plain bore sprockets in multiple tooth counts
  • High-quality components sourced from reliable manufacturers
  • Competitive prices with trade & bulk discounts
  • Expert technical support for sizing and application queries
  • Fast UK dispatch with reliable shipping options

When you need precision, durability, and flexibility, BEP Ltd has the right pilot bore sprocket for your job.

FAQs

Q1: What is the difference between a pilot bore sprocket and a finished bore sprocket?

A pilot bore sprocket has an oversized bore that requires machining. A finished bore sprocket comes pre-machined to a specific shaft size.

Q2: Is a pilot bore the same as a plain bore?

Yes — plain bore sprockets and pilot bore sprockets describe the same unfinished, machinable bore design.

Q3: Can I machine the bore myself?

Yes. Many customers machine the bore, keyway, and grub-screw holes in-house. We can also advise on machining allowances.

Q4: Are these sprockets compatible with standard roller chains?

Absolutely. All our sprockets fit 1/2” pitch BS roller chains.

Roller Chain Pilot Bore Sprockets - 1/2"

Pilot Bore Sprockets – 1/2” Pitch Roller Chain Sprockets

At Bolton Engineering Products Ltd, we stock a full range of pilot bore sprockets designed for reliable, efficient power transmission in machinery, conveyors, automation systems, and chain-driven equipment.

These plain bore sprockets (Type A) have an unprepared bore and require a keyway and set screw for installation, allowing them to be fully customized to fit any shaft size and meet your specific needs.

BEP Ltd have you covered – whether it be a light-duty sprocket or an item designed for continuous use, all our parts are made from high-strength materials and custom machined to tight tolerances at very competitive prices.

What Is a Pilot Bore Sprocket?

A pilot bore sprocket is a chain sprocket supplied with a basic, oversized bore, allowing engineers or machinists to finish-machine it to the exact shaft diameter or keyway required.

These sprockets are popular in:

  • Manufacturing & processing equipment
  • Agricultural and industrial machinery
  • Conveyors and material handling systems
  • Motorcycles, bicycles & chain-driven vehicles
  • General engineering and fabrication workshops

Their flexibility makes them a go-to choice for custom drive systems and OEM applications.

Technical Specifications

Specification

Details

Product Type

Pilot Bore / Plain Bore Sprocket

Chain Pitch

1/2” Pitch (BS Standard Roller Chain)

Tooth Count Options

8T to 50T+

Material

C45 Steel / Hardened Steel

Bore Type

Pilot Bore (Machinable to Required Shaft Size)

Mounting Style

Direct Shaft, Hub, or Bushing Mount

Tooth Profile

British Standard (BS / ISO Chain)

Applications

Industrial, Agricultural, Conveyor, Mechanical Drives

Finish

Untreated / Phosphate / Black Oxide (model dependent)

Key Features & Benefits

  • Customizable Bore: Machine the bore and keyway exactly as required.
  • Smooth Power Transfer: Precisely machined teeth ensure accurate chain engagement.
  • High-quality Steel made: Any types of metal work, 5” Heavy Duty.
  • Large Size Range: Will work small equipment all the way up to large industrial machinery.
  • Also compatible with BS standard: Suits all 1/2" pitch standard roller chains.
  • Bulk order discount: Great for OEMs, garages and maintenance facilities.

Why Choose Bolton Engineering Products Ltd?

As one of the UK’s trusted suppliers of pilot bore sprockets, BEP Ltd offers:

  • Large inventory of plain bore sprockets in multiple tooth counts
  • High-quality components sourced from reliable manufacturers
  • Competitive prices with trade & bulk discounts
  • Expert technical support for sizing and application queries
  • Fast UK dispatch with reliable shipping options

When you need precision, durability, and flexibility, BEP Ltd has the right pilot bore sprocket for your job.

FAQs

Q1: What is the difference between a pilot bore sprocket and a finished bore sprocket?

A pilot bore sprocket has an oversized bore that requires machining. A finished bore sprocket comes pre-machined to a specific shaft size.

Q2: Is a pilot bore the same as a plain bore?

Yes — plain bore sprockets and pilot bore sprockets describe the same unfinished, machinable bore design.

Q3: Can I machine the bore myself?

Yes. Many customers machine the bore, keyway, and grub-screw holes in-house. We can also advise on machining allowances.

Q4: Are these sprockets compatible with standard roller chains?

Absolutely. All our sprockets fit 1/2” pitch BS roller chains.

4sr12-pilot-bore-08b-1-2-pitch-sprocket

4SR12 (08B-1-12) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 12 Tooth

£2.68 - £2.68
£2.68
£2.68 - £2.68
£2.68

4SR12 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR10 Pitch 1/2 Teeth 12 Outside Dia (mm) 53 O...

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£2.68 - £2.68
£2.68
£2.68 - £2.68
£2.68
4sr16-pilot-bore-08b-1-2-pitch-sprocket

4SR16 (08B-1-16) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 16 Tooth

£3.66 - £3.66
£3.66
£3.66 - £3.66
£3.66

4SR16 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR16 Pitch 1/2 Teeth 16 Outside Dia (mm) 69.5...

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£3.66 - £3.66
£3.66
£3.66 - £3.66
£3.66
4sr14-pilot-bore-08b-1-2-pitch-sprocket

4SR14 (08B-1-14) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 14 Tooth

£3.11 - £3.11
£3.11
£3.11 - £3.11
£3.11

4SR14 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR14 Pitch 1/2 Teeth 14 Outside Dia (mm) 61.8 ...

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£3.11 - £3.11
£3.11
£3.11 - £3.11
£3.11
4sr18-pilot-bore-08b-1-2-pitch-sprocket

4SR18 (08B-1-18) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 18 Tooth

£4.09 - £4.09
£4.09
£4.09 - £4.09
£4.09

4SR18 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR18 Pitch 1/2 Teeth 18 Outside Dia (mm) 77.8 ...

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£4.09 - £4.09
£4.09
£4.09 - £4.09
£4.09
4sr15-pilot-bore-08b-1-2-pitch-sprocket

4SR15 (08B-1-15) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 15 Tooth

£3.48 - £3.48
£3.48
£3.48 - £3.48
£3.48

4SR15 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR15 Pitch 1/2 Teeth 15 Outside Dia (mm) 65.5 ...

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£3.48 - £3.48
£3.48
£3.48 - £3.48
£3.48
4SR19-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-19-Tooth

4SR19 (08B-1-19) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 19 Tooth

£22.14 - £22.14
£22.14
£22.14 - £22.14
£22.14

4SR19 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR19 Pitch 1/2 Teeth 19 Outside...

View full details
£22.14 - £22.14
£22.14
£22.14 - £22.14
£22.14
4sr20-pilot-bore-08b-1-2-pitch-sprocket

4SR20 (08B-1-20) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 20 Tooth

£4.79 - £4.79
£4.79
£4.79 - £4.79
£4.79

4SR20 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR20 Pitch 1/2 Teeth 20 Outside Dia (mm) 85.8 ...

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£4.79 - £4.79
£4.79
£4.79 - £4.79
£4.79
4sr13-pilot-bore-08b-1-2-pitch-sprocket

4SR13 (08B-1-13) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 13 Tooth

£2.84 - £2.84
£2.84
£2.84 - £2.84
£2.84

4SR13 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR13 Pitch 1/2 Teeth 13 Outside Dia (mm) 57.4 ...

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£2.84 - £2.84
£2.84
£2.84 - £2.84
£2.84

4SR16 25mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 16 Tooth

£11.67 - £11.67
£11.67
£11.67 - £11.67
£11.67

Roller Chain Sprocket 08B 4SR16 25mm Bore Key & 2 Set Screws 1/2" Pitch 16 ToothChain Pitch:08B-1Number of Teeth:16Bore & Keyway(mm):25mmMf...

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£11.67 - £11.67
£11.67
£11.67 - £11.67
£11.67
4SR12-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-12-Tooth

4SR12 (08B-1-12) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 12 Tooth

£12.61 - £12.61
£12.61
£12.61 - £12.61
£12.61

4SR12 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR10 Pitch 1/2 Teeth 12 Outside...

View full details
£12.61 - £12.61
£12.61
£12.61 - £12.61
£12.61
4dr17-pilot-bore-08b-1-2-pitch-sprocket

4DR17 (08B-2-17) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 17 Tooth

£5.15 - £5.15
£5.15
£5.15 - £5.15
£5.15

4DR17 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR17 Pitch 1/2 Teeth 17 Outside Dia (mm) 73.6 ...

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£5.15 - £5.15
£5.15
£5.15 - £5.15
£5.15
4dr14-pilot-bore-08b-1-2-pitch-sprocket-1

4DR15 (08B-2-15) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 15 Tooth

£4.85 - £4.85
£4.85
£4.85 - £4.85
£4.85

4DR15 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR15 Pitch 1/2 Teeth 15 Outside Dia (mm) 65.5 ...

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£4.85 - £4.85
£4.85
£4.85 - £4.85
£4.85
4dr12-pilot-bore-08b-1-2-pitch-sprocket

4DR12 (08B-2-12) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 12 Tooth

£3.40 - £3.40
£3.40
£3.40 - £3.40
£3.40

4DR12 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR12 Pitch 1/2 Teeth 12 Outside Dia (mm) 53 Ov...

View full details
£3.40 - £3.40
£3.40
£3.40 - £3.40
£3.40
4sr36-pilot-bore-08b-1-2-pitch-sprocket

4SR36 (08B-1-36) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 36 Tooth

£10.54 - £10.54
£10.54
£10.54 - £10.54
£10.54

4SR36 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR36 Pitch 1/2 Teeth 36 Outside Dia (mm) 151 ...

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£10.54 - £10.54
£10.54
£10.54 - £10.54
£10.54
4sr21-pilot-bore-08b-1-2-pitch-sprocket

4SR21 (08B-1-21) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 21 Tooth

£5.40 - £5.40
£5.40
£5.40 - £5.40
£5.40

4SR21 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR21 Pitch 1/2 Teeth 21 Outside Dia (mm) 89.7 ...

View full details
£5.40 - £5.40
£5.40
£5.40 - £5.40
£5.40
4sr19-pilot-bore-08b-1-2-pitch-sprocket

4SR19 (08B-1-19) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 19 Tooth

£4.38 - £4.38
£4.38
£4.38 - £4.38
£4.38

4SR19 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR19 Pitch 1/2 Teeth 19 Outside Dia (mm) 81.7 ...

View full details
£4.38 - £4.38
£4.38
£4.38 - £4.38
£4.38
4sr11-pilot-bore-08b-1-2-pitch-sprocket

4SR11 (08B-1-11) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 11 Tooth

£2.40 - £2.40
£2.40
£2.40 - £2.40
£2.40

4SR11 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR10 Pitch 1/2 Teeth 11 Outside Dia (mm) 48.7 ...

View full details
£2.40 - £2.40
£2.40
£2.40 - £2.40
£2.40
4sr10-pilot-bore-08b-1-2-pitch-sprocket

4SR10 (08B-1-10) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 10 Tooth

£2.03 - £2.03
£2.03
£2.03 - £2.03
£2.03

4SR10 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR10 Pitch 1/2 Teeth 10 Outside Dia (mm) 45.2 ...

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£2.03 - £2.03
£2.03
£2.03 - £2.03
£2.03
4sr09-pilot-bore-08b-1-2-pitch-sprocket

4SR09 (08B-1-09) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 9 Tooth

£1.50 - £1.50
£1.50
£1.50 - £1.50
£1.50

4SR09 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR09 Pitch 1/2 Teeth 9 Outside Dia (mm) 41 Ov...

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£1.50 - £1.50
£1.50
£1.50 - £1.50
£1.50

4SR20 28mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 20 Tooth

£14.55 - £14.55
£14.55
£14.55 - £14.55
£14.55

Roller Chain Sprocket 08B 4SR20 28mm Bore Key & 2 Set Screws 1/2" Pitch 20 ToothChain Pitch:08B-1Number of Teeth:20Bore & Keyway(mm):28mmMf...

View full details
£14.55 - £14.55
£14.55
£14.55 - £14.55
£14.55

4SR14 15mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 14 Tooth

£10.38 - £10.38
£10.38
£10.38 - £10.38
£10.38

Roller Chain Sprocket 08B 4SR14 15mm Bore Key & 2 Set Screws 1/2" Pitch 14 ToothChain Pitch:08B-1Number of Teeth:14Bore & Keyway(mm):15mmMf...

View full details
£10.38 - £10.38
£10.38
£10.38 - £10.38
£10.38
4SR15-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-15-Tooth

4SR15 (08B-1-15) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 15 Tooth

£17.05 - £17.05
£17.05
£17.05 - £17.05
£17.05

4SR15 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR15 Pitch 1/2 Teeth 15 Outside...

View full details
£17.05 - £17.05
£17.05
£17.05 - £17.05
£17.05
4SR20-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-20-Tooth

4SR20 (08B-1-20) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 20 Tooth

£24.61 - £24.61
£24.61
£24.61 - £24.61
£24.61

4SR20 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR20 Pitch 1/2 Teeth 20 Outside...

View full details
£24.61 - £24.61
£24.61
£24.61 - £24.61
£24.61
4SR24-BS-Stainless-Steel-Simplex-Pilot-Bore-08B-1/2"-Pitch-Sprocket-24-Tooth

4SR24 (08B-1-24) - BS Stainless Steel Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 24 Tooth

£30.92 - £30.92
£30.92
£30.92 - £30.92
£30.92

4SR24 Stainless Steel Pilot Bore 08B 1/2" Pitch Sprocket   For use with 08B-1 Simplex Chain   Part Number 4SR24 Pitch 1/2 Teeth 24 Outside...

View full details
£30.92 - £30.92
£30.92
£30.92 - £30.92
£30.92

Hi. Need any help?