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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 16mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 12 Tooth

£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54

Roller Chain Sprocket 08B 4SR12 16mm Bore Key & 2 Set Screws 1/2" Pitch 12 ToothChain Pitch:08B-1Number of Teeth:12Bore & Keyway(mm):16mmMf...

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£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54

4SR12 14mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 12 Tooth

£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54

Roller Chain Sprocket 08B 4SR12 14mm Bore Key & 2 Set Screws 1/2" Pitch 12 ToothChain Pitch:08B-1Number of Teeth:12Bore & Keyway(mm):14mmMf...

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£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54

4SR12 12mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 12 Tooth

£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54

Roller Chain Sprocket 08B 4SR12 12mm Bore Key & 2 Set Screws 1/2" Pitch 12 ToothChain Pitch:08B-1Number of Teeth:12Bore & Keyway(mm):12mmMf...

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£8.54 - £8.54
£8.54
£8.54 - £8.54
£8.54
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

£11.36 - £11.36
£11.36
£11.36 - £11.36
£11.36

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
£11.36 - £11.36
£11.36
£11.36 - £11.36
£11.36
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

£22.18 - £22.18
£22.18
£22.18 - £22.18
£22.18

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
£22.18 - £22.18
£22.18
£22.18 - £22.18
£22.18
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

£27.86 - £27.86
£27.86
£27.86 - £27.86
£27.86

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...

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£27.86 - £27.86
£27.86
£27.86 - £27.86
£27.86
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

£4.36 - £4.36
£4.36
£4.36 - £4.36
£4.36

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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£4.36 - £4.36
£4.36
£4.36 - £4.36
£4.36
4dr12-pilot-bore-08b-1-2-pitch-sprocket

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

£3.07 - £3.07
£3.07
£3.07 - £3.07
£3.07

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...

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£3.07 - £3.07
£3.07
£3.07 - £3.07
£3.07
4dr09-pilot-bore-08b-1-2-pitch-sprocket

4DR09 (08B-2-09) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 9 Tooth

£2.34 - £2.34
£2.34
£2.34 - £2.34
£2.34

4DR09 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR09 Pitch 1/2 Teeth 9 Outside Dia (mm) 41 Ove...

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£2.34 - £2.34
£2.34
£2.34 - £2.34
£2.34
4sr38-pilot-bore-08b-1-2-pitch-sprocket

4SR38 (08B-1-38) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 38 Tooth

£9.98 - £9.98
£9.98
£9.98 - £9.98
£9.98

4SR38 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR38 Pitch 1/2 Teeth 38 Outside Dia (mm) 158.6 ...

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£9.98 - £9.98
£9.98
£9.98 - £9.98
£9.98
4sr36-pilot-bore-08b-1-2-pitch-sprocket

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

£9.50 - £9.50
£9.50
£9.50 - £9.50
£9.50

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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£9.50 - £9.50
£9.50
£9.50 - £9.50
£9.50
4sr25-pilot-bore-08b-1-2-pitch-sprocket

4SR25 (08B-1-25) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 25 Tooth

£5.86 - £5.86
£5.86
£5.86 - £5.86
£5.86

4SR25 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR25 Pitch 1/2 Teeth 25 Outside Dia (mm) 105.8 ...

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£5.86 - £5.86
£5.86
£5.86 - £5.86
£5.86
4sr23-pilot-bore-08b-1-2-pitch-sprocket

4SR23 (08B-1-23) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 23 Tooth

£5.44 - £5.44
£5.44
£5.44 - £5.44
£5.44

4SR23 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR23 Pitch 1/2 Teeth 23 Outside Dia (mm) 98.2 ...

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£5.44 - £5.44
£5.44
£5.44 - £5.44
£5.44
4sr22-pilot-bore-08b-1-2-pitch-sprocket

4SR22 (08B-1-22) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 22 Tooth

£5.17 - £5.17
£5.17
£5.17 - £5.17
£5.17

4SR22 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR22 Pitch 1/2 Teeth 22 Outside Dia (mm) 93.8 ...

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£5.17 - £5.17
£5.17
£5.17 - £5.17
£5.17
4sr21-pilot-bore-08b-1-2-pitch-sprocket

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

£4.87 - £4.87
£4.87
£4.87 - £4.87
£4.87

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 ...

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£4.87 - £4.87
£4.87
£4.87 - £4.87
£4.87
4sr08-pilot-bore-08b-1-2-pitch-sprocket

4SR08 (08B-1-08) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 8 Tooth

£0.90 - £0.90
£0.90
£0.90 - £0.90
£0.90

4SR08 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR08 Pitch 1/2 Teeth 8 Outside Dia (mm) 37.2 ...

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£0.90 - £0.90
£0.90
£0.90 - £0.90
£0.90

4SR25 32mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 25 Tooth

£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

Roller Chain Sprocket 08B 4SR25 32mm Bore Key & 2 Set Screws 1/2" Pitch 25 ToothChain Pitch:08B-1Number of Teeth:25Bore & Keyway(mm):32mmMf...

View full details
£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

4SR25 25mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 25 Tooth

£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

Roller Chain Sprocket 08B 4SR25 25mm Bore Key & 2 Set Screws 1/2" Pitch 25 ToothChain Pitch:08B-1Number of Teeth:25Bore & Keyway(mm):25mmMf...

View full details
£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

4SR25 20mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 25 Tooth

£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

Roller Chain Sprocket 08B 4SR25 20mm Bore Key & 2 Set Screws 1/2" Pitch 25 ToothChain Pitch:08B-1Number of Teeth:25Bore & Keyway(mm):20mmMf...

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£17.06 - £17.06
£17.06
£17.06 - £17.06
£17.06

4SR21 20mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 21 Tooth

£13.79 - £13.79
£13.79
£13.79 - £13.79
£13.79

Roller Chain Sprocket 08B 4SR21 20mm Bore Key & 2 Set Screws 1/2" Pitch 21 ToothChain Pitch:08B-1Number of Teeth:21Bore & Keyway(mm):20mmMf...

View full details
£13.79 - £13.79
£13.79
£13.79 - £13.79
£13.79

4SR20 35mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 20 Tooth

£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

Roller Chain Sprocket 08B 4SR20 35mm Bore Key & 2 Set Screws 1/2" Pitch 20 ToothChain Pitch:08B-1Number of Teeth:20Bore & Keyway(mm):35mmMf...

View full details
£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

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

£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

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
£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

4SR20 25mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 20 Tooth

£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

Roller Chain Sprocket 08B 4SR20 25mm Bore Key & 2 Set Screws 1/2" Pitch 20 ToothChain Pitch:08B-1Number of Teeth:20Bore & Keyway(mm):25mmMf...

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£13.10 - £13.10
£13.10
£13.10 - £13.10
£13.10

4SR19 25mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 19 Tooth

£12.43 - £12.43
£12.43
£12.43 - £12.43
£12.43

Roller Chain Sprocket 08B 4SR19 25mm Bore Key & 2 Set Screws 1/2" Pitch 19 ToothChain Pitch:08B-1Number of Teeth:19Bore & Keyway(mm):25mmMf...

View full details
£12.43 - £12.43
£12.43
£12.43 - £12.43
£12.43

Hi. Need any help?