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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.

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

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

£9.83 - £9.83
£9.83
£9.83 - £9.83
£9.83

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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£9.83 - £9.83
£9.83
£9.83 - £9.83
£9.83
4sr30-pilot-bore-08b-1-2-pitch-sprocket

4SR30 (08B-1-30) - BS Simplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 30 Tooth

£7.13 - £7.13
£7.13
£7.13 - £7.13
£7.13

4SR30 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-1 Simplex Chain Part Number 4SR30 Pitch 1/2 Teeth 30 Outside Dia (mm) 126.1 ...

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£7.13 - £7.13
£7.13
£7.13 - £7.13
£7.13
4sr23-pilot-bore-08b-1-2-pitch-sprocket

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

£5.63 - £5.63
£5.63
£5.63 - £5.63
£5.63

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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£5.63 - £5.63
£5.63
£5.63 - £5.63
£5.63
4sr22-pilot-bore-08b-1-2-pitch-sprocket

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

£5.36 - £5.36
£5.36
£5.36 - £5.36
£5.36

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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£5.36 - £5.36
£5.36
£5.36 - £5.36
£5.36
4sr21-pilot-bore-08b-1-2-pitch-sprocket

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

£5.04 - £5.04
£5.04
£5.04 - £5.04
£5.04

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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£5.04 - £5.04
£5.04
£5.04 - £5.04
£5.04
4sr08-pilot-bore-08b-1-2-pitch-sprocket

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

£0.93 - £0.93
£0.93
£0.93 - £0.93
£0.93

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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£0.93 - £0.93
£0.93
£0.93 - £0.93
£0.93

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

£17.67 - £17.67
£17.67
£17.67 - £17.67
£17.67

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...

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£17.67 - £17.67
£17.67
£17.67 - £17.67
£17.67

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

£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

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...

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£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

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

£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

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...

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£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

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

£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

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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£13.57 - £13.57
£13.57
£13.57 - £13.57
£13.57

4SR18 22mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 18 Tooth

£11.88 - £11.88
£11.88
£11.88 - £11.88
£11.88

Roller Chain Sprocket 08B 4SR18 22mm Bore Key & 2 Set Screws 1/2" Pitch 18 ToothChain Pitch:08B-1Number of Teeth:18Bore & Keyway(mm):22mmMf...

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£11.88 - £11.88
£11.88
£11.88 - £11.88
£11.88

4SR16 20mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 16 Tooth

£10.89 - £10.89
£10.89
£10.89 - £10.89
£10.89

Roller Chain Sprocket 08B 4SR16 20mm Bore Key & 2 Set Screws 1/2" Pitch 16 ToothChain Pitch:08B-1Number of Teeth:16Bore & Keyway(mm):20mmMf...

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£10.89 - £10.89
£10.89
£10.89 - £10.89
£10.89

4SR15 30mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 15 Tooth

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

Roller Chain Sprocket 08B 4SR15 30mm Bore Key & 2 Set Screws 1/2" Pitch 15 ToothChain Pitch:08B-1Number of Teeth:15Bore & Keyway(mm):30mmMf...

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

4SR15 15mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 15 Tooth

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

Roller Chain Sprocket 08B 4SR15 15mm Bore Key & 2 Set Screws 1/2" Pitch 15 ToothChain Pitch:08B-1Number of Teeth:15Bore & Keyway(mm):15mmMf...

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

4SR15 14mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 15 Tooth

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

Roller Chain Sprocket 08B 4SR15 14mm Bore Key & 2 Set Screws 1/2" Pitch 15 ToothChain Pitch:08B-1Number of Teeth:15Bore & Keyway(mm):14mmMf...

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

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

£9.68 - £9.68
£9.68
£9.68 - £9.68
£9.68

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...

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£9.68 - £9.68
£9.68
£9.68 - £9.68
£9.68

4SR12 18mm Bore, Keyway & Grub Screws Roller Chain Sprocket 1/2" Pitch 12 Tooth

£8.84 - £8.84
£8.84
£8.84 - £8.84
£8.84

Roller Chain Sprocket 08B 4SR12 18mm Bore Key & 2 Set Screws 1/2" Pitch 12 ToothChain Pitch:08B-1Number of Teeth:12Bore & Keyway(mm):18mmMf...

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£8.84 - £8.84
£8.84
£8.84 - £8.84
£8.84

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

£8.84 - £8.84
£8.84
£8.84 - £8.84
£8.84

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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£8.84 - £8.84
£8.84
£8.84 - £8.84
£8.84
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

£15.91 - £15.91
£15.91
£15.91 - £15.91
£15.91

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...

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£15.91 - £15.91
£15.91
£15.91 - £15.91
£15.91
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

£28.85 - £28.85
£28.85
£28.85 - £28.85
£28.85

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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£28.85 - £28.85
£28.85
£28.85 - £28.85
£28.85
4tr14-pilot-bore-08b-1-2-pitch-sprocket

4TR14 (08B-3-14) - BS Triplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 14 Tooth

£5.67 - £5.67
£5.67
£5.67 - £5.67
£5.67

4TR14 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-3 Triplex Chain Part Number 4TR14 Pitch 1/2 Teeth 14 Outside Dia (mm) 61.8 ...

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£5.67 - £5.67
£5.67
£5.67 - £5.67
£5.67
4dr21-pilot-bore-08b-1-2-pitch-sprocket

4DR21 (08B-2-21) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 21 Tooth

£7.22 - £7.22
£7.22
£7.22 - £7.22
£7.22

4DR21 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR21 Pitch 1/2 Teeth 21 Outside Dia (mm) 89.7 ...

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£7.22 - £7.22
£7.22
£7.22 - £7.22
£7.22
4dr20-pilot-bore-08b-1-2-pitch-sprocket

4DR20 (08B-2-20) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 20 Tooth

£5.97 - £5.97
£5.97
£5.97 - £5.97
£5.97

4DR20 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR20 Pitch 1/2 Teeth 20 Outside Dia (mm) 85.8 ...

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£5.97 - £5.97
£5.97
£5.97 - £5.97
£5.97
4dr14-pilot-bore-08b-1-2-pitch-sprocket

4DR14 (08B-2-14) - BS Duplex Roller Chain Sprocket Pilot Bore 08B 1/2" - 14 Tooth

£4.15 - £4.15
£4.15
£4.15 - £4.15
£4.15

4DR14 Pilot Bore 08B 1/2" Pitch Sprocket For use with 08B-2 Duplex Chain Part Number 4DR14 Pitch 1/2 Teeth 14 Outside Dia (mm) 61.8 ...

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£4.15 - £4.15
£4.15
£4.15 - £4.15
£4.15

Hi. Need any help?