VÖLKEL Thread Repair Kits, BSF 5/16 - 1,5D

The V-COIL Thread Repair Kit BSF 5/16 x 22 - 1.5D is a complete repair kit for damaged, stripped or worn BSF internal threads. It brings together the STI short machine tap, STI twist drill, manual inserting tool, tang break tool and free-running Type S wire thread inserts required for a controlled repair sequence. Selection is based on the BSF 5/16 x 22 thread designation, the 1.5D insert length and the corresponding STI preparation with the 8.3 mm STI drill.

VÖLKEL Thread Repair Kits, BSF 5/16 - 1,5D

Features and applications

The V-COIL Thread Repair Kit BSF 5/16 x 22 - 1.5D is a complete repair kit for damaged, stripped or worn BSF internal threads. It brings together the STI short machine tap, STI twist drill, manual inserting tool, tang break tool and free-running Type S wire thread inserts required for a controlled repair sequence. Selection is based on the BSF 5/16 x 22 thread designation, the 1.5D insert length and the corresponding STI preparation with the 8.3 mm STI drill.

BSF designates a British Whitworth fine thread to BS 84 with a 55° flank angle. It is found on older British vehicles, machinery and spare parts. The repair does not simply recut the original internal thread. Instead, an STI receiving thread is produced first, and the stainless steel wire thread insert is then installed to restore the usable internal thread in the parent material.

Applications

• for repairing damaged or worn BSF 5/16 x 22 internal threads
• for components where the original internal thread no longer provides reliable holding force
• for thread reinforcement in materials with lower shear strength, such as aluminium and magnesium alloys
• for creating a durable internal thread with a free-running Type S wire thread insert
• for maintenance workshops, assembly work, service departments, machine building and metalworking
• Process: manual or assisted drive depending on your tool holder and machine configuration
• Use: thread cutting, thread recutting and thread cleaning depending on the condition of the thread

Benefits

• complete kit configuration for BSF 5/16 x 22 internal thread repair
• STI drill and STI tap are matched to the wire thread insert repair process
• 20 included wire thread inserts allow several repairs in the same thread size
• Type S is free running and restores a normal internal thread without a locking effect.
• stainless steel wire thread inserts support a strong and corrosion-resistant internal thread
• useful for service jobs where component replacement should be avoided
• the plastic case protects the individual parts and simplifies workshop organisation

Application limits

• The repair is only reliable when drilling, STI tapping and insert depth are carried out cleanly; follow the kit sequence carefully from preparation to final inspection.

Step by step

1. Inspect the damaged internal thread and confirm that the component structure is suitable for a wire thread insert repair.
2. Securely align the component and make sure the tool axis follows the existing thread axis.
3. Drill out the damaged thread area using the included 8.3 mm STI twist drill.
4. Cut the STI receiving thread with the STI short machine tap and a suitable cutting lubricant.
5. Clean the receiving thread thoroughly and remove all chips from the repair area.
6. Place the wire thread insert into the inserting tool and guide it straight to the receiving thread.
7. Install the insert in a controlled movement in the thread direction until the intended installation position is reached; never turn it against the running direction.
8. Remove the driving tang with the tang break tool.
9. Check the repaired thread with a matching screw or suitable inspection method.

Used together with

Each component in the kit has its own VÖLKEL item number for reordering.

• STI Short Machine Tap ISO 529 Form D HSS-G - BSF 5/16 x 22: item 03255
• STI-Twist Drill, 8.3 mm: item 00083
• V-COIL Inserting Tool No. 11: item 08011
• Tang Break Tool No. 11: item 07011
• V-COIL Wire thread insert Free running type S BSF 5/16 x 22 - 1.5 D: item 08365

How to choose

Before starting the repair, check the thread designation, component condition, wall thickness and available installation depth. Stable alignment is essential so the insert seats correctly in the STI thread.