The Borka Tools PTL-8 (8 Inch-Lbs Precision Torque Limiter) is a mechanical, factory-calibrated torque-limiting tool engineered for delicate firearms and precision optics assembly. Measuring 0.87" in outer diameter by 3.0" in length (22.1 mm x 76.2 mm) and weighing 3.5 oz (approx. 99 g), this non-powered hand tool delivers an exact, non-adjustable torque limit of 8 inch-pounds (0.90 Nm / 0.67 ft-lbs). Calibrated in clockwise rotation following ISO 6789 procedures, the unit operates within a tight factory accuracy tolerance of ±1% to ±3%. It features a 3/8" square drive female input for compatibility with standard manual ratchets or T-handles, and a 1/4" female hex drive output to accept standard driver bits, ensuring consistent fastener tension without thread stripping or component deformation.

Key Features

• Factory-Preset 8 In-Lbs Calibration: Delivers precise mechanical release at 8 inch-pounds (0.90 Nm) with ±1% to ±3% accuracy, exceeding standard ISO ±4% requirements.
• Bi-Directional Limiting Mechanism: Limits torque in both clockwise (tightening) and counter-clockwise (loosening) directions to protect internal mechanics from damage during heavy breakaway loads.
• Tamper-Resistant Construction: Includes an internally sealed manufacturer calibration screw that maintains exact factory tolerances and prevents unauthorized adjustments.
• Universal Drive Interfaces: Integrates a 3/8" square drive input for manual ratchets alongside a standard 1/4" hex drive output for small-diameter driver bits.
• Fragile Fastener Protection: Safely operates below the critical shear thresholds of small-dimension hardware, including 1/16" hex bits (rated to 10 in-lbs working limits).

Technical Specifications

• Preset Torque: 8 inch-pounds / 0.90 Nm / 0.67 ft-lbs
• Torque Calibration Standard: ISO 6789 procedures (CW rotation)
• Calibration Accuracy: ±1% to ±3%
• Input Drive: 3/8" square drive (female)
• Output Drive: 1/4" hex drive (female socket)
• Dimensions: 0.87" OD x 3.0" L (22.1 mm x 76.2 mm)
• Weight: 3.5 oz (approx. 99 g)
• Operation Type: Non-powered, purely mechanical hand tool

Who is the Borka Tools 8 Inch-Lbs Precison Torque Limiter for?

• Precision rifle competitors — requires an exact 8 inch-pounds limit to securely adjust fragile scope turret caps, zero-stop mechanisms, and elevation/windage set screws in the field without stripping micro-fasteners.
• Hunters maintaining high-end riflescopes — relies on a compact 3.5 oz precision torque limiter tool that couples directly with 3/8" square drive handles to service delicate optics hardware at the range or in camp.
• Custom gunsmiths — needs a dedicated 8 inch-pounds mechanical limiter with a 1/4" hex drive to prevent exceeding the structural 10 in-lb working thresholds of fine 1/16" driver bits during precision optic assembly.

Less suitable for: Fasteners requiring torque exceeding 8 in-lbs (such as scope ring caps at 15–20 in-lbs, optic bases at 25–45 in-lbs, or action screws at 45–65 in-lbs), which require an adjustable 10–70 in-lbs torque driver or higher-rated dedicated limiters; and high-speed operation, as this mechanical limiter is strictly prohibited from use with powered drills, electric drivers, or impact tools.