Quick Answer
Mountz Bit Holder Wrench Heads are interchangeable heads for compatible TBIH and TBX-12 break-over torque wrenches. They provide a stable interface for standard 4 mm or 1/4-inch bits, depending on the holder. The 4 mm Bit Holder is qualified to 5.65 N·m (50 lbf·in), while the 1/4-inch Bit Holder is qualified to 12 N·m (106 lbf·in). Actual allowable torque depends on the complete combination of the bit holder, bit, and torque wrench.
What Is a Bit Holder Wrench Head?
A Bit Holder Wrench Head allows a compatible break-over torque wrench to be used with interchangeable bits.
Mountz offers Bit Holder Wrench Heads for:
- TBIH break-over torque wrenches
- TBX-12 break-over torque wrenches
Mountz describes the holders as providing a stable interface for interchangeable insert and power bits.
Available Bit Holder Sizes
Mountz offers Bit Holder Wrench Heads designed to accept standard:
- 4 mm bits
- 1/4-inch bits
The specific holder should be selected based on the bit required for the fastening application.
View Bit Holder Wrench Heads:
- Bit Holder Wrench Heads for TBIH
- Bit Holder Wrench Heads for TBX-12
Maximum Torque Capacity
The Bit Holder itself has a documented qualification rating based on its size:
| Bit Holder | Qualified Torque |
|---|---|
| 4 mm | 5.65 N·m (50 lbf·in) |
| 1/4" | 12 N·m (106 lbf·in) |
These ratings apply to the holder itself under qualification testing.
The maximum allowable torque for an actual application depends on the complete combination of:
- Bit Holder
- Bit
- Torque wrench
The limiting component may be either the holder or the bit. A lower-strength bit may therefore reduce the allowable torque below the holder's qualified rating.
Mountz recommends validating the specific bit and holder combination before use, particularly for critical or safety-related assemblies.
Bit Compatibility
Mountz Bit Holder Wrench Heads are designed to accept standard off-the-shelf 1/4-inch and 4 mm bits.
Select the appropriate Bit Holder based on the bit size and fastening application.
Can the Bit Be Replaced?
Yes. The bit can be replaced, but the replacement process requires controlled removal and installation.
According to Mountz, each Bit Holder is engineered to support five bit replacements without degradation to performance or accuracy when proper installation procedures are followed.
Because the bit is secured using a retaining compound, Mountz recommends that replacement be performed by the Mountz service team or a qualified technician.
How Is the Bit Installed?
Mountz specifies Loctite 609 retaining compound for securing the bit in the Bit Holder.
When installing a new bit:
- Clean the bore and new bit shank thoroughly.
- Apply Loctite 609.
- Allow appropriate curing time.
- Recalibrate the tool before returning it to service.
How Is a Bit Removed?
Because Loctite 609 creates a high-strength bond, removing the bit requires force.
Mountz identifies two methods:
- Mechanical Force: Use a high-strength press, such as a hydraulic press, to push the bit out.
- Heat + Force: Apply controlled heat to soften the retaining compound, followed by mechanical force to remove the bit.
Avoid excessive side-loading or prying, which may damage the holder.
Because special tooling and controlled processes may be required, Mountz recommends contacting Technical Support or having a qualified technician perform bit replacement.
When Is Recalibration Required?
Mountz specifies recalibration when:
- The bit is changed.
- The torque setting is adjusted.
- The tool experiences an overload or impact.
- The periodic calibration interval is reached.
If torque performance falls outside the specified ±6% accuracy, the tool should be recalibrated or inspected.
Changing the bit or repurposing the Bit Holder for a different fastening application therefore requires recalibration before returning the wrench to service.
Material & Construction
The Bit Holder is manufactured from 17-4 PH stainless steel for strength and corrosion resistance.
This material specification applies to the Bit Holder itself and does not necessarily apply to the installed bit.
The current Mountz 4 mm Bit Holder product page also confirms 17-4 PH stainless steel construction and states that the holder is cycle-tested for repeatable torque application across its qualification range.
Can Custom Bit Holders Be Requested?
Yes. Mountz offers custom Bit Holder configurations for specialized applications.
Examples identified by Mountz include:
- Specialized head geometries
- Extended or reduced lengths
- Limited-access designs
- Application-specific designs
Custom configurations are evaluated individually for feasibility, performance, and lead time.
Requests exceeding published torque ratings are also treated as special requests and require Mountz review and engineering validation.
Selecting a Bit Holder Wrench Head
When selecting a Bit Holder, consider:
- Compatible torque wrench
- 4 mm or 1/4-inch bit requirement
- Bit type
- Required torque
- Torque capacity of both the holder and bit
- Application requirements
Do not select the Bit Holder based solely on its qualified torque rating. The complete bit + holder + wrench combination must be suitable for the application.
Media & Supporting Content
.png?width=670&height=838&name=Bit%20Holder%20Static%20Image%20(1).png)
- Bit Holder Wrench Heads FAQ
- TBIH Bit Holder Wrench Heads
- TBX-12 Bit Holder Wrench Heads
- Torque Wrench Head Selection Guide
Related Content
- Wrench Heads
- Open, Box & Flare Wrench Heads for TBIH & TBX-12 FAQ
- TBIH Break-Over Torque Wrenches
- TBX Break-Over Torque Wrenches
- Mountz Hand Tools Sales Bang Sheet
Need Help?
- Contact Applications Engineering for setup guidance
- Speak with Sales for product selection
- Call us:
- North America:(408) 850-9978
- International: +44 1428 741756
M-F 6am - 5pm PST
