Screwheads and Tools: Understanding Spanner Screws, Shear Bolts, and Non-Tamperable Fasteners
The screwhead you're describing sounds like a spanner screw or a security screw. It features a single hole in the center designed to require a special tool for removal, similar to a spanner screw but without the additional holes. These screws are often used in applications where tampering needs to be minimized. For example, they might be found in security doors or electrical panels to prevent unauthorized access.
One specific use of a spanner screw might be in a preset metering valve. This type of valve is commonly used in carburetors, oil burner furnaces, and fuel injectors. To adjust the flow rate, you would need a scriber or something long and pointed. You would use the scriber to adjust the position, then lock it into place with a nut.
Presetting Metering Valves
The process of adjusting a preset metering valve involves several steps. First, you need to carefully note the current position. Then, you would loosen the nut a little, use the scriber to adjust the flow rate, and then retighten the nut. This ensures that the valve is set to the desired flow rate, which is crucial for proper operation in engines and fuel systems.
Shear Bolts: A Type of Non-Tamperable Fastener
From the picture you showed, that appears to be a shear bolt. A one-way screw with a breakaway head design, it is used where only a controlled break is needed to release the fastener. If it is a shear bolt, it should be removable with a typical bolt remover tool, commonly referred to as an E-Z-Out.
Removing a Shear Bolt:
If the bolt is not removable, you can gently center punch and drill out the bolt. This will allow you to remove the bolt more easily.
Once you have the bolt drilled out, apply a suitable thread locker removal compound. Heat the hole slowly with a soldering iron or wood burner to break up the threadlocker. Be careful not to heat it too quickly, as the bolt is seated in aluminum, which heats up faster than steel.
Use a can of butane to blast the hole after it has been slowly warmed up to the point where it is too hot to touch. This will cause the threads to loosen, allowing the bolt to be removed more easily.
By following these steps, you can effectively remove even the most stubborn shear bolts.
Conclusion
Gaining a better understanding of these specialized screwheads and the tools required to remove them can be invaluable in various industries, from automotive to aerospace. Whether you need to secure sensitive equipment or remove worn-out fasteners, knowing the right methods and tools can save time and effort.
Related Keywords: spanner screw, shear bolt, thread locker removal