The aluminum hex wrenches are used to install specialized bulkhead couplings. The steel open-end wrenches are for more mundane tasks where conventional wrenches aren’t quite right for the job.
When conventional store-bought wrenches don’t seem to do the job, most builders find themselves occasionally grinding down or bending a cheap wrench from the local, discount Chinese tool store. But for more challenging problems, our Creative Homebuilder suggests you take the process a step further and make your own (MYO). He has made a variety of simple wrenches for specific purposes when no existing wrench was available. The grip ends of the tools typically start life as a steel flat washer that is cut, filed, and welded onto a suitable steel flat stock handle.
The aluminum hex wrenches seen in the photos were used to install specialized bulkhead couplings designed for hose and tube pass-throughs of the firewall, fuel tanks, or side skins. Sometimes the install locations restrict access for conventional wrenches, but these custom hex units, with a slight offset bend in the handles, make for an easy and consistent installation. The open-end steel wrenches are for more mundane jobs, such as loosening the hole cutter from the mandrel on Blair Rotabroach cutters.
The aluminum hex wrench has a slight offset bend in the handle. The open-end wrench is made from a steel flat washer welded to a steel flat stock handle.
Tightening a “bug nut” on push-pull cables, such as mixture or other engine controls, provides another challenge in the pursuit of the perfect wrench. As one tightens the Allen-head or slot-head screw into the cylinder (bug nut) drilled to pass the control cable through, the entire cylinder tends to twist and kink the cable. Bug nuts often provide no purchase points to grab while tightening the retaining screw. Our Creative Homebuilder, with a little welding and cutting, made a simple tool to manage this problem.
The wrench that he created slips over the bug nut, allowing the control wire to pass through the cut slots while allowing access to the retaining screw head. As the retaining screw twists and tightens, the wires in the slot provide resistance and keep the bug nut from rotating.