BRM Demonstrates How Flex-Hone® Tools Surface Finish Aircraft Spars

Brush Research Manufacturing (BRM), USA maker of flexible honing tools and a full line of industrial brushes, is announcing user feedback about Flex-Hone® technology for aircraft building.

Cylinder Honing for Aluminum Spars

As BRM's on-line article explains, Flex-Hone® tools are not designed for heavy-duty material removal. The flexible cylinder hones are not built to correct part geometries either. Hobbyists sometimes use ball hones in non-conventional ways, however, and demonstrate how Flex-Hone® technology is versatile, reliable, and easy-to-use with any type or size cylinder.

With the BD-4C airplane, the tube-like spar has a 6.5-in. inner diameter (ID) and runs the entire length of the wing. As the hobbyist in BRM's article discovered, however, the ends of this aluminum cylinder can be slightly oval-shaped instead of perfectly circular. By honing the cylinder walls with Flex-Hone® tools, the aircraft builder removed enough metal from the bore so that the spars could fit the fuselage.

How to Use Flexible Honing Tools

As BRM's new article explains, flexible cylinder hones can be mounted in handheld power tools such as electric drills. Built with a stiff, double-wire metal steam, the Flex-Hone® tool's most distinctive feature is the abrasive balls or globules that are permanently laminated to flexible nylon filaments. The BRM ball hone's low-temperature, low-pressure abrading process provides a soft cutting action.

Although the BD-4 aircraft builder honed the cylinder walls for longer than BRM recommends, the user's overall experience is instructive. For example, by honing with a coarser-grit Flex-Hone® and then a finer-grit tool, the hobbyist achieved a smooth surface finish that facilitated part assembly.