BRM's Flexible Honing, Surface Finishing, and Deburring Blog Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog is the place for conversation and discussion about how to solve difficult finishing problems. For over 50 years, Brush Research Manufacturing (BRM) has helped customers use brushing technology to clean, rebuild, and resurface components ranging from engine cylinders to brake rotors to flywheels to firearms. BRM's Blog on CR4 provides real-world examples of how flex hones and wire brushes work. It also evaluates related technologies and invites questions from the community.

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Ball Hones for Cylinder Wall Deglazing and Engine Rebuilds

Posted December 10, 2013 9:36 AM by Brush Research

Flexible honing tools have a few nicknames. Although our surface finishing solutions are known by the trade name Flex-Hone, some users call our tools ball hones because of their abrasive globules. Other users prefer names like grape hones, bead hones, bottle brush hones, and even dingleberry hones.

Flex-Hone tools are also called cylinder hones because they're used for rebuilding car, truck, and motorcycle engines. When engine blocks are manufactured, OEMs typically use large honing machines to size the bores. These tools are suitable for material removal, but it's difficult to match the controlled surface condition of the Flex-Hone for engine rebuilds. The plateau finish that a BRM engine hone imparts optimizes lubrication, reduces wear, and promotes piston ring seating and sealing.

Cylinder Deglazing Brush Tools

Over time, a piston's reciprocating movement polishes cylinder walls or liners and prevents engine oil from adhering properly. Instead of a uniformly-spaced series of grooves, the cylinder gets a "glaze" that can cause engine problems. Left unbroken, this overly-smooth finish impedes lubrication and increases friction. If the cylinder walls or liners are polished to a mirror finish, the piston rings can't provide a tight enough seal. This surface finishing problem affects diesel engines as well as gasoline-powered ones.

For automotive mechanics who rebuild engines then, cylinder wall deglazing is an important task. For The Bug Boys, a blogger who describes engine rebuilds and other automotive projects, the right tool for the job is the BRM Flex-Hone. Although some engine mechanics refer to our cylinder hone as a glaze breaker hone or a glaze buster hone, The Bug Boys writes about ball hones. During a recent rebuild of a Saturn engine, for example, the blogger explained that "I used a ball hone and it worked great."

How to Ball Hone a Cylinder

Although some manufacturers mount Flex-Hone tools in machine centers, hobbyists like The Bug Boys typically use a handheld electric drill. Versatile and easy-to use, BRM ball hones are self-centering, self-aligning to the bore, and self-compensating for wear. These engine hones require the use of a lubricant or honing oil, and should be inserted into the bore while the cylinder hone is spinning. Recommended revolutions per minute (RPM) vary with the diameter of the brush tool and the application.

As the Flex-Hone Resource Guide explains, BRM ball hones are low RPM tools. We're not sure which size tool The Bug Boys used, but its diameter was probably between 1/2" and 2" since he reported good results at 1000 RPM. The mechanic also followed best practices by starting slowly, increasing the RPMs, and then exiting the bore with the tool still spinning. "I got better cross hatch marks and a cleaner cylinder," he explained, adding that "your cross hatch marks should be about 45 degrees."

Finally, the engine mechanic cleaned the newly-honed cylinders and lubricated them with motor oil. As Flex-Hone users like Caterpillar know, the best way to clean a ball honed cylinder is with warm or hot soapy water and a cylinder washing brush. Lubrication is essential before installing the piston rings, which will now seat properly because the cylinder walls are deglazed and the Flex-Hone tool has imparted an optimum surface finish.


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