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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.

Flexible Honing for Engines

Posted July 21, 2014 4:54 PM by Brush Research

Do you rebuild gasoline or diesel engines? How about engine components such as valves, connecting rods, or crankshafts? Whether you're a professional engine mechanic or a dedicated do-it-yourselfer, Brush Research Manufacturing (BRM) offers surface finishing solutions that are versatile, reliable, and easy-to-use. BRM Flex-Hone tools can be used with a handheld electric drill, and do not require special training, expensive equipment, or complex setups or clean-ups.

Engine Cylinders

Flexible honing tools improve surface finish and remove burrs at the same time. Designed for inner diameter (ID) applications, BRM's flexible cylinder hones are also known as ball hones because of their distinctive appearance. Made with abrasive globules that are permanently laminated to flexible nylon filaments, ball hones are self-centering, self-aligning to the bore, and self-compensating for wear. Always use these engine hones with a lubricant, preferably BRM's specially formulated Flex-Hone oil.

With its low-temperature, low-pressure abrading process, flexible honing produces a substantially flat surface that's free of jagged peaks and cut, torn, or folded metal. The plateau finish that the Flex-Hone imparts features a cross-hatch pattern of oil-retaining valleys for optimum lubrication. With used engine cylinders, BRM ball hones can be used to break the glaze-like finish that forms on cylinder walls. In this way, cylinder deglazing promotes proper lubrication along with piston ring seating and sealing.

BRM engine hones are ideal for cylinder wall surface finishing, but they're not designed for heavy-duty material removal. Rigid hones can impart an uneven or unidirectional crosshatch, but honing stones are recommended for initial honing, cylinder resizing, and geometry correction. When selecting honing tools for cylinder wall surface finishing then, use the BRM Flex-Hone to deglaze or surface finish the walls of cylinders that are not out-of-round or that require resizing.

Engine Components

As BRM's Flex-Hone Blog attests, professional and DIY mechanics alike are using flexible honing tools to deburr, deglaze, and surface finish engine cylinders. These aren't the only engine-related applications for Flex-Hone® technology, however, as BRM explains on the automotive industry page of its website. In addition to these on-line resources, MSB Tuning has documented its own experiences using flexible cylinder hones on engine components.

In Flex-Hone Applications for Engines, the engine tuner describes the successful surface finishing of main bearing tunnels, conrod big-end tunnels, OHC camshaft tunnels, valve guides, DOHL lifter bores, and in-block hydraulic lifter bores. The engine shop also notes "miscellaneous uses" such as with water pump tubing. "If there is a hole and I need to surface finish it," the author explains, "then I Flex-Hone it".

Available for any type or size cylinder, Flex-Hone tools come in a variety of abrasive types and grit sizes. For example, to surface finish a connecting rod, MSB Tuning used an 800-grit silicon carbide (SC) cylinder hone. To impart a very fine fish, the tuner talked about using aluminum oxide (AO) instead. For complete information about abrasive selection, tool selection, and ball hone use, download the Flex-Hone Resource Guide from the BRM website today.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.

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DIY Disc Brake Rotor Resurfacing

Posted July 14, 2014 1:05 PM by Brush Research

Do your disc brakes squeak or squeal? As DSPORT magazine explains in a new article, and as Brush Research Manufacturing (BRM) shows in a new YouTube video, you may want to look at your brake rotors. Brake pad glaze and surface corrosion are common causes of noisy disc brakes. Fortunately, there's a surface finishing solution that's as easy-to-use as a power drill. Trusted by professional and DIY brake mechanics alike, the Flex-Hone for Rotors is ideal for new and turned rotors.

Rotor Refurbishment

In Glaze is for Donuts: Do-It-Yourself Disc Brake Resurfacing, Jun Chen of DSPORT magazine explains why BRM's Flex-Hone for Rotors is the right tool for rotor refurbishment. For years, Flex-Hone users such as machine shops, manufacturers, and engine builders have been using flexible hones to improve the surface finish of cylinder walls. The Flex-Hone for Rotors is designed for flat surfaces instead, but uses BRM's Flex-Hone technology to impart a superior, non-directional surface finish.

As the "Quick Tech" article in DSPORT's August edition explains, some motorists blame vibrations while braking on warped rotors. Most modern rotors are made of iron, however, and are unlikely to warp because of this metal's hardness and stability. Typically then, brake vibration is caused an uneven layer of material that's transferred from the brake pad to the brake rotor. Improper pad bedding isn't the only cause of brake problems, however, as surface corrosion and improper machining may be to blame.

Brush Tool Selection and Use

Suitable for use with a handheld electric drill, the Flex-Hone for Rotors comes in coarse, medium, and fine grits. Coarse-grit brush tools remove heavy buildup and corrosion. They also remove sharp edges on rotor slots and cross-drilled holes that can contribute to rotor cracking. Medium-grit Flex-Hone for Rotors tools also remove layers of pad material, but impart a smoother surface. Fine-grit flexible rotor hones impart the finest finish of all, and may be used after coarse-grit and then medium-grit tools.

To test the Flex-Hone for Rotors under real-world conditions, DSPORT magazine acquired four brake rotors from a race car with some time at the track. Equipped with cordless drill and a coarse-grit brush tool, the crew removed the transfer layer from each rotor's face. The DIY mechanics then switched to a medium-grit tool, and finally to a fine-grit tool. Because the Flex-Hone for Rotors is self-leveling and applies uniform pressure, keeping the brush tool square and flat was an easy task.

Best Practices for Resurfacing Brake Rotors

"Be sure to have at least a 50-percent overlap between passes to ensure that no rough our untouched edges remain," author Jun Chen advised DSPORT readers. As BRM explains in its Flex-Hone for Rotors brochure, users should work in towards the center and then out to the edge, applying light pressure to the rotor's face. Rotate the tool between 300 and 600 RPM, and remember that dwell time - not excessive pressure - produces the desired finish.

BRM also advises Flex-Hone for Rotors users to hold the rotor in a brake lathe, and to spin the rotor between 125 and 210 RPM during honing. DSPORT magazine recognized that some DIY brake mechanics don't have a lathe, however, so its crew placed the brake rotors on a workbench. "This process will leave a finish very similar to a new rotor", the author explained before concluding that "the Flex-Hone for Rotors can help you save a few bucks and get rid of that annoying brake judder for good.

Flex-Hone for Rotors users to hold the rotor in a brake lathe, and to spin the rotor between 125 and 210 RPM during honing. DSPORT magazine recognized that some DIY brake mechanics don't have a lathe, however, so its crew placed the brake rotors on a workbench. "This process will leave a finish very similar to a new rotor", the author explained before concluding that "the Flex-Hone for Rotors can help you save a few bucks and get rid of that annoying brake judder for good.

Author's Note: This CR4 blog entry originally appeared in BRM's Flex-Hone Blog.

17 comments; last comment on 07/18/2014
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Made in the USA Surface Finishing Solutions

Posted June 30, 2014 2:59 PM by Brush Research

What does the Fourth of July mean to American manufacturers? Independence Day is about more than parades and fireworks, of course, but many shops are closed so that their employees can enjoy the summer holiday. Brush Research Manufacturing (BRM) is no exception here, but we'd like to use this important occasion to remind readers that Made in America craftsmanship is truly exceptional.

Over a half-century ago, a Canadian immigrant named Steve Rands came to Los Angeles, California to build a better life. As the founder of BRM, he invented a flexible honing tool for surface finishing and deburring cylinder walls. Today, some 55 years later, the Flex-Hone is well-known worldwide. Available for any type or size cylinder, BRM ball hones have a long history of solving surface finishing challenges.

Flex-Hone Technology

Self-centering, self-aligning to the bore, and self-compensating for wear, BRM cylinder hones feature abrasive globules that are permanently laminated to the ends of flexible nylon filaments. The surface finishing and deburring tool's soft cutting action and low-temperature, low-pressure abrading process imparts a substantially flat or plateau finish with oil-retaining grooves for optimum lubrication.

Available in a wide variety of abrasive types, grit sizes, and diameters, flexible honing tools are trusted by manufacturers, machinists, metalworkers, engine mechanics, gunsmiths, and hobbyists. Built with a stiff, double-wire metal stem, Flex-Hone tools mount in handheld electric drills, as well as production machinery such as transfer lines, robotic cells, and CNC machine centers.

At manufacturing facilities across the United States and around the world, flexible cylinder honing tools are also used for edge blending and deburring, the process of removing cut, torn, folded, and jagged metal that's produced during machining. Flex-Hone applications include chamfering, which removes stress risers and micro-burrs that can interfere with machined components.

Supply Chain Strength

Flexible honing tools are used in a range of industries, and by large manufacturers with names that many Americans would recognize. Brush Research has grown since its founding in 1958, but is still a privately-owned company that builds and maintains strong relationships with its customers. Because BRM can react quickly to meet your needs, we do more than ship tools. We build supply chain strength.

Today, most of our products are Made in the USA, and we proudly employ 75 workers here in California. Through their hard work and commitment to quality, BRM also supplies hundreds of distributors across the United States and exports surface finishing solutions to more than 50 countries worldwide. From our consolidated headquarters in Los Angeles, BRM provides quick turnaround times on orders.

Our proximity to the Port of Los Angeles helps us to meet the needs of international partners, and our expertise in export shipping means that that we know how to deliver the brush tools you need - and when you need them. For more about our company and products, please visit the BRM website and watch this short YouTube video.

Enjoy July Fourth, everyone, and let's celebrate Made in the USA manufacturing.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.

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How to Select Twisted-in-Wire Brushes

Posted June 24, 2014 8:55 AM by Brush Research

Twisted-in-wire brushes are used for cross-hole deburring, the process of removing burrs from the intersections of cross-drilled holes. These industrial brush tools are also used for removing soot and carbon deposits from pipes, and for cleaning holes, flues, and threads. Because twisted-in-wire brushes can internally clean and deburr hard-to-reach places, these versatile brushing tools are helping leading manufacturers solve surface finishing challenges.

For industrial buyers, selecting twisted-in-wire brushes requires an understanding of brush types and specifications, especially filament type and tool diameter. Application requirements and Series-level options are also important to consider. Brush Research Manufacturing (BRM), an American supplier of surface finishing solutions, provides four major types of twisted-in-wire brushes: cross-hole deburring, thread cleaning, flue, and tube. Miniature cross-hole deburring tools are also available.

Cross-Hole Deburring Brushes

Cross-hole deburring brushes are used to internally clean and deburr cross-drilled holes. Series 81-A brushing tools come in diameters as small as .024" for micro burr removal. These sturdy twisted-in-wire brushes have stainless steel filaments that are resistant to rust, and are designed specifically for thru-hole applications. Series 81-AY deburring tools are also used for thru-hole cleaning and burr removal, but have abrasive-filled nylon filaments and come in diameters as small as .032".

TIW-Series 85 cross-hole deburring tools are recommended for closed holes. Available in diameters from 1/8" to 3", these twisted-in-wire brushes can have filaments made of brass, steel, nylon, or natural fiber. Designed for blind hole or bottom end applications, BRM TIW-Series 85 brush tools are so versatile that they're used for surface preparation, internal cleaning, and the removal of small surface imperfections.

Thread Cleaning Brushes and Flue Brushes

As their name suggests, thread cleaning brushes are used for cleaning pipe threads. BRM Series 83 brushing tools are twisted-in-wire brushes that are used also for deburring, de-scaling, and rust removal. Available in diameters from 1/4" to 2", pipe thread cleaners can have filaments made of brass, carbon steel, stainless steel, or nylon. BRM also supplies butterfly-type brush tools for all popular screw threads in diameters from 1/4" to 1-1/4". This type of brushing tool can be used also on tapered screw threads.

Flue brushes are twisted-in-wire brushes for removing soot and carbon deposits from pipes, and for cleaning tube sheets. These industrial brushes are available for various bore sizes and feature brass, carbon steel, stainless steel, or nylon filaments. BRM Series 90 flue brushes have a four-wire, double-wire spiral construction. Series 92 adapter-type flue brushes feature a double-stem, double-spiral construction instead. Typically, pipe nipples are attached to flue brushes.

Tube Brushes

Tube brushes or cylinder brushes are used for removing chips, dirt, oil, rust, and corrosion from the inside of holes. Series 83 twisted-in-wire brushes are general-purpose tube brushes that are cut for power and great for thread deburring, tube cleaning, de-scaling, and rust removal. Series 84 brush tools are the only BRM tube brushes that feature ring or loop handles instead of metal mounting stems.

Brush Research Manufacturing also offers Series 85 brush tools for blind holes and bottom ends. Series 86 twisted-in-wire tube brushes have tufts to prevent scratches. Series 87 center brushes are designed for automated setups, and Series 88 tapered brushes are suitable for powered operation or manual use. Series 89 condenser brushes are four-wire, single-spiral tube brushes that may include a pipe nipple.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.

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Flexible Honing for Airplane Parts

Posted June 10, 2014 6:36 AM by Brush Research

The Bede BD-4 is a light aircraft for general aviation that hobbyists with little or no metal fabrication experience can build at home. Manufactured by Bedecorp, this kit-built airplane measures over 21-ft. long, over 7-ft. high, and has a wingspan of nearly 26-ft. Powered by a single Lycoming O-320 engine, the BD-4C variant weighs over 1000 lbs. and takes approximately 700 hours to build.

Although the aluminum wings of the original BD-4 were easy to assemble, newer designs such as the BD-4B and BD-4C feature a more conventional metal wing with a tubular spar bonded to honeycomb ribs. In fixed-wing aircraft, the spar is the wing's main structural member. Metal ribs attach to the spar and help carry flight loads, as well as the weight of the wings while the aircraft is on the ground.

Cylinder Honing

As one hobbyist explains, the BD-4C's tubular spar has a 6.5-in. inner diameter (ID) and runs the entire length of the wing. At a blog called Cheerful Curmudgeon, the author of an entry entitled Wings Fit then described his frustration with being unable to connect the spar in the wing to the spar in the fuselage. Each end was slightly oval instead of perfectly circular, so wing installation required "a lot muscle".

"Once on," the amateur aircraft builder added, "they were thoroughly stuck". More muscle and some vigorous "persuasion" helped with the wing's removal, but disassembly was an exercise that the Bede enthusiast did not want to repeat. The solution, he was told, was to enlarge the ID of the spars in the wings so they would slide onto and off of the fuselage's center section.

"What do you use to hone the inside of a 6.5 inch aluminum tube?" the blogger then asked his readers. "A 6.5 inch Flex-Hone, of course," he answered. The airplane assembler's use of a flexible cylinder hone was somewhat unconventional, however, and demonstrates how hobbyists sometimes use Flex-Hone tools from Brush Research Manufacturing (BRM) in unusual but effective ways.

Flex-Hone Selection and Use

The Flex-Hone features abrasive globules attached to flexible nylon filaments. Available in a variety of diameters, abrasive types, and grit sizes, these flexible cylinder hones remove burrs and improve surface finish at the same time. With their soft cutting action and low-temperature, low-pressure abrading process, BRM ball hones are self-centering, self-aligning to the bore, and self-compensating for wear.

Typically, hobbyists such as the author of the Wings Fit blog entry chuck flexible honing tools into a handheld electric drill. The use of a good-quality lubricant is required. In the case of the Bede BD-4 build, the ball hone user followed these standard practices. He then used this BRM deburring tool for material removal and geometry correction - applications for which the Flex-Hone is not designed.

Ultimately, the aircraft builder was successful - even though he spent more time honing that BRM recommends for a standard finishing application. The user's experience with a 180-grit Flex-Hone and then a 120-grit tool is also instructive. As the Flex-Hone Resource Guide explains, it's better to start with a coarser grit tool, and then use a finer-grit one. Choosing the right abrasive type for the base material is also important.

Flying High in the Bede BD-4

Eventually, the Bede BD-4 airplane builder accomplished his surface finishing mission. Once equipped with a new 120-grit Flex-Hone tool, he performed "a couple more honing sessions" and discovered that "the wings finally slide on and off the center section of the spar very easily". BRM salutes him for his dedication, and hopes he's now flying high in his light aircraft. This hobbyist was looking for a versatile, portable surface finishing solution, and found what he was looking for in the Flex-Hone tool.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.

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Ball Honing for Pneumatic Cylinders

Posted June 03, 2014 4:52 PM by Brush Research

Pneumatic cylinders are fluid power devices that use a compressed gas such as air to move a piston in a reciprocating, up-and-down or back-and-forth linear motion. In double-acting cylinders (DAC), pressure causes the piston to extend and then retract. In single-acting cylinders (SAC), the compressed gas forces the piston in only one direction, typically outward, and a spring provides the return motion.

Other air cylinder designs are available, too, but all fluid power systems require proper maintenance for smooth operation. In a Machinery Lubrication article called Why Air Cylinders Fail, a pneumatics expert explains how "catastrophic failure can occur when cylinder seals have insufficient lubrication." Although some industrial buyers are now choosing so-called "non-lube" cylinders, seal failure remains a concern.

If the walls of a pneumatic cylinder are too smooth, there's higher adhesion friction between the O-rings and bore surfaces. In addition, the absence of oil-retaining grooves can affect lubrication. If the walls of a pneumatic cylinder are too rough, burrs and other surface irregularities can shear softer seal materials such as rubber. If seal failure occurs, pressure may be lost and air cylinder performance can suffer.

Deburring and Cylinder Surface Finishing

To protect the integrity of pneumatic systems, manufacturers and maintenance personnel alike need to ensure that bores have a proper surface finish. The Flex-Hone tool from Brush Research Manufacturing (BRM) removes burrs and improves surface condition at the same time. Suitable for any type or size cylinder, these flexible honing tools also impart a series of oil-retaining grooves for optimum lubrication.

As BRM's Gold Booklet explains, the Flex-Hone produces a crosshatch pattern of evenly-spaced "valleys". Flexible cylinder hones also remove torn, cut, folded, and jagged metal while reducing raised areas or "peaks" to a uniform height. With their distinctive abrasive globules, BRM ball hones use a soft, low-temperature, low-pressure cutting action for superior surface finishing and burr removal.

Flexible hones also feature a double-wire metal stem for easy mounting in handheld power tools or production machinery. As this YouTube video about ball honing a pneumatic cylinder shows, use the Flex-Hone® with a good-quality cutting fluid or honing oil. Because BRM ball honing tools are self-centering, self-aligning to the bore, and self-compensating for wear, no special training is required.

Rotate the Tool or Rotate the Part

The Flex-Hone Resource Guide provides information about tool selection as well as guidelines for use. Although general speed ranges are given, machine trials are required to verify parameters. In general, however, users need to remember that flexible cylinder hones are low RPM tools, and that revolutions per minute (RPM) is dependent upon tool diameter.

BRM cylinder hones should be rotated prior to entering the cylinder, and should continue rotating until fully removed from the part. Typically, users secure the Flex-Hone in a collet, chuck, or similar holding device and then rotate the tool along with the spindle. As this short YouTube video shows, however, it's also possible to rotate the part instead.

By using flexible honing tools, pneumatic cylinder manufacturers and plant maintenance personnel can remove burrs, improve surface finish, and promote optimum lubrication. Flex-Hone tools are proudly Made in the USA, and come in a wide variety of abrasive types, grit sizes, and tool diameters for fluid power and other commercial and industrial applications. For more information, visit the BRM website.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.

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