Flex-Hone® Cylinder Honing Tools
Australian Authorised Importer | 4mm to 18" Diameter
Also known as: ball hone, cylinder ball hone, flexible cylinder hone, glaze buster
- Self-centering and self-aligning — no setup required
- Plateau honing — improves ring seal, reduces oil consumption
- Finishes without removing significant material
- BC, GB & GBD series — engines, hydraulics, heat exchangers
- Silicon carbide, aluminum oxide, diamond & boron carbide grits
Australian Authorised Importer | Fast Delivery Melbourne, Sydney, Brisbane, Perth, Adelaide
What Is a Flex-Hone (Ball Hone)?
The Flex-Hone® — also widely known as a ball hone, cylinder ball hone, flexible honing tool, or glaze buster — is a resilient abrasive tool invented by Brush Research Manufacturing (BRM) in the USA in 1972. It consists of abrasive globules independently mounted on flexible nylon filaments, each suspended freely so the tool is inherently self-centering and self-aligning.
Unlike rigid hones or cutting tools that remove material by lifting chips upward, the Flex-Hone uses a "downward finishing" action — rubbing from the top of the surface downward to smooth microscopic peaks into a plateau finish. This creates the distinctive 45° crosshatch oil-retention pattern that is essential for piston ring seating and long seal life.
Cross Tools Co is the Australian Authorised Importer of Flex-Hone tools, stocking the complete range from 4mm to 18" (457mm) diameter, with larger sizes available by factory special order.
Flex-Hone Series — Which One Do You Need?
BC Series — Standard Duty
4mm – 76mm (up to 3")
- 200mm overall length
- Brake cylinders, valve guides, boiler tubes
- Multiple grits: 120, 180, 240, 320, 400
- Silicon carbide & aluminum oxide abrasive
GB Series — Standard Duty
83mm – 117mm (3¼" – 4⅝")
- 340mm overall length
- Automotive engine cylinders, hydraulic cylinders
- Multiple grits: 120, 180, 240, 320, 400
- Silicon carbide & aluminum oxide abrasive
GBD Series — Heavy Duty
76mm – 203mm (3" – 8")
- Length to suit diameter
- Large automotive, diesel & marine cylinders
- Multiple grits: 120, 180, 240, 320
- Silicon carbide, aluminum oxide & diamond
GBD Large Cored Series — Heavy Duty
216mm – 457mm (8½" – 18")
- Woodcore with separate hex shaft
- Large marine, industrial & oil/gas bores
- Multiple grits available
- Larger sizes (up to 900mm) by special order
Factory specials: Custom grit sizes from 20 to 800 grit, non-standard abrasives (boron carbide, tungsten carbide, diamond, CBN), and diameters up to 900mm (36") are available on request.
Applications — Where Flex-Hone Is Used
Engine Reconditioning
- Cylinder wall plateau finishing for piston ring seating
- Glaze busting on worn cylinders before re-ringing
- Race car engine preparation
- Diesel and marine engine cylinders
- 2-stroke engine porting and finishing
Hydraulics & Industrial
- Hydraulic cylinder finishing — up to 9x seal life
- Pneumatic cylinder honing
- Heat exchanger tube cleaning — double service life
- Boiler tube conditioning
- Valve body and actuator finishing
Specialist Applications
- Gun barrel cleaning and conditioning
- Valve guide refinishing
- Internal deburring of cross-holes and ports
- Brake master cylinder and caliper finishing
- Tube and pipe internal surface conditioning
Why Flex-Hone? The Plateau Finishing Advantage
Flex-Hone tools extend the service life of equipment by worthwhile amounts. Customers report results such as double the time between heat exchanger cleanings, up to 9× the service life of hydraulic seals, and dramatic reductions in downtime on race and high-performance engines.
Downward Finishing vs. Upward Cutting
Almost all metal processing tools — rigid hones, cutting tools, abrasive papers — use "upward cutting": they penetrate below the surface and lift material upward, leaving a jagged microscopic finish. Even a mirror-polished surface finished this way retains invisible sharp peaks that accelerate wear on mating parts.
Flex-Hone uses "downward finishing": the abrasive globules rub from the top of the surface downward, folding and smoothing the jagged peaks into a flat plateau finish. This creates a surface with 60%+ plateau area — the oil-holding crosshatch pattern that is critical for piston ring seating, seal life, and reduced blow-by.
Without Flex-Honing — jagged peaks accelerate ring and seal wear
After Flex-Honing — plateau finish with oil-retention crosshatch pattern
Flex-Hone Video Guides
How to use a Flex-Hone and choose what size you need
How to Use a Flex-Hone & Work Out the Size You Need
FlexHone - Let's Make Your Engines or Hydraulics Live Longer
Flex-Hone Advanced Techniques and Applications
Size & Specification Tables
Complete BC, GB and GBD sizing charts with bore diameter ranges and part numbers.
View ChartsGrit Selection & Usage Guide
How to choose the right grit, operating RPM instructions, and lubricant guide.
Read GuideGun Barrel Cleaning Guide
Using Flex-Hone tools for firearm bore cleaning and conditioning.
Learn MoreFrequently Asked Questions
What is a Flex-Hone tool?
A Flex-Hone (also called a ball hone or cylinder ball hone) is a flexible abrasive honing tool made by Brush Research Manufacturing (BRM) in the USA. It consists of abrasive globules mounted on flexible nylon filaments. Used to finish, deburr, and plateau-hone the internal surface of bores and cylinders without significant material removal.
What is the difference between a Flex-Hone and a ball hone?
No difference — they are the same tool. Both are BRM registered trademarks. Other names for the same tool include: dingleberry hone, grape hone, bead hone, bottle brush hone, glaze breaker, glaze buster, flexihone, and cylinder ball hone.
What are Flex-Hone tools used for?
Engine cylinder finishing for piston ring seating, hydraulic cylinder honing to extend seal life, plateau finishing, heat exchanger tube cleaning, internal deburring, brake cylinder refinishing, valve guide refinishing, gun barrel cleaning, and general tube and pipe internal surface conditioning.
What Flex-Hone series do I need?
Choose by bore diameter: BC Series (4mm–76mm) for small bores. GB Series (83mm–117mm) for standard automotive cylinders. GBD Series (76mm–203mm) heavy duty for larger bores. GBD Large Cored Series (216mm–457mm) for large marine and industrial applications.
What grit Flex-Hone should I use?
180 grit (medium) and 240 grit (medium fine) suit approximately 99% of applications. Use 120 grit for heavily glazed bores. Use 320–400 grit for precision hydraulic or sealing surfaces. Note: Flex-Hone grit is not comparable to sandpaper — 180 grit Flex-Hone produces a much finer finish than 180 grit abrasive cloth.
What RPM should I run a Flex-Hone at?
RPM varies by size: up to 1200 RPM for very small tools; around 700–800 RPM for 25–75mm tools; 450 RPM for 150mm tools. Always use cutting lubricant (10–30 weight oil). Do not use air tools or high-speed drill motors. Run 60–120 strokes per minute for 20–45 seconds per bore.
Will a Flex-Hone remove too much material?
No. The Flex-Hone is a surface finishing tool, not a material removal tool. Its "downward finishing" action only smooths microscopic peaks without changing bore dimensions. It is safe to use on precision bores requiring finishing rather than re-boring.
Can I buy Flex-Hone tools in Australia?
Yes. Cross Tools Co is the Australian Authorised Importer, stocking the full range from 4mm to 18" with rapid dispatch to Melbourne, Sydney, Brisbane, Perth and Adelaide. Call 1800 025 500 or email sales@crosstools.com.au.
Australia's Authorised Flex-Hone Importer
Cross Tools stocks the full Flex-Hone range — BC, GB and GBD series — with fast delivery across Australia. Call our technical team for help choosing the right tool for your application.