FLEX-HONE GB31212 Cylinder Hone, 3-1/2 Inch Bore, 120 Grit, Silicon Carbide
- The Brush Research GB31212 Flex-Hone is a heavy-duty cylinder honing tool engineered for 3-1/2" bore diameter applications. Featuring 120 grit silicon carbide abrasive, it delivers a medium plateau-style cross-hatch finish ideal for improving lubrication retention, reducing leakage, and preparing surfaces in engine blocks, hydraulic cylinders, and industrial components.
- Features:
- Self-centering, self-aligning, and flexible bead-style filament design ensures uniform surface contact
- 120 grit silicon carbide abrasive balances peak removal with preservation of oil-retaining valleys (approximately 35–50 µin Ra)
- Non-directional plateau cross-hatch pattern enhances lubrication flow and sealing consistency
- Robust construction optimized for demanding industrial and hydraulic applications
- Designed for consistent finish quality across large bore components
- Specifications:
- Bore Diameter: 3-1/2"
- Abrasive Material: Silicon Carbide
- Grit: 120 (Medium)
- Abrasive Length: 4"
- Overall Length: 11"
- Stem Diameter: 0.31"
- Recommended Speed: 350–600 RPM
- Typical Surface Finish: 35–50 µin Ra
- Applications: Engine bores, hydraulic cylinders, industrial piping
- The FLEX-HONE GB31212 can also be referred to as 3-1/2 Inch bore hone, GB31212 flex hone, silicon carbide cylinder hone, plateau finishing brush, and medium grit bore tool.
Brush Research Manufacturing has over 60 years of experience developing industry-grade surface finishing tools. Their GB-Series Flex-Hones are relied upon in professional automotive, hydraulic, and industrial applications for delivering consistent, plateau-style finishes and long-lasting performance.
Q: What bore diameter is this hone designed for?
A: The GB31212 Flex-Hone is specifically designed for use in 3-1/2" bore diameter cylinders.
Q: What finish does the 120 grit provide?
A: It produces a medium plateau finish in the range of 35–50 µin Ra, ideal for oil retention and seal surface preparation.
Q: Can I use this hone with a handheld drill?
A: Yes—when used with a drill press or handheld drill, maintain speeds between 350–600 RPM and use honing oil for lubrication.
Q: What materials is this hone suitable for?
A: Effective on cast iron, mild steel, stainless steel, and other ferrous materials commonly found in industrial cylinder applications.
Q: What lubricant is recommended?
A: Use oil-based honing oil to maximize tool life and finish quality. Avoid solvents that could damage the abrasive bond.
