Product Description
CMT 378.082.11 Dowel Drill with Countersink for Through Holes by CMT is a precision-engineered 5/16" diameter through-hole boring bit designed to drill, countersink, and fully penetrate panel materials in a single pass. Built for right-hand rotation and fitted with a 25/64" (10x20mm) shank, this 2-flute carbide-tipped bit delivers clean, accurate bores in chipboard, MDF, hardwood, and coated panels on multi-spindle CNC boring machines, boring centers, and panel processing equipment. The 70mm total length and 35mm cutting height make it well suited for repeatable production boring in furniture manufacturing and cabinet assembly applications.
Key Features
- Tungsten Carbide (HW) Cutting Tips - hard-wearing carbide construction maintains sharpness through high-volume production runs, reducing downtime and regrind frequency on abrasive engineered panel materials.
- Through-Hole Geometry with 60 deg. Countersink - the integrated countersink sharpening profile allows drilling and countersinking in one pass, eliminating a secondary tool operation and improving cycle times on boring lines.
- 2 Flutes and 2 Precision Spurs - dual-spur design scores the panel face before the main cutting edges engage, producing clean bore walls and preventing tearout on laminates, coated panels, and veneered surfaces.
- Right-Hand (RH) Rotation - designed for standard right-hand spindle rotation used on the vast majority of CNC boring centers and multi-spindle machines, ensuring direct compatibility without adapters.
- 10x20mm (25/64") Shank - consistent shank dimensions allow secure seating in standard boring machine chucks and adapters, minimizing runout for accurate, repeatable hole placement.
- 35mm Cutting Height with 29mm Secondary Cutting Zone (I1) - generous cutting height accommodates varying panel thicknesses and ensures full through-penetration without repositioning or multiple passes.
Why This Product
- Combines drilling and countersinking into a single-pass operation - reducing tool changes, simplifying machine programming, and improving throughput on production boring lines processing furniture components and cabinet panels.
- The 5/16" diameter and 70mm overall length suit a wide range of through-hole dowel applications, from shelf pin bores to connector hardware holes in MDF, chipboard, hardwood, and coated panel stock.
- Carbide-tipped (HW) construction resists the abrasive wear caused by resin binders in MDF and particleboard, delivering consistent hole quality over extended production use compared to high-speed steel alternatives.
- Precision-ground 2-spur geometry minimizes edge breakout on laminates and coated surfaces, making this bit a reliable choice for finished panel work where surface quality directly affects final product appearance.
Specifications
- Manufacturer Part Number: 378.082.11
- Brand: CMT Orange Tools
- Diameter: 5/16"
- Cutting Height: 35mm
- Cutting Height (I1): 29mm
- Total Length: 70mm
- Shank: 10x20mm
- Tooth Geometry / Sharpening: Through holes 60
- Number of Spurs: 2
- Number of Teeth: 2
- Rotation: Right-hand (RH)
- Blade Material: HW (Tungsten Carbide)
- Series: With Countersink - Through Hole
Approved Applications
- Chipboard and particleboard panels
- MDF (Medium Density Fiberboard)
- HDF (High Density Fiberboard)
- Hardwood
- Softwood
- Plywood
- Laminates and coated panels
Compatible Machines
- Multi-spindle CNC boring machine
- CNC boring center
- Panel processing center
- Boring machine with adapter or chuck
Frequently Asked Questions
What is the difference between the I and I1 cutting height values on this bit?
The cutting height (I) of 35mm refers to the full usable cutting length of the bit, while the secondary cutting height (I1) of 29mm refers to a specific zone within that cutting length - typically the primary flute engagement area. Both values are relevant when matching the bit to panel thickness and machine setup on CNC boring equipment.
What does "through holes 60" mean in the tooth geometry specification?
The sharpening designation "Through holes 60" indicates that this dowel drill is ground specifically for through-hole boring applications with a 60 deg. point geometry. This geometry is optimized for full panel penetration with the integrated countersink profile, as opposed to flat-bottom or blind-hole dowel drills.
Is this bit compatible with standard boring machine chucks without special adapters?
Yes. The 10x20mm (25/64") shank is a standard dimension used across most multi-spindle CNC boring machines, boring centers, and panel processing centers. It seats securely in standard boring machine chucks and adapters designed for this shank size.
Can this dowel drill be used on laminated or coated panel surfaces without causing tearout?
Yes. The 2-spur design scores the panel surface ahead of the main cutting edges, which significantly reduces edge breakout and tearout on laminates, melamine-coated panels, and veneered surfaces. The carbide (HW) tips maintain sharpness through repeated passes on these abrasive materials.
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