Hertel MR34-0858.438 Chucking Reamer 0.086 in Solid Carbide

Product Description

The HERTEL MR34-0858.438 is a solid carbide chucking reamer designed to finish-ream precision holes to a No. 44 wire gauge diameter of 0.0860 inches. Built from solid carbide throughout, it delivers the rigidity and wear resistance needed for tight-tolerance work in hard or abrasive materials. The spiral flute geometry with a left-hand spiral direction promotes smooth chip evacuation while maintaining a right-hand cutting action. With an overall length of 1.9685 inches and an 11 mm flute length, this reamer is sized for close-quarter drilling operations. Machinists and tool-and-die professionals install this tool in CNC machining centers, drill presses, or manual lathes where repeatable hole sizing is critical.

This reamer is suited for precision hole finishing in ferrous and non-ferrous metals, plastics, and composites where a No. 44 wire gauge bore is required. The straight shank interfaces directly with standard chuck-style toolholders, making it a straightforward drop-in for production or repair work. Its bright, uncoated finish makes it appropriate for applications where coating buildup could compromise the tight diameter tolerance of 0.0000 to plus 0.0003 mm.

Key Features

• Solid carbide construction for superior hardness and wear resistance in demanding materials
• Spiral flute, left-hand helix with right-hand cutting direction for smooth chip flow
• No. 44 wire gauge diameter — 0.0860 inches — with a tolerance of 0.0000 to plus 0.0003 mm
• Straight shank for direct chuck mounting without adapters
• 4-flute design balances chip clearance with surface finish quality
• Bright, uncoated finish — no risk of coating interference in tight-tolerance bores

Compatibility

Designed as an OEM-style precision chucking reamer for use in standard straight-shank chuck toolholders on CNC machining centers, drill presses, and manual lathes requiring a No. 44 wire gauge hole finish.

Installation Notes

Installation is performed by qualified machinists or tool-and-die technicians. Secure the straight shank fully in a suitable chuck or collet holder before use, and verify runout with a dial indicator to protect the tight diameter tolerance. Power down and lock out the machine spindle before changing or inspecting the reamer. Use appropriate cutting fluid for the workpiece material to extend tool life and maintain surface finish quality.