The extra-long solid carbide machine reamers with straight shank, K40 ultra-fine micrograin carbide and 6° left-hand spiral flutes are precision cutting tools designed for finishing, sizing and dimensional correction of deep or hard-to-reach holes on conventional and CNC machine tools. They are used when a hole must be brought to its final size with high accuracy, good roundness, geometric stability and controlled surface finish, even at greater working depths.

A reamer is not intended to create the hole from solid material, but to finish it after drilling, boring or rough machining. The tool removes a small and controlled amount of material from the internal diameter, improving the geometry of the seat and correcting minor irregularities left by the previous tool. This allows calibrated holes to be produced for precise fits with dowel pins, pins, bushes, small shafts, guides, centering components and mechanical parts intended for precision assembly.

The solid K40 ultra-fine micrograin carbide construction provides high rigidity, wear resistance and cutting edge stability. Compared with high-speed steel reamers, solid carbide reduces tool deflection and helps keep the hole size stable over time. The ultra-fine micrograin structure is especially useful in finishing operations because it supports a stable cutting edge, better surface quality and high dimensional accuracy when machine setup and clamping are correct.

The extra-long design allows the tool to reach deep holes, recessed internal seats, housings far from the entry point and areas that cannot be reached with standard reamers. This is important when machining machine bodies, supports, plates, fixtures, complex mechanical components and parts where hole depth requires extended tool reach. With extra-long tools, rigidity, runout and alignment must be carefully controlled, because the increased overhang makes the tool more sensitive to vibration and deflection.

The straight shank allows mounting in drill chucks, precision collet holders, clamping sleeves and suitable toolholding systems. To obtain maximum accuracy, clamping must be rigid, coaxial and low-runout. Final hole quality depends not only on the reamer itself, but also on toolholder accuracy, machine stability, alignment between tool and hole and secure workpiece clamping.

The 6° left-hand spiral flutes support stable and controlled cutting. This geometry helps limit the tendency of the reamer to self-feed into the hole and provides smoother behavior during finishing. In deep holes, the left-hand spiral contributes to predictable tool behavior and helps reduce the risk of sticking, vibration and loss of dimensional control.

For best results, the hole must be prepared with the correct stock allowance. If the pre-hole is too small, the reamer must remove too much material, increasing load, heat, wear and risk of breakage, especially with solid carbide and extra-long tools. If the pre-hole is too close to the final size, the tool may not cut uniformly over the full surface, leaving geometric defects, scoring or uneven finish.

During use, a stable machine, constant feed, suitable lubrication and accurate alignment between tool and hole are recommended. With extra-long tools, unnecessary overhang should be minimized, rigid toolholders should be selected and runout should be checked regularly. Vibration, misalignment, unstable clamping or impact may damage the cutting edges and cause out-of-tolerance holes, ovality or scoring.

These reamers are suitable for precision machine shops, CNC departments, machine building, automotive, toolrooms, industrial production, mechanical maintenance and subcontract machining. They are particularly useful for deep holes, internal cylindrical seats, dowel pin seats, bushes, pins, guides and components where hole quality directly affects assembly, coaxiality and component function.

The extra-long solid carbide K40 ultra-fine micrograin machine reamers with straight shank and 6° left-hand spiral are a professional solution for producing deep calibrated holes with high accuracy, rigidity and dimensional stability. The combination of solid carbide, ultra-fine micrograin, extended length, straight shank and 6° left-hand spiral enables reliable machining on conventional and CNC machine tools.