The hand reamers with straight shank and centesimal progression, DIN 206 / UNI 6852, made of HSS steel with 6° left-hand spiral form B, are precision tools designed for manual finishing, sizing and dimensional correction of existing holes. They are used when a hole must be brought to its final size with gradual cutting control, good surface finish and dimensional accuracy, especially in toolroom work, maintenance, reworking and operations where manual control gives the operator greater cutting sensitivity.

Unlike a drill, a reamer is not used to create the hole, 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 roundness, surface regularity and dimensional consistency. This makes it suitable for dowel pin seats, pins, bushes, small shafts, guides, centering holes and mechanical fits where hole accuracy directly affects assembly and component function.

The centesimal progression is one of the main technical advantages of this series, allowing the reamer diameter to be selected with very fine increments. This is especially useful when the hole size must be matched to a specific fit, avoiding excessive clearance or unwanted interference. In machine shops and maintenance departments, centesimal sizes allow accurate correction of existing holes, restored components or seats that must be brought to the final dimension.

The HSS steel construction provides good toughness, wear resistance and reliability in manual use. HSS is suitable for machining steels, light alloys, brass, cast iron and other compatible materials, depending on lubrication and stock allowance. In hand reaming, material toughness is important because the tool may be subjected to variable cutting forces, slight misalignment and less rigid conditions than on a machine tool.

The straight shank allows use with hand reamer wrenches, suitable manual holders and compatible gripping devices. During use, the reamer must be kept as coaxial as possible with the hole, avoiding angular errors that may cause ovality, taper, scoring or incorrect dimensions. The operation should be performed with controlled pressure and smooth rotation, without forcing the tool.

The 6° left-hand spiral flutes, form B, support stable cutting and good hole finish. The left-hand spiral helps control tool feed and limits the tendency to self-feed into the hole, which is particularly important in manual reaming. Form B is suitable for operations requiring cutting regularity, geometric accuracy and good surface quality.

For best results, the hole must be prepared correctly before reaming. The pre-hole must have a suitable stock allowance: if it is too small, the reamer must remove too much material, increasing manual effort, risk of sticking and cutting edge wear; if it is too close to the final size, the tool may not cut evenly over the full surface, leaving geometric errors or irregular finish. Correct hole preparation is therefore essential for obtaining an accurate and repeatable seat.

During use, a lubricant suitable for the workpiece material is recommended. The tool should be rotated smoothly and continuously, avoiding sudden movements and improper reverse rotation inside the hole. Chips should be removed periodically to prevent scoring and chip build-up that could damage the machined surface. When working on deep holes or tough materials, it is advisable to proceed carefully and check both hole condition and tool condition frequently.

Hand reamers are particularly useful in machine shops, toolrooms, maintenance departments, machine building, automotive, precision mechanics and component repair. They are chosen when an operator needs to correct, finish or adapt a hole without necessarily using a machine tool, or when the operation requires manual control, sensitivity and localized intervention.

To preserve tool precision, the reamer should be stored clean and protected, avoiding impacts on the cutting edges and accidental contact with other tools. Before use, the cutting edges should be checked to ensure they are intact, free from chipping, residues or oxidation. A damaged reamer can immediately produce out-of-size holes, scoring, poor finish or loss of accuracy.

The HSS hand reamers with straight shank and centesimal progression, DIN 206 / UNI 6852, are a professional solution for manual finishing of accurate and controlled holes. The combination of centesimal progression, HSS steel, 6° left-hand spiral form B and straight shank allows accurate work on mechanical components, improving hole quality, fit and assembly reliability.