the need for trimming;
small cut width;
work on curved layout.
The C-shaped bed, with an open loop, serves as the basis for the installation of the remaining nodes. In its middle part of one side there is no vertical section for the possibility of pulling wooden blanks on the table.
Saw pulleys are installed in the upper and lower block of the band saw. The equipment is closed and pulled on them, closed in a ring and moving in one direction along the perimeter of the housing.
The electric motor is mounted on the outside. The drive pulley is mounted on the protruding part of the shaft, as in the Einhell TC-SB 200; or set aside, connecting it to the motor, via a belt drive, as on the Jet JWBS-9X.
The advantage of this scheme is the absence of beats that occur when the shaft bearings wear.
The role of the frame.
On all table saws for wood, the frame is vertical. When choosing a machine, look at the material of its manufacture. Cast iron, like the Jet JWBS ‑ 14OS, giving the structure increased rigidity and resistance to vibration, or a steel profile and a bent sheet like Scheppach Basa 1.0.
The heavy thick-walled case prevents the saw from twisting under loads, ensuring stability of the tooling tension and increasing the dimensional accuracy of sawing. The massive base of a large area creates stability and full contact with the floor.
The lower drive belt pulley serves to convert the rotational movement of the electric motor into the translational movement of the tool. Its diameter is equal to the diameter of the upper follower, and the material of manufacture may vary.
Scheppach HBS 20 has both aluminum drive wheels, and the Axminster HBS350N has a massive massive cast iron bottom, which stores energy. With a quick supply of material or the passage of problem areas, for example, hard knots, it dampens the load by reducing the supply of kinetic energy and replenishes it with further work. This eliminates the occurrence of jerks and stabilizes the engine.
To improve the adhesion of the pulley to the tape, rubber or polyurethane is applied to its surface. The coating is convex, barrel-shaped and the tensioned equipment itself leaves on the central track of the wheel.
Desktop Band Saw.
Video: Metal Band Saw Setting
The workpiece is controlled and fed to the moving equipment by the operator manually on the table. It is made of aluminum casting with subsequent milling, as on the Jet JWBS-9X; steel like Scheppach HBS 20 or vibration damping cast iron like Scheppach Basa 1.0.
To obtain cuts other than 90 ° the table, by rotating the gear mechanism handle and subsequent fixing, is tilted at an angle of 45-50 ° from the machine, as with Scheppach HBS300 and up to 15 ° to it, like on Powermatic PM1800B.
To exclude touching the tool ends of the desktop, an aperture with a shallow chamfer is milled in it. A protection is inserted into the chamfer, a flat plastic part forming an even plane with the surface. With its help, it is convenient to process small workpieces that do not fall into the opening.
The device for tensioning the saw band.
New equipment is installed with teeth in the direction of the operator and requires pre-tensioning.
The axis on which the upper pulley is mounted is mounted not in the wall of the upper part of the housing, but in the console of the slider. Rotating the rod handwheel manually, the upper pulley is brought closer or moved away from the lower one.
Sharp vibrations emanating from the drive pulley, for example, when wood chips fall between it and the blade or when a poorly made welded joint is passed, are leveled by a spring damper, like a Powermatic PWBS-14CS band saw on a tree.
Failure of the saw band is usually caused by: not alignment of the impellers, their poor balancing and excessive tension.
Low tension is also undesirable. It causes: slipping on the lower pulley; heating due to increased friction; the waviness of the end face of the workpiece.
For precise finishing on professional band saws, such as JET JWBS-15-M, a tension indicator is installed. The arrow under the spring indicates the required force for the specific tooling width.
Centering the saw blade on the drive wheels.
The guiding devices, above and below the work table, limit the movement of the tape strictly in one plane. Adjustable side bearings exposed with a clearance of 0.05-0.4 mm serve as its support in width, preventing them from going left / right.
Freely rotating rollers are located at a distance from the equipment during idle rotation, occasionally contacting when feeding with the cheeks of the canvas behind the line of tooth cavities. With constant emphasis and friction of steel against steel, the tape would heat up, causing microcracks that increase when bent, when passing over the machine pulleys.
Even rigging with the required effort, with excessive supply of the wooden workpiece, can carry out an emergency escape from the pulleys.
To counteract its movement on all bandsaw machines on a tree, a thrust roller is installed, limiting the course of the blade and in contact with its end.