Hold-down Devices

Hold-down Devices Points : Hold-down Devices, Clamping Work to the Table , T-Bolts, Parallel Bars/Strips, Hold-Downs, Strap Clamps, Step Blocks, An Angle Plate, Stops, V-Blocks, Jack screw, C-Clamp, Parallel Clamp Before accurate work can be produced, it is necessary to set up the work correctly. This requires the use of certain attachments and accessories such as milling vises, T bolts, strap clamps, parallels, blocks and jacks, stops, V-blocks, angle plates, washers, nuts, etc. Work must be securely fastened and well supported so it will not move during the milling operation.
There are two important requirements to keep in mind when a job is being mounted for milling:

1. The job must be held securely, giving no opportunity of tool “walk-in” or “chafter.” The method selected must hold the work without marring its surface.
2. The work, or the device holding the work, must be aligned accurately with the path of the cutter, both as to its depth of cut and as to the direction in which it is cutting.

Clamping Work to the Table The table of the milling machine provides a surface upon which work and the work-holding fixtures and attachments can be fastened. The T-slots, which run lengthwise along the table, are used for locating and aligning the work as well as retaining the bolts used for clamping. The T-slots are accurately machined to size and are parallel to the sides of the table. Clamping the work to the table is common practice when castings of bulky size and irregular shape require milling. The principles of clamping work to the table, angle plates, V-blocks etc., are the same as for all types of machine work.