Drilling Machine Accessories Unit 39

Objectives Identify and use three types of drill-holding devices Identify and use work-holding devices for drilling Set up and clamp work properly for drilling

Versatility of the Drill Press Greatly increased by various accessories Two categories Tool-holding devices Used to hold or drive cutting tool Work-holding devices Used to clamp or hold workpiece

Tool-Holding Devices Drill press spindle provides means of holding and driving cutting tool End may be tapered or threaded for mounting drill chuck Most common Drill chucks Drill sleeves Drill sockets

Drill Chucks Most common devices used for holding straight-shank cutting tools Most contain three jaws that move simultaneously when outer sleeve turned Hold straight shank of cutting tool securely Two common types Key Keyless

Chucks Hold straight-shank drills Mounted on drill press spindle Taper Threads Held in spindle by self-holding taper in larger machines Four types of drill chucks Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Types of Drill Chucks Key-type Keyless Precision keyless Most common Three jaws move simultaneously when outer sleeve turned Tighten with key Keyless Chuck loosened or tightened by hand without key Precision keyless Holds smaller drills accurately Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Types of Drill Chucks Jacobs impact keyless chuck Hold small or large drills accurately using Rubber-Flex collets Gripped or released quickly and easily by means of built-in impact device in chuck Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Drill Sleeves and Sockets Used to adapt cutting tool shank to machine spindle if taper on tool is smaller than tapered hole in spindle Drill Socket Used when hole in spindle of drill press to small for taper shank of drill Used also as extension sockets Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Drill Drift Used to remove tapered-shank drills or accessories from drill press spindle Always place rounded edge up so this edge will bear against round slot in spindle Use hammer to tap drill drift and loosen tapered drill shank Use board or piece of masonite to protect table

Work-Holding Devices Angle vise Drill vise Angular adjustment on base to allow operator to drill holes at an angle without tilting table Drill vise Used to hold round, square or odd-shaped rectangular, pieces Bolt vise to table for stability Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Work-Holding Devices Contour vise V-blocks Step blocks Has special movable jaws that automatically adjust to shape of odd-shaped workpiece V-blocks Made of cast iron or hardened steel Used in pairs to support round work for drilling Step blocks Used to provide support for outer end of strap clamps Various sizes and steps

Work-Holding Devices Angle plate Drill jigs L-shaped piece of cast iron or hardened steel machined to accurate 90º May be bolted or clamped to table Variety of sizes Drill jigs Used in production for drilling holes in large number of identical parts Eliminate need for laying out a hole location

Work-Holding Devices Clamps or straps Used to fasten work to drill table or an angle plate for drilling Various sizes Usually supported at end by step block and bolted to table by T-bolt that fits into table T-slot Modifications are double- finger and gooseneck clamps Finger clamp U-clamp Straight clamp Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Clamping Stresses Don’t want stresses to cause springing or distortion of workpiece Clamping pressures should be applied to work, not step block Step block should be slightly higher than work Bolt close to work Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Clamping Hints Always place bolt close to workpiece Have packing block slightly higher than work surface being clamped Insert piece of paper between machine table the workpiece to prevent shifting Place metal shim between clamp and workpiece Use sub-base or liner under rough casting Shim parts that do not lie flat to prevent rocking