DRILL AND TOOL GRINDERS: MODEL 250A

Rush 250A
Machine Features

–  Taper Spindle
–  Self-Centering 6-Jaw Chuck
–  Enclosed Base Cabinet
–  Flood Coolant System
–  Optional Accessories: Semi-Automatic Version, Automatic Infeed System, Overhead Wheel Dresser, and Air-Bearing Fixture

Description

Models 250 and 252 have a capacity of 3/32″ to 2″ diameter.

Model 250A has a 2:1 ratio only. All models use hardened cams, and the cam change takes only 5 seconds. When no cam is in place, the workhead can be used to spin grind or index grind (12 positions). Model 250A incorporates a wide capacity and versatility in an affordable package. The innovative design of the 250A allows for grinding of almost any drill geometry, and most are completed in a single chucking. The versatility also extends to taps, reamers, countersinks, and end mills. Many of these tools can be ground with very little setup. Model 250A is available in manual, semi-
automatic, and automatic infeed versions.

Additionally, Model 250A is available a structural steel version, specially equipped for easily putting the structural steel point on drills.

 

Overhead Wheel Dresser

Timesaving option allows truing of the grinding wheel O.D. without changing the setup. (Not for use with diamond or CBN wheels.)

Features:

–  Sealed linear bearing with hardened guide shafts
–  Downfeed with ball detent in 0.001″ increments
–  Hardened downfeed screw with wiper seal
–  High-quality diamond included for truing standard and ceramic wheels

 

Air-Bearing Fixture

The Air-Bearing Fixture on the Model 250A Drill and Tool Grinder allows for precision sharpening of end mills, reamers, shell mills, and other cutters. The spindle is supported with a thin film of air providing nearly frictionless motion, resulting in a smooth, even grind. The fixture quickly mounts on Models 132C, 250A, 252, 380, or 382S grinders, or is available with a universal base to fit most tool and cutter or
surface grinders.

Features:

–  Hard chrome-plated and ground spindle with a 10″ stroke.
–  Tools are held in 5-C or 5-ST collets or extension bushings for up to 2″ (50mm) shanks.
–  Flute finger has dovetail crossfeed and micrometer vertical
adjustment.
–  Rocker arm tilts fixture away for easy movement from one flute  to the next.
–  Direct angle settings for up to 20 degrees for the O.D., 360 degrees for rotation, and +/– 30 degrees for tilt.
–  Grinds the O.D. of any number of flutes and includes 12-position index plate (others available) for end grinding.
–  Unique micrometer infeed built into fixture.
–  Allows fine-feeding of the tool into the wheel.
–  Graduated in 0.001″ or (0.04mm) of diameter.

Semi-Automatic Version

The power-driven workhead of the semi-automatic version offers a quiet, smooth rotation of the workhead. Manual effort is reduced for heavier grinding and spin grinding operations. Spark out is
allowed to occur by using a minimum of manual infeed along with a reduction in workhead rotation speed. The speed is controlled by a conveniently located valve; the adjacent four-way valve allows grinding in either direction. A hand knob on the workhead is used for indexing and setup.

 

Automatic Infeed System

The semi-automatic versions can be equipped with the automatic infeed system. This can increase productivity by allowing the
operator to do other nearby tasks while the drill is being ground. The system allows manual or semi-automatic grinding of all tool grinding, and use of the automatic infeed for standard drill points, countersinks and reamers. The grinding rate is adjustable and the counter can be preset for 1-99 cycles. An electroplated CBN wheel (standard) is used with the automatic infeed and requires no
dressing. Larger, three-phase motors are standard and an ammeter is provided to monitor the grinding load.