DRILL AND TOOL GRINDERS: MODEL 250A

Drill and Tool Grinder

 

 

 

Description:

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

The 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). The Model 250A incorporates a wide capacity and versatility in an affordable package. The innovative design of the Model 250A allows for the 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 change in set-up. The Model 250A is available in manual, semi-automatic and automatic in-feed version.

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

Features:

Selected Optional Accessories:

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.



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 .001″ increments
  • Hardened downfeed screw with wiper seal
  • High-quality diamond included for truing standard and ceramic wheels

Air Bearing Fixture

Air Bearing Fixture on Model 250A Drill and Tool Grinder
Allows precision sharpening of endmills, 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 the Model 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″ (50 mm) 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.
  • It is graduated in .001″ (or .04 mm) of diameter.