Use and Care Manual

6
4.0 General Specifications
The JET Model J-4421 20-inch diameter disc grinder is a high production, rapid stock removal tool. The stock
removal rate is controlled by the amount of pressure the operator applies to the work piece and the grit of the
abrasive sheet mounted on the drive disc. By using different grit values and materials, a wide range of
materials can be ground and an equally wide range of surface finishes achieved.
Because the Model J-4421 is of heavy-duty design throughout, large piece parts can be ground. The use of
either the miter system or the tilt table allows high production grinding of angles. When used in combination,
the miter/tilt design allows the grinding of compound angles.
The table tilt mechanism is a rigid, precision worm-and-sector gear controlled with a crank. Table angle is
shown on a protractor mechanism.
Table height with respect to the drive disc can be adjusted using a rack and pinion gear system controlled by a
crank. The table assembly is counterbalanced to make raising and lowering the table easier and to increase the
service life of the lifting components.
Model number ....................................................................... J-4421-2 ..................................................... J-4421-4
Stock numbers ........................................................................ 577010 ....................................................... 577011
.................................................................................. (prewired 220V) ......................................... (prewired 440V)
Motor ....................................................................................................... TEFC, 3HP, 3PH, 220/440V, 1725 RPM
Table size .................................................................................................... 27-1/2 x 10-1/2 in. (68.75 x 26.25 cm)
Disc speed ............................................................................................................................................. 1725 RPM
Disc diameter ................................................................................................................................. 20 in. (508 mm)
Table slot ....................................................................................................................... 3/8 x 3/4 in. (9.3 x 19 mm)
Table tilt ............................................................................................... 45 degrees downward; 15 degrees upward
Dust Port Diameter .......................................................................................................................... 3 in. (76.2 mm)
Overall dimensions ............................................................................. 30 x 27-1/2 x 53 in. (75 x 68.75 x 132.5 cm)
Net weight ....................................................................................................................................... 397 lb (180 kg)
Shipping weight ............................................................................................................................... 452 lb (205 kg)
The specifications in this manual were current at time of publication, but because of our policy of continuous
improvement, JET reserves the right to change specifications at any time and without prior notice, without incurring
obligations.