DISC WHEEL MOUNTING PROCEDURES
- Check Correct Disc - Verify the correct wheel has been removed from stock. Check that the Jowitt &
Rodgers specification tag matches the process sheet for the part. Contact your sales engineer if you have any questions
about if the disc is correct for the application.
- Check Maximum RPM - Verify that the disc grinder spindle speed does not exceed the maximum safe operating
speed labeled on the abrasive disc by the manufacturer. Do not operate the abrasive discs at speeds exceeding the
- Examine Disc Wheel - Check the disc for any obvious cracks. Perform a ring test if possible by standing
the wheel vertically on edge. Lightly tap the wheel with a hammer handle and listen to the sound. A sharp ring
indicates the discs are okay. A dull thud indicates in all probability the discs are cracked. Rotate the wheel
and check in four quadrants. Look for other flaws. Minor mold seam marks in the OD should not be a problem or breakouts
of less than 1/32 inch should not be a problem. When in doubt contact your sales engineer. It is not safe to run
a cracked or broken grinding wheel on any machine.
- Check Size of Disc Wheel - Insure that outside diameter, thickness, and centerhole size are correct.
The abrasive thickness capacity of the disc grinder should be known and not exceeded. The disc grinder is normally
equipped with exit and entrance guides contoured to closely fit the periphery of the abrasive disc. For this reason,
discs that are excessively oversize or undersize on the O.D. can cause problems. Oversize discs will obviously
cause an interference problem between the abrasive and the guide. Discs that are excessively undersize will leave
a gap between the guide and disc that in some cases cannot be tolerated. Many rotary carrier disc grinding applications
require that the centerhole of the abrasive be held to a specific dimension for the part to break center. The back,
or mounting side of the abrasive disc must be flat to within .015 inch. For suspect wheels lay a precision straight
edge and check gaps across the inserted nuts with a feeler gauge. The top of the inserted nut must not be recessed
into the abrasive.
- Check Mounting Plate - The steel mounting plates should be removed from the
grinder. Do not attempt to mount wheels while on the machine. Thoroughly clean the face of the steel mounting plates
and remove any burr with a bench stone. Be sure that all screw holes are clean. The steel mounting plates must
be flat. Check that the mounting plate is clean, free of burrs. The plate should be flat within .005 inch. For
suspect plates lay a precision straight edge and check gaps with a feeler gauge. Check aligning pin condition and
insure that their height is less than 0.400 inches.
- Check Wheel Bolts - Check that the mounting bolts are in good condition and do not protrude from the
mounting plate more than 3/8". The length of the disc wheel mounting screws is critical. Over length screws
will "bottom" and pull the inserted nut loose Check that the wheel bolt threads match the nut insert
on the grinding wheel. Normal inserts are either 3/8-16 or M10. Take caution in that a 3/8-16 bolt will screw into
a M10 insert, but it will be a sloppy fit.
- Disc Wheel Horizontal - Lay the abrasive disc face down on suitable table. The nut inserts should be
facing up towards you. Do not attempt to mount a disc wheel in the vertical position because you may pull a nut
insert or place the wheels out of balance.
- Lift Mounting Plate - Place two eyebolts 180 degrees apart through two of the spindle flange mounting
holes in the disc wheel. Attach a strap or sling through the eyebolts and lower the disc wheel in the horizontal
position over the abrasive disc.
- Mate Disc and Plate - Mate the mounting plate and grinding wheel. Make sure that dowel holes in the
disc wheel are properly lined up with the dowels extending from the back of the abrasive disc. Since the dowels
are different sizes , the disc wheel will only fit one way. With the disc wheel lying on the abrasive discs check
the gap all around with a .015" feeler gage. If it will fit in at any position, remove the disc wheel and
check for the cause. Do not attempt to tighten the bolts if the gap exceeds .015 inch.
- Insert Bolts - Insert and hand-tighten the bolts. All screws should be inserted before attempting to
tighten any one of them. Lightly tighten them with a standard 4 inch long allen wrench. Inspect the assembly to
insure the abrasive is flush with the mounting plate on both the O.D. and the mounting face.
- Tighten Bolts - When finally tightening the abrasive mounting bolts, the object is to insure even distribution
of mounting pressure over the entire surface of the disc. A normal torque of 15-20 ft-lbs is recommended. Use a
torque wrench to tighten the bolts to working in a "star'' pattern. Start with the innermost row, and continue
toward the O.D.
- Balance Assembly - If your grinder is equipped with a wheel balancing stand. Place the abrasive disc
and mounting plate assembly on the balancing stand. Arrange the movable weights in the mounting plate until the
wheel is balanced to within 1 ounce. Unbalanced wheels cause premature abrasive wheel wear and can harm spindle
- Install Disc On Grinder - When installing the mounted abrasive disc on the grinder, once again insure
the mounting surface of the steel disc wheel is absolutely clean. Give the same attention to the mating face of
the machine spindle. Again, make sure that only screws in good condition are used to mount the abrasive disc and
steel disc wheel to the spindle flange. Care should be taken to clean out the tapped holes in the disc wheel used
in mounting the disc wheel/abrasive assembly to the spindle flange. Insure that screws of the proper length are
used. Avoid screws that are long enough to bottom out against the abrasive. This will cause wheel cracking and
looseness of the mounting.
- Removing Discs - When removing abrasive discs from backplate, be sure that all screws and/or bolts are
free before attempting to remove the abrasive disc from the steel disc wheel. Any bolt or screw still attached
will in all probability pull loose its related inserted nut from the abrasive disc.
If the Backplate is not removed from machine
When mounting a wheel on to a horizontal spindle machine where the backplate is not removed, take care to centre
correctly before tightening any screws.
- Check contact - When mounting an inserted nut disc on the top of a double head vertical spindle machine,
it is important that the wheel is in full contact with the backplate before tightening any fixing screws. All screws
should be fully tightened prior to removal of the wheel supports in order that no sudden loads are placed on the
- Never suspend - the wheel on loose fixing screws as this could cause nut failure allowing the wheel
- Inspect - The wheel should be finally visually inspected and then run to the operating speed before
any grinding operation.