Jet IBGB-248VS, Operating Instructions And Parts Manual, Page: 16 / 36

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10.4 Changing wheels
The JET bench grinder comes equipped with a
general purpose grinding wheel. Wheels vary
according to types of abrasive, hardness, grit size,
and structure. Contact your local distributor for the
proper grinding wheel or wire wheel brush for your
application.
If you replace a wheel, obtain one with a safe rated
speed at least as high as the
NO LOAD RPM
marked on the grinder's nameplate. The
replacement wheel must be 8” OD x 1” W x 5/8”
Bore.
The bench grinder will accept most polishing,
buffing, and wire wheels available at dealers and
hardware stores.
The use of any other accessory
is not recommended and may result in serious
injury.
To change a wheel (see Figure 10-2) :
1. Disconnect grinder from power source.
2. Loosen spark guard (B) and tool rest (C) and
move them away from the wheel.
3. Remove wheel guard using a cross-point or
flathead screwdriver.
4. Stabilize wheel by placing a wood wedge
between wheel and tool rest.
Figure 10-2: wheel replacement
5. Unscrew arbor nut (D) with wrench. Note : Left-
hand threads; turn nut clockwise to loosen.
6. Remove outer flange (E), wheel (F), and inner
flange.
7. Clean flanges. Check the flanges to make sure
they are flat. Wheel flanges that are not flat will
cause the wheel to wobble.
8. Inspect the new grinding wheel and perform a
“ring test” (sect. 10.3). Do not install a damaged
wheel.
9. Install inner flange, wheel (F), outer flange (E)
and nut (D) on the shaft. Tighten nut counter-
clockwise.
Do not overtighten nut; this
may cause the wheel to crack. Maximum
safe torque on nut is 20 lbf•ft (270 kgf•cm).
10. Reinstall wheel guard. Adjust spark guards and
tool rests to 1/16" clearance from wheel.
10.5 Wheel balancing
With the grinder unplugged from the power
source , and arbor nut snugged down, rotate wheel
by hand and observe its motion.
A grinding wheel has proper balance when:
1. The wheel’s outside face spins true and round;
that is, its circumference rotates concentric to
the arbor.
2. There is no side-to-side wobble.
The operator who takes time to patiently perform
needed adjustments will be rewarded by a wheel
running true, and accurate grinding of work pieces.
10.5.1 Adjusting concentricity
If the outside face is not rotating concentric to arbor,
try shifting the wheel closer to arbor centerline
before tightening the nut.
Another method of achieving concentricity is the use
of a wheel dresser. “Dressing” is the removal of the
current layer of abrasive to expose a fresh surface.
A wheel dresser is also used to “true” a wheel; that
is, to make the grinding surface parallel to the tool
rest, so the entire wheel face presents an even
surface to the work piece. Proper use of a wheel
dresser will eliminate high spots and result in
concentric rotation about the arbor, as well as
minimize vibration. See
sect. 10.6 .
10.5.2 Correcting side-to-side wobble
The IBGB series Grinders have large, machined
flanges, making wobble unlikely if a good quality
grinding wheel is used. Should a wheel exhibit need
for adjustment:
1. Loosen nut and rotate the outer flange a little.
Snug the nut and spin the wheel by hand to
check.
2. If wobble still exists, continue repeating step 1,
rotating outer flange incrementally in the same
direction. See Figure 10-3. Make sure to keep
the wheel in the same position each time.
3. If complete rotation of outer flange has proved
ineffective, remove nut, outer flange, and wheel
(keep wheel in same orientation by placing a
pencil mark on it somewhere for reference).
Then rotate inner flange about 90° and repeat
the above steps for the outer flange.