Bench Grinders
Last updated on
Monday, December 12, 2011 05:42:41 AM
Eastern US Time Zone
Bench Grinder, Grinder Chuck, Jigs, Pedestal Feet, Wheel Dressers, Diamond Carbide Grinder
WARNING: Grinders are
Dangerous.
Grinding wheels can break apart while turning at high speeds.
Always use appropriate eye, breathing & clothing protection.
Read, understand &
follow all of the manufacturer's instructions.
Dust
from grinding tool bits is dangerous if inhaled.
Always wear
ANSI (Z87.1) approved safety eye protection,
breathing protection, & gloves during machine & tool use.
Refer to the Material
Safety Data Sheet, or
MSDS, for info regarding the properties of
a particular substance.
Stock bench grinders can be modified to make
them more useful for tool bit grinding & general shop use.
Often, a grinding wheel has
a 1" hole but is used on a ½" shaft & is usually adapted using concentric
plastic
spacer rings. Took a 1.000" aluminum dowel, centered it in the
9x20
4-jaw, faced it,
centered drilled, then drilled a
31/64" hole. Chamfer the opening & then use a
well-lubricated 0.500"
reamer at
the lowest RPM. When the
reamer is all the way through, stop turning the part & then withdraw to keep a
tight tolerance. The spacer is a
tight fit to both the wheel & the grinder shaft. The wheel is now held
more precisely in the grinder.
Use a
star dresser followed by a carborundum dressing
stick to make the surface smooth & flat.
Aluminum shaft spacer for grinding wheel
(1.000" OD, 0.500" ID & about ~0.75"
long).
Note: left-hand nut & thread on the left side of the grinder.
The next mod was the tool rest. Most grinders
have inadequate rests & mine was no different.
Replaced it with the Veritas
tool rest (tool
rest manual). It is a great improvement over the OEM rest.
It has a wide range of adjustment.
Its best feature is the ½" x ½" channel on the tool rest platform
that is used
to guide jigs. There are several jigs available but custom jigs may be fabricated to suit
any need. Shown is a jig that allows me to precisely grind
tool
bits at 60º for threading. The rest
mounts onto the
bench. Tapped holes into
the
grinder mounting plate & used ¼-20 socket head
cap screws with nylon
washers.
Note the
½" x ½" channel to guide jigs.
The rest's center hole is for
(Veritas) pivoting jigs.
The locking handles can be pulled & rotated to any detent position.
WARNING: DO NOT remove the shroud that covers the grinding wheel.
Grinder Chuck
Measuring total indicated runout (TIR) of the
chuck using a dowel pin.
One of the most useful
modifications was to mount a drill chuck
onto the right side shaft of the grinder.
The arbor
adapters are available at motor supply/repair shops in a
variety of shaft/chuck thread sizes.
A taper-mounted chuck is not recommended
since sideway forces could easily cause it to come loose.
The arbors
usually have only two, ¼-28 setscrews. Drilled & tapped
for three
more setscrews (as referenced
from the center of the pre-existing setscrew); one every 90º. Used
hardened USA made setscrews.
This setscrew arrangement allows adjusting the runout in the
same manner as a
4-jaw chuck.
Any chuck can be used.
Pictured is a Jacob's medium-duty 5/64" to ½" chuck.
This example is
mounted onto a ½-20 threaded arbor. One could use a keyless chuck
(not recommended) but
keyed chucks grip so much tighter. Hack sawed the shaft threads off
to place more motor
shaft into the arbor. Use the drill chuck on the right side of the
grinder since most
accessories (arbors, sanding drums, etc.) are made for that turning direction.
Use a
full-face visor for eye protection. The reflexive tape is for use with a laser
tachometer.
This grinder & its mounting plate were moved off the bench to make way for the carbide grinder. It is now
on a free-standing, cast-iron pedestal having rubber feet (manual). A drill-bit sharpener can also be used.Top & bottom view of a jig used to grind tool bits for threading. It is rotated 180º to grind both angles.
The guide bar is ½" x ½" x 2". As an alternative, use a lower temperature diamond grinder with its miter.
Pedestal foot detail.
Wheel Dressers
Wheel dressers.
½ hp, 3400 RPM, 100 lb. grinder for carbide with
a 220 grit
Norton diamond wheel (right side).
Motor can rotate
in either CCW or CW direction. An adjustable miter is included.
Quickly & accurately grinds carbide
tool bits &
hardened steel.
The cup has a valve & allows coolant to be dripped onto the part while grinding.
The large, cast-iron pans under each wheel catch the debris/liquid.
Reference the
Six-inch tool grinder manual.
The 220 grit makes a nice smooth finish but it removed metal too slowly.
Mounted a
more aggressive 100 grit diamond wheel on the left side making a good combination with
the 220 grit wheel.
Diamond wheels do not need (messy) dressing & last a very long time.
A solid square is used to set the adjustable tilting table to 90°.
The adjustable miter is being set to 90° using a solid square.
The adjustable miter is being set to 30° using a solid angle plate.
Diamond/CBN grinder wheel cleaning stick.
Grind only carbide & hardened steel. Soft
metals will load up the surface. If
shaping a brazed carbide tool bit,
first grind the soft steel area
using a regular aluminum oxide wheel then grind
only the carbide with the diamond wheel.
Deburr the screw driver slot & cap the two water cup holder pegs on top the
grinder for protection.
Bench Grinder, Grinder Chuck, Jigs, Pedestal Feet, Wheel Dressers, Diamond Carbide Grinder
