Bench Grinders
Last updated on Sunday, September 07, 2014 06:11:52 AM Eastern US Time Zone

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Bench Grinder, Grinder Chuck, Jigs, Pedestal Feet, Wheel Dressers,
Diamond Carbide Grinder, 2x42-inch Belt 6-inch Disk Combo Sander

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.

Bench Grinder

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 " 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 " x " 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 60 for threading. The rest
mounts onto the bench. Tapped holes into the grinder mounting plate & used -20 socket head
cap screws with nylon washers. Note the " x " 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, -28 setscrews. Drilled & tapped for three more setscrews (as referenced
 from the center of the pre-existing setscrew); one every 90. 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 " chuck.
This example is mounted onto a -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.

Jigs
 

Top & bottom view of a jig used to grind tool bits for threading. It is rotated 180 to grind both angles.
The guide bar is " x " x 2". As an alternative, use a lower temperature diamond grinder with its miter.

Pedestal Feet

Pedestal foot detail.

Wheel Dressers

Wheel dressers.

Diamond Carbide Grinder

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 5C fixture clamping a bolt for grinding. Holds parts normal (perpendicular); smooth finish.


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.

2x42-inch Belt 6-inch Disk Combo Sander

2x42-inch belt, 6-inch disk combo bench sander. Operator's Manual.
Specifications: 1/3HP, 120VAC, 3.5A, disk 3500 RPM, belt 4400 FPM, 2"x42" belt,
6" PSA (Pressure Sensitive Adhesive) disk, weight 32-lbs. 1"x42" belts can also be used.
The motor is fully enclosed to keep metallic & wood particles out. Heavy steel base with rubber feet.
I use this sander to finish metal or wooden surfaces & edges of small parts.


The upper disk housing is cast aluminum.


The table pivots on two protrusions that slide into L-slots shown here, then the locking knobs are attached.


If needed, zero the two red scale pointers after setup with the square.


The disk table angle is adjustable 0 to 60 (down). A 220 grit sandpaper disk is attached.


The miter is of all aluminum, albeit thin, construction.



The most accurate way to set the platen & miter is to use a square or other instruments e.g., a protractor.



Using a protractor to set a 20 table & miter compound angle.




Disk table removed to show the dust collection housing. Six screws are removed to replace the sanding disk.


Belt table or platen, installed. 120 grit belt, mounted. The angle is set in the same manner as the disk platen.
There is not miter & compound angles cannot be set on the belt table.


Steel work stop installed.


The easy access belt housing locking bolt.



Belt housing moved to & locked in the horizontal position. Housing supported by the horizontal stop (RT).




The belt housing is cast aluminum shown with its plastic cover removed.
Two captured knobbed bolts hold the cover.


Lower aluminum belt drum.


Spring-loaded belt release handle (RT). The belt centering adjustment bolt with locking nut is at the top-center.


Here a 1" x 42" 220 grit belt is mounted.


1" rear dust chute for the disk.
Tempering Colors  Temperature Conversion

Bench Grinder, Grinder Chuck, Jigs, Pedestal Feet, Wheel Dressers,
Diamond Carbide Grinder, 2x42-inch Belt 6-inch Disk Combo Sander

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