9x20 Tool Post Grinder
& Adapter Plates
Last updated on
Sunday, August 15, 2021 11:56:38 AM
Mountain US Time Zone
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Tool Post
Grinder,
Simple Mounting Bracket,
Single Point Dresser,
Grinding,
Tool Post Grinder Movie,
Pivoting Bracket,
Air Micro Die Grinder
Always wear
safety glasses
&
breathing
protection.
Note: Cover all ways, lead screw, & other exposed parts before grinding.
The grit dust is very abrasive to the ways & other parts.
Tool Post Grinder
Designed for the smaller
mini-lathe. I chose this
one because it has good clearance
around
the grinding wheel area & the mount is more generic
though it does not
have a chuck for ID grinding.
The grinding wheel is: 80mm (3.2") diameter, 10mm
(0.4") thick, & has a 20mm
(0.8") center hole.
The wheel center is about 57mm (2.25") above the
bottom of the mounting foot.
Some of the grits available
are: 60, 80, 120, 180, & 240.
No-load wheel speed
was measured at 7800 RPM (motor is 23,400 RPM).
3:1 pulley reduction uses a multi-V belt.
Note how
the foot has an alignment edge along one side.
Tool post grinder diagram.
Cover shown removed revealing two aluminum pulleys with a multi-V belt.
A simple grinder to cross slide adapter plate
is held
down using the same
four, M6-1 bolts & nuts
used
for the
QCTP clamping
plate.
A
0.426"" plate
placed the grinding wheel center
at the 9x20's
spindle
centerline.
The motor & belt housing are tilted
back toward the operator to allow a better
view.
Simple Mounting Bracket
Top view of the simple adapter plate.
A slot was milled
that allows the ledge of the grinder's foot
to align against.
The slot's top left edge was chamfered to allow a tight fit.
The foot was deburred & wire brushed to remove paint
overspray.
Two, M6-1 cap-head bolts with washers
are screwed into threaded holes to hold it in place.
Always wear eye protection
Mounted a
single-point, 0.75 carat diamond dresser into
the spindle using a 2" boring head
with a 1/2" shank arbor.
The spindle is in lowest speed & engaged to firmly
hold it in place.
DO NOT turn the lathe on.
I had made a 1/2" to 3/8"
boring-bar adapter
for the boring head which also holds the dresser shank.
I advance the wheel into the dresser about 0.0005"/pass.
Always dress the wheel before use.
A dedicated diamond dresser
fixture.
The 7/8" diameter holder has a 3/8"
precision-reamed blind hole for the
dresser.
Improved the dresser fixture
by reaming the 3/8" hole
for the dresser all the way through for more
adjustability.
The holder now has 1/4", 1/2", 3/4", & 7/8" steps
for added flexibility when mounting
in a collet.
Click on linked thumbnails
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Grinding
It puts a nice finish on steel.
The 80 grit wheel is
shown, above.
Reshaping a
removable/replaceable tip for a
General No. 79 automatic
center punch, below.
Removing a burr from an
interchangeable counterbore pilot.
Tool Post Grinder Movie
Cleaning-up the body of an imported countersink.
Both the
lathe & grinding wheel should turn CW so the
surfaces are moving opposite each other. This method
produces the best finish.
Tool post grinder movie.
In this movie the part appears to be turning the wrong
direction but this is due
to the camera's 30 fps sampling
rate. This is called the wagon-wheel effect which is caused
by under-sampled
(stroboscopic) apparent motion.
Grinding at a 35 deg angle as set by the pivoting bracket.
The
collet stop body did not fit inside all of the 5C
collets so it was
reduced using the tool post grinder.
During grinding, abrasive dust is produced;
protect the ways
with a cloth.
Pivoting
Bracket
In order to accurately rotate the grinder to different
angles, I made a
pivoting bracket (see drawing).
Top bracket was bolted down onto the
rotary
table with a scrap
plate on the bottom to keep
from
autographing the surface.
Indexing holes every
5 deg on the left & 15 deg on the right. First,
center the rotary
table
then indicate the plate off
the precision reamed, 1/4" hole in the center.
Base & top mounting plates to allow rotating the grinder.
Pivots on a
1/4" dowel pin. 1/8" reamed holes every 15 deg.
Each plate was fly-cut to 0.213" so when combined, it would
align the grinder wheel's center
with the
lathe's center.
The two larger holes on the top (right) plate were used to
clamp it to the 6" rotary table. The slots are a
1/4" wide.
Added indexing holes every
5 deg along second edge.
Detail of dowel pin with knurled knob, shown.
Note relief at both pocket ends.
The base has 6.5mm
clearance holes for the 6mm tie-down bolts.
Added an
alignment bracket
on the base (right) that
is placed against the
lathe's cross-slide table edge.
Three, 3-48 Phillips flat-head screws are used to attach
the bracket.
This bracket is 0.005" below the base's
top surface to allow rotation of the
upper plate.
Returning
the bracket to the same rotational
position reduces
the amount of
material that is removed while wheel
dressing.
Note the secondary zero-indexing holes.
Pocket for the foot's
alignment edge was milled
the same as
that for the
simple bracket.
A pocket is stronger than if cut all the way
through. Both ends of the
pocket were
relieved (milled) with small right-angle cuts so
they would not touch the foot's corners.
1/4-20 button-head bolts with
custom-sized brass washers
are used to clamp the upper rotating
plate to its base.
An aluminum knurled knob with a 1/8" dowel pin
insert is used to
align the plate indexing holes.
The base uses 4, M6-1 cap-head tie-down bolts.
Grinder set to &
used at 0 deg.
Grinder is shown set to &
used at 30 deg
to grind a 60 deg included angle point.
The guard interfered with the indexing pin at 45 deg so
a
secondary zero position was made 15 deg to the right.
Note how the base alignment bracket on the right
side is up against the
side of the cross slide table.
Air Micro Die Grinder
Air
micro die grinder shown
being held in the 3/4"
boring
bar tool holder using the 5/8" split adapter.
The die grinder has an 1/8" collet, uses 2 CFM @
90 PSI supplied air & can
turn 56,000 RPM.
Dress with a single-point diamond before use.
This setup is for precision ID
grinding.
Cover lathe bed ways to protect them from gritty
abrasive grinding dust.
Air micro grinder manual.
See
Air compressors &
accessories.
Precision holes are either
reamed,
bored or
precision
ground.
Click on
linked thumbnails #ad
Click on linked thumbnails
#ad
Tool Post
Grinder,
Simple Mounting Bracket,
Single Point Dresser,
Grinding,
Tool Post Grinder Movie,
Pivoting Bracket,
Air Micro Die Grinder