Tool Post Grinder & Adapter Plates
NOTE: Cover all ways, lead screw, & other exposed parts before grinding.
The grit dust is very abrasive to the ways & other parts.
Always wear eye protection
Tool post grinder from
LMS. 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: 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.
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.
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 de-burred & 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, 1 carat diamond dresser into the spindle using a 2" boring head
with its ½" 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 ½" to ⅜" 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 ⅞" diameter holder has a ⅜" precision-reamed blind hole hole for the
dresser.
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 counter-bore pilot.
In order to accurately rotate the grinder to different angles, I made a
pivoting bracket.
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° on the left & 15° on the right. First,
center the rotary
table
then indicate the plate off the precision reamed, ¼" hole in the center.
Base & top mounting plates to allow rotating the grinder. Pivots on a ¼" dowel pin. ⅛" reamed holes every 15°.
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
¼" wide.
Added indexing holes every
5° 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.
On the right side, added an alignment bracket
on the base 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.
¼-20 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 ⅛" 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°.
Grinder is shown set to & used at 30° to grind a 60° included angle point.
The guard interfered with the indexing pin at 45° so I made a
secondary zero, 15° to the right.
Note how the base alignment bracket on the right side is up against the cross slide.
Air
micro die grinder shown
being held in the ¾" boring
bar tool holder using the ⅝" split adapter.
The die grinder has an ⅛" collet, uses 2 CFM @ 90 PSI
supplied air & can
turn 56,000 RPM.
