Workholding, Rotary Tables & Dividing Head
Last updated on Wednesday, September 20, 2023 05:58:02 AM Mountain US Time Zone


Mill Vise, Indicating a Mill Vise, Parallel Sets, Parallel Separator,
Drawbar Tool, Work Stops, Edge Finders, Safety Shields
Precision Blocks, Work Hold-down Clamps, Rotary Tables,
Rapid Rotary Table Positioning, Fixtures,
Dividing Head

Mill Vise

TE-CO Parlec PSW-6900 6" wide angle-lock vise (Taiwan). 
75 lb, 9-3/16" opening, 1.75" jaw depth. 

Bed height 2.875" +/-0.0005".
Parallelism of base to bed 0.0006".
Perpendicularity of jaws to bed  0.0005".

 Flatness of base 0.001". Repeatability within 0.001".
Hardened vise bed & jaw plates.
Outside rail edges of the body machined. 80,000 PSI
high-nickel, ductile iron. 8200 lb clamping pressure. Powder

paint & sealed bearing system. Larger, precision
main screw & bolted solid jaw allow higher torque

loads. Dimensions are industry standard. Another reason
why I chose the Parlec vise was because the near
equivalent, Kurt Model D675, when fully closed,
has a movable-jaw nut that protrudes out the back 1.4"

 which would interfere with table travel on a smaller mill.
The Parlec does not have a large protruding nut.
Parlec PWS-6900 single station vise parts list    Parlec flyer

Indicating a Mill Vise
A common question is, "When I machine a surface
using an end mill, why do I get a small ridge

after each pass?" The answer may be that the
mill needs to be indicated (aligned). The spindle

(cutter) must be perpendicular to the table.
Other causes may include: excessive machine flex,

improperly adjusted/lubricated/worn dovetail ways,
improperly held cutter (e.g., a drill chuck),

worn spindle bearings and/or a dull/damaged end mill.

the Parlec solid jaw animation.
The slot on the top of the solid jaw can also be used.

Move the bed left & right, make minute adjustments
of the vise position until zeroed, then lock it

down. Minor (
+/-0.0001") variation may be observed
but that is usually manufacturing tolerances.

This Swiss Interapid DTI has 0.0005" resolution.
instructions on how to set tip geometry &
see illustration
. Lock the Y & Z axes
before aligning the fixed jaw of the vise.

the vise bed animation.
Note in the center location, only the

 small needle moves showing that
the large needle changed by 0.030".

Mill vise lock down hardware uses 3/8" thick
steel plates with hardened T-nuts, bolts, & washers.

A two-position speed handle.

Parallels accurately hold a workpiece or
fixture at different depths in vise jaws.

6" long, 1/32" (0.032") ultra-thin, 1/2"
through 1-11/16" by 1/16" increments. 

Needed when working close the piece's edge and/or
gripping near the top (1/16") of the vise jaws.

Parallelism +/-0.0001". These ultra-thins also clear the
tightening nut of the 5C collet fixture when it is used

in a vertical position. To keep closely-spaced parallels separated,
I place a piece of closed-cell foam in-between them.

A drop of light instrument oil will also stick parallels to
the vise jaws. For wider openings, I use a
Kurt separator.

6" long, 1/8" thick, 1/2" through 1-5/8"
by 1/8" increments, standard parallel set.

6" long, 1/4" thick, 3/4" through
1-3/4" by 1/8" increments parallel set.

6" long, 1/2" thick, 7/8" through 1-3/4" by 1/8"
increments parallel set. Accuracy +/-0.0003".

These thicker parallels form a very stable part
base when there is enough room for them.

Adjustable parallels. Two sets are handy.
Can also be used to gauge inside dimensions.

-1/2" long wavy parallels, made out of spring steel material,
compress when holding small pieces. Use one or two at a time.
One slightly compressed parallel will support a narrow piece.

3-inch long, parallel set.

Parallel Separator

Kurt spring-loaded parallels separator.

Holds the ultra-thin parallels nicely in place.

Prismatic V-jaw.

Drawbar Tool

Fabricated a 17mm drawbar wrench with an integral
brass hammer. Loosen the mill's hardened nut & give it

a tap. Used a 3/8" carbide end mill to make a hole through
the Craftsman six-sided (for strength) deep socket

for the tightly-fitting steel handle. There are milled flats
on both sides of the hole. The locknut fits inside the

milled flat edges. The handle is located midpoint.
The brass head has a tight-fitting peg pressed into the

square hole & is held in using an 1/8" roll-pin.
There is a heavy 45 deg chamfer on the hammer's face edge.
The longer handle allows a tighter draw down & the
socket keeps the nut in good condition. The open-ended

wrench was shorter & caused micro-burrs which were
stoned off so the socket would slide on & off smoothly.

Work Stops

5-axis milling stop with 1/4" rod; strong
construction & versatile low-profile positioning (USA).

The metal-constructed locking handle can be
easily repositioned by lifting upward & rotating.

One end of the steel rod is squared-off (diamond ground)
while the other end is hemispherical.

The stop came with a 5/8" T-nut so I had to make
one that was 1/2" to match the
RF-25 mill's slot size.
The T-nut is tapped with a 5/16-18 thread to match the stop's
hardware. It's not hardened but still performs well.

Made a blind hole slipover aluminum handle,
held on with 6-32 set screws, for the 1/4" hex wrench.

The three flush hex screws positively engage the flat.
Left off the
knurling so it would not hold dirt.

The stop rod engages the square 5C fixture edge.
The 5C collet has a depth stop screwed into its end.

Made a 1/4" steel stop rod that is 4-48 threaded so it
can accept different types of screw-in dial indicator tips.

The example shows an installed tip that uses a chrome steel ball bearing.

This stop attaches using two, 1/2-13 threaded holes in
the back of the solid jaw & is below the top of the jaws.

This work stop, which is below the part, attaches to the
mill table & is shown setting the position of a 5C fixture.

Only clamp a stop onto the
vise's solid (reference) jaw.

Hardened clamps.

The stop fixes the left part's position while the right
part acts as a spacer to even out the clamping pressure.
Only clamp a stop onto the vise's solid (reference) jaw.

Specialized rule that can be used on

lathes & mills. Stop-Loc instructions.

Edge Finders

Electronic edge finder with a 3/4" shank. The 0.400"
diameter ball tip is spring-loaded to prevent

damage from over travel. After the edge is detected,
zero the
DRO, retract the quill, move the axis
1/2 the distance of the ball's diameter (0.200") & then
zero the DRO, again. Electronic edge finder

LED edge finder animation. Note how the self-centering,
spring-loaded ball allows over travel without damage.

See more vises.

A variety of edge detectors & center finders with
3/4". 1/2", & 3/8" shanks. The spindle is turning.

The wiggler-type (right) works best at about
1000 RPM. The LS Starrett brand is superior.

Using a center finder to zero the DROs. The spindle
turns & the point is centered by gently pressing on it.

Edge finder animation. 
The spindle is turning at about 1000 RPM.

3/8" diameter Starrett edge finder with an adapter so
you don't have to change a collet just to indicate an edge.

Step sizes: 1/4", 5/16", 3/8", 1/2", 5/8", 3/4" & 1".
Step depths vary from .100" to .200".

A stepped center indicator for quick alignments.
Made out of stainless steel rod.
", 5/16", 3/8", 1/2" steps.
For the most accurate indication,
use a center finder or dial test indicator.

Dowel-centering tool. Gauges are far more accurate.
Be sure to start with a
center drill, first.
Handy for use on a drill press.

Safety Shields

Small, low, 1/16" thick, polycarbonate chip shield.
The aluminum base has five glued-in magnets.

Three, 6-32 set screws hold the shield into the base.

Larger polycarbonate shield on a magnetic base.
SS holder rod with aluminum edge holder.

Precision Blocks

Accurate, 1-2-3, 2-3-4 & 2-4-6 (inches)
precision-ground, hardened, steel blocks.

3/8-16 threaded & clearance holes allow clamping.

The 2-4-6 blocks are shown
being used to stiffen the setup.

Animation illustrating the use of precision
blocks to
help indicate the RF-25 table.
The 1st Word fixture by Sparro is discontinued.

RF_T_slot_specs.jpg (11910 bytes)
RF-25 mill table slot dimensions where:
24mm = 0
.945", 14mm = 0.551", & 10mm = 0.394".

Work Hold-down Clamps

The RF-25 slots require 1/2" T-Nuts using 3/8" studs.

Hold-down clamp set.

Rotary Tables

Six-inch Phase II+ rotary table. Perfect size for the RF-25
table (40- lb). Worm gear can cam out of mesh to

allow free/rapid rotation of the table. Before use, remove
the table scale index retention knob that is above the

 front left table locking lever, in order to fill the oil reservoir
through the hole. Plastic reservoir window to the right

of the front locking lever shows the oil level. Filled it to the
middle of the window with Starrett light instrument oil.
Phase2+ Rotary Table manual.

The 4" Sherline rotary table has a 3/8-16 threaded
center which is very handy when attaching parts.

The 6" table has an MT2 taper (1.5 deg) in the center
so I made a tapered plug with 3/8-16 threads.

There is still room to tram using the inner edge.

A bottom view of the 6" rotary table showing
a bolt holding the plug firmly in the MT2 hole.

Detail of the brass plug.

6" rotary table with 6" 4-jaw chuck mounted. 
Drilled using a Q letter-sized bit (0.332") & counterbored (1/2" end

 mill) four holes for 5/16-18 hardened hex bolts.
The bolts are halfway (45 deg) between the jaws & the threaded holes

 that mount the back plate. First trammed the rotary
table then trammed the chuck using the outside surface.

Using the rotary table to layout the bolt-hole pattern
for the 4" chuck to 6" rotary adapter plate. Precision

(reamed) center hole used to indicate part center in
the 4-jaw chuck. Engaged all table locks before drilling.

M8-1.25 counter sunk hex bolts use the existing
adapter plate holes. Hardened 5/16-18 hex bolts
hold the plate to the 6" rotary table. The aluminum
plate is made from high-precision (milled) stock.

Bolted  a narrow, milled bar with 3/8-16 threaded
mounting holes onto the bottom of the rotary table.

Just clamp it into the vise with the bottom of the table
resting on the top of the precision machined jaws.

The table aligns fine & it is quicker than
removing & re-installing the 75 lb Parlec vise.
4-5/8" of Z are lost but if the part is small, no problem.
The rotary table is also better centered.

Rapid Rotary Table Positioning

An animation illustrating how the worm gear can be
unlocked & cammed out to allow rapid table positioning.

Mounted the 4" rotary table onto a base plate for
quick mounting. The table already had three, 10-32

 threaded holes on the bottom. Used transfer screws
to align the three, 10-32 threaded holes with the plate.
The rotary table's bottom surface rests on the vise jaws.
25 lb maximum weight limit on this rotary table.

For an additional 1-3/4" (44mm) of Z, the plate allows
holding down inside the jaws plus parallels can be used.
The base plate has ten holes that align with the Taig mill
table slots mounting using 10-32 bolts with T-nuts.

A simple 3/8-16 to 10-32 adapter for the
4-inch rotary table. It has a screwdriver slot. 

A simple rotary table centering bolt;
3/8-16 bolt head machined to a 45 deg angle.

This black-anodized aluminum add-on bubble level
for tripods has a 60mm (ID) tray. It accommodated all

of my different tripod head bases except the

Manfrotto 498RC2 tilt-ball. To accurately mount the plate for
machining, a bolt head was cut to at an angle on the lathe.
Using this forced the part's hole to be tightly centered

on the table. 0.35mm (0.014") was removed to open-up
the plate for the 498RC2 which has a 60.5mm base.

Using the rotary table, three, 6mm holes were drilled
every 120 deg to clear the base-locking set screws.

If the screws are set out about one mm, they
keep the plate from rotating as the head is attached.


Example of a simple fixture. An aluminum collar
was machined to attach & center the part using
a 3/8-16 bolt screwed into the table's center.
A jig is a form of fixture.

To make a brass replacement washer
(broken plastic) I first drilled a 1" hole into the only stock
I had available. Brass was used because it is
for an outdoor application that pivots in the wind.

Used the band saw to slice off wafers.

Mounted the wafer onto a 1"
mandrel to make a 0.12" thick disk.

Held a piece that had a bored 1-3/8"
hole using the small 3-jaw chuck.

Milled to the traced line using a center-cutting,
2-flute, 1/4" TiN-coated end mill at 1900 RPM.

Here I used the mill to also make the straight cuts.
The DRO returns the table to center (0,0).

Two more parts needed smaller 1" holes so I
decided to make fixtures to match-up the centers.

The base has the 1" diameter step. The hubs are
not as thick as the part so they will clamp tightly.

Disk is mounted on its base.
Red Dykem was applied before scribing.

A 1-3/8" spacer holds/centers the first part I made.

A 3/8-16 bolt screws into the rotary table.
The aligned part is then traced with a scribe.

The fixture holds the part above the
table allowing clearance for the end
mill to cut all the way through.

This time I used the band
saw to make the straight cuts.

The parts were finished using a disk sander.

Completed parts with fixtures. 

Made an adapter plate to mount the 4"
rotary table centered on the tilt table.

Dividing Head

Dividing head with its center & integral dog.
The 1-1/2-8 threads are protected by the supplied plastic collar.
Also shown is its adjustable tailstock. Threaded (unfinished)
chuck adapter & additional index plates (top).

Dividing head with 5C collet chuck. The head can tilt
to different angles. Bemato dividing head manual.
This dividing head is made by Bemato (Taiwan).
This head is now used on the RF-25 mill.
Use a 4-jaw or collet chuck to get accurate centering.

dividing_head.jpg (62952 bytes)

gear_cutting.jpg (48963 bytes)
A single HSS toolbit can be ground to a gear profile.
My first try results. The three-jawed chuck did
not hold the stock perfectly centered. This is easily
corrected using a 4-jaw chuck or collets.

 I have now switched to CNC gears; making
them using the 4th A-axis & involute cutters.

Mill Vise, Indicating a Mill Vise, Parallel Sets, Parallel Separator,
Drawbar Tool, Work Stops, Edge Finders, Safety Shields
Precision Blocks, Work Hold-down Clamps, Rotary Tables,
Rapid Rotary Table Positioning, Fixtures, Dividing Head