Workholding, Rotary Tables & Dividing Head
Last updated on Tuesday, December 02, 2014 05:49:42 PM Eastern US Time Zone


Mill Vise, Indicating a Mill Vise, Parallel Separator, Drawbar Tool, Work Stops, Edge Finders, Safety ShieldsParallel Sets,
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-lbs., 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-lbs. 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
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 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 re the table. Other causes may include: excessive machine flex,
 improperly held cutter (e.g., a drill chuck), worn spindle bearings and/or a dull/damaged end mill.

Indicating 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 Interapid indicator has 0.0005" resolution. Its needle moves ~0.0001" in the center which is
well below the manufacturer's spec. See instructions on how to set tip geometry & see illustration.
Lock the Y & Z axes before aligning the fixed jaw of the vise.

Indicating 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 ⅜" thick steel plates with hardened T-nuts, bolts, & washers.

A two-position speed handle that was free with the vise purchase.

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 ⅜" 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 ⅛" roll-pin. There is a heavy 45 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 " 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 ⅝" T-nut so had to make one that was " to match the RF-25 mill's slot size.
The T-nut is tapped with a (non-standard) 5/16-18 thread to match the stop's hardware.

Made a blind hole slipover aluminum handle, held on with 6-32 setscrews, for the " 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 " 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, -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 fixing the position of a 5C fixture.

The stop is clamped only on the solid (reference) vise jaw.

The stop fixes the left part's position while the right part acts as a spacer to even out the clamping pressure.

Specialized rule that can be used on lathes & mills. Stop-Loc instructions.

Edge Finders

Electronic edge finder with a " 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
the distance of the ball's diameter (0.200") & then zero the DRO, again. Electronic edge finder manual.

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 ". ", & ⅜" 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.

⅜" diameter Starrett edge finder with its adapter so you don't have to change a collet just to indicate an edge.
Step sizes:
", 5/16", ⅜", ", ⅝", " & 1". Step depths vary from .100" to .200".

A stepped center indicator for quick alignments. Made out of stainless steel rod.
", 5/16", ⅜", " steps. For the most accurate indication, use a center finder or dial test indicator.

Safety Shields

Small, low, 1/16" thick, polycarbonate chip shield. The aluminum base has five glued-in magnets.
Three, 6-32 setscrews hold the shield into the base.

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

Parallel Sets
Parallels accurately hold a workpiece or fixture at different depths in the mill's vise jaws.

6" long, 1/32" (0.032") ultra-thin, " 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 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, ⅛" thick, " through 1⅝" by ⅛" increments, standard parallel set.

6" long, " thick, " through 1" by ⅛" increments parallel set.

6" long, " thick, ⅞" through 1" by ⅛" 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 gage inside dimensions.

" long wavy parallels, made out of spring steel material, compress when holding small pieces.

3-inch long, parallel set.

Precision Blocks

Accurate, 1-2-3, 2-3-4 & 2-4-6 (inches) precision-ground, hardened, steel blocks.
⅜-16 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.

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 " T-Nuts using ⅜" studs.

Hold-down clamp set.

Rotary Tables

Six-inch Phase II+ rotary table. Perfect size for the RF-25 table (40-lbs). 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.

Tramming the rotary table using an IndicOL holder with Starrett dial
test indicator (above) & a ⅛" collet holding a dial test indicator (below).

Animation showing the left-right (X-axis) of the rotary table being trammed using the precision ground inner edge.

Animation showing the front-back (Y-axis) of the rotary table being trammed.

The 4" Sherline rotary table has a ⅜-16 threaded center which is very handy when attaching parts.
The 6" table has an MT2 taper (1.5) in the center so I made a tapered plug with ⅜-16 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") & counter-bored (" end
 mill) four holes for 5/16-18 hardened hex bolts. The bolts are halfway (45) 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 chuck 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 ⅜-16 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.
4⅝" 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-lbs. maximum weight limit on this rotary table.

For an additional 1" (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 ⅜-16 to 10-32 adapter for the 4-inch rotary table. It has a screwdriver slot. 

A simple rotary table centering bolt; ⅜-16 bolt head machined to a 45 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
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.

This shows a Manfrotto MT294C3 carbon fiber tripod with a mounted & locked 804RC2 pan-tilt head.
Its aluminum base was just under 60mm in diameter.

A level tripod is recommended for taking panoramic photo sets that are to be subsequently stitched together.
All my monopod & tripod heads use the same (interchangeable) Manfrotto quick-release 200PL camera plate.

The slightly oversized base now fits the tray perfectly & can be locked with the three tripod set screws.


An aluminum collar was machined to attach & center the part using a ⅜-16 bolt screwed into the table's center.

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 1⅜" hole using the small 3-jaw chuck.

Milled to the traced line using a center-cutting, 2-flute, " 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 1⅜" spacer holds/centers the first part I made.

A ⅜-16 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 1-8 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)
My first try results. The three-jawed chuck did not hold the stock perfectly centered.
 I have now switched to CNC gears; making them using the 4th A-axis & involute cutters.
Also see Gearotic Motion software.

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