Precision Mensuration
Last updated on Monday, April 26, 2021 06:09:34 AM Mountain US Time Zone

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Definitions, Surface Plates, IndicatorsComparator Stands,
Z-Offset Gauges, Depth Gauges, Height Gauges, Universal Gauge,
Inside Diameter Gauges, Pin Gauges, Runout & Bore Gauges,
Calipers, Micrometers, Dial Test Indicators, Coaxial, Indicator Holders,
Thread Gauges, Angle Meter, Angle Gauges, Radius Gauges,
Infrared Thermometer, Tachometer,
Sound Level Meter, Scales

Definitions
Precision
-
Made so as to vary minimally from a set standard.
Mensuration
- The act, process, or art of measuring. Measurement of geometric quantities.
Resolution
- Smallest difference between indications of a displaying device that can be meaningfully distinguished.
For a digital display device, this is the change in the indication when the least significant digit changes by one step.
Measurand - A quantity that is being determined by measurement.
Accuracy - Closeness of the agreement between the result of the measurement & the true value of the measurand.

See Layout Tools Section.
Decimal Equivalents of Fractions 
Decimal Equivalents of # Drills 
Decimal Equivalents of Letter Drills

Inch to mm Conversion  
mm to Inch Conversion  
Metric & Inch Equivalents  
Machinist Calculator

Surface Plates

Granite surface plates (+/-0.0001")
in 18" x 12" x 3"
(85 lb.) & 12" x 9" x 2" (30 lb.) sizes.

Use surface plate cleaning fluid to remove
dirt, oil, & marks left by (aluminum) parts.
Protect with a custom-made all wood cover.

 

 

 

 
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Different Sizes & Accuracies available:

6" x 6" x 2"
6" x 8" x 2"
12" x 8" x 2"
12" x 9" x 2"
12" x 9" x 3" (40 lb
)
18" x 12" x 3" (80 lb
)
24" x 18" x 3" (150 lb
)
36" x 24" x 4" (495 lb
)
48" x 36" x 6" (1200 lb)

Grade A accuracy is +/- 0.000075"
Grade B accuracy is +/- 0.000150"

Granite Surface Plate checked using an autocollimator for accuracy
assurance to meet or exceed Federal Specification GGG-P-463c.
Includes a Certificate of Inspection.

Indicators

Mitutoyo electronic indicator
(1/2" range).
Resolution is 0.00005" (50 millionths).
Using a
linear encoder, it always displays the
spindle
's absolute position from the origin at
power-on.
Digimatic indicator manual & drawing.

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 
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Mitutoyo (Japan)
electronic indicators
(1/2" range)
with a Noga
(Japan) magnetic base indicator holder.
Both are best in class. See digital indicator manual.


Measuring QCTP deflection whilst parting mild steel.


A-axis tramming animation. Note the degrees scale.
Iteratively adjusted opposing pairs; 0-180 deg & 270-90 deg.


A wooden holder for 3/8" stemmed digital & dial
indicator gauges. Many tools are supplied with their

own indicator. Two came with dial indicator
comparator stands & two with gun cartridge measurement
fixtures. 2nd from the front is my first digital-style gauge
which was replaced by the front gauge that has much
higher resolution. The gauges vary by their respective
measurement ranges, accuracies, & resolutions.


Their positions are offset to accommodate the lug back mounts.
The plungers of the more costly units are not compressed while stored.

Mill & Router Spindle Square

A spindle square used to align a CNC router.
Likely not accurate enough for metal milling machines.
Eighteen inches long. To setup, mount in the chuck, place a

spacer under one indicator & zero then swing the
other indicator around to the same spacer & zero.

The bar has to be very straight, rigid & the
center dowel must be perfectly perpendicular. 


One-half inch interference fit shank
using a precision ground steel dowel.

 
Dowel pins come in a huge variety of sizes & precision.
Click on linked thumbnails

Comparator Stands

Two, dial indicator comparator stands.
Used for quality assurance (QA) size

measurements of many parts. Serrated
anvils are purportedly more accurate.


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Several two-inch range gauges were used on
various machines before changing to advanced DROs.
For example, I used two gauges just for the
Taig micro lathe & to good effect, providing excellent control.
I liked it so much I went digital for both X & Z-axes
but later extensively modified the
lathe to be CNC.
Surprising accuracy & repeatability though low
durability, but given the cost, acceptable if on a budget.


A two-inch range digital indicator that reads
to 0.0005" resolution. It has an 8mm stem.


The fine adjustment mechanism for the stand.


A collar was made to adapt the 8mm stem to 3/8".
The screw is threaded through to directly contact the stem.


Heavy-duty, Brown & Sharpe No. 731
10" x 3" x 1-3/4" (L x W x H) inspection holder (USA).


Note the robust adjustments.




Different types of dial gauge interchangeable
4-48 threaded indicator points. To keep from straining
or breaking a gauge's internal alignment pin,
completely depress the plunger so the rack absorbs the loosening &
tightening forces before changing the points. Never use Loctite.

 
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Z-Offset Gauges

4.000" height, Z-axis tool length setting gauge (USA).
One-inch contact face picks-up all the flutes of

large end mills, easy to read 2.2" dial face, a setting
repeatability of 0.0002", & hard, red anodize.

Needle-based Z-setting gauges are not damaged
by over travel like some electronic types.

The unit's overall ergonomic & mechanical
design is excellent & has a good, heavy feel.


Z-axis offset animation showing a 3/4" end
mill being set at 4.000" above the vise bed.

Starrett also makes a superior (expensive) 4-inch
special dial depth gauge for Z-height setting.


A 3.000" height offset gauge using a 40 mm (1.5") diameter
face Mahr dial indicator (GER) that reads to 0.0005".

Mahr is a top quality, durable, made in Germany,
dial test gauge; highly recommended instrument.

Stem is 8mm (.315"). The 7.5mm (0.295") diameter flat
tip is an ideal shape. The bracket is all steel construction.

All critical surfaces of the parts, including the round post
ends, were precision surface ground for high accuracy.

An adjustable, brass, over-travel stop was added
so the needle can only turn about one revolution.

This height gauge design has excellent sensitivity
for delicate end mills & does not require a lot of Z.




The bottom of this Z-offset gauge needed lapping
which was performed on a granite surface plate first using

320 followed 400 & 600 grit silicon carbide papers.
Moved the part in a figure-8 pattern to insure an even

removal of material. Significant surface improvement resulted.
The edges were deburred with an India stone.

 

 

 


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This offset gauge has a magnetic bottom
which attracts debris & the spring is too
strong for very small end mills.


1-2-3 Jo-blocks bolted together make a
very accurate, rigid, low-cost, 2" zeroing fixture.
Assemble flat, on a surface plate.
Jo-blocks are indispensible for use in mill setups, too.
 
Imperial or metric

 

 
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2" high Z-offset gauge. A 3" micrometer & a 1-2-3 Jo-block
were used to set the gauge's zero at 2.0000".

The recessed bottom required a Jo-block. The micrometer
was first locked at 3.0000" using the
gauge block.


Mill Z-offset gauge (instructions) used to set tool lengths.
Needle-based, Z-offset gauges set the  mill more quickly & accurately
than illuminated types plus they are not damaged by over travel.


Animation showing a 2.000" Z-offset height being set
on the Taig CNC Z-axis using the Mach3 MPG step mode.


Electric-type Z-offset gauge with 0.0002" repeatability.
It has a 1" x 2" x 3" form factor. Uses 2, LR44 batteries.
Aluminum faces do not chip brittle carbide end mills.
May not work properly on anodized surfaces (e.g., Taig).
The analog dial-type with a needle have superior
setting ease, accuracy, & repeatability.


Checking the height & light/battery circuit.
Z-offset gauge instructions.


An animation showing a 1.0000" Z-offset being set.


With the gauge light illuminated, the value (1.0000")
was then entered into the Z-axis of the
mill DRO.



Here the electronic gauge is working on the
CNC Taig mill's anodized table. The connection was
completed by grinding off the black anodize on
the T-nut inner face & making multiple punch marks.

The vise should not clamp the gauge that is deep in
the jaws as that would short-out the upper & lower plates.


The punch marks are raised & sharp thereby piercing
the table's inner T-slot anodized surface to complete

the connection. Though maybe not necessary, this
can be done for all the T-nuts that hold the vise in place.


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A tooling plate is mounted onto the anodized table
where a 0.2 ohm conductivity is realized via 6, T-nuts.



The gauge can also be used with
parallels & lightly clamped into the vise.


Depth Gauges

Baker dial depth indicator (India) with a 0" to 10" range &
where one gradation = 0.001".
Rod extension chart.


The dial indicator gauge itself has a
0 to 0.5" measurement range.
Example:
Measured
Depth = 0.1840" (dial reading) + 0" (extension rod length) = 0.1840".


Micrometer depth gauge with a 0-6" range.
One gradation = 0.001". Depth = reading + rod length.



 

 

 
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A Mitutoyo digital micrometer head combined
with a hardened & precision-ground depth base.

Note: Over tightening the set screw can distort
the mounting flange & bind the mechanism.


The scale is not reversed like its mechanical
counterpart, but digital micrometers can

be zeroed at any location & then the negative
sign is simply ignored for the readings.



Hardened & precision-ground depth base
attached to a Mitutoyo digital caliper.


Click on linked thumbnail


Digital depth gauge with a large base.
See digital caliper manual.

Height Gauges

A Mitutoyo, 8", 543-244 digital height gauge with fine
adjustment mechanism. The height gauge & a granite surface
plate make an accurate combination for measuring parts
or laying out precisely scribed lines. Resolution: 0.0005".
Absolute electrostatic capacitance type linear encoder.
A fine adjustment carriage is a requirement for fast, accurate
settings.
See Mitutoyo 543-244 digital height gauge
manual &
dimensional drawing. For accurate, repeatable
measurements, insure the surface plate, height gauge, &
scribe working surfaces are free of debris/grit. Check to
see if the scribe bracket is tight. Periodically inspect the
adjustable ways of the transducer for excessive play.


The heavy base has an excellent ergonomic design.
The bottom surface is ground & lapped to perfection.


Mitutoyo depth & center-finder
attachments for the height gauge.


Hole center-finder attachment.


Hole center finder animation showing how the fine adjustment
of the height gauge is used to zero the needle.

This tool allows comparative QC measurements
of many holes in production.


Using a test gauge in conjunction with a height gauge
allows measurements of both dimensions & tolerances

without having to use separate instruments.
See
instructions on how to set tip geometry & see illustration.


Height gauge with digital indicator for
both height & tolerance measurements.


Starrett No. 3751 digital height gauge. Auto-off in
5 minutes but retains zero; auto-on when the slide

is moved. Zero to 6.45" max range, 0.0005" (0.01mm)
resolution & +/-0.001" (+/-0.03mm) accuracy.

Supplied with an extra scribe & clamp plus an
excellent, padded, aluminum hard case. The vertical

column is set-in from the tip of the base's nose for
better stability. This height gauge's compact size

 is especially valuable when measuring parts with
very small features or using it on my two mills.

The scribes are not carbide-tipped. The fine-edged,
HSS scribes are limited to semi-hard metals &

the rounded tips limit scratch depth. This height gauge
is ideally suited for use on small, delicate work.


Starrett No. 3751 digital height gauge manual.


Adjusting to a specific height can be accomplished by
picking it up & using it much like a regular caliper.

 Slightly increasing the slide resistance of the transducer
(a small, side set screw) helps adjustability.

Setting an exact numerical value with this type
of adjustment mechanism is slower than

that of a height gauge equipped with a
fine adjustment carriage mechanism.


A Starrett Last Word DTI mounted onto the small,
3715 height gauge using the 711-49 bar attachment.


A carbide-tipped (Mitutoyo) 10", dial height
gauge on a granite surface plate
(+/-0.0001").
High accuracy can be achieved using
gauge blocks to set specified heights.
Use layout die to make the scribe marks easier
to see. Mitutoyo height gauge manual.
Surface plates are useful for precision
alignment when assembling parts, too.


Mitutoyo OEM wooden case.


Depth attachment. Rod accepts different 4-48 threaded
indicator
points. This was my first height gauge.
It is easier to miss-read an analog dial than a digital
readout though analog scales can be interpolated.


Measuring distances between holes using
a center-finder attachment from Mitutoyo.


Height gauge with digital indicator
for both height & tolerance measurements.

   

     

 

 
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Universal Gauge

Starrett No. 995E (USA) Universal Precision Gauge
set is best in class. This gauge has multiple uses:
height gauge, scriber, planer/shaper setup, an
adjustable parallel to measure a gap, transfer
measurements, precision level, & layout work on
a surface plate
using gauge blocks or a sine bar.
Starrett  Model No. 995E Universal Gauge exploded diagram.


Nominal dimensions of the base are 5.25" x  2.5" x 0.75" (W x H x D).
Hardened & precision ground. The slide has a combination
of both a flat & a V-way to provide excellent accuracy.


The slide has a fine adjustment mechanism
allowing faster & more accurate settings.

No other similar gauges have this important
feature. Note the mineral spirits bubble level.


Offset attachment with clamp bolt extends the nose for
a minimum height of 0.17" allowing use in tight areas.


One-inch & three-inch extension rods can
be screwed in at four different locations.


A post clamp holds a hardened HSS scribe which
is being set at 3.0000" height using a gauge block.


A Starrett Last Word DTI mounted onto the 995E
Universal Gauge using the 711-49 bar attachment.

Inside Diameter Gauges

Telescoping & half-ball Mitutoyo inside gauge sets (Japan). 
The half-ball type can get into a shallow, blind

hole better than a ball type. Expand into hole, lock & then
measure the gauge with a micrometer or caliper.


Left: The small (half-ball) hole gauge is expanded by the center wedge.
Right: The telescoping inside gauge posts spring outward,
self-center & are then locked via a knob on the handle.

They can then be accurately measured with a caliper or a micrometer.


Mitutoyo (Japan) tools have superior accuracy over the
full measurement range, repeatability, quality & durability.


This steel part is being held in a lathe.


The hole measured 1.6296". I then updated the
lathe's
DRO X-axis setting for further boring.

 

 

 

 

 

 

 

 

 

  


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Various ignition gauges.
The far right gauge is made by Bosch.


Full-ball, small hole gauge set.


Half-ball compared to full-ball small hole gauge types.

Pin Gauges

 Pin/plug Gauge Sets - ID type gauges for
measuring hole diameters & slot widths.
0.011" to 0.060" x 0.001" minus Class ZZ pin-gauge set (50 pieces).
Tolerance +.0000" -.0002".  10mm finish or better. Hardness 60-62 RC.

 0.061" to 0.250" x 0.001" minus Class ZZ pin-gauge set (190 pieces).
Tolerance +.0000" -.0002".  10mm finish or better. Hardness 60-62 RC.


Detail of the 0.061" to 0.250" x 0.001", minus
pin-gauge set (still in the grease). Two-inches overall lengths.

 
0.251" to 0.500" x 0.001", minus Class ZZ pin-gauge set (250 pieces).
Tolerance +.0000" -.0002". 10mm finish or better. Hardness 60-62 RC.


0.501" to 0.625" x 0.001", minus Class ZZ pin-gauge set (125 pieces).
Tolerance +.0000" -.0002". 10mm finish or better. Hardness 60-62 RC.

 
Dowel pins come in a huge variety of sizes & precision.
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Go/no go pin gauge handles for QC work.
Shown holding 0.25" & 0.050" pin gauges.


Runout & Bore Gauges

Back-plunger dial indicator set (India) with 'G' clamp,
universal clamp, swinging-arm assembly, tool post holder,

 holding rod, Tommy bar & 2nd anvil. Swinging-arm assembly
enables the back-plunger dial gauge for use on internal

work to a depth of 1.6" (40mm); similar to a lever-type
gauge. Allows multiple types of mounting possibilities for

gaging applications like concentricity checks, alignment of
machine tools, testing parallelism, & surface-plate work.






Back-plunger dial gauge with
a swinging-arm attachment.


Measuring the eccentricity & runout
of the ID of a
bored cylinder.


A self-centering, 1.4" to 6"
cylinder bore gauge (
instructions).
The gauge is first set up to measure a specific size (zeroed)
then run through the bore to measure its variation.

To keep the extensions in order, a vibrator engraver
was used to label each size on a non-critical surface.


The dial gauge must be inserted deep enough to preload
(or move) the needle about 1 revolution (0.050").

The black plastic shroud can be installed after
calibration to protect the head under heavy shop use.



These 1/2" travel digital indicators, preloaded to 0.050"
depth, can also be utilized but others may not work.


Exploded view of the 1.4" to 2" measurement head,
the 1.4" range anvil & knurled anvil lock nut. The pointed
rod end (at the lower left) engages a rod inside the handle.


Anvil installation animation.


The center measurement anvil moves in & out.
The outside mechanism depresses under
spring tension to center the head.


Small anvil animation.
 

Assemble the appropriate anvils & spacers
(left side) for the target measurement size.

Then, using a gauge block, set a micrometer
(e.g., 2") to the bore size & zero the dial scale.

The gauge is then run through the cylinder &
the variation from set size, noted.


Bore gauge measurement animation.
Note the small measurement anvil (left) depresses & the
self-centering guide mechanism slides to the right.

Calipers

Mitutoyo Absolute Digimatic caliper (Japan).
An excellent digital caliper that is very accurate
throughout its
entire measurement range.
Always maintains zero, large LC display, greater
than 3 years battery life. No irritating auto-off.


Mitutoyo digital caliper manual.

 

 

 

 

 

 

 

 

 

 


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A digital caliper (manual) that measures & displays inches,
millimeters & fractions to 1/64th-inch.

Handy for wood work & sifting through raw stock.


Chromed, dial caliper gauge with a 0 to 0.8"
measurement range & a 0.0005" resolution.

The jaws are spring-loaded closed & are opened
with
the lever. Custom wooden box storage.


Ball bearing tips.


Before use, calibrate the dial scale
against a
gauge block of appropriate size.


I bought these gauges to allow me to
make measurements in tight mill setups.

   

   

 

 


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A snap thickness gauge. Close & zero the scale first.


8-inch digital linear scale for instrumenting
tools like
drill presses, mills, & lathes.

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This open-weave drawer liner has (Microban)
antimicrobial properties that prevent bacterial growth.

The non-slip black cushion protects the instruments &
keeps them from moving (banging) around, too.


Mitutoyo digital measurement tools: depth gauge,
caliper & micrometer (older models).

Micrometers

Superior quality Mitutoyo (Japan) digital micrometer
that reads down to 0.00005" or 0.001mm.

The scales are engraved, not chemically etched
thus have superior readability & durability.

Even if the battery is removed, the micrometer's
scales allow it to be used as a standard instrument.

It has a micro-polished, carbide-faced
working surfaces & an effective spindle lock.

DO NOT store a micrometer (any style)
with its measurement anvils touching.


See micrometer manual.

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The holder adjusts to different angles & has rubber pads
that protect the instrument from clamping damage.


Another style micrometer stand/holder.
This model has a nice, heavy base.


Mechanical digital-type outside micrometer, 1-2" range.
Standard & adjustment tool, included.

Mechanical digital-type outside micrometers,
2-3" range (above) & 3-4" range (below).

Standard & adjustment tool, included.
Digit Micrometer Manual.


The one ten-thousandths-inch (0.0001")
measurements are read off the (barrel) vernier.


All three shown for size comparisons;
size standards included.


Small, 0.6" (non-locking) & standard 1" micrometers.
The smaller micrometer's scales are chemically etched,

the larger micrometer's scales, engraved. Superior
instruments have engraved scales for clarity & durability.


2-inch mechanical micrometer.


Micrometer set zero through six-inches
with its wooden storage case (import).

One, two, three, four & five-inch sized
standards plus adjustment wrench are included.

The plastic insulating grips on the standards
reduce warming effects (expansion) due to handling.

Acquired for use mainly on the 9x20 lathe.
Excellent accuracy, engraved scales, & a good value.

All micrometers read to 0.0001". The wooden
case was re-glued in places & then sanded.

See micrometer scale reading instructions.


Though low-cost, the scales are engraved, the positive
locking lever is metal, & the ratchet thimble is precise.

A good value for light use.


Detail of the 1" to 5" standards for
the 0" to 6" micrometer set.


6" to 12" micrometer set.
All micrometers read to 0.0001".

The smaller wooden case holds
size standards 6" through 11".


6" micrometer, shown.


12" micrometer shown with the standards case, open.
The holes lighten the instrument for easier handling.

I needed the 7", 8", & 9" micrometers (for e.g., a flywheel)
so it was more economical to buy the whole set.


I needed four, aluminum rods to be exactly 9.6250"
in length so the 9"-10" micrometer was used.


Two micrometer sets covering 0" through 12".
Eleven, size-standards; 1" through 11". Two
separate sets can make handling/storing the
boxes easier than one big heavy 0" ~ 12" set.


A 0.6" micrometer compared to a 12" micrometer.


A micrometer head that can be incorporated into
other devices e.g., an
adjustable lathe carriage stop.
The tip of the 0.2" diameter is domed & hardened.
The collar is 3/8" diameter x 0.32" long.
The mechanical mic heads are low cost items.


A 1/2" range, adjustable lathe carriage stop.


Mitutoyo digital micrometer head.


Hub micrometer that measures 0-1" to 0.0001" &
designed to clear through a 3/4" hole.

Handy in tight places especially in milling setups.


A 6" throated micrometer having a measurement
range of 0 to 1" maximum with a 0.0001" scale.


Locking levers made of metal are a plus for
durability & precision of the mechanism movement.


Caliper-type micrometer measures to 0.0001". 
Measuring anvils extend approximately 3/4".

The threaded mechanism that keeps the anvil from
rotating also acts as a somewhat effective lock.


Disk micrometer with a 0.0001" scale.


0-1" range, 0.07" diameter anvil, tube wall
thickness micrometer that measures to 0.0001".


0-1" range, 0.19" diameter anvil, tube wall
thickness micrometer that measures to 0.0001".


Carbide-faced electronic blade micrometer
for measuring in narrow slots & recesses.

The thread mechanism that keeps the
anvil from rotating also acts as a lock.

 A 0.00005" minimum readout.
Digital
blade micrometer manual.


The blades are 0.030" thick.


1 to 2-inch blade micrometer supplied
with a 1-inch standard & adjustment wrench.


Carbide-tipped, small faces or spline
micrometer for measuring in tight areas.
0-1" range with 0.0001 scale.
The anvils are 0.0775" diameter.


Carbide-tipped, point micrometer for measuring in
very tight areas. 0-1" range with 0.0001 scale.

Points have a radius of approximately 0.012".


Screw thread micrometer with five different anvil pairs
measure both unified & metric external pitch diameters.

0" to 1" measurement range with a 0.0001" scale.
The left anvil holder floats back & forth to allow zeroing then

 it is locked into place. However, the anvil itself always
floats rotationally to maintain ease of measurement.

SCREW THREAD MICROMETER ANVILS

ANVIL #

1

2

3

4

5

TPI RANGE

64 - 48

44 - 28

24 - 14

13 - 9

8 - 5

METRIC RANGE

0.4 - 0.5

0.6 - 0.9

1 - 1.75

2 - 3

3.5 - 5


Anvil pairs are clearly marked for pitch range.


Example measurement of a 1/4-20 screw.
The micrometer reading is 0.2160".
Table pitch value is 0.2164" max.

A fast & accurate thread measurement tool.
The bolt freely rotates around the micrometer's anvil axis.


Carbide-faced inside micrometer gauges with locking mechanisms.
The top gauge range is 1"-2" & the bottom

gauge range is 0.2"-1.2". Supplied with 1" & 0.2" inside
ring standards, respectively. One gradation = 0.001".

 

 

 

 

 

 

 
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Dial Test Indicators (DTI)

Interapid 312B-1 (Swiss). Best in class dial test indicator
having: a monobloc metal housing with two dovetails,

jeweled movement, ball-bearing lever system,
micro-polished carbide tip, large tilted dial face, & an additional

revolution counter. Bi-directional measuring with
automatic reversal inside the movement & extra wide +/-0.060"

range makes it especially versatile. True readings
when the angle between the stylus & work piece surface is 12 deg.

 

   

   

 

 

 

 

 

 


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Interapid Model 312B-1 Horizontal Style DTI
Graduation 0.0005"
Dial Reading 0-15-0
Range +/-0.060"
Point Length 0.687"
Point Diameter 0.080"
Dial Face Diameter 1.5"
Stem Diameter 0.156" (4mm) 5/32"
TESA Number 74.111370


Accessories (Swiss): slotted reduction sleeve 3/8" to 5/32",
height gauge bar w/clamp, contact point wrench &

axial support with 3/8" diameter stem. The white tube in
the gray fitted storage box holds extra contact points.


Note the small (right of center) secondary revolution
counter needle used to track the wide +/-0.060" range.


5/32" (0.15625" or 4mm) pivoting stem,
dovetail mount, & monobloc metal housing.


Tramming a steel part before boring in the mill.
Zeroed at front, back, left, right; X & Y tables then locked.


Starrett surface gauge & Interapid dial test indicator
on the granite surface plate being zeroed

 using a 1" gauge block. If possible, move the
part not the gauge when measuring a surface

unless, of course, the surface is being swept.


For highest accuracy, the angle between the stylist & part
surface should be as close to 12 deg as possible.


The wide-range (+/-0.060") Interapid held by the rigid,
precise Starrett base are an accurate combination on a surface plate.



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

The Interapid indicator has 0.0005" resolution.
See instructions on how to
set tip geometry & see illustration.
Here, the needle moves <0.0001" in the center
which is well below the manufacturer's vise spec.


An excellent BesTest Brown & Sharpe (Swiss) dial test
indicator set. One gradation = 0.0005". This model

incorporates an auto-reversing feature & dovetail mounting.
The Swiss instruments are quite sensitive.


This Starrett Model No. 711 DTI has a small side lever
to select the needle direction. No dovetail mounts.

   

   

 

 

 

 
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The carbide tips have multiple
spring-loaded detent positions.
Quick & easy tip changes.


Rugged LS Starrett No. 711 Last Word DTI &
attachments (USA). One gradation = 0.001".


Starrett 711-49 attachment: 2-5/8" OAL, 1/8" x 5/16" x 1-7/8"
rectangular shank, & a 3/4" long x 15/16" round tip.

Used to affix the Starrett 711 Last Word DTI to either
the
3751 Height Gauge or the 995E Universal Gauge.


Gem DTI (USA). One gradation = 0.001".
Rod & dovetail mounting. Gem dial indicators & accessories
.
See instructions on how to set tip geometry & illustration.
Essentially a copy of the Starrett No. 711 but with slightly
different dimensions so accessories are not interchangeable.


Federal Testmaster DTI (USA). One gradation = 0.0001".
Note needle reversing lever & dovetail mounting.


Various DTIs showing dovetails.
Top to bottom: Brown & Sharpe (Swiss), Federal, & Gem (USA).


Fowler DTI set (import).
One gradation = 0.0005". Dovetail mounts.

 
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Using Dial Test Indicators - Test indicators are primarily
used for the testing or checking of parts & for machine setups.
Test indicators come in two types; the plunger style &
the lever style. The lever style is more adaptable to smaller,
confined working areas. The lever style differs in measuring
because the lever contact moves in an arc rather than in a
straight line, as in the plunger style. This can cause a
slight inaccuracy called cosine error, if reasonable care is not
 used in setting the angle of the lever to the work piece.
If, for example, a lever was set off 20 deg more at the start of a
reading than it should have been, there could be an
error of .0006" in a .010" range (0.012mm in a 0.2mm range).
This is not important when zeroing-out, but only when
looking for a measurement. It is best to keep the contact at or near
90 deg to the direction of movement unless the manufacturer
specifies another angle (see illustration). Test indicators
 should always be 1/10 to 1/4 of a turn before measuring.
Test indicators are not hand-held absolute measuring
tools. They are comparative instruments that check & compare
to known standards or that are used to zero-out setups.

Coaxial Indicator


Coaxial indicator (import) that takes measurements
while the spindle is spinning (800 RPM maximum).
The point can be used to locate a punch mark.
See centering indicator instructions
.
Different length probes affect the scale's
absolute readout values. Good for large parts.

 
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Indicator Holders

Sparro 1st Word dial test indicator holder (USA).

Using a Sparro 1st Word holder & an LS Starrett Last Word DTI
to check the alignment of the mill/drill.
Nicely made, very rigid indicator holder.




Animation showing how to check alignment by
indicating the Rong Fu RF-25 mill table
& 1-2-3 blocks.


Noga indicator holder (Japan) for
both dovetail & 3/8" stem types.
Note the fine adjustment mechanism.



Noga NF1018 indicator arm (Japan) with 3/8" & dovetail clamp.
This style arm is very quick & easy to set up plus it has very good rigidity.


Noga arm held by a modified, V-groove tool post,
mounted off the headstock side T-slot of the Taig mill.

Setup shows indicating a work piece before rotating
to a specific cutting angle. The Noga arm is
good for aligning mills, lathes & rotary tables.


Zero-set universal dial test gauge attachment (import).


A Federal 0.0001", dovetail mount, DTI
being used to indicate the Parlec vise's solid jaw.


This style universal DTI holder gives
a broad sweep of the small 18" mill table.


IndicOL #178 (USA) DTI holder attaches an
indicator to the mill's spindle. Best in class attachment.

Dovetail or stem-style test dial indicators
can be attached to this holder.

 

 


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Half-round combination DTI (dovetail & stem) with a 1/4" shank.


Modified an indicator clamp to hold various stemmed DTIs;
close to the center; rigid, compact, & quick.

Reamed two, 3/16" holes & the thumbscrews are
6-32 SS cap-head screws with pressed-on plastic caps.


Added another set screw to hold
the half-round combination DTI holder.


Detail of the close-fitting brass bushing
(3/8" OD, 1/4" ID) that is held in using red Loctite.

Added a 5/32" hole & set screw for the Interapid stem size.


Tramming a 6", 4-jaw chuck on a rotary table. 
See
Rotary Tables.


A Mighty Mag (USA) magnet holds 3/8" (or smaller)
stemmed indicators. Very powerful magnet.

 
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Accurate low-cost 2" range analog positional readout.

Gauge blocks
can be used to extend range.

Thread Gauges

Left to right: imperial & metric (yellow) screw thread
gauges (2), fractional, & numbered drill bit gauges.
These plate-type thread gauges would be more
accurate if they were two or three times thicker.
Having just a few threads, it is easy to make an error.
For example, 10-32 & M6-1 are very similar threads.

 

   

    
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This metric thread gauge is 0.11" thick
whereas the others are 0.08" thick.


Fractional, numbered, & metric drill bit gauges.


A metric drill bit gauge 1mm to 13mm by 1/2mm.
A 1/4" hole is on the far right end.


These gauges check both nuts & bolts. Metric are
black oxide & imperial are galvanized. Sizes are clearly

stamped & colored. Superior to plate-type gauges
which use only a few threads per size for testing.

 
Standard imperial & metric thread gauges.

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Angle Meter

Starrett AM-2 angle meter (USA).
The RF-25 mill X-axis is shown being level.


Back label of the AM-2 angle meter.

 

 

 

 

 

 
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Also see Protractors Section

Angle Gauges

Angle Gauge Set: 5 deg to 90 deg every 5 deg.


Multiple edges provided for a given angle.


Countersink gauge with 1/32" scales.

Radius Gauges

Radius Gauge set 1/64" to 17/64" by 1/64" &
9/32" to 1/2" by 1/32", with handle.


Five edges provided to measure
a given inside/outside radius.

 
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Infrared Thermometer

Infrared Thermometer Model 96451

Measurement Range - 4 deg F to 968 deg F - 20 deg C to 520 deg C
Measurement Accuracy +/-4 deg F below 212 deg F +/-2% above 212 deg F
Response Time 500 msec
Distance to Spot Size 8:1
Battery Requirement Standard 9V


The red laser beam is used solely for aiming.
An infrared (IR) sensor actually measures the temperature.

The distance to spot ratio is 8:1., so for e.g., at a 16"
(407mm) distance the measurement area is 2" (51mm).

 

 

 

 

 

 


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Tachometer

Sampo Digital Tachometer:
five digits 18mm (0.6") White backlight LCD.

Sampo Digital Tachometer DT6234B Manual

ATTRIBUTE VALUE
Accuracy +/-(0.05%+1 digit)
Sampling Time 0.5 sec (over 120 RPM)
Range Select Auto-Ranging
Memory Max., Min., Last. Stores 96 sec of data
Time Base 6 MHz Quartz crystal
Detecting Distance 50~500mm
Power Consumption Approx. 55mA
Measuring Range 2.5~99,999 RPM
Resolution 0.1 RPM (2.5~999.9 RPM), 1 RPM (over 1K RPM)
Total Test Range 1~99,999
Frequency Range 1~1,666.6Hz
Resolution 0.01Hz
Battery 4x1.5V AA or external 6VDC regulated power supply


Measuring RPM of the 9x20 lathe variable DC motor.
Works best using a small patch of retro-reflective tape.

Sound Level Meter

Sometimes I want to know sound pressure levels of
equipment or to re-equalize my home theater systems.
Sit in prime listening position, measure C-weighted dB's using pink
noise then, for a given channel, adjust/equalize levels in the receiver.

 E.g., lathe sound pressure levels for the variable speed drive.
Sound level meter manual.


The meter's microphone.

 

Scales
 

 
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Fuzion WB200 Scale. Excellent hard case
that latches closed; superior to magnetic type.
Most stable after brief warm-up, as per manual.
200g capacity, 2 AAA batteries, 0.01g scale resolution,
180s auto-off, 6 weighing units (g, oz, gn, ct, dwt, ozt),
Tare weight full capacity, 128 x 88 x 22mm (L x W x H).
50g calibration weight & batteries, included.
Fuzion WB200 Scale Instruction Manual

Definitions, Surface Plates, IndicatorsComparator Stands,
Z-Offset Gauges, Depth Gauges, Height Gauges, Universal Gauge,
Inside Diameter Gauges, Pin Gauges, Runout & Bore Gauges,
Calipers, Micrometers, Dial Test Indicators, Coaxial, Indicator Holders,
Thread Gauges, Angle Meter, Angle Gauges, Radius Gauges,
Infrared Thermometer, Tachometer,
Sound Level Meter
, Scales

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