Layout Tools
Last updated on Tuesday, September 19, 2023 04:51:25 PM Mountain US Time Zone


Layout Tools, Levels, Scribes & Automatic Center Punches,
Layout Fluid, Precision Gauge Blocks, Surface Plates,
Surface Gauges, Height Gauges, Transfer Punches, Transfer Screws,
Protractor, Optical Protractor,
Machinist Calculator

Also refer to how to drill a hole where you want it &
how to drill the center of a rod
See Precision Mensuration.

Metric & Inch Equivalents
Inch to Millimeter Conversion Table
Millimeter to Inch Conversion Table
Metric & Inch Equivalents

Tap Drill Sizes For Fractional Size Threads
Decimal Equivalents of Letter Size Drills
 National /Unified Coarse/Fine Thread Dimensions & Tap Drill Sizes
Decimal Equivalents of 8ths, 16ths, 32nds, 64ths
ISO External Threads Medium Fit 
Decimal Equivalents of Number Size Drills
 Tapers & Angles
Rules Relative to the Circle
Triangle Chart

Layout Tools

Various types of squares, small rules, & protractors.
Starrett (USA) & Mitutoyo (Japan) are highest quality.

Starrett steel rules: a satin chrome finish,
machine-divided blade, & hardened steel.

Starrett is best in class followed by Mitutoyo.

Starrett Model No. 289A combination
square blade attachment (USA).

This accessory allows attaching a steel rule at right
angles to another rule or the blade of a square.

Accepts 1" (25.4mm) wide blades.
Attachment seat lengths:
blade 1-9/16" (40mm) x rule 1-11/16" (43mm).

Machinists' solid squares (top) are hardened
(RC55), ground, & lapped to high accuracy.

USA Starrett Nos. 13, 4R, & 14D squares (4 pieces).

Dowel center finder.

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

Made knobbed screws using cut-down 1/4-32 bolts.
The bolt was clamped by a
5C fixture & the
cut end was diamond ground flat/perpendicular.
The plastic knob press-fits onto the hex head bolt.

Very handy & quick when I was
parting 50 pieces on the lathe.

LS Starrett invented the combination square.
All three of these are hardened & ground (USA).

Protractor (top), square (left), & dowel center finder (right).
These hardened sets are best in class.
434-12-16R 12" Combination Square Set

A small scribe is stored in a
that has a spring retainer


Starrett No. 98 Four-inch Machinists' Level
ground & graduated vial (USA).

The base has a V-groove for leveling round parts.
Protective metal cover rotated closed.

Outside calipers, spring divider,
hermaphrodite, & inside calipers.

Scribes & Automatic Center Punches

Scribes & automatic center punches.
Top to bottom: Starrett surface gauge steel scribe,
a diamond-tipped scribe, a carbide-tipped scribe, two
large-body punches that make deep marks, two high-precision

punches that have fine, sharply pointed replaceable
tips & the last punch has small replaceable tips.

Regular punches have a 90 deg angled tip whereas
prick punches have a more narrow-angled point.

 Automatic center punch (Lisle 30280-70) exploded detail.
Assembly order is left to right, top to bottom.

If the cylindrical guide (middle row, far right) is turned around,
the punch will not work properly. The flat side faces the point
while the curved side faces the firing pin & ball bearing.

Though the above Lisle design incorporates a ball bearing,
most designs do not use one.
Assembly instructions for
three styles of General Tool automatic center punches:

No. 87  thin body, No. 70079  large aluminum body,
No. 78 steel body. Note: Before assembly, verify
that all parts do not have any type of lubrication.

Automatic center-punch replacement tips.
Lower-left: General No. 79P.

Screwing the spring-compression knob
out reduces the punching force.

For center punching softer materials
(e.g., gold, silver, plastic, wood)

the strong spring can be replaced
with a much lighter one.

Examples of center-punch force reduction.
Different springs will, of course, result in different
levels of punch depth so trial & error may be in order.

1-A punch using the original spring General Model 70079.
2-Smaller spring with adjustment screwed in.

3-Smaller spring with adjustment screwed out.
4-Lisle with weaker spring & the adjustment screwed out.

Standard center punch.

Layout Fluid

Apply Dykem layout fluid to make scribe marks highly visible.

CAUTION: Quickly makes permanent/semi-permanent stains on porous materials.

4 fluid oz. liquid with brush in cap applicator & 12 oz.
(340 g) of remover/surface prep spray.

Example, Dykem with scribe marks.

A second example of layout fluid & height gauge use.

Precision Gauge Blocks

81 piece, Grade B, hardened, precision gauge block set,
from 0.050 to 4.0", +/-0.000050" at 20 deg C (68 deg F).

Excellent for use with height gauges, depth gauges,
sine vises,
sine bars, sine plates, setups, etc. (import)
Example of a calibration reference table. See this
Starrett document for info on
wringing gauge blocks.

Left to right: 1", 0.5", & 0.2".
Note the middle, micro-lapped working surface.

Spacer gauge set

Used for setting stops,
setups, &
sine bars/plates/vises.

The ends are threaded so they
can be screwed together/stacked.

Hardened, dimensionally accurate 1-2-3, 2-3-4, &
2-4-6 (inches) precision-ground steel
3/8-16 threaded & clearance holes allow clamping.

Handy for surface-plate measurements & mill setups.

Surface Plates

surface plates (+/-0.0001") in 18"x12"x3" (85 lb) &
12"x9"x2" (30 lb) sizes (import). Use surface plate

cleaning fluid to remove dirt, oil, & marks left by (aluminum) parts.
Do not scratch the plate as it affects accuracy.

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

Granite Surface Platea checked using an autocollimator for accuracy
assurance to meet or exceed Federal Specification GGG-P-463c.

The top surface must be level in both directions.

A simple, all wood (glued only, no metal)
cover to protect the surface from damage.

Surface Gauges

Universal Starrett surface gauge
holding its hardened steel scribe.

Base is
2-13/16" (L) x 2-3/8" (W) & is
supplied with
9" & 12" spindle lengths.
Starrett Model 257 exploded diagram.

The base has a V-groove for centering on round parts.
The pins can extend to act as guides along an edge.

Base guide pins extended.

The fine (tilt) adjustment mechanism works very well.

 Starrett Model No. 56 toolmaker's surface gauge.
The small size helps when working in tight locations.

The base is 2-1/8" (L) x 1-3/8" (W) x 7/8" (H) &
the spindle length is 4-inches.

Starrett No. 56 surface gauge parts diagram.

The universal & toolmaker's
surface gauges compared for size.

Height Gauges

A Mitutoyo, 8", 543-244 digital height gauge
with fine adjustment mechanism.

The height gauge & a granite surface plate

make a
n accurate combination for measuring
parts or
laying out precisely scribed lines.
Resolution: 0.0005". Absolute
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.

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.

See Height Gauges in Mensuration for
additional descriptions of various accessories.

Starrett No. 3751 digital height gauge.

Starrett No. 995E (USA) Universal Precision Gauge Set.
A post clamp holds a hardened HSS scribe which
is being set at 3.0000" height using a gauge block.

Starrett  Model No. 995E Universal Gauge exploded diagram.

Transfer Punches

These punches are used to align parts & to
transfer the center of a hole to mate an adjoining part.
Transfer punch sets: Fractional - 3/32" through 1" by 1/64th", 0.0025" undersized.
Numbered - 1 through 60.  Lettered - A through Z.  Metric - 1mm through 13mm by 0.5mm.
 Black anodized & heat treated. Some of the original stands were replaced with Huot USA brand.
Note: Smaller, import punches sometimes have off-center
tips that need to be corrected using a lathe tool-post grinder.

A 5/16" transfer punch marked the center.
The bearing center was transfered to the gear plate.

A stand was fabricated.
Sizes 5-3/4" x 2-5/8" x 1/3" thick & the bottom plate is 1/16" thick.

A thick top plate keeps the punches vertical plus it's
easier to take them in & out than the multi-plate designs.

The holes were made using each bit of the entire
set of metric drills; the transfer punches are undersized.

After the plate was drilled, the top surface was fly
cut & then the holes chamfered to make a nice finish.

1-1/8" long, 4-40 steel standoff posts were used as spacers.
The bottom plate corner holes were first threaded,

the posts were then screwed in followed by a nylon-insert
lock nut that secures the post & acts as the feet.

Integer sizes were stamped onto
the top & filled-in with black marker.

Transfer Screws

Transfer screw sets for mating threaded parts
especially blind holes. Hardened screws stored inside handle.

Storing all the screws in the handle oriented one-way
e.g., tip in first) seems to help insertion & removal.

Handle end has a hex driver that serves as wrench.
Top to bottom examples: 3/4-10, 4-40 & M10-1.5 (metric).

A 10-32 transfer screw (top-center) in the end of a
3/8" dowel pin for the
Taig DRO x-axis modification.
This was part of the pre-CNC Taig Micro Mill DRO design.

A metal holder for the transfer screw sets.
The hardware: 1/4-20 cap-head bolts,
brass tubes, & lock nuts.

The lower plate has corresponding
holes that capture the tips.
The lock nuts also function as feet.

Modified all of the holders where
1/4-28 bolt heads now act as feet.


Holders for metric (L) & imperial (R) transfer screw sets.
Similar design to the
Silver & Deming drill bit stand.
The metric are imports & the imperial are USA manufactured.

These case-hardened M8-1.25 transfer screws
were made using a
hexagonal 5C fixture.


Accurate, all-metal protractor set.

There is an etched degrees scale with a
5' precision vernier (
nonius) scale.
 If the magnifier is needed, the two
screws are used for attachment.

A vernier scale as viewed under the magnifier
accessory. This scale is reading 0 deg 5' angle.

Also see Angle Gauges Section

Optical Protractor

An optical protractor excellent for ergonomic analyses
of cockpit & workstation display layout geometries.

OPTO-METRIX Optical Protractor OP-1a.
US Patent No.

Machinist Calculator

Machinist Calc Pro capabilities: cutting speed, spindle
speed (rpm), feed rate, cutting feed, feed per tooth

(chip load), built-in drill & thread size reference tables,
drill point cut depth solutions, wire sizes & 3-wire

measurements, bolt pattern hole layouts with center
x, y coordinates, right-triangle math, trigonometric

solutions, work in & convert between US & metric units
including decimal inches/mils, feet-inch-fractions, m,

mm, cm, area, volume & weight. Many of these
parameters can also be calculated using
DRO functions.
It defaults to 75% threads but I like being able to
quickly calculate any other needed % e.g., 50% or 65%.

After selecting a hole size, one can scroll up & down
the table to see the closest inch & metric bit sizes.

Their app is lower in cost but I did not want my
iPhone to be exposed to a shop environment.

Machinist Calc Pro 4087 Manual   Machinist Calc Pro 4087 Specs

Shop-hardened case with a sturdy double
hinge & two effective locks (front & back).


Layout Tools, Levels, Scribes & Automatic Center Punches,
Layout Fluid, Precision Gauge Blocks, Surface Plates,
Surface Gauges, Height Gauges, Transfer Punches, Transfer Screws,
Protractor, Optical Protractor,
Machinist Calculator