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Tapped Threads & Reference Tables

Refer to Introduction to Taps, pages one & two.
 Single-point threading Section    How to Drill a Hole    Hand tapper manual.

A hand tapping fixture allows precise, perpendicular, tap-to-hole alignment plus it reduces
 tap breakage that can easily occur when too much torque and/or side forces are applied.
The Phase2+ tapper is a superior product in terms of design, material & workmanship.
Hand tapper includes a set of adapters: #6, #8, #10, ¼", 5/16", 3/8", 7/16", ½" and 5/8".
The tap is first fixed to the adapter & then snapped into the spindle.
If the adapter is snapped in without a tap, it can be more easily removed by
first rotating the flat detent spring to release the ball bearing detent.
Be careful to not lose the ball detent.

Detail of the spring-loaded ball bearing detent for adapter retention in the precision ground spindle.
The flat spring has been rotated to expose the ball bearing detent.
The vise is allowed to float in two directions enabling easy tap/hole alignment.
The example shows tapping eight, #7 holes, with ¼-20 threads.
A rotary table was used to drill every 45°.

To steady the hand tapper, 5/16-18 SS bolts screw into bench hard points.
The ¾" holes were drilled using a Forstner bit. The hard points are held in underneath by wood screws.
I remove the tapper when not in use & screw the bolts up from the bottom until they are flush.
The bolt-down hole has also been ⅜-16 threaded to use the clamping studs, as needed.

Always chamfer the hole first & use the proper thread-cutting fluid.
Caution: For soft materials (aluminum, brass, plastic) use a smaller hole for 75% threads & for
harder materials (steel, SS) use a larger tap hole for 50% threads to reduce tap breakage. See table, below.
Certain materials, e.g., cast iron, can crumble, so coarse threads are easier to
cut more successfully than fine. Softer steels can have higher percentage threads (in the 60s).
There are formulae for calculating any desired % threads.


The adapter has a round hole with a set screw to hold in the tap &
a square hole at the end to positively engage the tap end to prevent rotation.
Note the recess for the spring-loaded detent. A spiral-fluted bottoming tap is shown.

This is a small hand tapper with adapters for seven different tap sizes 0-80 through 5/16".
Each hex-shaped adapter has a square hole & a set screw to securely engage & hold the tap shank.
The shaft rotates in a pressed-in brass bearing. The chromed, stop pin can be removed to
provide more table room for the vise/part. The pin's hole can also be used to bolt-down to a bench hard point.
The steel table is 8.5" x 6", the clearance height is 3.75", the throat depth is 4.5", & the overall height is 9".

This example shows a 0-80 tapping operation where a 3/64" tap hole is required for a 75% thread.

Tapping (6-32) a brass weight.

Tapping 2-56 in a brass rod.

Differently sized tap wrenches.
The two larger (top) handles are Sears & the middle (sized) one is from Germany.
The two smaller (bottom) handles are LS Starrett & are of superior design & quality.

 

Tap wrenches of various sizes.
The two black wrenches (left) have integral guides that mount in a drill press, mill, or lathe chucks.
The ratchet-type tap wrench (right of center) is useful in tight places.
Tap wrenches usually have a center-drilled hole on the end that can be used with a spring-loaded guide.
Smaller taps, themselves, have a chamfered (pointed) shank end &
larger taps have a center-drilled hole to use with guides.

 

Make & use a tapping guide block to keep the tap perpendicular when hand tapping.
The series of holes match the US standard tap major diameters.

 

 

The micro-tap guide (top) has a hardened, reversible tip. The pointed end fits into a center drilled tap wrench end &
the cupped end captures/guides the shank end of the tap, itself. Both have adjustable spring tension.
A Taig spring-loaded center is shown (bottom) that also works well as a tap wrench pivot.
A spring-loaded guide semi-automatically adjusts as the tap cuts deeper into the hole.

 

This tap handle slides on a steel rod & the 1" diameter handle that does not easily over torque the tap.
The long, precision fitted guide rod gives excellent, rigid support & tapping range.

 

Die handles: Top one is for 1½" diameter dies (a split-type is shown), next one is for hex-style dies.
The set included hex die-to-tap adapter is shown. One-inch (GER) & 13/16" (USA) round-die holders also shown.

 

Metric die & tap set (USA).

 

 

Drill & taper tap sets (18 pieces each) left to right: metric, National Fine (NF) & National Coarse (NC).
Metric: M2.5-.45, M3-.5, M3.5-.6, M4-.7, M5-.8, M6-1, M8-1.25, M10-1.5, & M12-1.75.

NF:  6-40, 8-36, 10-24, 10-32, ¼-28, 5/16-24, ⅜-24, 7/16-20, & ½-20.

NC:  6-32, 8-32, 10-24, 10-32, ¼-20, 5/16-18, ⅜-16, 7/16-14, & ½-13.

Note: the drill sizes are for 75% threads in Aluminum, brass & plastic.

 

 

 

Plug & bottom tap sets (USA). The spiral flutes remove swarf from blind holes.

 

Spiral flutes remove swarf, effectively.

 

HSS combination drill & tap. Sizes: 4-40, 6-32, 8-32, 10-32, 10-24, ¼-20 & ⅜-16.

Unified Tap Drill Chart: Tap drill references for Imperial, metric, & pipe threads.

Metric Tap Drill Chart

Pipe Threads
 

Thread diameter.

Drilled holes are for clearance. The resulting hole size is often larger than the drill & may not be perfectly round.
 Precision holes are either reamed or bored.

Screw thread micrometer with five different anvil pairs to measure both unified &
metric external pitch diameter. 0" to 1" measurement range with a 0.0001" scale.

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

Standard Unified & metric thread gages.