Name: Taper-Lok tapered-shank interference-fit bolts (NAS1724 / NAS1728)
Brand: PB Fasteners

Two-sided, interference-fit tapered bolt: “The Taper-Lok® is comprised of a tapered, conical-shank fastener, installed into a precision tapered hole.” (FAA-H-8083-31B (AMT Handbook, Airframe), p.4-55, Tapered Shank Bolt)

Shear: No ksi rating (loads per datasheet)
Blind bulb: n/a
Install: Both sides needed
Sizes: Not published in the free documents (NAS1724 / NAS1728 are AIA standards)
Lead-time risk (SpecLok assessment): Medium

Typical applications

·"Consequently, Taper-Loks are used in critical applications where cyclic loading is a problem." (NASA RP-1228 p.32)
·"The use of tapered shank bolts is limited to special applications such as high stress areas of fuel tanks." (FAA-H-8083-31B p.4-55)

Strengths

+"The interference fit compresses the material around the hole that results in excellent load transfer, fatigue resistance, and sealing." (FAA-H-8083-31B p.4-55)
+"When a tension nut is installed, this fastener can take as much tension load as a bolt of the same size and material" (NASA RP-1228 p.32)
+PB Fasteners: "used to enhance structural performance and manage electromagnetic effects in composite and multi-metal structure" (said of Taper-Lok and SLEEVbolt together)

Trade-offs

−"It is important that a tapered bolt not be substituted for any other type of fastener in repairs. It is equally as important not to substitute any other type of fastener for a tapered bolt." (FAA-H-8083-31B p.4-55)
−Needs a precision tapered hole: taper "1/4 inch per foot" (AFFDL-TR-75-93 p.90) and matched drill reamers
−No strength, size, torque or part-number data in the free documents; no published removal procedure

Also called Taper-Lok, Taperlok, Taper Lok, tapered shank bolt, tapered-shank bolt, interference-fit bolt, NAS1725, NAS1729. P/N: NAS1724 (100° flush) / NAS1725 (flush, O/S) / NAS1728 (protruding) / NAS1729 (protruding, O/S) · numbering not published free

Datasheet strength: No strength values are published in the free documents. "When a tension nut is installed, this fastener can take as much tension load as a bolt of the same size and material" (NASA RP-1228 p.32). Taper: "Since the shank taper is 1/4 inch per foot, diametral interference is the protrusion difference divided by 48." (AFFDL-TR-75-93 p.90).

Standards

NAS1724
NAS1725
NAS1728
NAS1729

Materials and galvanic compatibility vs CFRP

Alloy	Shear	vs CFRP	Notes	Source
Alloy steel	n/a	high	"high-strength alloy steel, H-11 tool steel" (NASA RP-1228); "ALLOY STEEL ... H-11" (Reid catalog p.19).	NASA RP-1228 p.32; Reid Products Product Guide p.19
Stainless (CRES)	n/a	low	"several stainless steels" (NASA RP-1228); "CRES ... 13-8" (Reid catalog p.19). Grades are not named in the free documents.	NASA RP-1228 p.32; Reid Products Product Guide p.19
Titanium	n/a	low	"as well as titanium" (NASA RP-1228); "TITANIUM" (Reid catalog p.19).	NASA RP-1228 p.32; Reid Products Product Guide p.19

vs CFRP: MIL-STD-889C Table I, graphite column: high = incompatible in all environments; low = compatible except sea-water immersion; unrated = SpecLok has not read a rating for this material.About derived ksi

Derived ksi values are min shear ÷ nominal shank area, computed from the datasheet's lbf/kN figures; the datasheet itself publishes no ksi.

Specs source: NASA RP-1228 Fastener Design Manual, Taper-Lok (p.31-32) ↗: Description, materials and Figure 51; heads from the Reid Products catalog (licensed manufacturer); hole preparation from AFFDL-TR-75-93. Lead-time risk is SpecLok's sourcing assessment, not a datasheet value.

2 head styles

Some variants only partly sourced

Not redrawn: no head dimensions for this variant in the documents on file. The data at right is from the cited document.

BOLT, SHEAR, 100° STD FLUSH HEAD, Taper-Lok ® · 100°

NAS1724: ALLOY STEEL, CRES, TITANIUM, H-11, 13-8
NAS1725 · oversize: ALLOY STEEL, CRES, TITANIUM, H-11, 13-8"BOLT, SHEAR, 100° STD FLUSH HEAD, O/S, Taper-Lok ®"

Source: Reid Products Product Guide (July 2003), p.28 index; p.19 materials ↗

NAS1724, NAS1725, NAS1728 and NAS1729 are AIA standards and were not read, so sizes, grips and materials per part number are not shown. Head titles are from a licensed manufacturer's catalog index.

Head styles (manufacturer terms)

BOLT, SHEAR, 100° STD FLUSH HEAD, Taper-Lok ® (NAS1724, NAS1725)
BOLT, PROTRUDING HEAD, Taper-Lok ® (NAS1728, NAS1729)

Figure 51. Taper-Lok installation (bolt, thread, "Nominal grip length in 16ths", forged head nut, typical installation).NASA RP-1228 Fastener Design Manual (1990), Figure 51, p.32 ↗ · US Government work, public domainWhy this family: NASA publication. Figure 51 carries no "(From ref.)" credit, unlike neighbouring figures that do.

Compare every family's mechanism

Installation verification and preload

Installed preload

Not published in the free documents; nut torque values are not public.

What to check after install

"Properly installed, these bolts become tightly wedged and do not turn while torque is applied to the nut." (FAA-H-8083-31B p.4-55)
"The interference fit allows the nut (tension or shear nut) to be installed and torqued to the required value without holding the lockbolt to prevent rotation" (NASA RP-1228 p.32)
Interference from head protrusion: "Since the shank taper is 1/4 inch per foot, diametral interference is the protrusion difference divided by 48." (AFFDL-TR-75-93 p.90, a research report)

Check gauges (1) and sources.Details

TLG 5160 fastener protrusion pin and TLG 5120 countersink depth gage, as used in AFFDL-TR-75-93 (p.47); no acceptance limits are published.

Sources: FAA-H-8083-31B p.4-55 · NASA RP-1228 · AFFDL-TR-75-93. Acceptance limits belong to the controlling spec; verify against your program's process documentation.

Print a shop verification card for the floor

Tool: Taper-Lok drill reamer and microstop drill cage for the tapered hole; nut torqued without holding the bolt
Special / proprietary: Special tooling · proprietary
Training: "New tapered shank bolt installation or rework of tapered shank bolt holes needs to be accomplished by trained personnel." (FAA-H-8083-31B p.4-55)
Inspection: "Properly installed, these bolts become tightly wedged and do not turn while torque is applied to the nut." (FAA-H-8083-31B p.4-55). No acceptance limits are published in the free documents.

"Tapered shank bolts are installed in precision-reamed holes, with a controlled interference fit." "New tapered shank bolt installation or rework of tapered shank bolt holes needs to be accomplished by trained personnel." (FAA-H-8083-31B p.4-55). "The lubricated lockbolt is driven into a drilled and reamed hole. The interference fit allows the nut (tension or shear nut) to be installed and torqued to the required value without holding the lockbolt to prevent rotation" (NASA RP-1228 p.32).

The published install tool and nose for each size, other access options, and the gauges that check the install, from the manufacturer's own tool tables.

Sizes	Published tool	Source
Taper-Lok drill reamer and microstop drill cage for the tapered hole; nut torqued without holding the bolt

Gauges: TLG 5160, TLG 5120

Full tool tables, envelopes, clearances and source notes Compare tooling burden across all 25 families

Removal

No published removal procedure found; follow the manufacturer's instructions. Manufacturer page ↗

P/N series NAS1724 (100° flush) / NAS1725 (flush, O/S) / NAS1728 (protruding) / NAS1729 (protruding, O/S) · numbering not published freePaste a full part number into the decoder.

Manufacturer: PB Fasteners
Category: Interference-fit tapered bolt

Datasheet (PDF) ↗
Manufacturer page ↗
NASA RP-1228 Fastener Design Manual, Taper-Lok (p.31-32) ↗: Description, materials and Figure 51; heads from the Reid Products catalog (licensed manufacturer); hole preparation from AFFDL-TR-75-93.

Find the part number for your stack

DiameterStack thickness, in

SpecLok has no dash-number table for this family yet: the quote line goes out as the family, part number to be confirmed.

QtyInclude install tooling

Sourcing

Lead-time risk (SpecLok sourcing assessment): Medium: Lead-time risk not yet assessed from sourcing data (default medium). PCC lists Taper-Lok bolts under PB Fasteners and SPS Technologies; the PCC locator says "TAPER-LOK® is a registered trademark of Deutsch Fasteners Corp."

Get quotes: SpecLok sources this from authorized distributors and returns price, lead time and certs.You buy from the authorized distributor, who is named on your returned quote. SpecLok is free for buyers.

Supply signalfor this family

No FLIS records linked to this family yet.
No SpecLok quotes yet.

A signal from records SpecLok holds, not availability, stock or a lead-time promise. FLIS lists who has recorded a part number for the item, not who makes it today. DoD awards carry no NSN or part number, so award activity is for the item name's class.

Sources: DLA FLIS Data Electronic Reading Room (PUB LOG) ↗, DLA PUB LOG ↗, USAspending.gov award search API ↗; DoD award data 2025-10-01 to 2026-07-06; compiled 2026-09-28.