Bsi bs a 211 1961 (2000)

Foreword iAppendix A Principles of flush es control and Appendix C Ta le for conv er ion of inches to Fig ure 2 — Diag ram showing ma imum and minimum hea conditions 3 Ta le 1 — For bear

Specification for

[ UDC 6 1.8 2.2 5:6 9.1 ]

This BritishStan ard,hav ing

b en a pro ed b the Air raft

In ustry Stan ards Commit e

an en or ed b the Chairman

ofthe Engine ring Divisional

Cou ci, was publshed u der

the uthority of the General

Cou ci of the Institution on

1 Octo er1 6

© BSI0 -2 0

Am endm ents is ued sinc publ cation

Amd No Date of is ue Comments

Foreword i

Appendix A Principles of flush es control and

Appendix C Ta le for conv er ion of inches to

Fig ure 2 — Diag ram showing ma imum and minimum hea conditions 3

Ta le 1 — For bearing leng th “ L”, clamping leng th “M”

Ta le 2 — Bearing leng th “ L”, clamping leng th “ M”

to prov ide for a rang e of ste l bolts with counter u k reces ed hea s and Unified

threa s W ith the exception of the reces es, the dimensions and tolerances

specified are the same as those g iv en in BS2A17 for cou ter u k slot ed hea

bolts

As in BS2A17 , the “ flushnes tolerance” method is a opted for the

dimensioning of the counter u k hea The b sic principles and a v antag es of

this method, fir t used in a BritishStand rd for cou ter u k hea fastener in

BS19 1, “Unified ma chine s r ews a nd ma chine s r ew n ts”, are outl ned in

Appendix A to this stand rd, tog ether with sug g ested methods of g aug ing Detais

of the method of g aug ing the s rew-driv er reces es are g iv en in Appendix B

Reference is ma e in the stand rd to the fol owing BritishStand rds:

BS A10 , B ol ts a nd nuts fr a ir cr a ft ( g eneral clauses)

BS S102, Ca r bon-molybd en m ste l

BS S10 , Ca r bon ste l

BS S14 , Nickel-chr omium-mol ybd en m ste l (ba r f r the ma nufa ctur e o f r ged

bolts only)

BS S14 , Low nickel-chr omium ste l (ba r fr the ma nufa ctur e o f r ged

boltsonly)

BS S14 , 1.7 perc nt nickel-chr omium-molybd en m ste l

BS S , 1 % chr omium-mol ybd en m ste l ba r s f r the ma nufa ctur e o fr ged bol ts

a nd f r ged nuts

)

NOT The v lues in British u its are to b re arded as the stan ard.A ta le is giv n in

App n ix C to prov ide a re dy me ns of calculating the a pro imate mi imetre e uiv lents of the

inch dimensions More ac urate conv r ions should b b sed on the ta les in BS3 0

A British Stand rd do s not purport to include al the neces ary prov isions of a

contract User of British Stand rds are responsible for their cor ect a pl cation

Com pl anc with a British Standard do s not of itselfc nfer im munity

f om leg al obl g ations

Summ ary of pag es

This document comprises a font cov er, an inside f ont cov er, p g es i andi,

1 Scope

This BritishStand rd specifies the material,

dimensions, finish and inspection requirements for

ste l bolts with10 ° cou ter u k reces ed hea s

and Unified threa s for air raft

The bolts shal comply with the relev ant

requirements of Part1 of BS A10 in respect of

man facture, s rew threa s, and anti cor osion

treatment

3 Material and m anufacture

a) The bolts shal be forg ed fom material which

compl es with the latest is ue of one of the

folowing BritishStand rds:

BS S102,

or BS S10 ,

or BS S14

or BS S14

or BS S14

or BS S

2)

b) In the final y heat-treated condition, the

mechanical properties of the material shal be as

folows:

a) All finished bolts, after the a plcation of the

anticor osion coating , shal conform to the

dimensions and tolerances g iv en in Ta le 1 and

Ta le 2

b) The clamping leng th M of the bolt shal

conform to the dimensions and tolerances g iv en

in Ta le 2, and shal be such that, when a

stand rd n t without cou ter in or a ring g aug e

without cou ter in has be n s rewed on as far

as pos ible b hand, its lea ing face is within the

distance M fom the up er sur ace of the bolt

hea The ru -out of threa shal not exce d twice

the pitch

c) The nominal leng th of the bolt shal be the

minimum bearing leng th L,which is determined

b the minimum clamping leng th M, les two

threa pitches

5 Scr w thr ads

The bolts shal hav e unified threa s of the form and

clas of fit specified in the relev ant requirements of

BS A10 , Part 1

6 Anti- corrosion coating

All finished bolts shal be coated with ca mium

7 Identification

The BritishStand rd n mber and p rt n mber

shal not be a pled on the bolts, but shal be clearly

marked on the la els of p r els of bolts

8 Inspection procedure

The bolts shal be inspected in ac ord nce with the

relev ant requirements of BS A10 , Part 2

9 Gaug ing

a) The method of hea dimensioning shown in

Ta le 1 defines ma imum and minimum hea

env elopes which control flushnes in the man er

des ribed in Appendix A

b) The ty pe of g aug e shown in Fig ure 4 and

Fig ure 5 is recommended as being suita le for

flushnes measurement, but the ty pe of g aug e to

be used is not a mand tory requirement of this

stand rd The g aug e shown in Fig ure 4 and

Fig ure 5 do s not control the hea ang le, which

wi l require to be checked at interv als during

production An a ditional g aug e wi be neces ary

for the a solute minimum hea diameter

c) The penetration of the reces shal be g aug ed in

ac ord nce with Appendix B

2)

In cour e of pre aration

0.1percent

pro f stres

not les than4 tons/ i

2

( 68kg / mm

2

)

Tensi e

streng th

not les than5 tons/i

2

( 87kg / mm

2

)

not more than6 tons/i

2

( 102 kg / mm

2

)

Elong ation

on4

not les than18percent

Iz d imp ct

v alue

not les than4 ftlb

( 6kgm) area

Fig ure 1 — Dim ensions

Fig ure 1a — Enlarg ed view of head

Figure 1b — Detai s of re es

Third ang le projection

NOT Gaug s suita le for control ng flush es are des rib d in App n ix A The lmits on he d protrusion do not p rmit the

e treme lmits on diameter to sharp corner an on he d angle shown b ( 1) an ( 2) to oc ur in one an the same he d This is

b cause the a plcation of these cou ter u k he ds deman s a high de re of flush es

( 1) In icates the ma imum he d protrusion o taina le with the minimum he d angle

( 2) In icates the minimum he d protrusion o taina le with ma imum he d angle

Fig ure 2 — Diag ram showing maxim um and minim um hea c nditions

Ta le 1 — For bearing leng th “L”, clam ping leng th “M” and overal leng th “E”, se Ta le 2

Nom inal siz

De im al

equiv lent

of nom inal

siz

Diam ete of

plain p rtion of

shan

A

2×pitch

Min length

of sc ewed

p rtion of

shan a

F

Re only

Diam ete ofhea Nom inal

hea depth

b

D

(For

r f r nc

only)

To sharp corne

s

V

(For r fr nc

only)

Absolute

m inim um

B

1

4

5

/

6

3

/

8

7

/

6

1

2

Nom inal siz

Gauging

dia

N

Hea protrusion

Ra ius

u de b lt

hea

R

Depth of

cham fe

G

RE ES

Protrusion

a o e

g aug ing dia

P

Flush es

(Pm ax

–Pm in.)

Depth

U Penetration

c Diam ete

S d

Re es

and

drive

p int

n m be

m ax m in m ax m in m ax m in m ax m in m ax m in nom

No 8–32UNC 0.2 71 0.0 76 0.0 38 0.0 38 0.0 0 0.0 0 0.0 0 0.0 0 0.0 6 0.0 3 0.0 5 0.0 2 0.1 6 2

No.1 –32UNF 0.3 47 0.0 99 0.0 59 0.0 40 0.0 0 0.0 0 0.0 0 0.0 0 0.1 4 0.0 1 0.1 3 0.0 0 0.1 4 2

1

4

inU F 0.4 45 0.0 53 0.0 07 0.0 46 0.0 0 0.0 5 0.0 0 0.0 0 0.1 6 0.1 3 0.1 9 0.0 6 0.2 0 3

5

/

6

inUNF 0.5 89 0.0 09 0.0 57 0.0 52 0.0 0 0.0 5 0.0 0 0.0 0 0.1 8 0.1 6 0.1 8 0.1 6 0.3 9 4

3

/

8

inU F 0.6 32 0.0 66 0.0 07 0.0 59 0.0 0 0.0 5 0.0 0 0.0 0 0.1 3 0.1 1 0.1 3 0.1 1 0.3 4 4

7

/

6

inUNF 0.7 76 0.0 22 0.0 57 0.0 65 0.0 0 0.0 5 0.0 0 0.0 0 0.2 8 0.1 6 0.1 8 0.1 6 0.3 8 4

1

2

inU F 0.8 20 0.0 78 0.0 07 0.0 71 0.0 0 0.0 5 0.0 0 0.0 0 0.2 5 0.2 3 0.2 5 0.2 3 0.3 5 4

a

This dimension is an a solute minimum as ociated with ma imum length M an minimum length E.I is not inten ed that it

shal b used for man facturing or insp ction purp ses

b

These dimensions ha e b en calculated as the me n b twe n ma imum an minimum he d de th, cor esp n ing to ma imum

an minimum diameter to sharp corner , the he d angle an shan diameter b ing taken as nominal

c

These dimensions refer to the p netration of stan ard g ug p ints used with sp cial p netration g ug es ( se App n ix B)

d

Diameter S is me sured at the p ints of inter ection b twe n the sides of the reces an the up er surace of the he d

Table 2 — Bearing leng th “L”, clamping leng th “M” and overal leng th “E”

Fig ure 3

Part

No

L

a

m in

M

+0

– 0

E

+0.0

– 0 Part

No

L a

m in

M

+0

– 0.0

E

+0.0

–

Part

No

L a

m in

M

+0

– 0

E

+0.0

– 0 Part

No

L a

m in

M

+0

– 0.0

E

+0.0

–

1 C 1.4 1.4 3 1.8 1 D 1.4 1.4 3 1.9

1 C 1.9 1.9 3 2.3 1 D 1.9 1.9 3 2.4

2 C 2.4 2.4 3 2.8 2 D 2.4 2.4 3 2.9

2 C 2.7 2.7 3 3.1 2 D 2.7 2.7 3 3.2

Bolt lengths gre ter than eight times shan diameter should b a oided where p s ible as o en dies ma b re uired in

man facture

a

Se Clause c)

Ta le 2— Bearing leng th “L”, clam ping leng th “M” and overal leng th “E”

1

inUNF

5

6

inUNF

3

inUNF

Part

No

L

a

m in

M

+0

– 0.0

E

+0.0

– 0

Part

No

L a

m in

M

+0

– 0

E

+0.0

– 0

Part

No

L a

m in

M

+0

– 0.0

E

+0.0

– 0

2E

3E

4E

5E

in

0.2

0.3

0.4

0.5

in

0.3 1

0.4 1

0.5 1

0.6 1

in

0.8

0.9

1.0

1.1

2G

3G

4G

5G

in

0.2

0.3

0.4

0.5

in

0.3 3

0.4 3

0.5 5

0.6 3

in

0.8

0.9

1.0

1.1

2

3

4

5

in

0.2

0.3

0.4

0.5

in

0.3 3

0.4 3

0.5 3

0.6 3

in

0.9

1.0

1.1

1.2

6E

7E

8E

9E

1 E

0.6

0.7

0.8

0.9

1.0

0.7 1

0.8 1

0.9 1

1.0 1

1.1 1

1.2

1.3

1.4

1.5

1.6

6G

7G

8G

9G

1 G

0.6

0.7

0.8

0.9

1.0

0.7 3

0.8 3

0.9 3

1.0 3

1.1 3

1.2

1.3

1.4

1.5

1.6

6

7

8

9

1 J

0.6

0.7

0.8

0.9

1.0

0.7 3

0.8 3

0.9 3

1.0 3

1.1 3

1.3

1.4

1.5

1.6

1.7

1 E

1 E

1 E

1 E

1 E

1.1

1.2

1.3

1.4

1.5

1.2 1

1.3 1

1.4 1

1.5 1

1.6 1

1.7

1.8

1.9

2.0

2.1

1 G

1 G

1 G

1 G

1 G

1.1

1.2

1.3

1.4

1.5

1.2 3

1.3 3

1.4 3

1.5 3

1.6 3

1.7

1.8

1.9

2.0

2.1

1 J

1 J

1 J

1 J

1 J

1.1

1.2

1.3

1.4

1.5

1.2 3

1.3 3

1.4 3

1.5 3

1.6 3

1.8

1.9

2.0

2.1

2.2

1 E

1 E

1 E

1 E

2 E

1.6

1.7

1.8

1.9

2.0

1.7 1

1.8 1

1.9 1

2.0 1

2.1 1

2.2

2.3

2.4

2.5

2.6

1 G

1 G

1 G

1 G

2 G

1.6

1.7

1.8

1.9

2.0

1.7 3

1.8 3

1.9 3

2.0 3

2.1 3

2.2

2.3

2.4

2.5

2.6

1 J

1 J

1 J

1 J

2 J

1.6

1.7

1.8

1.9

2.0

1.7 3

1.8 3

1.9 3

2.0 3

2.1 3

2.3

2.4

2.5

2.6

2.7

2 E

2 E

2 E

2 E

2 E

2.1

2.2

2.3

2.4

2.5

2.2 1

2.3 1

2.4 1

2.5 1

2.6 1

2.7

2.8

2.9

3.0

3.1

2 G

2 G

2 G

2 G

2 G

2.1

2.2

2.3

2.4

2.5

2.2 3

2.3 3

2.4 3

2.5 3

2.6 3

2.7

2.8

2.9

3.0

3.1

2 J

2 J

2 J

2 J

2 J

2.1

2.2

2.3

2.4

2.5

2.2 3

2.3 3

2.4 3

2.5 3

2.6 3

2.8

2.9

3.0

3.1

3.2

2 E

2 E

2 E

2 E

3 E

2.6

2.7

2.8

2.9

3.0

2.7 1

2.8 1

2.9 1

3.0 1

3.1 1

3.2

3.3

3.4

3.5

3.6

2 G

2 G

2 G

2 G

3 G

2.6

2.7

2.8

2.9

3.0

2.7 3

2.8 3

2.9 3

3.0 3

3.1 3

3.2

3.3

3.4

3.5

3.6

2 J

2 J

2 J

2 J

3 J

2.6

2.7

2.8

2.9

3.0

2.7 3

2.8 3

2.9 3

3.0 3

3.1 3

3.3

3.4

3.5

3.6

3.7

3 E

3 E

3 E

3 E

3 E

3.1

3.2

3.3

3.4

3.5

3.2 1

3.3 1

3.4 1

3.5 1

3.6 1

3.7

3.8

3.9

4.0

4.1

3 G

3 G

3 G

3 G

3 G

3.1

3.2

3.3

3.4

3.5

3.2 3

3.3 3

3.4 3

3.5 3

3.6 3

3.7

3.8

3.9

4.0

4.1

3 J

3 J

3 J

3 J

3 J

3.1

3.2

3.3

3.4

3.5

3.2 3

3.3 3

3.4 3

3.5 3

3.6 3

3.8

3.9

4.0

4.1

4.2

3 E

3 E

3 E

3 E

4 E

3.6

3.7

3.8

3.9

4.0

3.7 1

3.8 1

3.9 1

4.0 1

4.1 1

4.2

4.3

4.4

4.5

4.6

3 G

3 G

3 G

3 G

4 G

3.6

3.7

3.8

3.9

4.0

3.7 3

3.8 3

3.9 3

4.0 3

4.1 3

4.2

4.3

4.4

4.5

4.6

3 J

3 J

3 J

3 J

4 J

3.6

3.7

3.8

3.9

4.0

3.7 3

3.8 3

3.9 3

4.0 3

4.1 3

4.3

4.4

4.5

4.6

4.7

4 E

4 E

4 E

4 E

4 E

4.1

4.2

4.3

4.4

4.5

4.2 1

4.3 1

4.4 1

4.5 1

4.6 1

4.7

4.8

4.9

5.0

5.1

4 G

4 G

4 G

4 G

4 G

4.1

4.2

4.3

4.4

4.5

4.2 3

4.3 3

4.4 3

4.5 3

4.6 3

4.7

4.8

4.9

5.0

5.1

4 J

4 J

4 J

4 J

4 J

4.1

4.2

4.3

4.4

4.5

4.2 3

4.3 3

4.4 3

4.5 3

4.6 3

4.8

4.9

5.0

5.1

5.2

Bolt lengths gre ter than eight times shan diameter should b a oided where p s ible as o en dies ma b

re uired in man facture

a

Se Clause4 c)

Table 2— Bearing leng th “L”, clam ping leng th “M” and overal leng th “E”

1

inUNF

5

6

inUNF

3

inUNF

Part

No

L

a

m in

M

+0

– 0

E

+0.0

– 0

Part

No

L a

m in

M

+0

– 0

E

+0.0

– 0

Part

No

L a

m in

M

+0

– 0

E

+0.0

– 0

4 E

4 E

4 E

4 E

5 E

in

4.6

4.7

4.8

4.9

5.0

i.n

4.7 1

4.8 1

4.9 1

5.0 1

5.1 1

in

5.2

5.3

5.4

5.5

5.6

4 G

4 G

4 G

4 G

5 G

in

4.6

4.7

4.8

4.9

5.0

in

4.7 3

4.8 3

4.9 3

5.0 3

5.1 3

in

5.2

5.3

5.4

5.5

5.6

4 J

4 J

4 J

4 J

5 J

in

4.6

4.7

4.8

4.9

5.0

in

4.7 3

4.8 3

4.9 3

5.0 3

5.1 3

in

5.3

5.4

5.5

5.6

5.7

5 E

5 E

5 E

5 E

5.1

5.2

5.3

5.4

5.2 1

5.3 1

5.4 1

5.5 1

5.7

5.8

5.9

6.0

5 G

5 G

5 G

5 G

5.1

5.2

5.3

5.4

5.2 3

5.3 3

5.4 3

5.5 3

5.7

5.8

5.9

6.0

5 J

5 J

5 J

5 J

5.1

5.2

5.3

5.4

5.2 3

5.3 3

5.4 3

5.5 3

5.8

5.9

6.0

6.1

7

6

inUNF

1

inUNF

2L

3L

4L

5L

0.2

0.3

0.4

0.5

0.3 0

0.4 0

0.5 0

0.6 0

1.0

1.1

1.2

1.3 3N

4N

5N 0.3

0.4

0.5

0.4 0

0.5 0

0.6 0

1.2

1.3

1.4

6L

7L

8L

9L

1 L

0.6

0.7

0.8

0.9

1.0

0.7 0

0.8 0

0.9 0

1.0 0

1.1 0

1.4

1.5

1.6

1.7

1.8

6N

7N

8N

9N

1 N

0.6

0.7

0.8

0.9

1.0

0.7 0

0.8 0

0.9 0

1.0 0

1.1 0

1.5

1.6

1.7

1.8

1.9

1 L

1 L

1 L

1 L

1 L

1.1

1.2

1.3

1.4

1.5

1.2 0

1.3 0

1.4 0

1.5 0

1.6 0

1.9

2.0

2.1

2.2

2.3

1 N

1 N

1 N

1 N

1 N

1.1

1.2

1.3

1.4

1.5

1.2 0

1.3 0

1.4 0

1.5 0

1.6 0

2.0

2.1

2.2

2.3

2.4

1 L

1 L

1 L

1 L

2 L

1.6

1.7

1.8

1.9

2.0

1.7 0

1.8 0

1.9 0

2.0 0

2.1 0

2.4

2.5

2.6

2.7

2.8

1 N

1 N

1 N

1 N

2 N

1.6

1.7

1.8

1.9

2.0

1.7 0

1.8 0

1.9 0

2.0 0

2.1 0

2.5

2.6

2.7

2.8

2.9

2 L

2 L

2 L

2 L

2 L

2.1

2.2

2.3

2.4

2.5

2.2 0

2.3 0

2.4 0

2.5 0

2.6 0

2.9

3.0

3.1

3.2

3.3

2 N

2 N

2 N

2 N

2 N

2.1

2.2

2.3

2.4

2.5

2.2 0

2.3 0

2.4 0

2.5 0

2.6 0

3.0

3.1

3.2

3.3

3.4

2 L

2 L

2 L

2 L

3 L

2.6

2.7

2.8

2.9

3.0

2.7 0

2.8 0

2.9 0

3.0 0

3.1 0

3.4

3.5

3.6

3.7

3.8

2 N

2 N

2 N

2 N

3 N

2.6

2.7

2.8

2.9

3.0

2.7 0

2.8 0

2.9 0

3.0 0

3.1 0

3.5

3.6

3.7

3.8

3.9

a

Se Clause c)

Ta le 2— Bearing leng th “L”, clam ping

leng th “M” and overal leng th “E”

7

6

inUNF

1

inUNF

Part

No

L

a

m in

M

+0

– 0

E

+0.0

– 0

Part

No

L a

m in

M

+0

– 0.0

E

+0.0

– 0

3 L

3 L

3 L

3 L

3 L

in

3.1

3.2

3.3

3.4

3.5

in

3.2 0

3.3 0

3.4 0

3.5 0

3.6 0

in

3.9

4.0

4.1

4.2

4.3

3 N

3 N

3 N

3 N

3 N

in

3.1

3.2

3.3

3.4

3.5

in

3.2 0

3.3 0

3.4 0

3.5 0

3.6 0

in

4.0

4.1

4.2

4.3

4.4

3 L

3 L

3 L

3 L

4 L

3.6

3.7

3.8

3.9

4.0

3.7 0

3.8 0

3.9 0

4.0 0

4.1 0

4.4

4.5

4.6

4.7

4.8

3 N

3 N

3 N

3 N

4 N

3.6

3.7

3.8

3.9

4.0

3.7 0

3.8 0

3.9 0

4.0 0

4.1 0

4.5

4.6

4.7

4.8

4.9

4 L

4 L

4 L

4 L

4 L

4.1

4.2

4.3

4.4

4.5

4.2 0

4.3 0

4.4 0

4.5 0

4.6 0

4.9

5.0

5.1

5.2

5.3

4 N

4 N

4 N

4 N

4 N

4.1

4.2

4.3

4.4

4.5

4.2 0

4.3 0

4.4 0

4.5 0

4.6 0

5.0

5.1

5.2

5.3

5.4

4 L

4 L

4 L

4 L

5 L

4.6

4.7

4.8

4.9

5.0

4.7 0

4.8 0

4.9 0

5.0 0

5.1 0

5.4

5.5

5.6

5.7

5.8

4 N

4 N

4 N

4 N

5 N

4.6

4.7

4.8

4.9

5.0

4.7 0

4.8 0

4.9 0

5.0 0

5.1 0

5.5

5.6

5.7

5.8

5.9

5 L

5 L

5 L

5 L

5.1

5.2

5.3

5.4

5.2 0

5.3 0

5.4 0

5.5 0

5.9

6.0

6.1

6.2

5 N

5 N

5 N

5 N

5.1

5.2

5.3

5.4

5.2 0

5.3 0

5.4 0

5.5 0

6.0

6.1

6.2

6.3

a

Se Clause4 c)

Bolt lengths gre ter than eight times shan diameter should b

av oided where p s ible as o en dies ma b re uired in

man facture

Appendix A Principles offlushnes

control and r com m ended g aug ing

practice

1 The major requirement of the user of a

cou ter u k hea bolt is that the up er sur ace of

the hea should fit with as g reat a deg re of

flush es as pos ible with the sur ace into which it

is inserted This flush es is dependent upon both

the tolerance on the hea of the bolt and that on the

cou ter u k hole into which the hea is fit ed The

method of dimensioning a opted in this stand rd

directly controls the flush es ac uracy of the bolt in

relation to the counter ink, the result in an actual

as embly being dependent upon the tolerance

a pled to the cou ter in , which is outside the

s ope of this stand rd

2 In the tra itional method of dimensioning

cou ter u k hea bolts, the l mits on the bolt hea

thick es are afected b the tolerance on the shan

diameter This howev er is of no consequence in the

mat er of flush es and it would be neces ary for

any deg re of flush es to exer ise a closer control

on hea thick es and/ or shan diameter if the

tra itional dimensioning methods were used

3 The recommended methods of g aug ing flush es

are simple and do not cal for any measurement of

dificult or dubious dimensions

4 The most important aspect ofthe bolt hea in the

at ainment of flush es is the position of the flat

up er sur ace of the hea in relation to the conical

under surace The g aug ing dimension b which this

is controled is that betwe n the flat up er surace

and a plane which cuts the conical sur ace normal to

its a is at a specified diameter k own as the

g aug ing diameter ( se Fig ure 2) The dimension

measured is k own as the “ hea protrusion” and its

tolerance as the “lush es tolerance”

5 The v aria les which afect the flushnes tolerance

are:

a) The diameter to sharp corner ( the

hy pothetical inter ection of the flat up er surace

and the conical u der surace ofthe hea ) and

b) The included ang le of the hea

The g aug ing diameter is at a proximately

one-third of the hea depth fom the up er

sur ace

6 The elements which define the bolt hea and

which are required to be controled b inspection

are:

a) hea protrusion, the lmits of which define the

flushnes tolerance;

b) diameter of hea to sharp corner ; this is

controled indirectly b the inspection of a) and

d);

c) actual diameter of hea for which a minimum

is specified and which is the diameter at the land;

d) included ang le of the conical u der sur ace;

e) ra ius betwe n conical surace and shan

It is not a requirement of this stand rd that a

p rticular method of inspection shal be employ ed

Hea protrusion ma be checked b means of a

g aug e of the ty e shown in Fig ure 4, b a G -NOT G

g aug e, b optical projection, or b any other suita le

means The actual diameter ma be checked b

direct measurement or b a G -NOT G g aug e The

hea ang le and ra ius at shan ma be checked b

optical projection

7 Fig ure 4 i lustrates a ty pe of g aug e which has

achiev ed some popularity for use with air raft

cou ter u k hea bolts and riv ets in the U.S.A

Detai s of a suita le g aug e block are g iv en in

Fig ure 5

The inter ection of the hole X with the top surace of

the g aug e block forms the diameter on which the

cone of the bolt hea rests The diameter of the

holeX is sl g htly les than the g aug ing diameter N

to permit the edg e of the hole to be broken to form a

land a proximately0.0 3in wide b la ping with a

hardened ste l b l unti the dimension Z is within

the stated lmits The dimension Z is calculated fom

the formula

W hen the bolt is inserted in the block, the dial

indicator is used to g iv e a direct rea ing of hea

protrusion which is the amou t b which the top

surace of the bolt hea protrudes a ov e the top

surace of the g aug e block