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Details of special features on some wrenches,spanners and sockets.

(1) Ratchet heads for spanners,reverse direction by turning spanner over.These spanners are flat which helps where access is difficult.These spanners typically need only 8 degrees of movement to engage the next tooth on the ratchet.

(2) Spanner ratchet head with swivel.All the advantages of the above but the spanner handle has a swivel joint built in close to the ring end.Handy when spanner can't be used flat,for example where a cranked ring spanner would normally be used to give access.

(3) A bi-hex or twelve sided socket,same configuration normally used on ring spanners.Impact sockets are normally mono hex (six sided) for strength.

(4) A mono or six sided socket. This one is an impact type (black finish and designed not to shatter under shock loads).Normally used with an air tool.

(5) A box spanner. Tubular construction.Used where access around fixing is limited,an alternative to a deep socket. For relatively light use only.

(6) A deep socket. Used where nut or bolt head is recessed. This expample is a six sided impact but deep sockets are also made in twelve sided versions.

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Whitworth to B.S.F to Imperial to metric bolt size conversion tables.

More comprehensive conversion charts etc are here.

Whitworth and BSF (British standard fine) refer to the thread size of the bolt or nut.(ie) a spanner marked 7/8 inch whit fits a 7/8inch whit threaded nut or bolt (or a 1 inch B.S.F) it is however not 1 or even 7/8 inches wide.To help with nut or bolt identification,whitworth is a coarser thread than BSF. and A.F (across flats) is the size measured in inches (or mm) across opposite flats,(ie) a 3/4 inch af spanner is 3/4 inch wide,the same applies to a metric spanner.On older macines it's not at all uncommon to find a mixture of Whit,BSF,a.f and even a BA or two thrown in.

Whit/BSF and the metric or imperial Equivalent.

 

Imperial to Metric

Whitworth

BSF.

Metric.

Imperial (af).

 

A.F

MM.

1/8

3/16

8.64

.340

 

1/4

6.35

3/16

1/4

11.3

.445

 

5/16

7.94

1/4

5/16

13.34

.525

 

3/8

9.52

5/16

3/8

15.24

.6

 

7/16

11.11

3/8

7/16

18.03

.710

 

1/2

12.7

7/16

1/2

20.83

.82

 

9/16

14.29

1/2

9/16

23.37

.92

 

5/8

15.88

9/16

5/8

25.65

1.010

 

11/16

17.46

5/8

11/16

27.94

1.100

 

3/4

19.05

11/16

3/4

30.48

1.200

 

7/8

22.22

3/4

7/8

33.02

1.300

 

15/16

23.81

7/8

1

37.59

1.480

 

1.00

25.40

1

1.1/8

42.42

1.670

 

1.1/16

26.93