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1/2-Drive Sockets

In the pages below we'll look first at some examples of early 1/2-drive sockets, beginning with the simple broachings (6-point and 4-point), and then continue to other broachings and drive sizes.

Hex and Square Sockets

S/O-Overstrike Marking

Snap-On S/O Overstrike Sockets]
Fig. 1. Snap-On S/O-Overstrike Sockets, from Left: 7/16(6pt), 1/2(4pt), 13/16(6pt), 7/8(6pt), 1"(6pt).

Fig. 1 shows a group of sockets with the first marking style, the S/O-Overstrike. These are all single-hex (6-point) except for one square (4-point) socket, and all have a knurled center band and tapered walls.

Note that the overstrikes are not very consistent; they look as if they were marked by hand with a hammer and punch, which may very well have been the way it was done.

[Unmarked Socket with S/O Overstrike Socket]
Fig. 2. Unmarked Socket with S/O-Overstrike Socket, from Left: 25/32(6pt), 13/16(6pt).

Fig. 2 shows a possible unmarked Snap-On socket, with one of the S/O-Overstrike sockets for comparison.

The socket on the left is marked only "25/32" and has the same dimensions and construction as the comparison socket, a close 13/16 size. The only notable difference is that the knurled center band is wider on the unmarked socket.


Logo and Size Only Marking

In the next photograph we see four examples of sockets marked with the Snap-On logo and fractional size, but without model numbers.

[Snap-On Sockets Without Model Numbers]
Fig. 3. Snap-On Sockets Without Model Numbers, from Left: 3/8(4pt), 7/16, 13/16, 1".

These sockets are all 6-point except for one 4-point, as noted in the caption. Three of these sockets also have date codes, as can be seen in Fig. 4 below.

[Snap-On Date Codes]
Fig. 4. Date Codes on Reverse of Above Sockets, from Left: 3/8(No Date), 7/16(1929), 13/16(1929), 1"(1928).

Model Number Marking

The next group of figures show examples of sockets with model numbers.

[Snap-On 4-Point Sockets]
Fig. 5. Snap-On 4-Point Sockets With Model Numbers, from Left: 9/16(No. 418), 5/8(No. 420), 3/4(No. 424).

Fig. 5 shows several 4-point sockets with their model numbers, which follow the pattern "NO. 4xx" where xx is the size in 32nds, e.g. "NO. 420" for a 5/8 square opening.

These particular sockets aren't marked with date codes and so were probably made during 1924-1926.

[Snap-On 6-Point Sockets With Model Numbers]
Fig. 6. Snap-On 6-Point Sockets With Model Numbers, Sizes 7/16 to 1".

Fig. 6 shows a nearly complete set of 6-point sockets with model numbers, with sizes ranging from 7/16 to 1" (with a couple of sockets missing.) Two of the sockets have date codes: sizes 19/32 and 31/32 both have a "-7" code for 1927.

A close look at the largest three sockets in the photograph reveals a small problem. (You might have anticipated it already.)

Models numbers for 1/2-drive 6-point sockets were given the form "NO. xx0", where xx is the size in 32nds, but a lack of foresight caused these numbers to collide with the numbers used for 5/8-drive sockets. Hence when the 1/2-drive 15/16 size (and larger) sockets were created, their model numbers were appended with a small "1/2" to make them distinct from the "NO. 300" (and up) models already in use. (This glitch in the numbering system persisted until 1950!)


Broaching Details

Snap-On Sockets Showing Broaching Details]
Fig. 7. Closeup of Snap-On 6-Point Sockets Showing Broaching Details.

For one last look at the 6-point sockets, Fig. 7 gives a closeup photograph showing details of the broaching. The left socket with S/O-Overstrike and right socket from 1928 show similar details.

The center of the flats have tooling marks where the socket was first drilled, and there is a large recess under the broached area. This was the standard technique for making sockets at the time; the bored recess allowed for easy removal of the chips from the broaching.


Double-Hex and Double-Square Sockets

In 1927 Snap-On started producing sockets with double-hex (12-point) and double-square (8-point) openings, and as was the case earlier, a confusing number of styles and markings resulted. In this case the sockets themselves were made in different formats; one type had tapered walls like the older examples and were basically just the older sockets with a double broaching. The other type was quite different though; it had straight and much thinner walls and could be used in tighter places.

Neither of the new double-broached styles were given model numbers initially, but differences in marking still resulted from patent notations added to the straight-wall sockets. Additional changes came later in 1929 when the new 1930s style was previewed. The paragraphs below will show some examples of the new sockets and explore the differences.

Tapered-Wall Sockets

[Snap-On 12-Point Tapered Sockets]
Fig. 8. Four 12-Point Tapered Sockets, from Left: 19/32, 11/16, 11/16, 13/16.

Fig. 8 below shows four 12-point sockets in the tapered-wall format. These closely resemble the 6-point sockets, though the knurling is somewhat less coarse. Three sockets are in unfinished steel, but the third from the left (11/16 size) has an early plated finish, possibly cadmium.

[Date Codes]
Fig. 9. Date Codes on Sockets from Fig. 7, from Left: 1929, 1927, 1929 + 1931, 1929.

In Fig. 9 we see the date codes on the reverse side of the above sockets, and once again the third socket from the left holds a surprise. It shows an obvious "*" asterisk, the date code for 1931, but on careful examination you can see a smaller "9" code, to the upper right of the asterisk.

For these early tools, double-stamped date codes mean that the socket was sold some time after it was made, and the customer of course wanted to get the full term of the guarantee. Presumably this meant that the dealer had to add the current year's code to make the sale -- did Snap-On dealers of the day all carry date-code punches?


Straight-Wall Sockets

[Snap-On 12-Point Straight-Wall Sockets]
Fig. 10. 12-Point Straight-Wall Sockets, from Left: 1/2, 5/8, 13/16, 1.

Fig. 10 shows four 12-point straight-wall sockets. The two leftmost sockets appear to be of unfinished steel, while the two in the right show a thin plating with a yellowish tint.

[Snap-On Straight-Wall Sockets With Date Codes]
Fig. 11. Date Codes on 12-Point Straight-Wall Sockets, from Left: 1/2(1929), 5/8(1928), 13/16(1929), 1(1929).

Fig. 11 shows the date codes on the reverse side of the Fig. 9 sockets.


The Mystery Patent

In addition to the logo and size markings, some straight-wall sockets will have the notation "Pat. Appld For" or a comparable phrase, typically at the base (drive end) of the socket. Sometimes the marking may appear on the side of the socket instead, and later sockets (1929 or after) may have just a simple "Pat." notation. Obviously Snap-On must have filed for and expected to receive a patent on its 12-point sockets, but what was the patent? It was common at the time for companies to mark tools with their patent numbers, or at least to give the patent date, but Snap-On offered neither.

Earlier versions of this article speculated that the patent might be #1,424,069, which is known to have been marked on later sockets. However, it turns out that the patent in question is actually #1,772,723. The mystery was resolved by reference to the 1933 Snap-On catalog, which cites this patent with the listing for straight-wall 12-point sockets.

Patent #1,772,723 describes an improved method of broaching sockets. Previously socket blanks were first drilled and then bored to undercut the area at the base of the broaching, so that the chips from the broaching could be removed easily. (An earlier figure gives an example of Broaching for illustration.)

The patented method avoids the need to bore an undercut, by first broaching part way into the socket, then inserting a second mandrel to cut off the chips. The advantages stated in the patent include superior strength (for a given wall thickness), as well as cost savings by avoiding the boring operation. The patent was filed by Walter Klein on Aug. 5, 1928 and issued on Aug. 12, 1930, with an assignment to the Snap-On Wrench Company.

The results of this new method can be seen easily by examining the 12-point straight-wall sockets made in 1928 or later; typically the socket will have a somewhat irregular shelf at the base of the broaching, below which can be seen some remnants of the chips. Snap-On used the new process for all of its straight-wall sockets, but continued to use the older method for the tapered sockets.

Finding this patent has helped to clear up a misconception (on my part, at least) that the new straight-wall sockets used an early hot-broaching process; the new method did not heat the work piece before broaching. Snap-On was apparently satisfied with the results, however, as they continued to use this cold-broach process until sometime in the late 1940s. It's worth noting that some tool companies, notably Duro/Indestro and Herbrand, had switched to a true hot-broach process by the mid to late 1930s. (See here for details on the Duro Hot-Broach Method.)

While we're in the section on mystery patents, a side note on another patent is in order. Patent #1,424,069 does appear on sockets made in the 1932-1933 time frame, but it's not clear what claim is being made. The patent was actually issued in 1922 (to F. Blackmar) and only later acquired by Snap-On, and appears to apply primarily to deep offset wrenches with 12-point openings. The patent number also appears on 12-point wrenches made by Blue Point, Mossberg, and Williams (and the 1933 Williams catalog acknowledges the Blackmar patent.) Apparently Snap-On thought that the patent (in some readings) could apply to sockets, but by 1932 everyone in the industry was making 12-point sockets.


The Knurled Base

For the 1930s Snap-On changed the design of its sockets, with most socket series being given a thin knurled band around the base. (The knurling was too shallow to afford a grip and so must be regarded as purely decorative.) The sockets also received model numbers, with the 1/2-drive shallow sockets being designated the "SW-xx0" series, where xx was the opening size in 32nds. The "SW" stood for "straight-wall".

[Snap-On Knurled-Base Sockets]
Fig. 12. Snap-On Sockets with New Style, Late 1929, from Left: No. 416 (1/2 8pt), SW-280 (7/8 12pt).

The 1930s socket design actually started appearing in 1929, as sockets may occasionally be found with the above features but 1929 date codes. Fig. 12 shows examples of both 8-point and 12-point sockets with the new knurled base, with the righthand socket also showing its new "SW-280" model number. Although the 8-point sockets received the same knurling make-over as the 12-pointers, they remained stuck with the old "No. 4xx" numbering system, even though this meant that a new 8-point socket would get the same part number as an older 4-point one.

[Date Codes on Knurled-Base Sockets]
Fig. 13. Date Codes on Sockets with New Style, both 1929.

Fig. 13 shows the date codes on the knurled sockets, both from 1929 as expected. Both sockets show the early thin plated finish characteristic of 1929.


5/8-Drive Sockets

The markings for 5/8-drive sockets show the same basic styles as the 1/2-drive examples, that is, S/O-Overstrike, logo with sizes only, and logo with model numbers and sizes. The 5/8-drive tools were not introduced until early 1923, close to the time that the S/O-Overstrike markings were being phased out, so this marking style is less common.

The early 5/8-drive sockets were produced in hex (6-point) and square (4-point) broachings, although the latter are less common. Later in the decade double-hex 5/8-drive sockets were added, although the hex models remained in production.


Early S/O Overstrike Sockets

We'll begin with a look at the 5/8-drive sockets with S/O overstrike markings, the earliest form.


5/8-Drive Hex Sockets with S/O-Overstrike Marking

[Snap-On 5/8-Drive S/O-Overstrike Sockets]
Fig. 14. Snap-On 5/8-Drive S/O-Overstrike Sockets, ca. 1923, from Left: 1-3/8, 1-7/16.

Fig. 14 below shows two 5/8-drive S/O-Overstrike sockets, with sizes from the left of 1-3/8 and 1-7/16.

The production date is likely 1923, since the overstrike markings were phased out after this year.


5/8-Drive Short-Format Sockets with S/O-Overstrike Marking

Although it's not documented in the catalogs, early 5/8-drive sockets were apparently made in two formats, a short form as well as the standard (long) form. Later sockets were made only in the standard format, so the short sockets are less commonly found.

We were fortunate enough to find an early set of 5/8-drive sockets in which all six of the smallest sizes were in the uncoomon short format. In addition, the sockets were marked with the S/O overstrike, and there was one additional oddity to be explained below.

[Snap-On 5/8-Drive Short-Format Hex Sockets] [1-1/16 S/O Overstrike Detail] [1-1/8 S/O Overstrike Detail] [1-1/4 S/O Overstrike Detail] [15/16 S/O Overstrike Detail] [31/32 S/O Overstrike Detail] [1 Inch S/O Overstrike Detail]
Fig. 15. Snap-On 5/8-Drive Short-Format Hex Sockets, ca. 1923.
S/O Overstrike Detail: Hide Show

Fig. 15 below shows the six smallest sizes of the set, all short-format 5/8-drive sockets. All of the sockets have S/O overstrikes, except for one with no markings other than the size. The sizes are, front row from the left, 15/16, 31/32, and 1 inch; and the back row from the left, 1-1/16, 1-1/8, and 1-1/4.

The sockets are finished with nickel plating, which still has quite a shiny surface even after 80+ years. (The golden sheen in the photograph is a reflection of the lighting, not the normal daylight tint of the sockets.)

The S/O overstrike markings can be viewed by clicking on the socket of interest, or with the selector button at the bottom of the figure. (Clicking on the photograph outside of any socket will bring up an enlarged view, as usual.)

Note that the S/O markings are all a little bit different, and that the 1-1/4 socket has no marking at all. (The section shown is diametrically opposite from the size marking, where the S/O overstrike is normally placed.)

[Snap-On 5/8-Drive Hex Sockets] [1-1/16 S/O Overstrike Detail] [1-1/8 S/O Overstrike Detail]
Fig. 16. Snap-On 5/8-Drive Hex Sockets, ca. 1923.
S/O Overstrike Detail: Hide Show

The two largest sockets from the short-format set are shown in Fig. 16, and these have the standard height for 5/8-drive sockets. The sockets are marked with an S/O overstrike and the fractional size, and the sizes are (from the left) 1-3/8 and 1-1/2.

The S/O overstrike markings can be viewed by rolling over the socket of interest, clicking on the socket, or by using the selector button.

Readers familiar with the Snap-On 1923 catalog "A" may have noticed an oddity here. According to the 1923 catalog, 5/8-drive sockets were offered only up to the No. 460 1-7/16 size, but here we have an example of an early socket in size 1-1/2 inches.

Comparison of Short and Standard 5/8-Drive Sockets

[Comparison of Snap-On 5/8-Drive Short and Standard Sockets]
Fig. 17. Comparison of Snap-On 5/8-Drive Short and Standard Sockets.

The difference in the height of the short and standard forms can be seen in Fig. 17, a comparison of two 1-1/8 sockets. The socket on the left is from our short-format set, and the socket on the right is a Snap-On No. 360 socket of later production, probably 1924-1926.

5/8-Drive 1-1/4 Square Socket with S/O-Overstrike Marking

[Snap-On 5/8-Drive 1-1/4 Square Socket]
Fig. 18. Snap-On 5/8-Drive 1-1/4 Square Socket, with Insets for Broaching and Marking Detail, ca. 1923.

Fig. 18 shows a 5/8-drive Snap-On 1-1/4 square socket, stamped with the S/O overstrike on the front with the size on the reverse (see lower inset).


Later Marking Styles


5/8-Drive Sockets with Logo and Size Only Marking

Snap-On 5/8-Drive Sockets]
Fig. 19. Snap-On 5/8-Drive Sockets with Sizes Only, from Left: 1-1/8 (1929), 1-3/8 (1924-1926).

Fig. 19 shows two sockets marked with the Snap-On logo and sizes but without model numbers. The socket on the left has a date code for 1929. The righthand socket has no date code, so production was likely in 1924-1926.


5/8-Drive Sockets with Model Number Marking

[Snap-On 5/8-Drive Sockets with Models]
Fig. 20. Snap-On 5/8-Drive Sockets with Model Numbers, ca. 1924-1926, from Left: 31/32(No. 310), 1-1/8(No. 360).

Fig. 20 shows two 5/8-drive sockets marked with model numbers as well as the logo and sizes. Neither socket has a date code, so the production date should be in the range 1924-1926.


5/8-Drive Double-Hex Sockets

In the late 1920s Snap-On introduced 5/8-drive sockets with double-hex broachings. Based on our current knowledge, the 5/8-drive double-hex sockets were offered only in the standard tapered-wall style.

It's not known whether 5/8-drive double-square sockets were produced.


5/8-Drive Sockets With Double-Hex Broaching

[Snap-On 5/8-Drive 12-Point Sockets]
Fig. 21. Snap-On 5/8-Drive 12-Point Sockets, 1929, from Left: 15/16, 1-1/16, 1-1/4.

Fig. 21 shows three examples of 5/8-drive 12-point sockets, all marked with the logo and size, and all in the tapered-wall format.

All of these sockets have date codes from 1929.


Differences in Socket Construction

We'll close this section with a quick look at the differences in socket construction for the older and newer styles.


Comparison of Socket Construction

[Comparison of Socket Construction for Straight-Wall and Tapered-Wall Styles]
Fig. 22. Comparison of Socket Construction for Straight-Wall and Tapered-Wall Styles.

Fig. 22 illustrates some details of socket construction, and shows differences between the two types of 1/2-drive 12-point sockets and the 5/8-drive 12-point sockets. The leftmost socket is a 1/2-drive straight-wall example from 1929, with construction using a new patented broaching process. (See the Mystery Patent above for details.) There is no recess below the broached area, and small flanges of displaced material have been pressed back against the wall.

The middle and righthand sockets, 1/2-drive and 5/8-drive respectively, both have tapered walls, and both show the older standard cold-broach construction, with a distinct recess below the broached area to clear the metal chips.

That concludes our review of the Snap-On early sockets. The next section will look at the various types of drive tools.


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