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Early Socket Sets

[Duro Metal Products Logo]
Logo from a Duro Socket Set, ca. 1929-1930.

By the mid 1920s (or earlier) Duro and Indestro were producing socket sets for automotive repair, a rapidly growing market at the time. In this section we'll look at a number of these early socket sets.


Hex-Drive Socket Sets

Hex-drive socket sets were among the most popular and best-known products offered by Duro/Indestro. Production of these sets began in the early 1920s (or possibly earlier) and continued into the 1960s or beyond, although the peak of their popularity was probably in the 1920s and 1930s. The sets were typically supplied in a compact metal holder, often with a clever design for retaining the pieces in place.


Indestro No. 220 1/2-Hex Drive Socket Set

Early Indestro No. 220 1/2-Hex Drive Socket Set]
Fig. 47. Early Indestro No. 220 1/2-Hex Drive Socket Set.

Fig. 47 shows an early Indestro No. 220 1/2-hex drive socket set, complete with a steel container with an embossed lid. The fractional sizes are written in the style "5-8" rather than expected "5/8" form; this appears frequently on early sockets, though some socket sets have the syles in mixed format.

Note that the sockets are marked with five-pointed stars on either side of the size markings; this pattern appears on several examples of Indestro sockets, suggesting that this was intended as a specific mark for Indestro. (As a counterargument though, early sockets from Bog Mfg. of Chicago also show similar markings with stars on either side of the size.)

The sockets in this set use 1/2 inch hex drive and have hex (six-point) broachings. The sockets were constructed by machining and cold-broaching, and were then hardened, making them impervious to wear but subject to cracking. The band of knurling is coarse enough that it was likely intended to be functional, to allow the socket to be turned by hand.


Indestro No. 19 1/2-Hex Drive Socket Set

[Indestro No. 19 1/2-Hex Drive Socket Set]
Fig. 48. Indestro No. 19 1/2-Hex Drive Socket Set with Streamlined Holder, ca. Mid 1920s.

Fig. 48 shows an Indestro No. 19 1/2-hex drive socket set, packaged in a clever "streamlined" holder resembling a locomotive. The set includes a 1/2-hex drive Ell-handle marked "Indestro Mfg. Co. Chicago", eight sockets marked with fractional sizes, and a screwdriver bit.

The sockets have hex (6-point) broachings and a reduced base, and the construction is similar to that in the previous example. A knurled band is provided to assist with hand turning.

This set is not marked with a model number, but was identified as an Indestro No. 19 by a listing in a 1925 catalog from United Hardware & Tool Corporation. (The catalog lists two other Indestro socket sets as well.) The 1941 Indestro catalog lists an updated version of this set as No. 1219, with 12-point sockets instead of 6-point.

The socket holder is rather complicated, with three separate moveable pieces attached to the base. To open, the nose piece first folds forward to release the hex wrench, then the tail piece pivots to the side, and finally the retaining rail lifts up to free the sockets. (The retaining rail even has a slot to engage the tip of the screwdriver bit.) Duro Metal Products developed and patented a number of such socket kits, although this particular one doesn't appear to be patented.


Duro Metal Products LTX316 1/2-Hex Drive Socket Set

We recently acquired a Duro Metal Products LTX316 socket set, a compact set with a driver and sockets in a tapered metal box. The set was manufactured around 1930 and so provides a valuable snapshot of Duro socket production at that time.

[Cover of Duro Metal Products LTX316 Socket Set]
Fig. 49. Cover of Duro Metal Products LTX316 Socket Set, ca. 1929-1930.

Fig. 49 at the left shows the top cover from the socket set, a lid that slides into place on the tapered box. The center is stamped with a fancy logo for Duro Metal Products, a design also seen on their valve grinder tools.

The stamped "LTX" and "316" markings are presumed to identify the model number for this set, but currently no catalog reference is known for this model.


[Duro LTX316 1/2-Hex Drive Socket Set]
Fig. 50. Duro Metal Products LTX316 1/2-Hex Drive Socket Set, ca. 1929-1930.

Fig. 50 shows the Duro Metal Products LTX316 1/2-hex drive socket set, consisting of an L-T convertible handle, 12 hex sockets, and three square sockets. The set is contained in a tapered metal case with a sliding cover, a popular means of storage for socket sets of this type.

The driver and sockets all use 1/2-hex drive, and the generous assortment of sockets includes hex sizes 5/16, 11/32, 3/8, 7/16, 1/2, 9/16, 19/32, 5/8, 11/16, 3/4, 25/32, and 7/8. The three square sockets have sizes 5/16, 11/32, and 3/8.

The L-T handle is a convertible design and has been noted previously in our section on Duro patents; the corresponding patent is #1,744,413, filed by E.H. Peterson et al in 1929 and issued in 1930. This particular example is marked "Duro Metal Products Co." and "Chicago U.S.A.", with a "Pat. Pend." notation at the left. Based on the patent filing date, the pending status indicates a manufacturing date of 1929-1930. The bright finish appears to be nickel plating.

A later example of this tool, taken from a very similar socket set, can be seen as the L-T Handle Patent.


1/2-Hex Drive L-T Convertible Handle in Tee-Handle Position

[Duro 1/2-Hex Drive L-T Handle]
Fig. 51. Duro 1/2-Hex Drive L-T Handle Showing Open Position, ca. 1929-1930.

The L-T handle was normally stored with the L-handle inserted into the sheath, as shown in the figure above, and it could be used as an L-handle in this form if desired.

If operation as a T-handle was required, the handle was first removed, then the short arm inserted into the sheath. The arm locks into place against a stamped dimple in the sheath. Fig. 51 at the left shows the L-T handle as it appears when assembled as a T-handle.


[Duro 1/2-Hex Drive Sockets]
Fig. 52. Duro 1/2-Hex Drive Sockets, ca. 1929-1930.

Most of the sockets in the LTX316 set are marked only with the fractional size, but several of them also have a distinctive trapezoid symbol marked on each side of the size. Fig. 52 shows two of the marked sockets, both with hex broachings and sizes 3/8 and 7/16. (Note that the opening shown in the photograph is the 1/2-hex drive end.)

The trapezoid symbol resembles a stylized "D" and has been identified in a catalog as a mark for Duro production. This symbol is referred to as the D-Trapezoid logo in the text, and additional examples will be shown later with the Duro 1/2-Drive Sockets.

The sockets have been machined from bar stock, cold-broached, and then hardened, the standard construction method at the time. The decorative band of cross-hatching appears around the top of the larger sockets, but around the base of the smaller sockets shown in the figure, as these have been inverted to simplify the manufacturing. The finish is cadmium plating.

To place this socket set in context, the LTX316 set appears to be virtually the same as a socket set listed in the Sears Roebuck 1929-1930 Fall and Winter catalog. The Sears set is listed as the "Merit Tool" 16-Piece Socket Wrench Set, and the description mentions the L-T handle, 15 sockets ranging from 5/16 to 7/8, and the metal case with a sliding lid. There are a few minor differences -- the metal case is green, and the tool finish is described as white nickel -- but these changes could be easily made during manufacturing. (The listing is on page 1122, for any readers with a copy of this catalog.)

The "Merit Tool" brand appears to have been a generic name used by Sears for whatever tools had been selected by their buyers, and may or may not have been actually marked on the tools. One of the advantages of the metal container used for this set is that the cover could be easily stamped with whatever brand the customer wanted. The price for the "Merit Tool" set was just $0.95.


Indestro No. 2104 3/8-Hex Drive Socket Set

[Indestro No. 2104 3/8-Drive Socket Set]
Fig. 53. Indestro No. 2104 3/8-Hex Drive Socket Set, with Insets for Side View and Marking Detail, ca. 1935-1936.

Fig. 53 shows a 3/8-hex drive Indestro No. 2104 socket set in a metal holder, stamped "Indestro Mfg. Corp. Chicago" and "Pat. Pend." on the Ell handle. The set consists of nine hex sockets with a 3/8-hex Ell handle, all held together in a patented (pending) metal case.

The model number was not marked on this set, but the 1937 Indestro catalog lists this as a No. 2104 "Pee-Wee" socket set.

The socket sizes are, from the left, 9/32, 5/16, 11/32, 3/8, 7/16, 15/32, 1/2, 9/16, and 5/8. The sockets are marked with the fractional size and have a band of cross-hatched knurling around the base.

The overall length is 6.8 inches. The finish is cadmium plating for the tools and red paint for the metal holder.

The patent pending status corresponds to patent #2,065,340, filed by McNaught and Peterson in late 1935 and issued in 1936. The patent describes the metal holder for the set, which includes metal tabs to secure the sockets and a bracket on the back to lock the Ell handle in place (see top inset).

The very similar McNaught and Peterson 1936 patent #2,065,341 describes a socket set holder with a slightly different arrangement for securing the sockets, placing the scalloped tabs in front of the sockets instead of at the back.


Early 1/2-Square-Drive Socket Sets

The 1/2 square drive size had emerged as a standard well before 1920 and was the preferred size for more demanding socket wrench applications. The early makers of these tools included Blackhawk, Snap-On, and Walden, and it's likely that Duro and Indestro had joined the group by the early to mid 1920s.

In the article we'll refer to 1/2-square drive as simply 1/2-drive when the meaning is clear from the context.


Indestro 1/2-Drive Hex Sockets

[Early Indestro 1/2-Drive Hex Sockets]
Fig. 54. Early Indestro 1/2-Drive Hex Sockets.

Fig. 54 shows a group of three early 1/2-drive hex sockets from an Indestro socket set. Note that the markings include five-pointed stars on either side of the size, a feature noted in the earlier No. 220 Socket Set as well as on the Indestro Socket Wrench shown elsewhere in this article. The production date of this set is unknown, but likely dates from the mid to late 1920s.

The construction of these sockets is similar to those in the No. 220 set. The sockets were first machined, then cold-broached for the six-point hex opening, and finally hardened; they also appear to be finished with a thin bright plating.

[Broaching Detail for Early 1/2-Drive Indestro Sockets]
Fig. 55. Broaching Detail for Early 1/2-Drive Indestro Sockets.

Fig. 55 at the left shows a closeup of the socket construction. If you look carefully at the upper righthand socket, you can see a small burr left by the broaching, showing that the broaching came after the recess was machined. The centers of the flats also show tooling marks where the socket was drilled out prior to broaching.


Early Duro Metal Products "Double Guarantee" 1/2-Drive Socket Set

This next figure shows an unusually complete and well documented early Duro socket set, referred to as the "Double Guarantee" set for reasons explained below.

Duro Metal Products Double Guarantee 1/2-Drive Socket Set]
Fig. 56. Duro Metal Products "Double Guarantee" 1/2-Drive Socket Set, ca. 1929-1931.

Fig. 56 shows an early Duro Metal Products 1/2-drive socket set, sold through Sears Roebuck and still retaining a Sears "Double Guarantee" paper label on the lid. The set consists of a No. 672 ratchet, a No. 660 L-T convertible handle, an extension, a drive plug, and 15 hex sockets ranging from 5/16 up to 1 inch.

The No. 672 ratchet is stamped "Duro Metal Products Co." and "Chicago" on the handle and has a "Patent Pending" notation, known to be a reference to patent #1,798,481. (This ratchet is a familiar tool and further information can be found in the section for the Duro 672 Ratchet.)

The No. 660 L-T handle also has a patent pending marking, in this case a reference to patent #1,744,413. The pending status for the ratchet and L-T handle places the manufacturing date for the set in the range 1929-1931.

The socket sizes from the front left are 5/16, 3/8, 7/16, 1/2, 9/16, 19/32, 5/8, and 21/32, and from the back left are 11/16, 3/4, 13/16, 7/8, 15/16, 31/32, and 1 inch. The sockets are all stamped with the fractional size, and most are marked with a stylized "D" referred to as the Duro D-Trapezoid logo, although the "D" marking has been omitted on at least one socket.

The socket set is furnished in a green metal box with a hinged cover, with spot-welded dividers to organize the sockets. The box has dimensions 10.9 inches wide by 4.3 inches deep by 1.6 inches high.

This set was reasonably complete as acquired, but was missing the 11/16 socket, which has been replaced from our general inventory. Currently we don't have a Duro catalog reference for this set, but the 1929 Sears catalog lists a very similar set as the "Merit Tool Ratchet Wrench Set". The description of the Sears set includes the same drive tools, with 14 hex sockets from 5/16 to 1 inch, plus a screwdriver socket. If this is the set described in the Sears catalog, the set as pictured has one extra socket (possibly the 31/32 size) and is missing the screwdriver socket.


Duro No. 660 1/2-Drive L-T Convertible Handle from "Double Guarantee" Socket Set

Duro No. 660 1/2-Drive L-T Convertible Handle]
Fig. 57. Duro No. 660 1/2-Drive L-T Convertible Handle, with Inset for Marking Detail, ca. 1929-1931.

Fig. 57 shows the Duro No. 660 L-T 1/2-drive convertible handle from the "Double Guarantee" set, configured as a Tee-handle for the photograph. The sheath is stamped "Duro Metal Products Co." and "Chicago U.S.A.", with a "Pat. Pend." notation at the right.

The overall length is 10.6 inches, and the finish is nickel plating.

The pending status refers to patent #1,744,413, filed by E.H. Peterson et al in 1929 and issued in 1930.

The L-T convertible handle consists of a 5/8-diameter Ell-shaped bar with 1/2 square drive studs on each end, together with a sheet metal sheath to form a hand grip. The sheath can be placed either over the short end of the bar to form a Tee-handle, as in the photograph here, or placed on the long end of the bar as a grip and extender. The sheath can be completely removed from the bar if not needed.

Duro also supplied the L-T handle in a 1/2-hex drive version, an example of which can be seen as the Duro 1/2-Hex Drive L-T Handle.


Duro No. 660 1/2-Drive L-T Convertible Handle in Ell-Handle Position

Duro No. 660 1/2-Drive L-T Convertible in Ell-Handle Position]
Fig. 58. Duro No. 660 1/2-Drive L-T Convertible Handle in Ell-Handle Position, ca. 1929-1931.

Fig. 58 shows the Duro No. 660 L-T 1/2-drive convertible handle with the sheath installed to form an Ell-handle. The sheath is stamped "Duro Metal Products Co." and "Chicago U.S.A.", with a "Pat. Pend." notation at the right.

The overall length is 10.6 inches, and the finish is nickel plating.

The pending status refers to patent #1,744,413, filed by E.H. Peterson et al in 1929 and issued in 1930.


Duro No. 672 1/2-Drive Ratchet from "Double Guarantee" Socket Set

Duro No. 672 1/2-Drive Ratchet]
Fig. 59. Duro No. 672 1/2-Drive Ratchet, with Inset for Side View, ca. 1929-1931.

Fig. 59 shows the Duro No. 672 ratchet from the "Double Guarantee" set, stamped "Duro Metal Products Co." and "Chicago", with a "Patent Pending" notation at the right.

The overall length is 9.4 inches, and the finish is nickel plating.

The pending status refers to patent #1,798,481, filed by N.F. McNaught et al in 1928 and issued in 1931.

More information on this tool can be found in the section on the Duro 672 Ratchet on a previous page.


Duro 1/2-Drive 8 Inch Double-Male Extension from "Double Guarantee" Socket Set

Duro 1/2-Drive 8 Inch Double-Male Extension]
Fig. 60. Duro 1/2-Drive 8 Inch Double-Male Extension, ca. 1929-1931.

Fig. 60 shows the unmarked Duro 1/2-drive 8 inch double-male extension from the "Double Guarantee" set.

The overall length is 7.7 inches, and the finish is nickel plating

The extension is constructed from a square bar with a detent ball at each end, with two pinched tabs to act as stops.


Duro 1/2-Drive Large Sockets from "Double Guarantee" Socket Set

Duro 1/2-Drive Large Sockets from Double Guarantee Socket Set]
Fig. 61. Duro 1/2-Drive Large Sockets from "Double Guarantee" Socket Set, with Inset for Broaching, ca. 1929-1931.

Fig. 61 shows the three largest sockets from the Duro Metal Products "Double Guarantee" 1/2-drive socket set, with sizes (from the left) 15/16, 31/32, and 1 inch. The sockets are stamped with the Duro D-Trapezoid logo on each side of the fractional size, except that the 1 inch socket has only one "D" logo.

The finish is nickel plating.

The larger sockets in the set (from 11/16 up) have a distinctive design with a reduced diameter at the 1/2-square drive end, a pattern mirroring the reduced diameter at the service end for the smaller sockets.

The sockets have a band of cross-hatched knurling at the service end, with the knurling coarse enough to assist with turning a nut by hand. The photograph shows some of the variations in the knurling pattern -- the left socket has a very fine rectilinear grid, and the middle socket has a more coarse diamond cross-hatch pattern. Most of the sockets have a medium-fine cross-hatch pattern similar to the right socket, but at least one socket in the set had no knurling at all, probably due to a production accident.


Duro 1/2-Drive Medium Sockets from "Double Guarantee" Socket Set

Duro 1/2-Drive Medium Sockets from Double Guarantee Socket Set]
Fig. 62. Duro 1/2-Drive Medium Sockets from "Double Guarantee" Socket Set, with Inset for Broaching, ca. 1929-1931.

Fig. 62 shows a group of three medium-sized sockets from the Duro Metal Products "Double Guarantee" 1/2-drive socket set, with sizes (from the left) 1/2, 9/16, and 19/32 inch. The sockets are stamped with the Duro D-Trapezoid logo on each side of the fractional size, except that the 19/32 inch socket is marked with just the size.

The finish is nickel plating.

These smaller sockets have a reduced diameter at the hex service opening, in order to provide clearance for nuts in tight places. The band of cross-hatched knurling appears at the drive end, with the knurling coarse enough to assist with turning a nut by hand.


Early Duro No. 825 1/2-Drive 25-Piece Garage Socket Wrench Set

The next figure shows one of the first socket sets acquired for the Alloy Artifacts collection, but which until recently had remained unidentified.

Duro No. 825 1/2-Drive 25-Piece Garage Socket Wrench Set]
Fig. 63. Duro No. 825 1/2-Drive 25-Piece Garage Socket Wrench Set, ca. 1928-1931.

Fig. 63 shows an early Duro No. 825 1/2-drive socket set, consisting of a No. 672 ratchet, No. 652 short speeder, drive plug, extension, 17 hex sockets from 5/16 to 1 inch, and four square sockets from 1/2 to 3/4.

This set was not marked with a label or decal, but was identified as a No. 825 "25-Piece Garage Socket Wrench Set" by a Duro catalog.

The hex socket sizes are, beginning at the lower right edge, 5/16, 11/32, 3/8, 7/16, 1/2, 17/32, 9/16, 19/32, 5/8, 21/32, 11/16, 3/4, 25/32, 13/16, 7/8, 15/16, and 1 inch. The four square socket sizes are, from the left, 1/2, 5/8, 11/16, and 3/4. The sockets are stamped with the fractional size flanked by D-Trapezoid logos on each side, and the finish is nickel plating.

The ratchet in the set is basically identical to the Duro No. 672 1/2-Drive Ratchet shown with the previous set. The presence of the patent pending marking indicates a likely production date in 1928-1931.

The set was furnished in a red steel box with a hinged cover, with socket organizers spot-welded along the back and side. The dimensions of the box are 14.4 inches wide by 6.5 inches deep by 1.9 inches high.

This set was acquired with the ratchet and most of the sockets present, but was missing the speeder and extension. The speeder has been filled in from our general inventory, and the extension was borrowed from another early Duro set. A few missing sockets have been replaced from inventory or borrowed from a similar set.


Duro 652 1/2-Drive Short Speeder

[Duro 652 1/2-Drive Short Speeder]
Fig. 64. Duro 652 1/2-Drive Short Speeder, with Inset for Marking Detail, ca. 1925-1931.

Fig. 64 shows the early 1/2-drive Duro 652 short speeder from the No. 825 set, stamped with "Duro Metal Products Co." and the model number on the shank.

The overall length is 12.6 inches, and the throw is 3.7 inches. The finish is nickel plating.

This speeder is the correct model for the No. 825 socket set, but was acquired as a separate item. Duro frequently omitted the markings from speeders included in their sets, so the markings on this example suggest that it was purchased as an individual tool.


Duro 1/2-Drive Sockets from No. 825 Socket Set

[Early Duro 1/2-Drive Sockets from No. 825 Socket Set]
Fig. 65. Early Duro 1/2-Drive Sockets from No. 825 Socket Set, ca. 1928-1931.

Fig. 65 shows a group of three 1/2-drive Duro sockets from the No. 825 socket set. The sockets in the photograph are, from the left, a 25/32 hex socket viewed from the service end, a 5/8 square socket viewed from the service end, and a 1/2 hex socket viewed from the drive end.

The sockets are stamped with the Duro D-Trapezoid logo on each side of the fractional size, and the finish is nickel plating.

These sockets were among the first found with the (then mysterious) D-Trapezoid symbol. Further discussion of the Duro D-Trapezoid Marking can be found in the section on socket identification.


Durobilt "20-Piece" 1/2-Drive Socket Set [Duro No. 820FA]

The 1931 Sears Roebuck Spring and Summer catalog devotes half a page to "Durobilt" brand socket sets, and the tools in the illustrations closely resemble the known Duro and Indestro socket sets. Although these Durobilt sets are now somewhat hard to find, we have been able to acquire two examples of the sets and can confirm that Duro Metal Products was the manufacturer.

Our first example was listed in the 1931 Sears catalog as a Durobilt "20-Piece Socket Wrench Set", with a note recommending it for Model "A" Ford owners.

Durobilt 20-Piece 1/2-Drive Socket Set]
Fig. 66. Durobilt "20-Piece" 1/2-Drive Socket Set, ca. 1930-1931.

Fig. 66 shows a Durobilt "20-piece" 1/2-drive socket set, consisting of a Duro No. 660 L-T convertible handle, 15 hex sockets, three square sockets, and a screwdriver socket.

The set is marked with a Durobilt decal on the inside lid, badly chipped but still mostly readable. The decal is printed with "Durobilt" and "Special Analysis Steel" in the center of the diamond, with "Unconditionally Guaranteed" and "Heat Treated Hardened" along the borders. Readers can refer to the Durobilt Decal shown with another set for a more readable example.

The No. 660 L-T handle in the set is basically identical to the Duro No. 660 L-T Handle shown in a previous figure.

The hex socket sizes are, from the left in front, 11/32, 3/8, 7/16, 1/2, 9/16, 19/32, and 5/8, and from the left in back are 21/32, 11/16, 3/4, 25/32, 13/16, 7/8, and 15/16. The large hex socket at the back left corner has size 1-1/8.

The three square sockets in the main compartment have sizes, from the left, 3/8, 7/16, and 1/2.

All of the sockets are stamped with the fractional size, but only three of the original sockets are marked with the Duro D-Trapezoid logo. The finish is nickel plating.

The socket set is furnished in a red metal box with a hinged cover, with spot-welded dividers to organize the sockets. The box has dimensions 10.9 inches wide by 4.3 inches deep by 1.6 inches high. (This box has the same size and style as the box used for the Duro "Double Guarantee" Set shown in a separate figure.)

This set was acquired in a nearly complete state, but showed signs of hard use and abuse. The original Ell-handle had been damaged beyond usability and was replaced with an equivalent tool from another set. Two sockets were missing, the 21/32 and 3/4 sizes, and these were replaced from our general inventory. After an electrolytic derusting bath for the L-T sheath and a thorough cleaning for the sockets and box, the set is now fully functional and in good cosmetic condition as well.

Although this particular set was sold under the Durobilt brand, the set was also available as the Duro No. 820FA socket set. The 1933 Ducommun catalog "H" lists the Duro No. 820FA set with the same components as shown here, and notes that it would fit almost all of the nuts on the Ford Model "A". The description notes that the sockets are made of "special analysis steel" with a nickel plated finish. (The illustration shows the sockets in a slightly different arrangement, with two of the square sockets in the front row, and the other square socket and the screwdriver in the main bay.) Ducommun offered the set for a $4.00 list price.


Duro 1/2-Drive Screwdriver Socket from "20-Piece" Socket Set

Durobilt 1/2-Drive ScrewdriverSocket]
Fig. 67. Duro 1/2-Drive Screwdriver Socket, ca. 1930-1931.

Fig. 67 shows the unmarked Duro 1/2-drive screwdriver socket from the "20-piece" socket set.

The overall height is 1.5 inches, and the width of the blade is 0.5 inches. The finish is nickel plating.


Durobilt "36-Piece" 1/2-Drive Socket Set

Our second Durobilt example is listed in the 1931 Sears catalog as the Durobilt "36-Piece Wrench Set", and the illustration shows a substantial collection of drive tools and sockets in a hinged metal case. (The set is on page 483, for any readers with this Sears catalog.) A check of the contents with the catalog listing showed that our set is nearly complete, with only a few pieces missing.

Duro Durobilt 36-Piece 1/2-Drive Socket Set]
Fig. 68. Duro Durobilt "36-Piece" 1/2-Drive Socket Set, ca. 1930-1931.

Fig. 68 shows the Durobilt "36-Piece" 1/2-drive socket set as acquired, but with two missing tools filled in from our general inventory.

The ratchet handle in the set is the Duro 672 model discussed in a prior section, and the ratchet is marked with a patent pending notation. The patent status together with the known catalog reference places the manufacturing date right around 1930-1931, and this will prove very helpful in providing a time context for other Duro tools.


Durobilt Decal from 36-Piece 1/2-Drive Socket Set]
Fig. 69. Durobilt Decal from "36-Piece" 1/2-Drive Socket Set.

Fig. 69 shows the Durobilt decal on the inside lid of the case, printed with "Durobilt" and "Special Analysis Steel" in the center of the diamond, with "Unconditionally Guaranteed" and "Heat Treated Hardened" along the borders.

The decal matches the one shown in the Sears catalog, so the identification of the set is quite certain.

The Durobilt sets are quite significant, as these are among the earliest known examples of 1/2-drive socket tools sold by Sears Roebuck, at least for which a reasonable estimate of the manufacturing date can be made. The 1930-1931 origin of the sets predates the Craftsman C-Series and Craftsman "BE" Series socket sets by several years.


Early 12-point Socket Sets

During most of the 1920s sockets were generally made with six-point (or four-point) broachings, but by the late 1920s several companies had started producing 12-point (double-hex) sockets. By the early 1930s Duro/Indestro had begun producing 12-point sockets as well; although the exact date is not known, we do know that by 1931 Duro and Indestro socket sets were definitely available in 12-point broachings.

The first confirmation comes from the 1931 Sears catalog, which lists several "Durobilt" brand socket sets that are easily recognizable as Duro production. The high-end set featured chrome-nickel sockets in the standard 6-point broaching, but with 12-point sockets available at a slightly higher price.

A second confirmation is even more direct: by fortunate circumstance we were able to acquire an early Indestro "Chromium Vanadium" 12-point socket set, compete with a dated sales receipt from 1931. The set consists of a speeder, sliding Tee-handle, ratchet adapter, extensions, universal, and ten 12-point sockets, with most of the pieces being marked "Chromium Vanadium". The speeder was also marked "Indestro Chicago", and the metal box has an Indestro decal on the top, similar to the Indestro Logo shown below.

The sales receipt shows that the set was purchased on August 8, 1931 from a Western Auto store in Texas, for a price of $5.35. As additional verification, a 1932 Western Auto catalog does indeed offer a "Chromium Vanadium" socket set matching the above description, and for the same $5.35 price.


Indestro "Chromium Vanadium" 1/2-Drive Socket Set

Indestro Chromium Vanadium 1/2-Drive Socket Set]
Fig. 70. Indestro "Chromium Vanadium" 1/2-Drive Socket Set, 1931.

With the above introduction, Fig. 70 shows the Indestro "Chromium Vanadium" socket set from 1931. The ten double-hex sockets are all marked "Chromium Vanadium" except for one, and most of the drive tools are similarly marked.

Since this is an alloy steel set, we'll defer further discussion to a later section, where the set is shown as the Indestro "Chromium Vanadium" Socket Set.


Indestro "Chromium Vanadium" 1/2-Drive Double-Hex Sockets from 1931 Socket Set

Indestro 1/2-Drive Chromium Vanadium Double-Hex Sockets]
Fig. 71. Indestro 1/2-Drive "Chromium Vanadium" Double-Hex Sockets, with Inset for Detail, 1931.

Fig. 71 shows a group of nine of the sockets from the set; the smallest (7/16) socket didn't match the others, and appears to be a replacement. All of the sockets shown are marked "Chromium Vanadium" and have a star symbol on each side of the size, a characteristic marking for Indestro sockets.

The sizes are, from the front left, 1/2, 9/16, 5/8, 21/32, and 11/16; and in the back row, 3/4, 13/16, 7/8, and 15/16. The inset shows a typical "Chromium Vanadium" marking.

The sockets have a coarse knurled band around the base, probably intended to help with turning a loose nut by hand.

The socket construction is cold-broached with a bored recess at the base. If you look carefully at the full-sized photograph, you can see chatter marks typically left by cold broaching.


Duro No. 500 Socket Set

As 12-point broachings became standard for alloy steel sockets, Duro/Indestro changed its carbon steel (or "Select Steel") economy socket sets to 12-points as well. Although the dates are uncertain, the two examples below are thought to be representative of Duro and Indestro economy-line 12-point sockets in the early 1930s.

Duro 500 Hex Handle With 12-Point Sockets]
Fig. 72. Duro 500 Handle with Early Hex-Drive 12-Point Sockets.

Fig. 72 at the left shows a partial No. 500 set consisting of a Duro 500 hex-drive handle and several sockets. The handle is marked "Duro Metal Products Co." and "Chicago U.S.A", along with a notice for patent #1,788,535, issued in 1931.

The full No. 500 set included a No. 673 ratchet, Ell-handle, screwdriver bit, and eight sockets, all contained in a distinctive fold-open metal case. (The metal case is the subject of the patent mentioned.) We recently acquired complete set of somewhat later origin, and will add a photograph in the near future.

We currently have two catalog references for the No. 500 set, the first of which is the 1933 Ducommun Catalog "H". This catalog illustrates the No. 500 set, as above but with hex sockets, and also shows a No. 500XX set with 12-point sockets. The price listed was $2.00 for No. 500 and $2.25 for NO. 500XX.

The second reference is the 1939 Duro catalog, which lists the Duro No. 500 socket set with contents as above.


Duro 673 1/2-Hex Drive Ratchet

[Duro 673 1/2-Hex Drive Ratchet]
Fig. 73. Duro 673 1/2-Hex Drive Ratchet, with Inset for Side View, ca. 1930s.

Fig. 73 shows a 1/2-hex drive Duro 673 ratchet, stamped with "Duro Metal Products Co." and the model number on the handle.

The overall length is 7.0 inches, and the finish is nickel plating, with extensive losses due to rust.

The No. 673 ratchet was an inexpensive model constructed of two identical sheet metal stampings riveted together. (Both sides are marked.) This ratchet was included in several of Duro's socket sets, including the No. 500 set.


Indestro No. 1236 1/2-Hex Drive 12-Point Socket Set

[Indestro No. 1236 1/2-Hex Drive 12-Point Socket Set]
Fig. 74. Indestro No. 1236 1/2-Hex Drive 12-Point Socket Set, ca. Mid 1930s.

Fig. 74 shows a mostly complete Indestro No. 1236 1/2-hex drive socket set, consisting of a ratchet, a hex handle, a screwdriver bit (doing double-duty as the ratchet plug), and 12-point sockets, all wrapped up with one of the clever holders that were an Indestro specialty. No model number is marked, but the set is similar to the No. 1236 set shown in the 1941 Indestro catalog, with a few sockets missing.

Of the pieces here, only the ratchet is marked, with "Indestro Mfg. Co. Chicago, U.S.A.". The sockets have been simplified to a plain cylindrical form, although they retain the fine cross-hatching at the base.


Indestro No. 1513 1/2-Drive 12-Point Socket Set

The Indestro No. 1513 1/2-drive socket set consists of a sliding Tee handle, long extension, short, extension, and nine double-hex sockets, all contained in a metal box with a sliding cover. The model number for the set was not marked, but the set was identified as the Indestro No. 1513 "13 Piece Master Socket Set" based on the illustration in the 1937 Indestro catalog.

The socket sizes are 7/16, 1/2, 9/16, 5/8, 21/32, 11/16, 3/4, 13/16, and 7/8.

Fig. 75. Indestro No. 1513 1/2-Drive 12-Point Socket Set To Be Added.

Indestro No. 1536 1/2-Drive 12-Point Socket Set

[Indestro No. 1536 1/2-Drive 12-Point Socket Set]
Fig. 76. Indestro No. 1536 1/2-Drive 12-Point Socket Set, ca. Mid 1930s.

Fig. 76 shows an Indestro No. 1536 1/2-drive socket set in a metal case, consisting of a ratchet, speeder, and other drive tools, along with 20 double-hex and eight double-square sockets. The model number for the set was not marked, but the set was identified as the Indestro No. 1536 "36 Piece Master Socket Set" based on the illustration in the 1937 Indestro catalog.

Based on the list of contents in the 1937 catalog, the set in the Fig. 76 is nearly complete, missing only the short extension (ratchet plug), screwdriver bit, and the valve grinder attachment. (This set also includes one extra double-hex socket.)

The catalog description lists the hex socket sizes as 5/16, 11/32, 3/8, 7/16, 1/2, 17/32, 9/16, 19/32, 5/8, 21/32, 11/16, 3/4, 13/16, 7/8, 15/16, 31/32, 1 Inch, 1-1/16, 1-1/8, and 1-1/4, all double-hex except for the three smallest. The double-square socket sizes are 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4, and 7/8.

The empty corral in the upper left corner of the case was for six drain plug sockets, apparently an optional item for the early versions of this set. By 1937 the illustration showed the small corral holding some of the smaller hex sockets, with the main corral having been reduced in size.

This set provides a good example of the carbon-manganese steel economy grade socket sets sold by Duro and Indestro in the 1930s. The 1937 catalog price for the No. 1536 set was just $6.40, less than half the price of a similar "Super Quality" chrome-vanadium steel set.

[Decal for Indestro No. 1536 Socket Set]
Fig. 77. Decal for Indestro No. 1536 Socket Set.

Fig. 77 shows the Indestro decal on the lid of the No. 1536 set, though it's a bit difficult to read due to the glare from the finish. This decal is identical to the decal on an earlier socket set, examples from which were shown as the Early Indestro Sockets above, so apparently these sets were sold for some period of time.

One additional note regarding this set: of the tools in the set, only the ratchet handle had an identification mark, and that was only the patent number for the ratchet. If the decal with the Indestro logo case were lost or obliterated, or the tools dispersed from the case, it would be difficult to identify them as part of an Indestro set.

Although the sockets in this set are marked only with the size, the Indestro catalogs did assign model numbers to the series, similar to the numbering used for the Duro D-Trapezoid sockets described above. The 1937 Indestro catalog (p. 26) shows these sockets in a table "Master Sockets", with model numbers of the form 66xx where xx is the size in 32nds, e.g. 6624 for the 3/4 size. Similar to the case for Duro, the square and double-square sockets have a "-S" appended, e.g. 6624-S.

While we're mentioning the Indestro 1937 catalog, it's worth noting a statement from the catalog that may prove significant for a later discussion. In referring to the "Selected Steel Sockets", the catalog states: "The Sockets are accurately broached and the heat treating, tempering, and hardening is done under our own supervision, in our own factory ...". Note that the careful wording doesn't say that Indestro actually machined the socket blanks.


Indestro 1/2-Drive 13 Inch Speeder

[Indestro 1/2-Drive 13 Inch Speeder]
Fig. 78. Indestro 1/2-Drive 13 Inch Speeder, with Inset for Marking Detail, ca. Late 1920s to 1930s.

Fig. 78 shows an Indestro 1/2-drive 13 inch speeder, stamped "Indestro Mfg. Corp." and "Chicago U.S.A." on the shank.

The overall length is 13.7 inches, and the throw is 4.0 inches. The finish is plain steel, with light pitting due to rust.

This speeder is similar to the Indestro C-V Speeder included in a 1931 "Chromium Vanadium" socket set, but is not marked to indicate alloy steel.


Indestro 642 1/2-Drive Valve Grinding Adapter

[Indestro 642 1/2-Drive Valve Grinding Adapter]
Fig. 79. Indestro 642 1/2-Drive Valve Grinding Adapter, ca. 1930s.

Fig. 79 shows a 1/2-drive Indestro 642 valve grinding adapter, unmarked but identified by an illustration in the 1937 Indestro catalog.

The overall length is 2.5 inches, and the finish is cadmium plating.

This tool is typical of the valve grinding adapters often included in early socket sets. The points on the blades fit into small indentations on the head of the valve, and the slotted blades can be adjusted to fit different valve sizes by means of two machine screws.


Indestro 657 1/2-Drive Ratchet

[Indestro 657 1/2-Drive Ratchet]
Fig. 80. Indestro 657 1/2-Drive Ratchet, with Insets for Side View and Marking Detail, ca. 1930s.

Fig. 80 shows a 1/2-drive Indestro 657 ratchet, stamped "Indestro Mfg. Corp." and "Chicago U.S.A." on the shank.

The overall length is 10.1 inches, and the finish is cadmium plating.

Although not marked with a patent, this ratchet appears to be of the same design as the Hinsdale H-1 Ratchet, which is described by the McDonough 1927 patent #1,650,085. In this design the pawl is actually a hardened point at the end of the handle, and the head assembly pivots to lock or release the drive gear.


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