US3104404A - Shoe last with tack-retaining plug - Google Patents

Description

Sept. 24, 1963 c. I. STODDARD 3,104,404

SHOE LAST WITH TACK-RETAINING PLUG Filed May 25, 1959 INVENTOR. 66074 5 Z. J'Zadr/ard United States Patent 3,104,404 SHOE LAST WITH TACK-RETAINING PLUG Charles I. Stoddard, Hartswood Road, Dover, N.H. Filed May 25, 1959, Ser. No. 815,567 5 Claims. (Cl. 12-140) This invention relates to shoe lasts and more particularly to an improved shoe last having novel tack-receiving portions therein for securing parts of the shoe to the last by tacking.

In certain lasting procedures, portions of the shoe, for example an insole, are tacked to the last to hold them in place preparatory to subsequent operations. Since every time a last is used a tack must thus be driven, the wood of the last eventually becomes so filled with tack holes that it will not hold the tack securely. In order to enable the last to hold tacks for a longer period, it has become customary to insert plugs of wood, cork, rawhide or the like into the substance of the last at the portions where the tacks are inserted. However these materials also lose their usefulness after a period of time and then the plug must be drilled out or otherwise removed and replaced. The insertion and removal of these plugs is difiicult and time-consuming and can result in injuring the last beyond repair.

It is the principal object of this invention to provide lasts for shoes having improved, inserted, tack-receiving plugs. Further objects include the provision of a last wherein the plug elements are readily applied to the base material; wherein the plug elements are unusually tenacious with respect to tack-holding power, thus making it possible to employ tacks which are smaller than usual, and so reducing costs; wherein the plugs are cheaper and easier to make and install in the first instance, and which are self-healing so that they may be restored to initial condition after use, merely by the application of heat and without removing them from the last; thus cutting down the cost and time consumed in repairing the last; and which can be reused without actual replacement.

These and other objects will be more readily apparent from the following more detailed description and by reference to the drawings wherein:

FIG. 1 is a bottom view of a shoe last according to one embodiment of the invention;

FIG. 2 is a side elevation, partly in section, of the last shown in FIG. 1; and

FIG. 3 is a rear elevation of the same last.

Referring to the drawings, the embodiment illustrated comprises a conventional wood "last 1, having a metal plate 2 secured to the bottom thereof, and having cavities 3 which are filled with tack-receiving plugs 4 of a material to be hereinafter described. The metal plate 2 on the bottom of the last is provided with openings 5 which overlie the cavities in the wood so as to expose the material 4 at the bottom surface of the assembled last. Metal plates, such as the plate 2, are customarily provided where the inlasted margin of the upper is to be secured to the insole by tacks, so that the points of the tacks, after passing through the insole, are turned by the metal. This plate can obviously be omitted where not required.

In accordance with the present invention, the material 4, filling the cavities 3 in the last, comprises a resinous plastic material which is meltable or permanently fusible at a temperature which will not injure the last; which is hard at room temperature; and which has excellent tack-receiving and retaining proper-ties. Meltable resinous adhesives which are hard and substantially non- 3 ,1 4 Fatented Sept. 24, 1 963 tacky at room temperature have been found particularly suitable for this purpose. Resiuous adhesives which can be handled as a solid at room temperatures and melted near the point of application are excellent examples of such materials, and the thermoplastic pol-yamide-epoxy adhesives disclosed in United States Patent No. 2,867,592 have been found particularly desirable.

The selected resinous material 4 is melted and poured or pressed into the preformed cavities 3 and allowed to harden. The completed last is then used according to to usual practice. When, by reason of repeated use, the points of the tacks have formed a large number of holes in the plugs, it is necessary merely to heat the last, or at least the plugs 4, thereby to re-fu'se the plugs into a solid, hole-free condition. Thus, since the plugs 4 are completely self-healing by means of heat, it is not necessary to remove and replace the plug as heretofore. Furthermore, the resinous materials above described have excellent tack-retaining properties which are superior to materials heretofore in use.

As illustrated in FIGS. 2 and 3, the last has a cavity in its rear end filled with a plug 4a of the same material as that above described for the reception of the point of the tack which is employed for temporarily attachin-g the rear end of the closed shoe upper to the last during the assembly operation.

While a wooden last has been herein described, lasts of other materials such as metal or plastic can be provided with the novel tack plugs herein disclosed.

It should be understood that the foregoing description is for the purpose of illustration only and that the invention includes all modifications falling within the scope of the appended claims.

I claim:

1. A shoe last comprising a main body of conventional non-thermoplastic material having cavities therein at predetermined tack-receiving portions, and means filling said cavities for receiving and retaining tacks driven therein, said means comprising a meltable resin which is hard, tack-retaining and self-healing under heat at a temperature not substantially exceeding C.

2. A shoe last, according to claim 1, wherein said tack-receiving means comprises a resinous material having tack-retaining and heat-healing physical properties characteristic of a permanently fusible polyamide-epoxy adhesive which is substantially non-tacky at room temperature.

3. A shoe last adapted for extensive use where tacks are repeatedly driven into predetermined portions thereof, said last comprising a body of conventional nonthermoplastic material wherein said predetermined portions comprise a hard, tack-retaining and meltable polyamide-epoxy adhesive.

4. A shoe last, according to claim 3, having a metallic bottom plate, said plate having openings therethrou-gh at which said portions of adhesive are exposed for the reception of tack points.

5. A wooden shoe last having therein a tack-retaining plug of heat-fusible polyamide-epoxy adhesive which is a hard, tack-retainingsolid at room temperatures.

References Cited in the file of this patent UNITED STATES PATENTS 1,757,594 Shaw May 6, 1930 2,445,791 Lovell July 27, 1948 2,617,129 Petze Nov. 11, 1952 2,867,592 Morris et al. Jan. 6, 1959

Claims (1)

1. A SHOE LAST COMPRISING A MAIN BODY OF CONVENTIONAL NON-THEMOPLASTIC MATERIAL HAVING CAVITIES THEREIN AT PREDETERMINED TACK-RECEIVING PORTIONS, AND MEANS FILLING SAID CAVITIES OF RECEIVING AND RETAINING TACKS DRIVEN THEREIN, SAID MEANS COMPRISING A MELTABLE RESIN WHICH IS HARD, TACK-RETAINING THE SELF-HEALING UNDER HEAT AT A TEMPERATURE NOT SUBSTANTIALLY EXCEEDING 150*C.

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