This is an appeal from the decision of the Board of Appeals holding claims 1 and 3 of application serial No. 325,808, filed November 19, 1963, for "Machine Keys" to be unpatentable over the prior art under 35 U.S.C. § 103. Claims 2 and 4 through 14 stand allowed.

The invention relates to a hexagonal key for holding two machine members, such as a shaft and hub, in fixed relative position. The key has four flat pressure faces and two parallel-edged nonpressure faces, the latter being opposite each other on the hexagonal key, typically as the top and bottom faces thereof. One half of the key, such as the two upwardly converging pressure faces and the associated top nonpressure face, is tapered longitudinally throughout the key length; the other half is not tapered, so that the latter fits snugly into a keyway of uniform depth, which is usually in the shaft.

3. A machine key consisting of a solid elongated body having, at top and bottom, longitudinally straight faces of uniform width throughout the engagement length of the key, one of said faces being slightly inclined longitudinally with reference to the other, two upwardly convergent flat faces of the key adjoining said top face and other two downwardly convergent flat faces of the key adjoining said bottom face.

  Grafton                      408,835              August 13, 1889
  Von Bechtolsheim             867,468              October 1, 1907

Grafton shows and describes a hexagonal key having four flat pressure faces and top and bottom nonpressure faces. The patent discloses that either the shaft or hub keyway, preferably the former, is of uniform depth, the other keyway being of gradually varying depth. The Grafton key is longitudinally tapered on all six sides, so that it takes the shape of the lower part of a regular hexahedral pyramid.

Von Bechtolsheim shows a key with six faces, two of which, namely the upwardly convergent pressure faces, are convex. The two downwardly convergent pressure faces are flat, as are the top and bottom nonpressure faces. The drawings show that the top nonpressure face is parallel-edged and that the lower half of the key is not tapered, so that the latter fits snugly into a shaft keyway of uniform depth.

The ground of rejection is stated in the examiner's answer as follows:

Claims 1 and 3 stand rejected as being unpatentable over * * * Grafton in view of Von Bechtolsheim * * *, it being held obvious that only one pair of pressure faces and the associated non-pressure face need be inclined longitudinally on the key of Grafton, * * * as taught by Von Bechtolsheim * * * so as to achieve a seating of the key.

In affirming this rejection, the board further commented:

We therefore find as did the Examiner that the claimed structure is an obvious deviation over that of Grafton, particularly in view of the teaching of Von Bechtolsheim which discloses a key having nonpressure faces with parallel sides and wherein the lower nonpressure face lies in a plane parallel to the bottom of a key-way of uniform depth.

Appellant's major argument is that the obviousness rejection is improper since the primary reference, Grafton, discloses only inoperable subject matter, since a key tapered on all sides will not snugly fit into a shaft keyway of uniform depth, contrary to the Grafton specification teachings. While there is a factual dispute as to the operability of the Grafton key as described, we need only determine whether or not the primary reference key could obviously be made operative by one of ordinary skill in the machine key art with the mere use of such ordinary mechanical skill. If the subject matter thereof could so obviously be made operative, then the Grafton patent is a good reference. In re Jacobs, 318 F.2d 743, 50 CCPA 1316.

We are persuaded that, although the Grafton key might perhaps be inoperable as described, it could be made operative by the use of mere mechanical skill, especially in light of the following statements which were added to appellant's brief before the board at the "urgent request" of applicant-appellant, and representing "his personal contribution":

* * * it [the Grafton key] can and must advance in the driving, and remain during operation, in a raking or down-tilted position, the bottom face being substantially lower at the front end than at the rear end of the key. The reason for this peculiar down-tilting position is apparent from inspection; it is simply that the front end of the key, being narrower than the rear end, at the bottom face or any other level, must sink lower in the V-shaped keyway to find its wall bearing, the keyway being deepened as much as necessary to clear the front end of the bottom face of the key. [Emphasis ours.]

We agree with appellant's personal view, also shared by the board, that it would be obvious to modify the uniform shaft keyway so as to provide a tight fit for the Grafton key. It is logical that a key tapered on all sides would only fit snugly into a keyway having a complementary taper. In the alternative, if one wished to obtain the benefits of a shaft keyway of uniform depth, we think it would be obvious to modify Grafton's hexagonal key in light of the subsequent Von Bechtolsheim patent so that only the top half of the key is tapered, providing no taper at all for the bottom half. In that event, the top half would fit snugly into a hub keyway of gradually varying depth, and the bottom half would fit tightly into a shaft keyway of uniform depth. We do not consider such a modification of the lower half of Grafton's hexagonal key to be unobvious, especially in view of appellant's statement in his reply brief before the board that the common driven key of Grafton's time, the Von Bechtolsheim key, and the standard keys of today all have "exclusively top-entry draft," i. e., taper only on the top half of the key.

For the above reasons, the decision of the board is affirmed.

Affirmed.

SMITH, J., concurs in the result.