This appeal is from a decision of the Patent and Trademark Office (PTO) Board of Appeals (board) sustaining the examiner’s rejection of claims 1-6 as obvious under 35 U.S.C. § 103. We affirm.
Appellant’s invention (as set forth in his application for “Camshaft with Hardened Cam Surfaces”) involves camshafts in which the camming surfaces although engageable over their entire widths by cam followers are hardened in central regions and remain unhardened along edge regions, with both of the regions being engaged by the cam follower.1 The examiner and the board held a patent precluded by § 103 because *1332Ackerman et al. in view of Turkish discloses a cast iron (hardened) camshaft with cam lobes engaged with actuating members, and the British patent to Maybach-Motorenbau shows the use of hardened central areas of cams with softer edges.2 Appellant challenges only the reliance on Maybach.
The Maybach patent discloses figures showing, first, the hardening of a journal and, second, the hardening of the cam itself (especially fig. 3, which is reproduced in the dissent). With respect to the latter, the patent describes placing a weld bead of hardened material (16) in the cam and then states:
The built-up material 16 forms with the basic material of the shaft 11 an interpenetration zone 15, as shown by the cross hatching. The material 16 applied in the hollow fillet 13 runs straight to such an extent that only a small amount of grinding is necessary, and since the narrow lateral boundaries 14 lie for the most part in the interpenetration zone 15 between the basic material and the built-up material, the grinding wheel cannot be fouled if it grinds over these parts.3
The board and the examiner, interpreting this prior disclosure as showing the edge regions of the cam as softer than the hardened central region of the cam, considered that appellant’s invention would have been obvious to persons of ordinary skill in the art.
In fact, Maybach shows cams with hardened central regions and less hardened edges (which the PTO characterized as softer). Appellant’s invention presupposes a hardened center but calls for unhardened edges. We agree in this instance with the PTO that the change, if there is a difference, from less hardened edges to unhardened edges would have been obvious to persons skilled in the art. Both inventions involve camshafts of cast iron or comparable hard material; neither involves a truly soft material; and both concern problems arising from contact between the speedily rotating shaft and the actuating members. The less hardened edges of Maybach and appellant’s unhardened edges are concerned with different aspects of these problems, but both call for a hardened center and not-so-hard edges of the cams (in neither case with truly soft edges). Maybach’s less hardened edges are appropriately described as softer than the center, just as appellant’s unhardened edges can properly be so described. The latter’s own application to the PTO states (R. 8): “As a result [of the hardening of the center] the edges of the cams remain relatively soft * *. * ” (emphasis added). To those in the camshaft-designing art, Maybach showed that softer edges of cams, with harder centers, can have significant consequences for alleviating problems arising from friction between the shaft and the members.4 In appellant’s claims, “hardened” and “unhardened” are similarly relative terms; we have to give them the broadest reasonable interpretation during the prosecution of the patent application. In re Pearson, 494 F.2d 1399, 1404, 181 USPQ 641, 645 (Oust. & Pat.App.1974).
It makes no difference to this case that Maybach dealt with a different specific problem, within the narrow area of minimizing or taking advantage of the effects of such friction, than does Heck. As the Court of Customs and Patent Appeals said in a section 103 case (In re Lemelson, 55 Cust. & Pat.App. 1294, 397 F.2d 1006, 1009, *1333158 USPQ 275, 277 (1968)): “The use of patents as references is not limited to what the patentees describe as their own inventions or to the problems with which they are concerned. They are part of the literature of the art, relevant for all they contain.” Maybach suggests, as we have pointed out (see note 4), the tendency of softer material to grind away more easily, and the use of that softer material in connection with harder material (i.e. a harder center). In that instance, the difference between the two types of material was used to lessen the grinding away of the softer material, while here the applicant’s purpose is to have the softer edges wear away more rapidly. But the use together of the two types of material, as well as the difference in wearing-away quality, were known in the prior art (through Maybach), and it would have been obvious to those skilled in the art to use them together when a differential in wearing-away was desired, even though appellant’s particular purpose was different from that of Maybach. See In re Gershon, 54 Cust. & Pat.App. 1066, 372 F.2d 535, 538-39, 152 USPQ 602, 605 (1967).
For this reason, we do not consider Maybach as “teaching away.”5 Its specific use was different, but the broader disclosures of that patent were made known, were useful and were legally available to appellant. The prior art involved in this case is very narrow, directly related to the automotive camshafts with which Heck’s invention is concerned, and zeroes in on the difference in the wearing-away of hardened and less hardened materials of cams. Persons of ordinary skill in the cam-designing art are presumed to be familiar with this precise background.6
What we have said disposes of claim 1, the major and independent claim. Claims 2 through 5 simply add variations in the relative dimensions between the hardened region and the unhardened regions, or specify the use of grey cast iron. The examiner rejected these claims as “obvious choices of routine design,” and the board affirmed rejection of these claims without separate discussion. Appellant has not shown, or made a substantial attempt to show, unobviousness of such minor changes in degree if claim 1 would have been obvious (as we have held). Cf. In re Reni, 419 F.2d 922, 924-25, 164 USPQ 245, 247 (Cust. & Pat. App.1970). (Claim 6, adding that the actuating member engages the cam surface substantially in line contact, has not been argued separately from the main claim and falls with it.)
AFFIRMED.
. Claim 1 is set forth as representative:
“1. In a camshaft having a central shaft and a plurality of cams each having an outer surface engageable with an actuating member, the improvement wherein said camshaft is made of cast iron and said surfaces are hardened only over a central region and have unhardened edge regions, said actuating member engaging said surface at said central and edge regions.”
. These references are as follows:
Turkish 3,272,189 Sept. 13, 1966
Ackerman et al 3,384,515 May 21, 1968
Maybach-Motorenbau 859,327 Jan. 18, 1961
(British Patent)
. The “interpenetration zone” is where the hardened and unhardened materials are mixed, resulting in material in that zone which is not as hard as the weld bead 16. After grinding a surface results that is thicker at the middle than at the edges.
. The Maybach specification says: “If, however, the coated contact surfaces and the adjacent shaft sections are ground down to the same diameter, the soft basic material is ground away with the coating layer and leads to fouling of the grinding wheel” and (after describing the Maybach invention) “The fouling of the grinding wheel which occurs when grinding soft material is thus completely avoided.”
. Before the examiner and the board appellant did not make the argument that Maybach “taught away,” but he does make it before us.
. Appellant does not rely on any of the “secondary considerations” of Graham v. John Deere Co., 383 U.S. 1, 86 S.Ct. 684, 15 L.Ed.2d 545, 148 USPQ 459 (1966) and United States v. Adams, 383 U.S. 39, 86 S.Ct. 708, 15 L.Ed.2d 572, 148 USPQ 479 (1966).