What motivated them? Cost would still have been a factor, of course, as it was for the older manufacturers of traditional tapered irons. And indeed the argument about material cost savings still holds.
Indeed, since both companies were making Bailey-style planes that used much thinner cutters that those found in the wooden planes that had predominated in the previous century, the material cost calculation ought to have been more pressing given the expensive metal needed to form the cutting edge represented a larger proportion of each blade.
Both companies continued to insist on using crucible steel to form the important part of the cutters. As we have seen, the methods used to create this type of steel were much less efficient than the mass production processes that made the mild steel used for the remainder of the cutter, so we can assume the difference in price between the two metals remained significant.
Having said all that, the material cost savings have to be balanced against the additional manufacturing costs needed to weld and form the two parts into a single piece and the fact that Stanley and Record did – eventually – abandon the practice of laminating their cutters.
How they were made
A clue can be found in this 1937 flyer produced by Stanley:
This refers to a process called ‘casting on’ where the harder metal part is placed in a mould and the backing softer metal cast on to it. We also learn from the flyer that the blades were made by a Sheffield steel maker who would presumably would also have arranged for the laminated material to be rolled and cut or stamped out before being sent to Stanley for heat treatment and grinding.
Record also produced laminated irons and refer indirectly to the same in their promotional book, Planecraft, which was first published in 1934:
Stanley’s slightly apologetic flyer does highlight at least one genuine benefit to the user of a laminated cutter, namely that they will spend less time sharpening since there is less of the harder metal to remove.
Of course this benefit would have been more apparent for users of old tapered irons which were considerably thicker and thus required more metal to be removed at each sharpening. Indeed it could be argued that the benefit when translated to a much thinner cutter is so slight as to be of little relevance to most users (particularly those people using a mechanical grinder), but it is a benefit nonetheless.
Similarly, although harder to prove, the theoretical advantage that the flexible mild steel backing afforded when hardening the steel bit might have allowed Stanley and Record to produce cutters that held an edge longer than would otherwise be possible1)although they would still have to content with the usual trade-offs – hardening the cutting bit increases wear resistance but reduces strength (that is, makes it more brittle) which can be problematic for something that will occasional collide with the hard knots found in much timber.
Given the marginal benefits to the end user, my theory – and it is little more than a hunch – is that there were elements of tradition and marketing behind Stanley’s decision to continue to use expensive crucible steel and, so long as they did, it simply made financial sense to use laminated cutters.
Stanley were still advertising their laminated cutters int he 1940s:
.. and seem to have discontinued them in the late 1950s. An advert in Education 114 (1959) says:
As we saw earlier, the handful of operational crucible furnaces that remained open during the 1950s all closed before the end of the decade, and it is likely that Stanley simply lost access to a supply of laminated crucible steel cutters at this point and had to switch to an alternative.
Were Stanley putting a brave face on it when they dismissed the laminated cutters as ‘old fashioned’? Probably not: the technology to make modern steel alloys was progressing at a pace and it was inevitable that at some point the modern techniques would surpass the abilities of the crucible steel makers who relied so heavily on skill, experience and good judgement to sustain the quality of their product.
We can’t date the Record switch to solid steel cutters precisely either, although a bit of research done by participants on the ukworkshop forum concluded that every ‘square shouldered’ record cutter in our collections was laminated2)see the discussion here : https://www.ukworkshop.co.uk/forums/record-stanley-laminated-plane-irons-t106851.html.
David Lynch’s research concluded that this profile of cutter was in production until the mid 1950s 3)http://www.recordhandplanes.com/dating.html so we can hypothesise that Record switched around the same time as Stanley. And so ended the mainstream production of laminated plane irons4)this is true in the West at least. There is still a tradition for laminated tools in Japan, and laminated chisels and plane irons are still made there.
References [ + ]
|1.||↑||although they would still have to content with the usual trade-offs – hardening the cutting bit increases wear resistance but reduces strength (that is, makes it more brittle) which can be problematic for something that will occasional collide with the hard knots found in much timber|
|2.||↑||see the discussion here : https://www.ukworkshop.co.uk/forums/record-stanley-laminated-plane-irons-t106851.html|
|4.||↑||this is true in the West at least. There is still a tradition for laminated tools in Japan, and laminated chisels and plane irons are still made there|