kootenay joe wrote: ↑Sat Aug 29, 2020 5:53 am
If it was shrinkage then there would have been shrinking in both directions...
kj
While that is certainly true, I'm still sticking with the shrinkage theory. Let's work some math.
If we assume a certain material shrinks 5% in all directions over time then a 80mm long handle slab would shrink 4mm in length. If that same piece was 15mm wide it would shrink by 0.75mm in width. This would leave an immediately apparent 2mm gap at each end but only 0.375mm of shrinkage at the top and bottom edges of the slab. The shrinkage at the ends would be much more visually obvious than at the top and bottom.
Imperial's shell-handled knives immediately come to mind. So very many of them exhibit obvious shrinkage in length while it it is NOT obviously pulled away from the top and bottom.
I can't say as I know exactly why this discrepancy presents itself but that's what I see when I look at knives like the ones in these pics. I don't really see lateral shrinkage.
example 1
example 2
example 3
example 4
jxr1197 wrote: ↑Fri Aug 28, 2020 10:45 pm
You may be right. I know very little about plastic. My argument against shrinkage boils down to the uniformity of it – they’re all identical. The material is a non-celluloid DuPont blend that I believe is more likely to have been shelved due to poor timing (this was made immediately before Delrin) than to poor performance. Or maybe those two factors were concurrent. If it’s shrinkage that stopped them from selling the knives it would have happened almost immediately after being made. Is that kind of speed a known characteristic of plastics that shrink? I know that some number of them were sold but I believe that’s a pretty small number. Two of the knives I have in that pic above I bought from descendants of the original owners. Both of those original owners were jobbers, which puts the knives in the distribution chain.
I can see our theories being complementary. As far as I know, Schrade would do a big run of a popular pattern and might well create far more than they already had orders for. They would have these in-stock and ready to ship when an order came in.
Perhaps this material shrunk so much, so fast that they looked like this before they even had orders for them. Perhaps as soon as Schrade saw the in-factory shrinkage they nixed the material, switched to delrin and did a run of a zillion delrin ones that were then ready and waiting for future orders. When these future orders came in they shipped the delrin ones and the ones with shrinkage were filed under "history".
I doubt the reason the manufacturer of this material only made one batch was because the recipe required hard-to-find moon-dust or dragon scales. The "timing" that you speak of regarding delrin's appearance sank this material for a reason. Delrin must have been superior for some reason and perhaps a lot of reasons. To me, a "preponderance of evidence" implies that delrin wouldn't-didn't-doesn't shrink like this material does.
My guess is delrin won performance-wise regarding shrinkage (and maybe other factors too) so industry moved on.
I might be totally wrong on this but I haven't heard anything yet that convinces me Schrade or Ulster would have sold knives looking like that as "firsts". They knew how a knife-handle should fit. There would have been no necessary learning-curves for Baer-and-crew other than the properties of the failed material. Both companies were obviously very familiar with making stockman knives by the time this material showed up.
If contracted handles arrived cut too short they wouldn't have been paid for. Industrial orders for machined parts always have tolerances attached. Plus or minus .01% etc. I don't think the Baers would have paid their employees to haft free not-to-spec handles and waste all the other knife parts.
