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Old 10-19-2014, 08:39 PM
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Jacknola Jacknola is offline
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History of Delrin as a substance

Before declaring that the 3-7 Delrin is indeed 1960 vintage, we need to ask (1) was Delrin available in 1960? and (2) could this knife have been rehandled in Delrin later in the 1960s?

Could Delrin have been used as a handle material in a knife of this age? The answer appears to be yes... The literature indicates the first US commercial plant was completed by Dupont in 1959 and became operational in January, 1960. So it is possible that a sample was supplied to Randall who experimented with the material in that year.

(Note: Prior to constructing the plant, DuPont had sent out samples of Delrin to 250 businesses produciing over 400 different products in late 1950s to determine commercial viability. It is just possible that a sample was sent to Randall, or transferred to him. It is Here is a picture of a sample being provided to Ford.

http://books.google.com/books?id=Ikn...istory&f=false

Mr. Randall was apparently experimenting with many things during this late '50s early '60s time, including Micarta, inverse tang nuts, epoxy-glues v pinned handles, major blade profile changes, alternative sheath manufacturers, "Randall Made" sheath stamp, etc. And keep in mind that he was already using tenite, a plastic artificial materal)


This January, 1960, timing would just allow the component sheath features, knife age markers, and the availability of Delrin to align with a knife construction date in 1960-61.

My guess is that there is only one person today who might have personal knowledge about the use of Delrin in 1960. That would be Mr. Gary Randall himself. As it is unlikely that he would find the time to comment, we must therefore decide for ourselves whether Randall used a sample of Delrin in 1960, or if this knife was ... say ... originally handled in ivory which cracked and was then re-handled in the late 1960s with Delrin.

After examining this knife, I can find no evidence that it was rehandled - though I'm not sure if there would be identifiable evidence of a shop-rehandle. The material looks appropriately slightly age discolored and marked, use seems consistent with blade, and the soldering and construction, inscription plate look original as best I could estimate without exact comparables. The guard is mishappen, and may have been modified from a dual...but it might be odd to have retained that guard if the knife were re-handled. Furthermore, if the original handle were ivory, ivory handles without a butt cap do not seem to crack or check like those with a cap. This would tend to add a modicum of support to the Delrin handle as being original.

I therefore tentatively conclude that this knife could be the oldest Delrin handled knife known and dates to 1960. If that is the case, it can be speculated that this use of Delrin was probably an experiment with a new material by the shop that eventually resulted in the catalog listing. (However, re-handling by the shop in late '60s, complete with inscription plate, mis-shappen guard, etc., cannot be completely ruled out).

While we are speculating, I suspect that initially Delrin, as a replacement for ivory, was only offered to customers who were personnally in the shop ordering ivory handled knives. Only that circumstance would seem to allow the "sales pitch" discussion of the problems with ivory and the alternative, Delrin. Later Delrin handles could have been supplied by dealer request ... dealers being the customers who would have become familiar with the option. This could reasonably explain the smattering of Delrin handled knives that predate the catalog offering.

Documentation of the availability of Delrin in January, 1960.
http://en.wikipedia.org/wiki/Polyoxymethylene

"...Around 1952 research chemists at DuPont synthesized a version of POM, and in 1956 the company filed for patent protection of the homopolymer ... ...DuPont completed construction of a plant to produce its own version of acetal resin, named Delrin at Parkersburg, West Virginia, in 1960...."

See also: http://newswire.net/newsroom/pr/0008...copolymer.html

http://books.google.com/books?id=6ld...istory&f=false

P. 490. ??A year later, the committee authorized construction of the plant which went into commercial operation in January, 1960.?
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Why was Delrin ultimately dropped as a material by Randall? I speculate that two issues with Delrin, machining and bonding of the material to the tang, led to white/gold macarta displacing Delrin in the Randall option list in the early '70s. Difficulties machining Delrin are backed up by a page from "the Randall Chronicles." Here is what Mr. Pete Hamilton had to say about Delrin:

"Q. What is Delrin and when is it used?

"A. This material was the first attempt at a replacement for ivory. Delrin came in white and off white. Both were tried. The material was fairly soft and easy to grind. Sanding and polishing was very touchy. The uses of this material went from the late 1960s to early 1970s."
(Note: Mr. Hamilton is apparently mistaken about the earliest dates of the use of Delrin.) My notes: apparently belt sanding and/or wheel polish finishing of Delrin can cause friction temperature to reach the material's melting point. I suspect the shop discovered this and dealing with that is what Mr. Hamilton referred to as "touchy."

Wiki-comments on characteristics of Delrin:

"Machining

"When supplied as extruded bar or sheet, POM may be machined using traditional methods such as turning, milling, drilling etc. These techniques are best employed where production economics do not merit the expense of melt processing. The material is free-cutting, but does require sharp tools with a high clearance angle. The use of soluble cutting lubricant is not necessary, but is recommended.

"Because the material lacks the rigidity of most metals, care should be taken to use light clamping forces and sufficient support for the work piece."

"Bonding

"POM is typically very difficult to bond. Special processes and treatments have been developed to improve bonding. Typically these processes involve surface etching, flame treatment or mechanical abrasion.

"Typical etching processes involve chromic acid at elevated temperatures. DuPont has a patented process for treating acetal homopolymer called satinizing which creates anchor points on the surface, giving an adhesive something to grab. There are also processes involving oxygen plasma and corona discharge.[6][7]

"Once the surface is prepared, a number of adhesives can be used for bonding. These include epoxies, polyurethanes, and cyanoacrylates. Epoxies have shown 150-500 psi shear strength on mechanically abraded surfaces and 500-1000 psi on chemically treated surfaces. Cyanoacrylates are useful for bonding to metal, leather, rubber and other plastics."


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Conclusion As previously stated, from best evidence and applied logic this knife could be the oldest Delrin handled Randall knife known and dates to 1960. Furthermore, given the start-up date of commercial manufacture, it may be the first Delrin-handled knife of any manufacture.

The above is my current analysis and speculations. I've tried to show my reasoning and thought process. However, I am completely open to comments, suggestions and contrary reasoning be it age progression of model 3s, or availability of Delrin, or how to identify a re-handled Randall knife, etc.

I hope this discussion will become the benchmark for those interested in Delrin-handled Randall knives. In any case, I've personally discovered a lot about Randalls with Delrin during the Vietnam era...and whether this knife was "Delrined" in 1960 or rehandled later, I now have this set (below). And I like this set ... a lot.







Regards, Jack

Last edited by Jacknola; 07-26-2017 at 07:27 PM.
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