Jigged Bone Sod Buster Jrs How does the pivot compare to classic Delrin handled one?

[OrangeJoe]

Per title, for jigged Bone Sod Buster Jrs - How does the pivot compare to classic Delrin handled one?

The Case Sod Buster Jr is often recognized for having an oversized pivot which makes it a hard working knife. Many Blade Forum members report carrying one for decades.

Here is the Bear & Sons Yellow G10 version (left) with a pivot similar in size to Case Delrin version (right).

The fancier Jigged Bones versions from Case look to have a much smaller pivot, is this correct or is that only a pin to hold the bone scales?

If it is a smaller pivot, how much does it take away from the "work knife" character/longevity of this pattern?

Stock Case jigged bone Sod Buster Jr picture:

 

[ConBon]

Well, the pivot pin itself is only about 5/32" on the classic style Large Soddie, but it is peened into a washer sort of. See the pictures I have.

This is the pin, you can see it popping out of the washer it is peened into. Mine is 40 years old and well used, so I've had to squeeze and repeen it. I don't think you can see it on a new knife as they are sanded flush.

Connor

 

[Alnamvet68]

Post not what OP is looking for

 

[OrangeJoe]

It's been surprisingly hard to find a pic showing the over-sized pivot on the Sod Buster JR.

The only answer I can come up for the smaller pivot on bone handled knives is that the oversized pivot on the Classic Delrin model transfers loads to the scale and -in the absence of bolsters- that would not be a good idea with fragile bone.

I'd still prefer to hear someone with actual experience versus typing my own rationalizations for the difference in pivot design and diameter.

 

[shipwright]

I think Connor answered your question. I believe the pivot pin on both models is the same size. Since Delrin is soft, the pin is peened flush into a larger diameter washer to share the load from the pin and keep it from stretching out the hole in the Delrin. Once the handle is polished, the pin and washer appear as one, that's what you're seeing. The bone is stronger and doesn't need the washer, but the pivot pin is the same size.

 

[Obsessed with Edges]

The Case delrin soddies don't use a pin for the pivot. They use a 'cutlery rivet' for that instead, a two-piece fastener with male and female halves. When pressed together, the end of the male half essentially widens/expands within the female half, which is what locks them together. It's not a pin peened to larger diameter.

See the patent links below for a cutlery rivet. The illustrations show how they fit together.

http://www.google.com/patents/US3316793
http://patentimages.storage.googleapis.com/pages/US3316793-0.png

The larger diameter of the rivet heads I think serves mainly to prevent the fastener from pulling through the softer delrin if the blade were twisted or laterally torqued very hard against the handle. A smaller diameter pin would be much easier to pull through the delrin if treated similarly, because the delrin would more easily deform under that stress.

I suspect the Delrin handle with the cutlery rivet might be stronger, if only because the larger head, which distributes the torque load, in tandem with the somewhat more resilient & flexible Delrin, would handle the stress of twisting/bending better. In the bone version, I'd be concerned about the bone cracking or chipping at the pivot under more focused pressure from the smaller diameter pin, if that version were twisted or torqued similarly. But that sort of torquing or twisting is what I'd consider abusive for most any traditional folding knife (if the pivot doesn't fail, the blade would likely be damaged anyway), and the bone-handled soddie should handle 'normal' EDC use easily, I'd bet.


David

 

[ConBon]

David,
I had figured it was a cutlery rivet originally, but it didnt make sense when I squeezed it in a vice and had the center pop out like that. I think it is a male half of a cutlery rivet that is peened over a washer, then sanded and buffed flush.

Maybe we could ask Case?

Connor

 

[Cory Hess]

I wanted to add that there are knives with bone, and stag, that have the birdseye pivots. Here's one of Trevor's pictures of some of his Moore Makers.

As David said, I'd much rather have the birdseye on any sodbuster I was planning on using. I would think that Case's decision to go with just the pin is an aesthetic one. If you look through the thread that I quoted Trevor's picture from there are examples of birdseye and regular pivots on bone and stag covered sodbusters.

The only answer I can come up for the smaller pivot on bone handled knives is that the oversized pivot on the Classic Delrin model transfers loads to the scale and -in the absence of bolsters- that would not be a good idea with fragile bone.

I'm not an expert in these things, but I don't think that this is right. The stress is going to get transferred to the bone whether you have the birdseye pivot or just the pin. The only difference would be that the birdseye would spread that stress over a larger area, making cracking less likely.

 

[Obsessed with Edges]

David,
I had figured it was a cutlery rivet originally, but it didnt make sense when I squeezed it in a vice and had the center pop out like that. I think it is a male half of a cutlery rivet that is peened over a washer, then sanded and buffed flush.

Maybe we could ask Case?

Connor

I hadn't originally been aware of what it was, until seeing some posts from BF member 'Seals' (Don Seals) who has re-handled many Case soddies with custom handles (some seen & posted in the Trad forum), and therefore had taken the Case apart and seen how it was constructed. He identified it as a cutlery rivet. I trust his input on the pivot construction. See his comment in the thread linked here (post #8 in particular):

http://www.bladeforums.com/forums/s...one-this-tweek-before?highlight=cutlery+rivet


David

 

[ConBon]

Ahh, I didnt know if we had any take apart input. Interesting, thanks for the link!

Connor

 

[Obsessed with Edges]

Something else I found sort of interesting, the cutlery rivet patent documents I linked earlier were filed in 1965 and published in 1967 (patent assigned to Textron Industries, Inc.). Case first released the original Delrin-handled Sod Buster pattern (2138) in 1967. Just a coincidence? Maybe entirely, but it's interesting timing, nevertheless. Maybe they wanted to try out a design with something new.


David

 

[afishhunter]

I thought the cutler's rivet/cutlery rivet dated from the early 1800's or maybe a little earlier.

 

[Obsessed with Edges]

I thought the cutler's rivet/cutlery rivet dated from the early 1800's or maybe a little earlier.

Wouldn't surprise me if some version of it came about a long time ago. There might be some unique characteristic of the more recent version that justified the patent (see below for quoted text from the 1967 patent document), as is often the case with patented inventions.

" A conventional cutlery rivet is in fact an assembly of a tubular and a solid rivet. The ID. of the tubular rivet is smaller than the CD. of the shank of the solid rivet, whereby when assembled under compression the ID. of the tubular rivet is expanded and the solid rivet is frictionally secured within the tubular rivet.

The present approved practice of assembling the knife tang and handle with conventional cutlery rivets specifies an interference fit between the tubular rivet and the tang. Thus the rivet is held in place only by the frictional fit between the rivet and tang.

Where all elements of such an assembly, including dimensional tolerances, rivet wire hardness and diameter of the hole in the tang, are all held within relatively narrow limits, a satisfactory assembly results. However, the quality of such an assembly is extremely sensitive to small variations in said tolerances.

An object of the invention is to provide an improved assembly of the type described wherein increased dimensional tolerances are acceptable in providing a satisfactory and tight assembly.

Another object of the invention is to provide an improved form of cutlery rivet wherein the two rivet components, when under compression, are deformed and interlocked against separation. "

David