The perfect tang pin...

GTAsteel

GTAsteel

Joined
Oct 24, 1999
Messages
782
Ok Im gonna start this again. :rolleyes:

As I continue to ponder such things, I have a new thought, kind of… Has anyone else noticed that the tang pins on the Tachyon are much longer proportionately than any other Bali’s, that I have seen? Compared to BM’s 42 they are twice as long. Nearly as long as the handles are thick. The pins on the 42 are about half the length and the 42 has a little thicker handles. Are there other Bali’s out there like this? How are they holding up? I think this may well minimize the wear between the pin and the handle because there is a lager surface to absorb the force of the opening and closing impact. Thoughts?

So… so far (until someone tells me why I’m wrong) the properties of a perfect tang pin are:

*Thick (how thick?)
*Long, almost as long as the handles are thick. Any longer and I think they would get in the way.
*Heat treated, for toughness.
*???

Now it’s time for thoughts from the group. What do YOU think?
 
Not sure all the features together make up the "perfect tang pin", as each has it's own advantages and disadvatages.

Thick (as seen on the Monarch):
Advantages:
*Thicker mass, for more rigidity, and thus less prone to damage. But not immune to compression.
*Wider mating surface area for better installed grip to the tang. Harder to knock loose.
*Wide surface area to absorb/disperse impact energy.

Disadvantages:
*Requires a wider tang for more gap space between tang pin hole and outside wall. Although the Monarch didn't heed this advise and seems to work fine.
*Will increase the gap space between handles when in use, and may affect latch geometery over time, should either the tang pin compress or the tang pin cup enlarge.
*Greater gap also complicates the cutting of the tang pin cup, as now you will have a larger margin of error due to the increased diameter of the tang pin cup.

Long (as seen on the Tachyon):
Advantages:
*No tang cup, it now a semicular groove. Easier to machine.
*Exponsed tang pin isn't that drastic a departure from the clean handled/hidden tang pin look of old.

Disadvantage:
*If press fitting, will require greater pressure with a longer pressing process. Elevates the margin of error.
*Rear tang pin has greater exposure to damage, when closed, with it's higher profile.

Heat treated: Well, you already know where I stand on this, and in decending order in terms of hardness: Blade>Tang Pin>Handle. A RC of mid to low 40's would be adequate for the tang pin. And with my liquid nitrogen freeze-install method, you can pretemper the pin to your desired RC before milling to the correct thickness.

I'll probably come back with more.
 
Tony, all your points (as usual) seem to make a lot of sense. But again, I'm going to have to throw in the idea of a big fat SQUARE tang pin (chamfer the corners of course). Now, I remember the one big dispute with this idea is that it would be almost impossible to machine within good enough tolerances to mate it with the blade, leaving no space. Is it really that difficult? And what's stopping someone from making the pin and blade out of the same chunk of steel? I'm conviced (despite all logical reasoning given :D) that it would make a superior pin. A big flat surface against another big flat surface. Sure, it could probably up the cost of any bali 15% in machining, but have any of us ever cared about that before? We're looking for a perfect pin here, not a perfect price.

So fill me in, why wouldn't the square t.p. not work?
 
The only way to machine a true square hole is to EDM it, Electrical Discharge Machining. Basically you take a piece of carbon the shape you want the hole to be, apply current to the carbon and the workpiece and burn the hole in. Everything is submerged in EDM fluid to there is no heat damage. It is a very cool process to watch and is used extensively in the mold making process. If anyone wants to try it my CNC friend is also a master EDM machinist so we could work something out.

Mer
 
Originally posted by Mer
If anyone wants to try it my CNC friend is also a master EDM machinist so we could work something out.

Mer
Click to expand...
Now we're getting somewhere... The process sounds really cool, and it also sounds like it'll work. So what do you think of the idea Mer? I know you've got the skills and know-how to make balis work well, do you think that a square pin would have any benefits??
 
And here I was thinking that there were some bali subjects that were just too controversial to discuss...

I'd like to see a square tang pin, or maybe even one made out of hex stock!!
 
How about an alternative to a tang pin? Maybe a blade with a long, fairly narrow projection on the tang end, differentially heat-treated? Handles could be milled, or if sandwich, would need pins in them to mate with the tang (if carefully done, mebbe these handle pins could also eliminate the need for a kick or _any_ pins in the blade?).

Could be lousy for manipulation, since the tang projection would poke/pinch your fingers (wouldn't be able to do rollovers at all), but as a weapon only, kubotan techniques would _hurt_ a lot more.
 
.....an eccentric tang pin that could be removed when the lock-up starts getting loose, turned a few degrees to make it 'bigger', and reinstalled??? Maybe a splined 'shaft' could be used as the raw material then the 'cam' could be EDM'd or machined on each end.....

Speaking of tang-pins, how does the single-sided pin on that fancy bali you've got work out, tonyccw????
 
I always thought a rectangular pin would work............ actually, cutting a piece of round stock (and inserting it horizontally) would probably be better, both functionally and asthetically.

You could notch the end area (of the blade) out completely, slide the piece into position, then use set screws to keep the "pin" in position.

This would offer more contact area between the pin and the handles, giving a nice solid lock-up. Also, I don't think you'd have to mill the tang pin slots into handles as the pin "contact area" would actually be flat.

This would also make the pins easily replacable.
 
Blasto: I always liked the idea of a square pin, installed in a diamond configuartion, as it gives much better lockup than a round pin. Much less lateral travel. In my eariler post, the problem is with the edges of the square tang pin hole. EDM is the ONLY way to effectively create a perfect 90 degree cornor. That would mean the pin would also have to perfectly squared and sized to match. But here's the other problem with a sqaure pin installation: When you istall it, it'll have to done perfectly straight down. Any deviation and you could damage the those nice 90 degree corners. Also, a square pin will offer more resistance to the downward pressure of the pin being pressed through the tang pin hole, as now the resistance is from 4 seperate opposing angles, instead of a continous infinite tangent one of the round pin. You can minimize the cornor damage with the chamfered cornors you mentioned, but then you get into issues as matching the radius of the chamfering. So you have added cost and a difficult installation.

All is not lost. No one said the shape of the pin has to match the hole. If you squared off the exposed part of the pin, but leave the insertion part round, you overcome the 4-sided installation issues, and the EDM cost. But now you have to match the square pegs on the handles, and you could EDM them, or machine to a close radius, and hand file the rest. A little more labor intensive, but equally cost effective as a round pin installation.

Blade 420: Increasing the # of sides makes mating the handle that much harder. You could get sloppy and just leave the tang pin cup semi-circular, but then you'll reducing the lock up advantages of the square pin, and reducing the ease of installation of the round pin.

Ryan M: I'm not 100% sure what you are designing, but I suspect in a sandwich construction sandwich bali, you'll still need a mechanism to stop the blade from traveling through the handles, as was the job of the second tang pin.

Dawkind: I like your idea, but I suspect that if the pin can be so easily removed for adjustment, it won't be mated tight enough to sustain all the impacts of manipulation, unless a lockdown system is introduced to prevent the pin from moving and/or rotating.

Clay: Any way to get a drawing of this to me? I'm intrigued by the concept, but am a little confused by the "flat" contact patch.

Let's keep them coming. And of course, please, if I'm wrong, correct me.
 
I'm not 100% sure what you are designing, but I suspect in a sandwich construction sandwich bali, you'll still need a mechanism to stop the blade from traveling through the handles, as was the job of the second tang pin.
Click to expand...

Well that's what the handle pins would do; the "outer" surface of the pin would mate with the tang projection, and the "inner" surface of the pin would mate with the blade at the ricasso, below the edge.

Imagine taking a milled bali handle, and grinding away most of the bottom of the channel, but leaving the portion that contacts the kick. In a sandwich bali with a pin in that location, the ricasso could even be concave, if the pin were large. Perhaps a large choil could provide the mating surface for the pin. Hm, would probably have the least wear, and be sturdiest, if the pins were elliptical or rectangular.
 
Hell.. just post it here if it's not a burden/secret. I'm sure the rest of us would love to see it. I myself am confused, (though much of this is over my head, I'm trying to learn).. but a pic is worth those 1000 words ;)

Cynake
 
Ryan M: I think I finally see what you're talking about. Move the tang pin to be within the handles. I don't think you need to increase the tang "tongue" all that much. If you elimate the horns, you could easliy slip it right behind the pivot pin so the net length required is minimal. Plus, if you use mated screws, they could be easily replacable if damaged. If bent, lots of room in the handle channels to cut it off. You'll need to add some form of grip serrations in the handle area near the tang to compensate for the lack of purchase the horns use to give the thumb.

Clay: Almost got it. Came up with a few possible ways you might mean, but what gets me is how to do the set screw. If you cut a notch in the tang, and cut two grooves into the pin, widthwise, and slide into the groove, where would the set screw go? Same question if you slide it in lengthwise. Also, how would you prevent the notch from expanding over time?

I like the "outside the box" thinking shown here. Keep them coming.
 
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