Moncoques...

[Carlos]

Yet another hairbrained monocoque handle idea:



We talked before about the possibility of creating a "semi-monocoque" from two molded laminate half-shells permanently bonded together.



I wanted to elimitate the the second liner needed by a compression lock in laminate handles, so I was thinking to use bolsters -- or actually a single unified bolster, like a "C" with the opening on the bottom. The idea is that two half-shell laminate elements (which make up the last 2/3 of the handle) when being bonded could lock around a projection/ridge at the rear end of the bolster unit, creating a permanent monocoque from three subparts (2 parts laminate, 1 part metal).



This would eliminate the need for a second liner, and the locking liner (compression or linerlock) could be nested into one side and secured with screws. I suppose using a bolster would also allow one to up the potential strength of a compression lock.



It would require actual testing but I think that something like this would distribute most stress throughout the handle, and not just on the pins/screws that hold conventional layered slab handles together.



Edited by - Carlos on 11/9/2001 11:51:27 PM

[panguero]

Edited by - sharp1 on 2/19/2002 10:51:39 PM

[Carlos]

I wish I had a scanner -- it would be easy for me to draw freehand (former artist) but using MS Paint is a huge pain. I'll try to come up with some basic drawings if I have time.

I think that the real barrier to something like this would be cost. The idea is very simple, but degree of refinement required would be pretty high to have everything fit together perfectly.

Could you tell us more about M55J? All I know is that it is a carbon fiber composite.

[sal]

Hi Carlos. Interesting notion. I question how strong it would be. The anvil pin is nested into the steel liners. That's what keeps the anvil pin from blowing out of the top when breaking the lock. Two steel (strong) liners are necessary to hold fast the anvil in and the pivot pin.

sal

[Carlos]

&quot;...a beautiful hypothesis slain by an ugly fact.&quot; <img src="wink.gif" width=15 height=15 align=middle>

Hi Sal,

The metal &quot;C&quot; bolster wouldn't be strong enough for the pivot and anvil pins? Or ar you saying that enough pressure on the lock would break the bolster free from the laminate half of the monocoque?

[Carlos]

I've done a quick and dirty concept drawing. I imagined the &quot;C&quot; bolster also being screwed to the lock liner, but perhaps a plain old semi-moncoque with dual liners would be the superior solution.

[panguero]

Edited by - sharp1 on 2/19/2002 10:52:48 PM

[Carlos]

Thanks for the info. I think the bulk molded version of M55J sounds like something that should also be looked into as a high-end alternative to standard FRN.

While my basic idea was to use layered epoxy laminate (glass or carbon) molded in forms for the two half-shells of the rear end of the monocoque, which would be epoxied together permanently with the &quot;C bolster (like bonded CF bicycle frames). Your idea adds a whole new twist, and something else for Spyderco R&amp;D to play with. <img src="wink.gif" width=15 height=15 align=middle>

Also, I've enhanced my rough sketch by adding the anvil pin and highlighting it. The whole concept of using a &quot;C&quot; bolster is that it would hold both the pivot and anvil pins, thus eliminating the need for the second liner.

Query for Sal: Would magnesium or aluminum be sufficiently strong for this kind of &quot;bolster&quot; design, or would it have to be steel? (BTW, is my &quot;C bolster&quot; really a &quot;bolster?&quot; )

Edited by - Carlos on 11/10/2001 11:09:42 PM

[panguero]

Edited by - sharp1 on 2/19/2002 10:54:15 PM

[Carlos]

Unfortunately most of those questions are over my head technically -- I'm not an engineer, rather a mere enthusiast who knows just enough to cause trouble (for Sal). <img src="smile.gif" width=15 height=15 align=middle>

I was thinking of Mg, an Mg alloy, or Al for the &quot;C&quot; bolster, due to their light weight. But like steel there is the galvanic corrosion issue, which may or may not be relevant to this proposed application (once more over my head). Ti eliminates the corrosion problem -- so lets assume titanium for the &quot;C&quot; bolster.

OTOH, if the laid up laminate were based on S-glass rather than CF we could eliminate the galvanic corrosion issue, and keep Mg and/or Al as viable options for the bolster. The whole package would cost less than CF with Ti by quite a wide margin. Would Ti be necessary for the bolster if used with BMC M55J?

As far as the technique for laid up laminate: I don't know what Spyderco is using for their laid up fiberglass Temperance handle. If this is being done in-house then what they have experience with and are equipped for would be most logical.

For the rest of the questions...what are your thoughts?

BTW, about the bulk molded M55J -- what kind of tooling costs would you project for a folder handle (for the various filament lengths)? Sal previously mentioned $30,000+ for regular FRN molds (Zytel/Grivory), so I'm guessing that it couldn't be too far above that to be considered a feasable technology even for hypothetical discussion.

Edited by - Carlos on 11/11/2001 5:27:26 AM

[panguero]

XX

Edited by - sharp1 on 2/19/2002 10:53:34 PM

[Carlos]

I've been thinking about these exotic notions -- like semi-monocoques, compression molding, etc., and realized that technologies like this probably represent a potential for production knife companies to tread where custom knife makers can't.

Unless of course these scheme's are too cracked to ever be made real. <img src="wink.gif" width=15 height=15 align=middle>

[sal]

Hi Guys. I guess I'm back for a while. Sure has been an intersting discussion thus far.

Carlos. The &quot;C&quot; boster should work fine. It could work with a variety of materials as well. Just speaking hypothetically, a cast MIM titanium part would probably supply sufficient strength for at least a &quot;heavy duty&quot; lock strength rating and still solve lot of the tolerances problems.

As mentioned, fastening the handle material(which I am asuming is monocoque), would be the most difficult part. If the handle was
also a &quot;C&quot; that slid up into grooves in the &quot;C&quot; bolster, it could almost be a &quot;snap&quot; fit with a keyway release, in theory.

The compression lock could also be made as a module that could nest into a &quot;full&quot; monocoque handle. Also possible, I think.

So many ideas, so little time (&amp; money).

sal

[Carlos]

Hi Sal,

I had a few different idea's regarding how to implement the C-Bolster in real world designs.

#1: Mate the C-Bolster with an injection molded FRN or CRN monocoque - in the snap-and-lock fit that you mention, or snapped and epoxy bonded. Imagine this as an alternative to the way the Vesuvius handle was contructed, with its two FRN slabs, extra steel liner, and assorted posts/backpacer(?) and screws.

#2: The other idea was to use a &quot;Semi&quot; monocoque laminate for the handle - which we previously defined as a shell made from two half-shells which are bonded together. The semi-monocoque idea was to get around the problems of attempting to lay-up a ful monocoque. The other advantage of this concept is that you could in theory bond the two sections of laminate half-shell around the C-bolster's tenon: starting with 3 pieces and ending with one permanent monocoque (2 parts laminate, 1 part metal).

3. The other option is Sharp1's idea of to injection mold this other exotic carbon fiber around the C-Bolster, which creates the finished (and permanent) monocoque in one step.

[panguero]

Edited by - sharp1 on 2/19/2002 10:54:43 PM

[Carlos]

I share the dream of the true monocoque -- though Sal previously explained the manufacturing difficulty of laying up a true laminate monocoque, and the need for extra metal reinforcement for a compression lock when using injection molded handles or laminate scales -- thus the whole C-bolster concept. That second liner has got to go! <img src="wink.gif" width=15 height=15 align=middle>

Bonding seems to work pretty well for the bicycle industry. Have you heard of any failures of bonded CF bicycle frames?

Edited by - Carlos on 11/23/2001 2:49:10 AM

[panguero]

Edited by - sharp1 on 2/19/2002 10:55:50 PM

[panguero]

Edited by - sharp1 on 2/19/2002 10:57:12 PM

[panguero]

XX

Edited by - sharp1 on 2/19/2002 10:57:51 PM

[Carlos]

Excellent. Your grip design brings to mind some of what Sal has been doing with the Navigator pattern and Temperance Jr. handle.

I would like to see something similar applied as a monocoque overlay to a Chris Reeve style framelock. Though I guess it is best to start first with fixed blades?

When do we get to see the finished piece? <img src="smile.gif" width=15 height=15 align=middle>

Edited by - Carlos on 11/25/2001 1:21:41 PM

[panguero]

Edited by - sharp1 on 2/19/2002 10:58:41 PM

[panguero]

XX

Edited by - sharp1 on 2/19/2002 10:59:27 PM

[Carlos]

Okay this is definitely moving in the right direction. Screws are for wusses!

I wonder how two bonded laminate half-shells would compare to a regular injection molded FRN handle (like the Moran's) in destructive testing. I would like to see &quot;theoretically stronger&quot; turned into &quot;10% stronger,&quot; &quot;25% stronger,&quot; etc. I suppose Sal could give us some numbers regarding knife handles. I am wondering how high the cost of diminishing returns is here as we push for stronger and simpler designs.

Edited by - Carlos on 11/25/2001 5:32:37 PM

[panguero]

Edited by - sharp1 on 2/19/2002 11:00:04 PM

[sal]

Hi Sharp. Nice pics. Do I see a bit of design evolution occuring? That's how it goes.

I'm still after the molded CF Lil' Temperance handle. Just too much going on right now to give it the time. soon.

sal

[aero_student]

I am into bicycles and one of the truly innovative companies is kestrel. The pioneered carbon fiber in the bike industry and use moncoques. I have NEVER heard of anyone stress damaging one of their frames. I would suggest you guys look into what they have done as far as modifying filaments and mass producing these bad boys.

[panguero]

Edited by - sharp1 on 2/19/2002 11:00:41 PM

[Carlos]

Hi all,

How strong we need it is really a question more up Sal's alley. The true FRN monocoque is already prevalent and successful for lockback knives like the Endura, but if you look at the Vesuvius they couldn't use a FRN monocoque since its not strong enough for the compression lock. They ended up using two steel liners with FRN slabs (?), all screwed together. Likewise, G10 linerlocks can function adequately with a single liner, but as yet both of the G10 compression lock knives again needed two steels liners since the G10 isn't structurally stong enough to hold the anvil pin alone.

I think that Speedtech's CNC machined aluminum monocoques were very strong, but so expensive that they wen't out of business rather quickly.

Edited by - Carlos on 11/27/2001 2:00:33 PM