SOG Arc Lock - some pictures and how it works

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Sergiusz Mitin

Sergiusz Mitin

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Nov 25, 1999
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<center><font size=4>Arc Lock - view from inside</font></center>
<a href="http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492291&Sequence=0" target="_blank"><IMG align=right SRC="http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492292&Sequence=0" border="3"></a>Here is my Night Vision stripped. It can be done without any difficulties but I have use four different drivers to do it:
* torx # 10 for pivot pin and large screw mounting pocket clip,
* torx # 6 for stop pin, locking cam axis and 2 screws mounting back spacer,
* slotted screwdriver for locking cam operation button,
* philips # 1 driver for 2 small screws additionally holding pocket clip
After I stripped all I considered that pocket clip shouldn't be removed to reach locking mechanism. The springs are remaining between G-10 scales and steel liners, I didn't remove them. No problem to put the knife together. Adjusting pivot tension it's worth to remember that it depends not only on pivot screw tightness. Stop pin and locking cam pivot screws are influencing blade pivoting force quite noticeable.
Do not take your knife apart for curiosity only, your warranty will be voided!
By the way, no worries about steel amount around pivot hole!

And here are some pictures explaining how it works.
<center><a href=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492294&Sequence=0 target="_blank"><IMG SRC=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492296&Sequence=0 border="3"></a> <a href=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492297&Sequence=0 target="_blank"><IMG SRC=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492298&Sequence=0 border="3"></a> <a href=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492299&Sequence=0 target="_blank"><IMG SRC=http://albums.photopoint.com/j/View?u=222944&a=1811604&p=25492301&Sequence=0 border="3"></a></center>

As you can see Arc Lock appears similar to BM Axis Lock only until striped. The locking principle here is absolutely different.
Springs are permanently loading the locking cam in direction towards opened knife blade tip. Starting to open your knife you have to turn locking cam against spring load direction. This holds blade very securely in closed position and pulls it back into the handle with small opening angles.
On the other hand it is very easy to flick the blade open if locking button is depressed in direction towards handle butt.
At the central photo the blade opening angle just passed critical point. Now the blade is not pulled back into closed position.
When the knife is opened and locked negative load applied to the blade doesn't try to bend locking cam anyway. It does try to squeeze it. This locking cam is quite thick (as thick as the blade) and wide. I can't imagine what could happen with it under any imaginable load.
Rather I can imagine that locking cam pivot could be bent under very high negative load. But in this case the locking cam operating buttons will take the load directing it onto steel liners. With hard bent or broken locking cam pivot Arc Lock would start to work like Axis Lock.

I have tried also some spin whacking to see how this lock behaves under impulse load and it passed all my whacking against both hard and soft target. Handle twisting also seems to don't be an issue for Arc Lock. I also couldn't find any grip position which could affect lock security anyway.
In other words, so far I couldn't find the way to let it to fail.


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Sergiusz Mitin
gunwriter
Lodz, Poland

[This message has been edited by Sergiusz Mitin (edited 08-02-2000).]

[This message has been edited by Sergiusz Mitin (edited 08-02-2000).]
 
A picture's worth a thousand words. I had read all the descriptions and still couldn't figure it out. Thanks Sergiusz!
 
Sergiusz,

Thanks for the pictures...VERY well done!

Thanks for the warranty disclaimer!
smile.gif
Nice touch.

Touch base with us when you've "played" with it some more.

Ron@SOG

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Website: www.sogknives.com
Email: ron@sogknives.com
 
Cool. There's "less" pivot-area metal than with other designs, but not radically so. And since that's not a common area of failure in the first place. looks like we're OK.

Except I can't put an order in for a PE2 just yet because I'm recovering from the financial hit put in by my recent emergency move after some twit turned my apartment building into a crispy critter.

Sigh
smile.gif
. (No, I didn't lose anything important...)

Jim
 
Is it safe to say that you like the lock mechanism or is the jury still out? How do you like it in comparison to the axis lock? Better design? Worse? Do you see any potential weaknesses?

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Dennis Bible
 
What looks good here is that for a full-tilt failure where the blade swings closed, it has to fail "twice".

Pressure is first applied to the upper fixed pivot point of the locking cam. If that pivot pin gets jammed straight up, the pushbuttons at the bottom of the cam stick out sideways through the grip on both sides (ambi lock release, remember) and the buttons hitting the dual steel liners should form a "second line of defense".

Slippage shouldn't be a problem. Spring failure shouldn't be an issue...I assume there's dual coil springs, one embedded in each grip scale driving the bottom of the cam forward. REKAT uses just one spring on one grip scale, but since they went to a coil spring instead of the early leaf, there's been no reported failures.

Could grit screw it up? Doesn't look like it...there's no "nook or cranny" near the lockup point for crud to gather.

That leaves grease? I assume they tested to make sure groteque levels of over-oiling didn't leave the bottom of the cam able to slip backwards against spring pressure? That's one thing you could field-check fairly easily. If there was any feel of "slippage" under pressure to the spine when the lock was greasy, increasing the spring tension would help. You can "pre-load" the spring in most cases by putting in a little cylinder of some hard material, or putting in a tighter spring. This is just a minaturized version of a motorcycle fork tube mod job
smile.gif
.

Overall, I approve. A lot.

Jim
 
WOW! Nice work, Sergiusz Mitin. And awesome job on the lock design, SOG and Ron. Now the big question: Does the knife come with a, umm... well.... um... "more conventional" blade shape?
wink.gif
Like, not "tanto"? And <u>NOT</u> serrated?

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iktomi
 
Dennis,
Yes, I can say certainly - I like it! It is true new generation locking device, clear step towards higher reliability and safety comparing with popular liner locks and lockbacks.

But I can't say certainly do I like it more or less than Axis Lock. As Jim rightly noticed it have some kind of "second line of defense". On the other hand, Axis Lock can tolerate more obstruction between blade tang and stop pin. Here I have described how I tested Axis Lock for obstruction tolerance, the Arc Lock failed to lock up with the same insert between stop pin and blade tang.
Blade retention in closed position is closely comparable.
Both locks are equally easy to operate and truly ambidextrous.
To compare critical strength it would be necessary simply break the knives with both locks and see which will need more force to be broken. To make experiment clear from random obstructions it should be repeated several times with each knife. So far I'm not planning such evaluation
biggrin.gif


Jim,
After I have read your post I immediately literally flooded my Night Vision with MILITECH Synthetic Based Weapon Grade Metal Conditioner and performed some tests.
First of course spin whacking against hard target (wooden board) and soft one (phonebook).
Then I placed locked blade into the vice (with felt inserts of course) and tried to shake the handle alternately in opening and closing directions. First with light force and as high frequency as I could, then with lower frequency but with more force, up to medium (as to my abilities).
Nothing wrong occurred!
Arc Lock seems to be really rock-strong and very stable.

Now I'm working on my review on Night Vision knife, I'll publish it shortly.

[This message has been edited by Sergiusz Mitin (edited 08-04-2000).]
 
Cool, that means they're using strong enough springs. Good to know. You can see why I'd ask the question though, right? Just looking at it, it would seem you might be able to slide the bottom of the cam "uphill" to the rear...the springs put a halt to that.

Very nice.

Jim
 
I must be missing something because the design seems a lot like a Axis to me. OK, one moves straight and one moves in an arc.

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Roger Blake
 
Roger,
You are missing what takes the load and which way.
In Axis Lock the locking bar supported at the ends with liners takes the load in direction what tries to bend it.
In Arc Lock the locking cam takes the load in direction what tries to squeeze it.
Quite important difference from mechanics standpoint and I think even more important from patent cleanliness standpoint. But here I'm not an expert
smile.gif

 
Originally posted by Sergiusz Mitin:
Roger,
You are missing what takes the load and which way.
In Axis Lock the locking bar supported at the ends with liners takes the load in direction what tries to bend it.
In Arc Lock the locking cam takes the load in direction what tries to squeeze it.
Quite important difference from mechanics standpoint and I think even more important from patent cleanliness standpoint. But here I'm not an expert
smile.gif
Click to expand...


It appears that the cam or link transfers forces to either pin which transfers forces to liners. Where as the Axis the transfer is direct to liners. Yes that is different.

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Roger Blake
 
Nice job, Serguisz.

I'm with RS on this... Another blade style would be nice, say a drop and/or clip point.

sing

AKTI #A000356
 
And something in plainedge!

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Dennis Bible
 
For example, with titanium handles anodized in some funny color compositions.
Drop point blade:
<a href="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=25791518&Sequence=0" target="_blank"><IMG SRC="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=25791528&Sequence=0" border="2"></a>
or clip point:
<a href="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=25791511&Sequence=0" target="_blank"><IMG SRC="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=25791525&Sequence=0" border="2"></a>
 
As a fan of reviewing patents I recently pulled Bob Brothers Rolling Lock patent off the USPTO website. Although I'm not a patent attorney it does not take much brains to figure out the Arc Lock is an infringment of the Rolling Lock patent.

I don't know if SOG's designer Spencer Frazier did his homework before producing the Arc Lock. Regardless, from a patent standpoint Bob Brothers is the one holding all the marbles. My guess is we will be hearing more about this in the future.
 
Hi Tiger,

Thanks for your comments. You can be assured that in the development of the ArcLock, that SOG did all the appropriate "homework" needed regarding patents.

We appreciate, though, you looking out for us!

Ron@SOG

------------------
Website: www.sogknives.com
Email: ron@sogknives.com
 
Tiger, I own a Rolling lock, and I've studies these Arclock pics in *detail* in preparation for buying a PE2 soon.

The Arc-lock is NOT an infringement on the Rolling. If anything, it's possible both infringe on the old Blackie Collins Bolt-Action as used on the Gerber Parabellum and others, and apparantly Meyerco still uses it on at least one model.

However, I recall seeing my first Parabellum at around age...17 or so, tops. And I'm 36. And patents run 17 years I believe?

The only similarity between the Arc and Roller is the side switch. The method of lockup is different enough. The basic idea in the Arc, Roller, Axis and Bolt-action is "cram a piece of metal into a cutout area of the tang" on all three, plus a "forward/reverse direction release switch on at least one side".

If anything, the Axis is the closest to the Bolt-Action.

I don't think SOG has anything to worry about, nor did SOG "rip anybody off".

Jim
 
To Jim:

The Rolling Lock and Arc Lock are rather different than the Bolt Action. The Bolt Action uses a pin to slide into a knotch in the tang in a straight line of action. Yes, I agree the Axis Lock works on this same principle. On the Rolling and Arc Locks, both use a rotating means to engage a knotch in the tang. Here is where the similarity exists.

Yes there are visual differences between the Arc Lock and the Rolling Lock. However when it comes to patents it is the patent claims that determine the scope of the invention. There is at least one specific claim in the Rolling Lock patent that describes the functional operation of the Arc Lock to a T.

A utility patent has little to do with the appearance of a mechanism. It is the functionality of that invention and how the invention is described in the claims that determines what is protected by the patent.

Again I am not a patent attorney but I believe if SOG first came out with the Arc Lock and filed the same claim as Bob Brothers, then it would be the Rolling Lock that infringes the Arc Lock. The functionality of both locks and how the patent claim describes that functionality is that close. The bottom line is in this situation the patent rights go to the Rolling Lock.

Ron, you said that SOG did their patent homework before developing the Arc Lock. If I were SOG I'd go back and do a little more studying.


[This message has been edited by Tiger (edited 08-11-2000).]
 
I must agree with Tiger ,look at USP5685079 p6 of 6.My Arc developed the old up and down after the usual cajoling.Couldn`t tune it out either[3 screws to tune!].Neither RR norAxis and for that matter any well made LLs develope this type of fault.Side play has also occured and if I tune that out the nice Axis-like return is gone.I tore it down, Tiger, and those springs look awful familiar.All that and 20 bucks more!Nice to find this out at home, before the "big fishing trip"

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pogue mahone
 
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