Demko AD-15: possible design improvements?

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insta9ves

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Apr 3, 2007
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I love the design of the Triad & Scorpion lock. I've been following Demko's Instagram as well as some youtube reviews of the AD-15. While it's a big improvement over the triad lock in terms of ease of use, I personally feel like the closing action of the current design seems a little bit awkward. E.g. the Scorpion lock bar extends all the way to the end of the handle and you may have to open up your palm when closing the knife.

I've had an idea on the improvement ever since i saw this lock, and i figured i would draw it up and share it here hopefully Mr. Demko can see it. My idea is to move the pivot of the Scorpion lock bar forward to the front of the handle while using the traditional backlock/triadlock backspacer spring to provide tension to the lockbar. This basically turns the design into a hybrid of the Scorpion & Triad lock. It also resembles the old Tiger Claw thumbstud triad lock design that didn't go into production.

The benefit of this design is that you will now be able to close the knife with just your thumb without opening your palm, very much like a vertical axis lock. You can also move the pivot point further forward/backward depending on the strength/ergonomic requirement, very much like how the triad lockbar's position changes between models. I believe it's easier/cheaper to make as you do not need to mill the complicated titanium backspacer attached to the lockbar.

One disadvantage i can think of is that it will no longer be an open construction like the Scorpion lock. Also, the benefit of the Scorpion lock, being an open construction is that the blade can sit deeper in the handle which means less footprint when closed, while the proposed design will be more like triad lock. However i believe it still preserves the better blade to handle ratio.

Here is the diagram:

test014.png


Please let me know if it's a good idea. Really hope that CS/Demko will give it a shot and see how it works.
 
BTW, here is a video showing the disassembly of the Scorpion lock for comparison:

[video=youtube;WGJo7tgTg_E]https://www.youtube.com/watch?v=WGJo7tgTg_E[/video]
 
Really interesting idea, but wouldn't that more traditional spring/backspacer occupy more space in the handle and prevent the closed knife from being quite so slim?
 
You would likely make the lock vastly more difficult to close. Longer lever = less force needed to lift the lock. Your design would reduce the length of the lever by about 2/3rds which would hugely reduce the leverage working for you.
 
HammerHill said:
Really interesting idea, but wouldn't that more traditional spring/backspacer occupy more space in the handle and prevent the closed knife from being quite so slim?
Click to expand...

Yeah, that was one of the potential disadvantage i pointed out. But i think they can try to move the design of the backspacer & spring around to maximize the space.
I dont really mind the closed width of the knife, as wider knife is actually more comfortable to carry in the back pocket(how i carry my knife 90% of the time). What's important is that it still preserve the better blade to handle ratio vs the triad lock.
 
Insipid Moniker said:
You would likely make the lock vastly more difficult to close. Longer lever = less force needed to lift the lock. Your design would reduce the length of the lever by about 2/3rds which would hugely reduce the leverage working for you.
Click to expand...

It may increase the tension but i think it's depends on multiple factors such as the placement of the pivot(fulcrum in this case) & the spring, as well as the spring tension itself. Even at the same position illustrated in the pic, i think the tension is still much less than the triad lockbar as triad lock's cutout are usually much closer to the fulcrum. The lever here is still much longer than on the standard triad lock, since it's on the opposite direction.

Also, the way you disengage the lock will be different. On Demko's demo videos on instagram, you can see that the most convenient way to close the AD-15 is to turn the knife, edge facing you, and disengage the lockbar using the index & middle finger, then close the blade with your thumb. The grip is less secure as most of your fingers are working to close the blade.
With Triad lock, you have to move the knife forward then depress the lockbar with your thumb. The other fingers are still holding the handle, but the blade could potentially drop free on your index finger because of the position.
With this design however, you will turn the knife sideway when closing(like the Axis lock). The rest of your fingers are still holding the handle and only your thumb is needed to close the knife by moving sideway, like finger snapping. IMO this is less awkward than pressing down like the Triad, anatomically speaking.

Anyways, we will never know unless someone build a prototype and test it. I honestly think that this could be an improvement, and really hope Mr Demko would give it a shot. I'm not looking for any credit or financial gain, just a knife guys who loves innovative technologies.
 
That can be an option. I experimented with many different variations of the scorpion lock, especially the length of the top half of the frame, and drive springs. In fact the first designs were very similar to what you drew as it's most similar to a lock back or triad, then evolved to what you see now. thank you for your interest in my work
 
Just watched a video on this lock. Very impressive idea. Cant wait to see it tested against the tri-ad.;)
 
DemkoKnives said:
That can be an option. I experimented with many different variations of the scorpion lock, especially the length of the top half of the frame, and drive springs. In fact the first designs were very similar to what you drew as it's most similar to a lock back or triad, then evolved to what you see now. thank you for your interest in my work
Click to expand...

Thanks for jumping in Mr Demko! Yeah based on the old Tiger Claw prototype i thought you must have tried the front release mechanism on the Scorpion lock as well. You mentioned that the first designs were similar to the drawing, what was the reason for moving away from it? Just curious since you have the first hand experience in testing it, is it because the release tension is too high or that it took too much space in the handle?

Looking forward to seeing more interesting stuffs from you!
 
The main reason was there is not much room for the lock pivot and spring. I wanted the blade to set deeply in the handle when closed and use a large pivot for the yoke. Also it is nice to have the yoke (upper frame ) longer so the grip can reinforce the lock up.
 
DemkoKnives said:
The main reason was there is not much room for the lock pivot and spring. I wanted the blade to set deeply in the handle when closed and use a large pivot for the yoke. Also it is nice to have the yoke (upper frame ) longer so the grip can reinforce the lock up.
Click to expand...

Hmm that makes sense. I saw your width comparison of AD15 vs triad lock when closed, definitely a big difference. Oh well, there are always trade offs. Another benefit i can think of is that, with the shorter yoke, you can potentially use steel instead of titanium, which would increase the strength while not gaining significant amount weight. Also the aluminum backspacer would offset the extra weight. Not sure how significant this is tho, since you did mention before that the lock usually fail at the pivot area where it can shear off from the handle.
 
I have an ad-15 that I have been using and carrying for the last few weeks. I can assure you it is very intuitive to close once you get used to it. This lock has the potential to be a game changer in the folding knife world.
 
I have to concur with johnnytoxin. I have had my AD15 a few weeks, and and after getting used to the lock for a few days, I don't think I would make any changes to it. It is a really great design, and seems very strong. I would venture to guess it is close to as strong as the Triad, maybe Andrew can chime in on that, but regardless, I can't imagine ever being able to make the lock fail. It is easy to actuate, and I really like the flow through design, which makes it easy to clean.
 
johnnytoxin said:
I have an ad-15 that I have been using and carrying for the last few weeks. I can assure you it is very intuitive to close once you get used to it. This lock has the potential to be a game changer in the folding knife world.
Click to expand...

I'd love to own an AD15, and appreciate Demko's continued innovation <cause without it we wouldn't have the TriAD>... but like the saying goes, "It's hard to improve on perfection." :cool:

And the TriAD is lock perfection in terms of simple, tough, intuitive locks...I don't even think its arguable at this point with all the PROOF for the TriAD's superiority.

So, do you think the Scorpion Lock is BETTER than the TriAD, or is it just DIFFERENT?
 
PeteyTwoPointOne said:
I'd love to own an AD15, and appreciate Demko's continued innovation <cause without it we wouldn't have the TriAD>... but like the saying goes, "It's hard to improve on perfection." :cool:

And the TriAD is lock perfection in terms of simple, tough, intuitive locks...I don't even think its arguable at this point with all the PROOF for the TriAD's superiority.

So, do you think the Scorpion Lock is BETTER than the TriAD, or is it just DIFFERENT?
Click to expand...

Definitely different. According to Andrew, strength is comparable to similar sized triads. The ease of use however definitely goes to the Scorpion lock. The action is also really slick.
 
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