Electrical resistance and folder design.

[Carlos]

I find it interesting that one of the primary properties of E-glass based G10, is its high electrical resistance. This led me to wonder how one would design a folder where the hand holding the the knife would be safely shielded from from any electrical current (say, home or automotive levels) that might accidently pass through the blade.



I thought this might be an interesting design exercise to share with the TJ forum.



My own thoughts are:



1. lock should be of a poor conductor like titanium

2. a hidden pivot pin

3. recessed lock opening

4. rubber caps/plugs over the screws, or deeply recessed screws

5. handle design should include a prominent guard and thumbshelf (instead of using the hump as a thumbshelf)



I think that the issue of electrical resistance might be worth thinking about in the design of emergency/rescue type folders.

[Gatekeeper]

I had a similar idea in my head when i originally researched g/10 and found that they used it for circut boards and what not.
I think you have a good idea going as long as you rescess the metal parts you implement.
There should be little or no current to "bite " the user.? Correct?

[ftkinney]

you could have the outside encased like eletrical resistant tools ontop of the g-10 and the metal areas.

FTK

[Knife Knut]

How about Ceramic parts where possible, but esp. a ceramic blade, and a second set of G-10 scales to isolate and cover the unavoidably metallic parts. I don't think recessing alone would/could be deep enough to prevent arcing. Metalic clips would be right out of course, thus eliminating the problem of a metallic liner which is necessary to secure screws, at least in G-10 The collarary problem is that one falls back to attatchment issues that prompted the replacement of FRN clips w/ metal.
Couldn't find data on electricall resistance of G10, but what about FRN handles w/ the above mentioned scales? Of Course a ceramic blade would not be chewed up by the high temperature arcing like steel is be if you hit something live. (I screwed up a pocket change knife this way once when in a bad mood I used it to short out a 120 V light socket.)
As I recall from the Spyderco Story book Syderco's experimentation in ceramic blades
ended when an unmentioned company (Boker) put their ceramic blades on the market.
BTW these ideas ideas come from the study of my G-10 Police.

Edited by - Knife Knut on 12/6/2001 7:30:38 PM

[panguero]

XX

Edited by - sharp1 on 2/19/2002 10:35:13 PM

[Lsaulog]

Naah,

I'm only bold enough to strip 220v myself! <img src="wink.gif" width=15 height=15 align=middle>

"Hope for the best. Be prepared for the worst. You'll never be disappointed."

[Carlos]

Hi Sharp1,

I was thinking mostly in rescue/emergency designs, where there are often live wires about causing trouble. I recall the talk of a firefighters knife, and the possibility that it would be used to break through walls/sheetrock, etc.

[panguero]

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

[Knife Knut]

After some searching on the web, I have found ceramic: screws, Threaded Bolts, Nuts and Washers; they all appear to be white grade aluminum oxide.

As far as composites, if you want to get _REALLY_ esoteric, how about Fibre Reinforced Ceramic Matrix Materials

Not finished researching the Ceramics angle;
Of course for hard use like fire/emergency, the possibility of lock failure might preclude the use of a folder in the first place, but let us continue this brainstorming session.

[panguero]

Edited by - sharp1 on 2/19/2002 10:40:21 PM

[Carlos]

Here is a brief exchange I had with Sal on the use of ceramics:


Carlos: &quot;I know this is wandering off topic, but I just had a weird notion: Exotic ceramics have been used for blade materials for awhile now, but has anyone ever tried a ceramic handle? If the handle were molded, then you could have texture that would never wear, a handle that would never rust or corrode in anything, etc. Watch companies that I know of that have used ceramic for watch cases have used a reinforcing structure (sort of like steel reinforced concrete) to help cope with shocks. Would there be a weight advatage or disadvatage with ceramic?&quot;

Sal: &quot;I think the ceramic would eventually crack. I think the support structure like steel could hold up, but the ceramic would crack around it.

I think it would be VERY difficult to mold to shape and even more difficult to grind if a flaw existed.&quot;

Keep the ideas coming guys!

[panguero]

XX

Edited by - sharp1 on 2/19/2002 10:41:06 PM

[Carlos]

I asked sal to look into MMC (Al), and he said that the machining costs were a big downside.

[Dijos]

ok, as a practicing electrician, I will tell you that is not safe. in the various accidents I've had, 220/240 is plenty enough power to blow the tip off of a screwdriver. also, electricity will jump 7-10 inches at that voltage. I have rubber handled screwdrivers with a blade length of 8&quot;. I would never bring a knife near a live wire.

[liko]

But if you didn't have a choice, such as in a rescue situation where someone plowed into a telephone pole and there are live wires around, but you still have to cut the person out?

How bout this: Ceramic serrated sheepsfoot blade, lanyard hole instead of a clip, G-10 handle, and recessed screws covered with insulate plastic or rubber plugs? You may possibly need a handguard as well, to try and avoid arcs to the hand from a high-voltage line. Or, the user could just wear an electrical work glove, the ones that can protect up to thousands of volts of potential. Are these the types of considerations you're putting into the new Rescue?

[JBE]

Having been a paramedic for almost 9 years now I feel compelled to respond to these posts. Never, and I repeat never, would or should, any rescue personnel ever try to extricate somebody from a vehicle, or any other situation for that matter, while there are live wires present, no matter the circumstances or material of the knife blade involved. This is a very dangerous practice that has caused more than 1 rescuer to end their career and even their life prematurely. If I get killed or injured in the extrication process than I become a victim myself and am no longer able to provide patient care. I have always waited until the lines were turned off and removed from the hot zone before going in, no matter the patient's condition and my own emotions.

[Knife Knut]

So then we should narrow this discussion down to nusiance, for lack of a better word, level currents like household and automotive.

[Carlos]

The basis for the question is that you may not always *know* whether there is a live wire or other conducting element in an emergency situtation, especially in a hurry. Is there anything you could do to a rescue or firefighters knife design to help the user survive an *accidental* contact with an unseen live current?

[dialex]

I saw some knives concealed as hair brushes. The interesting thing was they were made entirely of nylon, but they cut pretty good, according to the manufacturer.
Now I wonder if that G10 (or something similar) would be suitable to make a blade out of it. Sorry if I look like a moron with this ideea.

[Pachucko]

Nope, I've seen knives made out of G-10, you're on the right track.
Pachucks

[Knife Knut]

Don't want this thread to get pushed into oblivion.

Knife Knut on a shoestring budget.

[WTFOver]

It might just be me but all of the G10 blades I have owned were very good &quot;Stab-ers&quot; and not so hot &quot;Slice-ers&quot;.

[tique]

I have to agree with the last post... I'm a fan of non-metallic blades for curio/gadget factor, but most of them ain't that great. I've never tried to cut with one of them, but the edge doesn't feel like it would do too well.

Supposedly there is a Ti alloy that works well at protecting against electrical currents, but they also have a plastic handle attached which I'm sure helps some as well.

[Talon]

How about a G10 blade molded around a thin steel blade that's only exposed on the edge. You could make it so the exposed steel edge runs from the tip and only half the length of the blade so it's away from the users hand. You could cut with it, still draw an arc, but it would away from the hand.

[Knife Knut]

Something similar has been done with a Carbon Fiber / Steel laminate for the full length of the blade. Since it was a knife for show I did not pay much attention to it.

Knife Knut on a shoestring budget.