Jump to content
THX1138

Making armour from steel washers?

Recommended Posts

This is maybe a bit of a stupid idea but I live in colourful Merseyside, UK where knifecrime is increasing and my mother is concerned about me being in the city after dark (knows someone who knows someone who got stabbed) but did seem less concerned when I mentioned the price of stab-resistant armour! Decent armour that protects the neck and sides and arms (all these areas make an appearance when searching Google images for stab wounds) as well as front and back torso is expensive so I was considering making something myself. I'm a maker-wannabe so I like making stuff but I don't want it to take forever so I'm not looking to painstakingly reproduce ancient techniques or anything like that - I hope this doesn't offend the mail connoisseurs of this forum; I was actually thinking of using washers like in this:

http://www.mailleartisans.org/gallery/gallerydisplay.php?key=7057

except I'd be using 40 mm zinc-plated washers with 6 mm holes. I'm not yet certain whether I'd want to sew them into some kind of garment a bit like this:

https://ae01.alicdn.com/kf/HTB1c_GYvKuSBuNjy1Xcq6AYjFXaR.jpg

or connect them to each other with steel wire, similar to the project I linked above. I'm interested in any shortcuts I could take; I don't want to spend months fashioning this thing!

 

Share this post


Link to post
Share on other sites

Well, I've never made washer armour myself, but I have seen a few shirts other people had made for larping, and I don't think it is much faster to make than chainmail.  It is usually heavier and less flexible though, and flexibility is important if you want something around your neck and arms...

Though, really, if you want something stab proof, you probably have to start with welded chainmail fabric, what they use for shark diving suits or butcher protection equipment.

Share this post


Link to post
Share on other sites

If the connecting rings aren't welded or riveted, it won't be stab-resistant.  Any ring you can twist open with pliers can just as easily be opened with a knife. Also, as a general rule, life safety equipment is horrible place to start a first time DIY project.

Not trying to dissuade you from an enjoyable hobby--just want you to be 100% realistic. 

Share this post


Link to post
Share on other sites

I suppose I can add my two cents also.

It is very, very much too bad that the United Kingdom thinks knife control is going to solve knife crime any better than gun control solves or even hampers gun crime in the States (it doesn't).  With a reasonable apprehension of knife attacks, you might as well equip yourself with a four- to six-inch blade, even a secondhand kitchen knife, kept concealed, and chance the consequences of being caught by the police, while putting yourself in some kind of position to inflict consequences on the guy who wanted to stick a knife in you.

A passive defense like a piece of armor defends, but leaves the bad guy able to run off, quite uncured of the error of his ways, which curing really seems the more permanent solution.

A washer waistcoat could certainly do a lot, though such a load of washers is also quite heavy, because modern washers are thick things.  Avoid letting anyone push you off a  bridge!

Arm wounds from knives I understand are primarily what are called "defensive cuts," from trying to block an incoming knife by flailing at it with an arm.  The baddie isn't trying to cut your arm, but your vitals or your arteries.  The defender's arm just gets in the attackers way, and suffers by chance.  You are likely to get better protection for weight carried if you only armor your vitals, and let your limbs take their chances.  Your limbs are better employed deploying weaponry, say a very strong yet not heavy walkingstick -- or a gun, that the baddie may be discomfited all the more:  he can't cut you and ugly red spots break out all over his person.  And they aren't hives...  But too, there you go, breaking another badly conceived, criminal abetting law that says because you're the good guy, *your* fighting power must be restricted, while the criminals' in effect is not.  With gun control in place at all, bad guys may increasingly rely on targets helpless to fight back, and the same goes with knives as I said.  And those guys really facking need an icepick through the eyeball to sort them.  There are innocent looking blunt instruments you can get by mail order from America, too.  Try Cold Steel, of Ventura, California.  They offer reinforced-polymer whacking-sticks that double as walking sticks.  Less likely to break than even oak -- more comparable to ash, just at a guess.  More range than a Belfast potato, too, allowing you a thrusting counterattack.

Something that would have more sartorial elegance as a protective underlayer, but also more labor for you, would be a sleeveless, Borderer-style pennyplate jack.  It was the Borderer's budget brigandine (one, on X-raying, proved to be of salvaged 15th-c. brigandine plates, cut up and re-punched) made of light stainless steel in about the thickness of a tin can's walls -- less worry about corrosion than with the same in galvanized steel.  Still, don't get yourself pushed off a bridge with this one either.  Though it's an attractive article itself, with its pattern of thongs holding the penny-plates in place inside the cloth, and the plates overlap for seamless yet flexible torso protection.

To build a pennyplate jack in the garden shed probably means getting a benchtop slitting shear.  This is about the least expensive type of bench shear, and workable because making octagonal pennyplates is all straight cuts, and that's what that type of bench shear is good for.  Even in stainless, which is resistant stuff and dislikes to be sawn.  Shearing works better.

Each pennyplate should then be punched in the center, about a 6 to 8mm dia hole, and slightly dished with a softfaced hammer to both give the plate a little more strength from giving it a 3-D shape and to make it fit on you better -- your whole body is composed of various convexities, and dishing the pennyplates a bit will tuck their edges in, out of the way, so they don't "print," and betray their presence.

Edited by Konstantin the Red
more description needed

Share this post


Link to post
Share on other sites

Thanks for everyone's contributions. The cheapness of my approach (£10 for washers, £24 for ferrules and £10 for steel cable) is one of the reasons I'm considering it, rather than speed of manufacture. That said, I'm not keen on making the plates myself.

I'm thinking of using small loops of 2 mm steel cable to make the connections between washers and the loops of steel cable would be held closed with crimped aluminium ferrules. I think if the ferrules are crimped properly, it should not be possible to open them with pliers and if that's a decent standard to go by, shouldn't be seperable by a knife.

I could dish the washers by spanning them across 41 mm steel channel and tightening a bolt through them with a ratcheting socket (I did this recently accidentally) but it would take a long time for a few hundred washers.

100 M6 40 mm steel washers of the kind I'm considering apparently weight 0.75 kg and I guessed that if I need 500 total, that's only ~4kg plus the wire (~0.4 kg) and ferrules. I don't mind it being heavy; I've heard of people wearing chain mail just to help keep fit. Being pushed off a bridge will of course be my Achilles' heel.

I considered just buying this but it leaves the neck and shoulders unprotected which I think are a likely target in a knife attack.

Share this post


Link to post
Share on other sites

while i think there are other issues with this (mostly weight and flexibility), i think eric is incorrect that it won't be stab resistant - at least in the pattern in your first link.  with any direct stab, the point would be collected by the hole in the washer and the "separating force" will all be pushed onto the solid washer, not on any of the connecting rings.  the only pressure on connecting rings would be from tugging a stopped blade or a glancing cut which would not threaten bodily harm anyway.

Share this post


Link to post
Share on other sites

Of course, if the main reason why you want to build this is to defend against knife attacks, I feel the need to mention that aikido has many techniques for knife defense.  And of all those thechniques, this is widely recognized as the best one :  https://www.youtube.com/watch?v=xt9AkDyodMc   so, make sure your armor is light, and start training 😉

 

Share this post


Link to post
Share on other sites

I've tested a lot of armor and I have to agree that anything that isn't welded won't be very stab resistant.  As far as cost goes, how much is your life worth? 

I would suggest that you at least call my company and get a quote on a stab resistant shirt. It'll be far better than anything you can make yourself and probably not as expensive as you think. If you do be sure to mention to whoever you speak to that I offered you the highest discount rate.

Share this post


Link to post
Share on other sites
On 3/21/2019 at 1:00 PM, lorenzo said:

I've tested a lot of armor and I have to agree that anything that isn't welded won't be very stab resistant.  As far as cost goes, how much is your life worth? 

I would suggest that you at least call my company and get a quote on a stab resistant shirt. It'll be far better than anything you can make yourself and probably not as expensive as you think. If you do be sure to mention to whoever you speak to that I offered you the highest discount rate.

It's been a long time since I did any materials science stuff but my gut tells me that a welded 1/4", 18 gauge stainless shirt would be more stab resistant than a butted 1/4", 16 gauge stainless shirt. not by much though. The 18 gauge piece would be infinitely more wearable, too.

Share this post


Link to post
Share on other sites

Have to admit, a shallow cut is better than a deep one.

Taking martial arts keeps you in physical shape, is not particularly expensive, and offers you a protection option that cannot be taken away even by a strip-search.

Among Cold Steel's options is the 91WALK Walkabout stick, 26oz and slightly under a meter's length of reinforced polypropylene, flat black, walkingstick knob on the end, so fairly low profile.  The 91STA City Stick is the same walking stick idea, somewhat lighter weight and slimmer profile, with a walking stick knob in aluminum.  They offer the "Stun, Stagger, and Stop" DVD to teach you their effective use.

Edited by Konstantin the Red

Share this post


Link to post
Share on other sites
On 3/22/2019 at 5:33 AM, Rob MacLennan said:

It's been a long time since I did any materials science stuff but my gut tells me that a welded 1/4", 18 gauge stainless shirt would be more stab resistant than a butted 1/4", 16 gauge stainless shirt. not by much though. The 18 gauge piece would be infinitely more wearable, too.

It's safe to say that the welded piece would be an order of magnitude more stab resistant, all other things being equal. As a rule butted mail has very little stab resistance although it's pretty good against slashes.

Share this post


Link to post
Share on other sites

I just did the math really quick, it should take 275lbs of force to break open a welded 18g stainless ring.  That's probably closer to two orders of magnitude more.

Share this post


Link to post
Share on other sites
22 hours ago, lorenzo said:

I just did the math really quick, it should take 275lbs of force to break open a welded 18g stainless ring.  That's probably closer to two orders of magnitude more.

I'm getting the same number: 75ksi * (18swg ^ 2) * pi/4 * 2 =~ 275lbs , but that's just the absolute upper bound--what it would take to break two strands of load balanced 18swg stainless wire. Pushing a dagger through the ring creates wedge leverage and initiates cracks. I suspect the force required at the handle is much less than 275lbs.

Edited by Eric

Share this post


Link to post
Share on other sites

You only have to break one, but your math is still off. You're using yield strength of annealed stainless bar stock, you should be using UTS and 120Ksi is typical for commercially available rings and wire. Annealed stainless wire is still usually about 100Ksi. The finer the wire is drawn the higher the baseline numbers will be due to grain refinement of the metal.

Typically you'll get a mechanical advantage of about 2:1 for most blades that can penetrate maille armor without breaking, but the majority of modern carry knives or improvised blades will just break or blunt immediately. A good dedicated stabbing weapon would get you about 3:1, say a spear or a dagger. Weapons optimized for armor piercing can push 4:1 but you will never likely see one of those. These mechanical advantages apply against butted rings as well, so it's still going to be about two orders of magnitude or roughly 100x stronger, no matter what.

You're also wrong about crack propagation, that doesn't occur unless the wire is very hard, especially with stainless alloys. Also keep in mind that any padding or give to the armor will bleed off a large amount of force.

Historical maille armor averaged about 18g to give good protection vs spears and daggers but with modern alloys and welding 20g can be just as strong. In practice 22g is enough to defeat most attacks with a modern knife and most stab resistant armor in use today runs from 21g-24g wire depending on the application.

Share this post


Link to post
Share on other sites

I just put the numbers into my ring strength calculator, but the basic idea is cross sectional area of the wire multiplied by UTS of the wire.

Edit; Actually, it looks like I was wrong too. My calculator was set for square wire, for round wire it's about 215lbs. So just to double check that would be (((0.048i/2)^2)pi)120,000lb/i^2= ~217lb

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×