The EXTREMA RATIO FULCRUM

The (Mighty) EXTREMA RATIO FULCRUM

(In this case the desert warfare model)

by BCT

The Extrema Ratio Fulcrum has to be Extrema Ratio's signature model if there is such a thing. It's design was based upon the request from COMALP (Commando Truppe Alpine) ie the Aline Troops Command of the Italian Army for Extrema Ratio to design and implement a modern multipurpose knife. Since it's inception it has been a standard issue for operation Nibbio and also issued to troops in Afghanistan. The Extrema Ratio Fulcrum is Battle Tested.

The spine has a thickness of 6mm, 1/4 inch and has been tested to hold up to 150kg without failure across the guard.

I think it would be fair to suggest that Extrema Ratio were the first to pioneer a interaction between university researchers in biomechanics of the human hand, in order to design a truly ergonomic grip, or as close as practically possible to design such a grip in order to accommodate various hand shape/sizes. 

Extrema Ratio utilises the synthetic polymer FORPRENE as the material of choice. Forprene has many beneficial characteristics both for chemical resistance and absorption of vibration/shock plus great mechanical resistance to deformation. Despite this "funky"appearance, this grip is amazingly comfortable and secure to hold.

One Fixing bolt. This bolt can be removed with either a flat bladed object or an Allen driver wrench. I've even used a key to undo this bolt on other models I own.

The wide spine at the tip enables this knife to be easily struck with a baton.

Being a combat knife it goes without saying some serrations will make quick work of cutting or starting cuts on ANY fibrous materials. One large, two small shallow concave pattern arrangement allows for a compromise between "overall strength Vs stay sharpness" in my humble opinion.

So the blade doesn't weigh a ton because it is made from a slab of 6mm Böhler N690, they use their signature fuller (like a half "I beam design" if you like) to keep the weight down. Although the knife does feel weighty at (I measured) 330 grams/11.6Oz, they say: 321/11.3Oz (knife only). The weight is towards the tip (great for hacking into things, more on this later).

MADE IN ITALY

Field maintenance is super easy, only straight edges to maintain! (serrations by their very nature take a lot to actually make them go blunt). This almost chisel like point is extremely tough and useful for the so called "bush crafter" because it can very effectively drill divots for fire drills amongst many other useful outdoor tasks. (How do I know this? Because I've taken my Fulcrum S and Fulcrum NFG on many outdoor adventures into the wilderness around the globe).

Let's talk briefly about the funky geometric pattern (also a first by them). it is a function of the interaction of the LASER with theN690 steel.

Just in case you've forgotten they go are far as actually letting you know the HRC is 58 LOL!

It's no good having a knife which you call "multi-purpose" without a lanyard hole. The lanyard hole can also be used (like any lanyard hole) to bend thick wire, ie other than simply being used to secure it to your person. On another cool note, should the fixing bolt be lost in the field a cord can simply be tied into the lanyard hole to securely maintain the grip to the knife tang, ow about that eh? A bit of redundancy built in!

One of great things about this company is their attention to detail. Many companies can make great knives but not necessarily make a great scabbard or a scabbard which equals the knife in quality and versatility. Not so with Extrema Ratio. Their scabbards are excellent. Well-stitched, as good as a quality pair of Italian made boots! Just see below for evidence of this.

This scabbard carry system is very cool, supposedly to allow paratroopers to carry this knife without the potential for the parachute or other items to get caught around the actual knife handle. here it is totally encased within the scabbard. (the outer flap can be easily removed of course). From a civilian standpoint, this system allows for a no nonsense low profile (as in visible that it is a knife) carry and does not appear threatening in any way.  

Multipurpose Molle straps and leg loop

Lovely even stitching throughout!

Thorough user safety

What protects the user from being accidentally impaled upon this blade if they happen to fall upon it? Inside the high denier fabric sits a very rigid glass fibre reinforced insert (complete with drainage holes), which can be easily removed for maintenance by removing the small two pronged lug (seen next to keyboard).

I don't think I'd be whinging if I only had this beast strapped to my side up a saltwater crocodile infested mangrove estuary in the  Northern Australian wilderness!

Blade length is 180mm or approximately 175mm of actual cutting surface and the balance is right at the ricasso, ie approx 5mm away from the Forprene grip or there about.

Ok enough said. Stay tuned to the channel for more on this, the Extrema Ratio Fulcrum. You can also see it here:

And you can also see it in action here as well

Plus see it in more action here:

BushCampingTools

 

A Custom Made Resistive Heater on my PCP REXIMEX Rifle

 A Custom Made Resistive Heater on my PCP Rifle

I want to talk about PV=nRT (the Ideal Gas Equation) and that basically, if you have forgotten your physics, to remind you that when some pressure vessel gets hot, the gas inside of it wants to expand and hence the pressure will rise in accordance with the temperature change and conversely, if the temperature gets colder the gas pressure will decrease within the vessel.

However since the volume of our cylinder doesn't change we actually need to derive another formula from the ideal gas equation.

From Joseph Louis Gay-Lussac 

P1/T1=P2/T2

Here we are comparing the same substance under two different conditions.

Where P1  and T1 are the following: initial pressure and initial temperature, and P2 and T2 are the final pressure and temperature.

Pressure is measured in Pa  (pascals)

1 bar=100 Kpa = 100,000 Pa

200 bar is then = to 200X 100,000= 20,000,000 (Pa) ie 20 Mpa

or 2 e7 Pa.

Temperature is measured in degrees Kelvin (K) and to convert C to K you must add 273 to whatever temperature is given in Celsius.  In this case we will start at a comfortable 25C and work our way down to below zero C.

On a 200bar system with a 500cc capacity tank, how is this affected by varying the temperature? Let's see!

If we fill our cylinder to 200Bat at 25C and then examine the pressure drop at the following ambient temperatures:

15C, 10C and 0C. 

In order to perform this calculation we need to first convert degrees celsius to degrees Kelvin by adding 273 to each degree C value.

Now we find that the pressures are as follows:

193 bar at 15C

190 bar at 10C

183 bar at 0C

For this PCP, the minimum recommended operating temperature is -5C, for which your starting pressure at this temperature would be approximately:

180 bar.

So we can see the gun is not  recommended to be operated below 180 bar.

Now these values are only what you see here as long as the volume of gas remains the same. So prior to shooting in cold whether check your actual gas pressure.

Hence for the safe operation and or optimal operation of a PCP air gun, the there will be certain limitations upon the functionality of the weapon due to whatever ambient temperature it is operated at and the duration of operation.

Operation outside of the manufacturer's specifications  range for temperature could prove fatal for the operator! Especially if one exceeds the maximum operating temperature (usually around 40C/104F).

However, it is unlikely that one will be shooting at 40C! it is more likely one could be shooting at temperatures lower than 20C/68F during cooler months of the year (if outside). 

BTW what would the pressure be at 40C?

Approx: 210 bar. Well within the safety limits of the original pressure vessel.

This is where I placed a small flexible and water resistant resistive heating element encapsulated within a Silyl ether polymer (can withstand temperatures up to 80C). The heater is powered from X2 AA alkaline cells and sits atop of the steel regulator cylinder of my Reximex throne. The closed cell foam is added for insulation.

Further testing is still required as the mass of metal associated with the regulator pressure vessel is very large and made from a lower conductive steel alloy.

I marked the "Power wheel' so to to be able to reproduce particular power settings on this PCP rifle.

We made a "custom camouflaged' AUTUMN lightweight bottle cover. (See video)

Using a Vortex Red Dot Crossfire sight for close range moving targets up to 25m.

The only other thing I did to this PCP was to replace a small diameter castellated metal washer (inside the grip-not shown) with several wider (but same internal diameter) stainless steel washers to help take up a very small but annoying "slop" in the grip and to evenly distribute the load from the grip bolt upon the plastic molded grip.

BCT

FITWELL BIG WALL TREK BOOTS

Well after absolutely astonishing service of almost 3 years, I have to say a partial goodbye to my FITWELL BIG WALL boots because the Vibram soles are almost bare and the uppers are starting to fail on me-EVER SO SLIGHTLY!!!

BUT!!!! this is only after wearing them EVERY DAY for almost 3 years! Hiking, camping, caving, fishing, hunting, in the snow and in the arid zones; MAN ALIVE this FITWELL BRAND rocks! No I'm not saying this because they gave me a pair of boots; no I BOUGHT THEM!

AND now I need a new pair So I decided to try something along the same lines but this time the FITWELL BIG WALL TREK.

Expertly crafted in Italy with Vibram soles just like my FITWELL  Big Wall BOOTs.

This is a super grippy but long lasting sole tread pattern from Vibram.

I know this EVENT membrane really goes the distance, in fact I reckon better than GORTEX!

The difference we see now is that there are eyelets on all the lower laces and metal lugs for the last two laces places.

The main difference is that the leather upper now reaches to the lower sole midway (instead of the rubber rand) because these boots are not intended for the super harsh side scraping big wall ascents but rather for light snow to 3 season usage. To be honest you would have seen me many times wearing my Big Wall Boots IN THE SNOW, albeit they were never intended for this activity because they are not designed for prolonged standing around in the sub zero weather.

Heavy rubber rands used where it counts for maximum friction and abrasion resistance. If you are not familiar with this type of boot construction, then let me tell you, this type of rubber is used in the construction of climbing shoes which encounter huge frictional forces and hav to last without failure against such forces. choosing to use similar construction methods for walking and hiking bots, mean that your boots will easily be able to encounter contact with rocks and other abrasive surfaces without any problems and in fact enable you to moe over tricky terrain.

Seriously thick synthetic reinforcing and accurate stitching tell the story of Italian made quality!

As the name says...............and believe me this is no idle boast by them!

FITWELL make this special inner sole that actually helps move the air around under the inner sole.

 Full event membrane lining, right up high on the tongue.

What more to say??? Do yourself a favour, the BIG WALL model has been personally blasted by me on every adventure excepting the full on snow, so there is is ZERO reason to think the BIG WALL TREK will not serve me the same.

The video Review

BCT