Cast-in-place aluminum knife handles

[RX-79G]

I had seen a video of a US company that makes inexpensive kitchen knives this way, but went digging and found the Ruana line of knives and the Murphy combat knife.

Casting aluminum around a blade tang appears to be an extremely solid way to make a knife. Aluminum is strong, light, resists corrosion and has a "warm" feel that makes people like to use it for pistol grips and folder scales. Compared to just about any other material of encasing a blade tang, it is the strongest and most rigid. And aluminum melts between 865 and 1240F, so it isn't going to structurally damage the blade steel alloy. Aluminum is easy to machine and polish. And being low density, it preserves a decent balance to the finished knife.

Due to the good bond with the steel and high rigidity of the aluminum, I would expect a hidden tang knife with cast-on handles to be stronger than a full tang knife with any handle material bonded to it. If the tang isn't allowed to flex, it can't be broken unless the aluminum breaks first (which ain't easy).


For a hard use it would appear that a cast-on aluminum handle over a properly designed tang would offer tremendous strength and utility. What do you think?

http://www.ruanaknives.com/how.aspx

 

[Insipid Moniker]

I won't purchase a fixed blade with a metal handle due to comfort and heat conduction issues, not to mention grip. I don't know enough to say if the cast aluminum would be stronger, but it wouldn't appeal to me in the least.

 

[Blue Sky]

I don't think aluminum should be considered "warm" in any way. Titanium is considered "warm" in the hand due to it's low heat conductivity. Your hand warms the immediate area of your grip quickly because the heat is conducted away from the area very slowly. Feels warm. Aluminum is quite the opposite, it has high heat conductivity. On a cold day aluminum is going to drain the heat from your hand at a high rate, that's going to feel cold.

They do look good, and are probably strong and durable too.

 

[RX-79G]

I won't purchase a fixed blade with a metal handle due to comfort and heat conduction issues, not to mention grip. I don't know enough to say if the cast aluminum would be stronger, but it wouldn't appeal to me in the least.

Have you ever used a metal framed handgun or aluminum knife like Gerber Mk II? Aluminum does not conduct hot and cold like brass or steel. Aluminum "warms to the touch" more easily because it has a lower volumetric heat capacity.

And the grip comes from whatever texture you apply - it doesn't have be be smooth, bare metal. It can be knurled, coated, bound in leather, etc.

 

[Scurvy092]

Have you ever used a metal framed handgun or aluminum knife like Gerber Mk II? Aluminum does not conduct hot and cold like brass or steel. Aluminum "warms to the touch" more easily because it has a lower volumetric heat capacity.

And the grip comes from whatever texture you apply - it doesn't have be be smooth, bare metal. It can be knurled, coated, bound in leather, etc.

Aluminum framed guns still have grips on them and the stippling on the front and back strap area reduces surface co tact.

Aluminum is an excellent conductor of heat which is why its used in so much cookware. It cannot retain heat very well which is there the low heat capacity comes into play. So if its cold outside and you are holding a piece of aluminum, it will literally suck the heat out of your hand with a quickness.

 

[Insipid Moniker]

Have you ever used a metal framed handgun or aluminum knife like Gerber Mk II? Aluminum does not conduct hot and cold like brass or steel. Aluminum "warms to the touch" more easily because it has a lower volumetric heat capacity.

And the grip comes from whatever texture you apply - it doesn't have be be smooth, bare metal. It can be knurled, coated, bound in leather, etc.

I've handled aluminum in cold weather and it gets painful pretty quickly. Much more so than wood, kraton, FRN, micarta, etc. The grip issue is more that when you make a metal handle grippy it all too often becomes more abrasive than I like. These things don't matter as much to me on folders because I'm usually using them quickly and then storing them in my pocket where my body heat will do the job of keeping them warm, but both factors apply to fixed blades and aggravate each other. If my hands are already cold, I don't want a handle that is slick because I'll have lost some degree of manual dexterity. I also don't want an abrasive handle as that will contribute to raw, chapped hands.

I think that it's possible to address all these concerns with various design elements, but I rarely see manufacturers do so. That means it's just easier and safer for me to stick with handle designs and materials that don't require work arounds.

 

[B34NS]

I've handled aluminum in cold weather and it gets painful pretty quickly. Much more so than wood, kraton, FRN, micarta, etc. The grip issue is more that when you make a metal handle grippy it all too often becomes more abrasive than I like. These things don't matter as much to me on folders because I'm usually using them quickly and then storing them in my pocket where my body heat will do the job of keeping them warm, but both factors apply to fixed blades and aggravate each other. If my hands are already cold, I don't want a handle that is slick because I'll have lost some degree of manual dexterity. I also don't want an abrasive handle as that will contribute to raw, chapped hands.

I think that it's possible to address all these concerns with various design elements, but I rarely see manufacturers do so. That means it's just easier and safer for me to stick with handle designs and materials that don't require work arounds.

Inversely out in the desert heat, aluminum just "stays" hot.

My only issue with aluminum handles would be lateral stress, aluminum like Ti, will take tons of abuse and then without warning fail.

 

[rustyrazor]

agreed on handling aluminum in cold/hot weather. in my experience, cold aluminum makes cold hands, not the other way around and hot aluminum wont hurt your hands at all... because you'll likely put it down until it cools. it works fine as a hard use material, but it definitely isn't "warm". I'd prefer a molded FRN handle over aluminum.

 

[POCEH KOCEB]

Have you ever used a metal framed handgun...
And the grip comes from whatever texture you apply...

Have you ?
Aluminum frame guns usually have non-aluminum grips. Here is my gun:

Aluminum pistol grips are popular in IPSC because they are light, that's it, other than this, there are only few grips that I can think of that are aluminum, with semi-aggressive texture, mostly for Sig Sauer, CZ models and some pimped-up 1911s. In general, they are more good looking than practical.
You can powder coat aluminum handle or apply some other type of coating, but eventually with usage, coat goes away and bare aluminum will stain your hand.
Also if dropped on hard surface, aluminum will stay abrasive and unless you smooth it out, it won't be very comfortable for holding and working.
Knives with aluminum grips are matter of choice of course, IMHO I would not use one for number of reasons, some of them are already mentioned in the thread.
Also, aluminum expands differently than steel and if you live in hot areas, as I do - in Florida, and have such knife outside for a 30-40min during summer, taking direct hit from the sun, two things are guaranteed: You won't be able to hold the knife and the aluminum will expand enough so in the long run will most likely separate from the tang . Of course this is general statement, it depends of handle design and so on, but again: I would not use a knife with such design and I don't know many hunters or people around me that would prefer such knives.

Why are you asking about opinions, are you planing on purchasing such knife ?

 

[Jody744]

We have a bunch of Rada knives, from childhood, yard sales, NIB, etc.
No issues with cold handles in winter, because of indoor kitchen use.
Best value per $ imho. Wife loves their paring knives...

 

[bpeezer]

Due to the good bond with the steel and high rigidity of the aluminum, I would expect a hidden tang knife with cast-on handles to be stronger than a full tang knife with any handle material bonded to it.

I would not think of aluminum as a "high rigidity" material. Steel is more rigid than aluminum. As an example, 1095 steel heat treated and tempered has a modulus of elasticity ~3x that of 6061-T6 aluminum. I would definitely trust a full tang knife over a cast handled knife. Aluminum and steel also have different rates of thermal expansion, which doesn't inspire confidence during cyclical thermal loading.

The beauty of full tang knives is that the handle doesn't actually carry the load. The handle slabs are mostly just there to provide a comfortable grip, while the steel tang provides support.

 

[jfk1110]

I know that during WW 2 the leather handles on kabar rotted away in the Pacific campaign and naval machinists would redo knives for fellow soldiers with scavenged materials whenever possible. Interesting history. Kabar makes a repro of the E.W.Stone knife and offers a little insight on their site if your interested

 

[RX-79G]

I would not think of aluminum as a "high rigidity" material. Steel is more rigid than aluminum. As an example, 1095 steel heat treated and tempered has a modulus of elasticity ~3x that of 6061-T6 aluminum. I would definitely trust a full tang knife over a cast handled knife. Aluminum and steel also have different rates of thermal expansion, which doesn't inspire confidence during cyclical thermal loading.

The beauty of full tang knives is that the handle doesn't actually carry the load. The handle slabs are mostly just there to provide a comfortable grip, while the steel tang provides support.

1/8" thick steel is not stiffer than a 1/2" aluminum and steel laminated together. Nor is FRN as stiff as aluminum:

This is what happens when your handle material does not support the underlying tang:

On full tang knives the handle doesn't carry the load, so the knives weak point is often the the narrowest part of the tang or the furthest forward pin hole in the tang. The strength of full tang knives is entirely dependent on how many holes there are, where they are and what support the scales can provide to prevent the tang from flexing.

My only issue with aluminum handles would be lateral stress, aluminum like Ti, will take tons of abuse and then without warning fail.

Aluminum is so much stronger than most handle materials that talking about it failing doesn't make much sense. Pick up a 1/2" bar of aluminum and try to get it to break with any tool and you'll be floored by how it doesn't act like how you're describing. It will bend long before it cracks. Even thin walled aluminum bicycle frames don't break all at once.


I'm interested in molded on aluminum handles because they fairly inexpensively do what full tangs do not - make it impossible for the handle to fail before the blade. And the heat issues (which the many bare metal handled Gerber and other knives out there suggest aren't issues) are most easily dealt with by coating or wrapping the aluminum. I've owned handguns with aluminum frames and grips. I've also owned one (Steyr GB) with and steel frame coated with grip paint. 0.5mm of plastic paint is really all the insulation anyone would ever need.

And the process can be done both on a factory level and by individuals with basic tools. I am considering it for the knives I make.

 

[bpeezer]

1/8" thick steel is not stiffer than a 1/2" aluminum and steel laminated together. Nor is FRN as stiff as aluminum:

This is what happens when your handle material does not support the underlying tang:

On full tang knives the handle doesn't carry the load, so the knives weak point is often the the narrowest part of the tang or the furthest forward pin hole in the tang. The strength of full tang knives is entirely dependent on how many holes there are, where they are and what support the scales can provide to prevent the tang from flexing.

Every example you provided was not failure due to the material weakness of steel, but rather failure due to structural design of the blade. Those failed at holes or thin hidden tangs. These are textbook examples of design elements causing stress concentrations in a piece under load.

If you do make aluminum handled knives, I would be highly interested in seeing some failure testing. I do not welcome lofty claims about miracle solutions, but I will readily accept irrefutable evidence that demonstrates superiority of a certain solution over the alternatives.

 

[jfk1110]

Forgot to add the materials used was mostly aluminum from Japanese zeroes.

 

[RX-79G]

Every example you provided was not failure due to the material weakness of steel, but rather failure due to structural design of the blade. Those failed at holes or thin hidden tangs. These are textbook examples of design elements causing stress concentrations in a piece under load.

If you do make aluminum handled knives, I would be highly interested in seeing some failure testing. I do not welcome lofty claims about miracle solutions, but I will readily accept irrefutable evidence that demonstrates superiority of a certain solution over the alternatives.

I agree - the structural design of full tang knives is the problem, not the steel itself. Taking a piece of good steel and drilling holes in it, then bonding a flexible scale to each side is not as strong as other methods.

I'm not suggesting aluminum is a "miracle solution". I'm saying that embedding a wide tang in a highly rigid material (metals, fiberglass, micarta, CF) is much stronger than making a leaf-spring type sandwich held together with low shear strength glue and pins. As you bend that sandwich, the scales don't do anything to support the tang, so the tang breaks where it is weakest - like the pin holes.


Cast handled knives have been around since before WWII, so it should be easy to find stories or photos of a Kabar, Gerber, Rada, E.W. Stone, Parker, Lifeknife, 1918 trenchknife, Ruana or the like that cracked or bent enough to break the knife tang. I've looked, and come to the conclusion that a steel tang embedded in metal is so much stronger than even the ricasso that there is no way for it to break before the exposed blade itself.

If you can find a broken one, I'd love to hear about it.

 

[craytab]

I won't purchase a fixed blade with a metal handle due to comfort and heat conduction issues, not to mention grip. I don't know enough to say if the cast aluminum would be stronger, but it wouldn't appeal to me in the least.

These are my feelings on the subject as well.

 

[RX-79G]

These are my feelings on the subject as well.

Even though those issues can be fixed with a simple coating?

 

[craytab]

Even though those issues can be fixed with a simple coating?

Yup.

I prefer full tang with Micarta, G10, FRN (or the like), or kraton over any metal, "simply" doctored or not. I would not even consider a metal handled fixed blade. IM summed it up nicely again:

I've handled aluminum in cold weather and it gets painful pretty quickly. Much more so than wood, kraton, FRN, micarta, etc. The grip issue is more that when you make a metal handle grippy it all too often becomes more abrasive than I like. These things don't matter as much to me on folders because I'm usually using them quickly and then storing them in my pocket where my body heat will do the job of keeping them warm, but both factors apply to fixed blades and aggravate each other. If my hands are already cold, I don't want a handle that is slick because I'll have lost some degree of manual dexterity. I also don't want an abrasive handle as that will contribute to raw, chapped hands.

I think that it's possible to address all these concerns with various design elements, but I rarely see manufacturers do so. That means it's just easier and safer for me to stick with handle designs and materials that don't require work arounds.

 

[ron_m80]

If you want abl better argument for aluminums rigidity and duty worthyness why not mention the Geber Mark 1's? And they saw plenty of duty in hot weather too.

Don't forget Mr. Richtig cast aluminum handles as well, on some of his knives.

-ron