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Paul Carter

Smoke colored 1084 knife

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Here is a knife I made from 1084. It's just under 12" long with a 6.5" blade. It's 2" wide and 3/16" thick. Hardness is between 60 and 65 RC. I etched in coffee for the smoke color. Handle wood is Cocobolo in the middle and Kingwood on the ends. I used copper pins in the Cocobolo and brass in the Kingwood, and blue liner material in between. It weighs about a pound. The sheath is the first one I made from scratch. I call it the "Carter Cutter". It's also been Cryo treated since I'm a Cryo treater.

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Edited by Paul Carter

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Hi Paul

 

This is a very busy knife and not really my taste. A lot of this is related to my tastes but I’ll give you my 2c FWIW.

 

Firstly the workmanship looks very good (other than the small chip-out you got on one scale at the butt but c’est la vie). Your pins are nicely spaced though the lanyard hole is very close to the edge and the pins look a little large. I suspect you aligned the wood grain on the handle the way you did to prevent the guard/butt splitting at the edges but these sharp changes in direction interferes with the flow of the handle to my eye. Your fit appears very good. It’s a bit difficult to see the blade with the smoke colour but it looks fine.

 

The sheath looks well made but again is very busy with the picture on it.

 

I hope this helps but feel free to ignore any/all of it.

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Hi @Paul Carter

 

As Charles said there is a lot going on.

 

Alot of it is very good in execution but not my style. Sometimes we have all these ideas that we want make but this piece feels like you've tried to put all of them all into one knife. 

 

I can appreciate the amount of time spent on this project, so thanks for sharing. 

 

 

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Charles and Chris, thanks for replying. I appreciate your comments and those kinds of opinions are what I'm looking for. It's good to get perspective from other bladesmiths. A little history on some of what you two touched on.

I first designed a knife like this for myself. I drew it out on a piece of steel and cut it out. I really like the look so I use it for various chopping and cutting needs. I showed it to my cousin and he had to have one, so I made him one and sold it to him. A friend and customer of mine saw my cousins knife and wanted one, so I made and sold him one. Then another friend wanted one so that' was #3. Then another one wants one. So for me anyway, it seems to be popular since out of 5 knives I have sold, 4 have been of this style.

 

I agree on the grain direction change on the handle. The only reason it is like that is because I cannot find 2" wide scales. Everyone I check with sells 1.5" scales so that is why I had to cut a pair of scales in half and use them on the front and rear. If anyone knows of where I can buy 2" wide wood[preferably Cocobolo] scales, feel free to let me know as this handle is a lot of work to complete the way it is. I have about 11 hours in the handle alone. I would much rather use just a pair of scales.

 

Charles, good eye on the chip in the pin hole. I've been using duct tape on the wood to try to prevent it, and it works most of the time, but still sometimes I get break-outs. Is there a way to prevent this? Thinking about it now, I suppose I could just drill against another piece of flat wood. I'm an engine machinist and Cryo treater by trade so I can't help but make the pins equally spaced and centrally located. That's just the machinist in me. Thanks for noticing!

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Hey @Paul Carter, your welcome. If you selling them the  onvisouly people like them so go nuts.

 

As for the chip out; If you can get over sized wood a small chip out with be removed with grinding/shaping, or as you suggested having it flat against another piece of wood works fine also. 

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For wider scales, don't buy scales.  Get planks or turning blanks and cut them yourself.

 

https://www.woodcraft.com/products/cocobolo-2-x-2-x-24

 

https://www.bellforestproducts.com/thin-stock-lumber-1_2/?gclid=EAIaIQobChMI3NPZjMy45wIVgYCfCh2gnwX8EAQYAyABEgIA_vD_BwE

 

That last place has 1/2" x 3 x 24" for $38.  That's quite a few scales, especially if you have a bandsaw you can split it down the middle with.  

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I rather like the alternating grain direction. 

I'd get rid of the hump in the spine, and drop the point a bit to be more in line with the center of the handle. 

I'd like to know how you got the blade so hard yet functional, the cryo? My results are not nearly as good. 

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Alan, thank you for the links!

 

Michael, the Cryo treat does a lot of good for the blade. Most importantly, it finishes off the heat treat. What I mean by that is when heat treating, not all Austenite is converted into Martensite. This retained Austenite creates solid voids within the steel. If a blade breaks, it will break where the most Austenite crystals are conglomerated. Think about them like marbles in a wad of clay. It's all one solid mass, but the marbles are not part of the clay, so if you pulled on the clay, it will rip apart where the most marbles are located. That is the weakest point. When you take the steel down below -240°f[Cryo is -320°f], the retained Austenite finishes converting into Martensite. Now you've eliminated all the marbles in the clay, so to speak, and now have one solid mass without solid voids within. In the process of converting the retained Austenite to Martensite, it is possible to gain a little bit of hardness. Usually 1-3 points on the RC scale, depending on how good the initial heat treat was.

Cryo also relieves any and all stress within the blade.

In the process of realigning the molecular structure, Cryo also makes the surface finish microscopically smoother so you have more area to hold a cutting edge and absorb wear, so they hold an edge longer.

I Cryo treat every blade I make and have never broke one.

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This is interesting. I've never heard of cryo treatment before. Do you have any links to info about it?

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I want to try cryo treatments sometime, specifically for my 14C28N blades. 

I know it works because everybody including the manufacturer says so, but I find it very difficult to comprehend that changes will occur in the blade at those temperature...

A glowing hot blade, no problem, a frozen blade and the mind boggles....

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12 hours ago, Gerhard Gerber said:

I want to try cryo treatments sometime, specifically for my 14C28N blades.

 

14C28N (and several other stainless alloys) really require cryo to get best performance.  13C26 can be finished off in the freezer to gain a couple points of hardness.  And while it certainly won't hurt to use cryo on 1084, it probably doesn't do a whole lot IF you've done the rest of the HT properly, as retained austenite is more of a high-alloy hypereutectoid thing.  In the event the 1084 was quenched from too high a temperature it might have some retained austenite, of course.

 

The following articles will make your brain sweat, but they get the idea across, particularly the first one:

https://knifesteelnerds.com/2018/12/03/cryogenic-part1/

https://knifesteelnerds.com/2018/12/10/cryogenic-processing-of-steel-part-2/

https://knifesteelnerds.com/2018/12/17/cryogenic-processing-of-steel-part-3/

 

And for the Sandvik steels and nitrogen alloys, these two:

https://knifesteelnerds.com/2019/03/04/all-about-aeb-l/

https://knifesteelnerds.com/2019/09/23/nitro-v-its-properties-and-how-to-heat-treat-it/

 

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Whacko Crazy.jpg  Cryo causes my brain to freeze!!!!!!!!!roflmao.gif

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13 hours ago, Gerhard Gerber said:

... but I find it very difficult to comprehend that changes will occur in the blade at those temperature...

A glowing hot blade, no problem, a frozen blade and the mind boggles....

I understand the struggle, but what you have to come to understand is that we humans live in a very narrow temperature band.  The rest of the universe continues to move about and do it's thing, at varying rates, all the way down to -273C.  So, from the molecular/atomic point of view of the steel, room temperature is still quite warm.

 

To put it another way, room temperature to the steel is sort of like a +300C tempering oven to you.

Edited by Brian Dougherty
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20 hours ago, Paul Carter said:

Alan, thank you for the links!

 

Michael, the Cryo treat does a lot of good for the blade. Most importantly, it finishes off the heat treat. What I mean by that is when heat treating, not all Austenite is converted into Martensite. This retained Austenite creates solid voids within the steel. If a blade breaks, it will break where the most Austenite crystals are conglomerated. Think about them like marbles in a wad of clay. It's all one solid mass, but the marbles are not part of the clay, so if you pulled on the clay, it will rip apart where the most marbles are located. That is the weakest point. When you take the steel down below -240°f[Cryo is -320°f], the retained Austenite finishes converting into Martensite. Now you've eliminated all the marbles in the clay, so to speak, and now have one solid mass without solid voids within. In the process of converting the retained Austenite to Martensite, it is possible to gain a little bit of hardness. Usually 1-3 points on the RC scale, depending on how good the initial heat treat was.

Cryo also relieves any and all stress within the blade.

In the process of realigning the molecular structure, Cryo also makes the surface finish microscopically smoother so you have more area to hold a cutting edge and absorb wear, so they hold an edge longer.

I Cryo treat every blade I make and have never broke one.

 

There is a bit to unpack here, but I can't really let it go.  As Alan mentioned, 1084 isn't really going to get any benefit from cryo if it is done right.  Quenched from the proper temperature, you should have about 99% or so conversion from austenite to martensite by 100 *F.  Some argue that the martensite finish temp for 1084 is about 100 *F, some say there never really is a martensite finish - you just keep getting closer and closer to 100%.  Other alloys, such as the 14C28N mentioned, really do need it as the martensite transformation finishes at a lower temp.  Next, a blade is not really likely to fail because austenite is terrible.  It will fail in the martensite because it is brittle, whereas the austenite will bend.  Austenite isn't too great at impact toughness, but that really isn't that much of a problem for most blades (since most blades are more knife like than sword like and such).  When the martensite has failed, the austenite will rapidly fail too, as there is much less of it left to hold the load.  It is also possible that austenite can cause a stress riser/concentrator within the steel structure.  Cryo does not relieve stresses in the blade.  At all.  If anything, it adds them as you will have more un-tempered martensite.  Cryo will not make the metal surface smoother.  The grains are facing all random directions, so if the FCC to BCT change is imbalanced, you could even get a rougher surface.  That is all pretty theoretical and meaningless anyway, since the difference between austenite and martensite lattices is very small.  FCC is cubic, so the length to width ratio is 1:1.  BCT is not an equal ratio, and is dependent on carbon, approximately 1:(1+.045*%C).  So for 1084 it is 1:1.000378. For BCT that is about 290.98:291.09 picometers.  For austenite the 1:1 is at 356.38 picometers.   You should be polishing your blade and honing the edge after thermal processing anyway. 

 

Edited to add:  The lengths given are assuming Fe to Fe bonds.  Obviously they will be slightly different in reality due to the other elements present in the alloy.  The point is that while FCC and BCT are different in size, the length difference between the short leg and long leg of the BCT unit cell is pretty small.  

Edited by Jerrod Miller

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