WIP give away knife - concluded & winner picked

Hickman1 - You're in.

Chris & Strig - I'll answer about sub-zero+ tomorrow. #2 + another 52100 blade ht didn't turned out well, so I have been busy re-ht them while the dry-ice still around.

GAW blade handle has fresh epoxy, so I'll let it cure overnight before working out it tomorrow. Expect full harden 24hrs.
 
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Knife after sanded progression: 60, 100, 220, 400, 800, 1500 and white compound. Pictures after 1st application of tung oil.
0il9.jpg

07y2.jpg


Heat-treatment, reasons for sub-zero (temperature -70 to -85C via dry ice) and cryogenic (temp below -180C via liquid nitrogen):

First of all, I'm new at this so knife makers and metallurgists please feel free to correct & educate readers...

Steel get heated until it reaches critical temperature where carbon free from iron crystal structure (bcc). In Austenite state (soft) - carbon distributed among elements/solution. Rapid cooling will trigger shear crystalline structure (martensite transformation). Depend on type of steel & alloying, the majority % of austenite are transform into martensite structure at room temperature.

Typically martensite transformation starts (Ms) around 200C and 100% finish (Mf) any where between 65C to -150C. The un-transform austenite (calls retained austenite, RA) are dangling, which need to convert to martensite quick. Sub-zero or cryo at this stage will finish the martensitic transformation. At this point, martensite steel structure are in high stress and some weak/stress crystalline structure. Tempering will soften, hence reduce stress and convert weak crystalline into stronger form. Tempering also convert some RA into martensite too. But now, the steel has new weak/stress structure, therefore necessitate 2nd and or 3rd tempering.

For some steel (such as 52100), with time RA can stabilize into permanent structure, which no longer convertible to martensite. Which is why it's a time critical for step between quench and sub-zero or cryo and tempering.

According some research publication, cryo does more than just convert RA into martensite. Well, until I can get some LN2 to play with, I am not joy jumping for precipitate carbides and crystal packing yet...
 
Wow that turned out beautifully! I liked learning something, too. The handle looks awesome as I always pinch the blade in front of the handle when working at a cutting board. There is enough room to put a finger around even.
 
Turned out great looking! I thought I had entered this one when I voted, but must not have posted it.

The winner will have a great kitchen utility knife there!
 
All - thanks.

Bigfattyt - voted = implied in.

WIP: The handle will receives 2 more coats of tung oil and a hand finishing buff. Then I'll sharpen+test this knife in the kitchen, hopefully it performs well. Yesterday, I bought some poplar wood boards for strop base and or backing. Don't forget #3 blade is lurking behind as an alternate. Yesterday, it received the last temper. It's around 62rc. Today, I'll straighten it.
 
Choil shot. This knife will clean shaves dry facial stubble. There are 2 very small micro-chips, which I leave and eventually taken out by subsequence sharpens.
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Strops making - wood, leather, photo paper, some sample of diamond suspension. Going to make 3, 1, 0.5, 0.25, 0.1 monocrystalize and 0.1 poly diamond. Leather for 'balanced strop'.

I used an old 1um diamond strop to polish the convex bevel to almost mirror finish. That's a lot of metal on this strop. If you were using it just to strop, it will strop probably hundreds or into thousand of knives before a strop get that blacken.
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I broke the #2 blade tang (only 1.25" remain) while straightening. Well more like, I was amused at how strong this knife can support my weight - the 2 small wood block suspending the knife shifted, hence snapped. 1.25" tang is plenty strong for a handle, so I'll make this knife regardless.
 
Very nice and clean. Nice job. The finishes on the blade and handle both look very well done. I'm not sure if I missed it, but what's the grind on the blade?
 
Thanks Lone_Wolfe & Minibear464.

The blade is almost FFG with slight distal tapering toward the tip. Bevel is convex around 4mm tall with cutting edge angle around 26* inclusive.

Thickness: 1.7mm spine at heel, 1.2mm at 20mm from tip, 0.4mm behind the edge (0.015") - need to be a little bit more stout for a petty.

Also keep in mind that cpm-m4 will darken/patina with use, so mirror finish blade is not practical for a user.
 
Thanks, bluntcut for this very interesting thread. I'm impressed with your work even with less than ideal conditions, and I've learned a lot.
 
JustSomeGuy & hickman1 & 78LilRed - thanks.

WIP: The knife saw kitchen duty last night. Cut large obo/squash + vegies for 20-30 minutes. Tip cut great, heel is good but not laser. Rapid+aggressive cut always result with the blade stuck to the cutting board. Afterward this blade still push cut phonebook paper (at 45 degrees into grain). There is a trade off between laser & food release, the current edge & grind geometry balance between the 2, so it will ship out as it.

I put too much diamond suspension on strops, thus need to wait another 12hrs for them to adequately dry for shipping. A couple oil-based suspension are slow to dry.

For fun - I put on a handle for the broken tang #2 (34mm of leverage remain). G/Flex epoxy is now cured, the handle is solid - no vert nor hor tang flexes whatsoever. Honduran Rosewood is fine grain and very strong hard wood, so as cocobolo. I continue to use hidden pins because I felt it will be plenty strong for normal non-abusive uses.
8ae3.jpg
 
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Happy 4th of July everybody!!!

There are 80 posts up to 6/28 date, the number of entries are much less than 80. I wrote a quick sql rand() to generate 20 numbers between 1 and 80.

DECLARE @i int=20, @ubound float=80.0;
DECLARE @x float=rand(@ubound+datepart(ms,getdate()));
WHILE (@i>0)
BEGIN
PRINT ceiling(rand() * @ubound);
SET @i -= 1;
END

My wife executed this script one time. Here is the result (I replace line break with comma)

34 --- cautioning is the winner of the gaw, congratulation! You've until July 7th to claim this gaw, otherwise fall through to the next entry.

30, 63 (Kristopher), 65, 34
16, 38, 19, 39, 22
74, 63, 58, 61, 12
64, 61, 6, 26, 80

cautioning - Please post your claim here and send me your shipping address to flexdog 2008 ta mailg.

w6wl.jpg
 
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Oh man! Thanks Bluntcut! It has been really cool seeing this progress and learning the process. This thing looks awesome, I am very grateful. I'll send you an email now.
 
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