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Kreg

Geometry question

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I have someone wanting me to make a Siberian cleaver. I want it to pass the brass rod test. Thinking 1084 or maybe giving some 52100 a try.

Single bevel. What angle should I shoot for ...maybe 10* or so?? Is it possible to have a blade sharp enough to cut paper and the rod test??

Thinking 1/4 steel.....not that I think gonna have much or any difference to my question.

 

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Not familiar with a Siberian cleaver. 

"Single bevel" does this mean a chisel grind or no secondary bevel?

Just as a couple of thoughts from what I think I understand of the project. Think 80CrV2. Whatever you think you would get from 52100 is probably easier to get, and maybe better with 80CrV2 especially if the brass rod test is critical. 

I think there are too many unseen factors for someone to answer the angle issue with certainty. Depending on the design and variables it may take trial and error to reach you goals.

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Posted (edited)
26 minutes ago, Vern Wimmer said:

Not familiar with a Siberian cleaver. 

"Single bevel" does this mean a chisel grind or no secondary bevel?

Just as a couple of thoughts from what I think I understand of the project. Think 80CrV2. Whatever you think you would get from 52100 is probably easier to get, and maybe better with 80CrV2 especially if the brass rod test is critical. 

I think there are too many unseen factors for someone to answer the angle issue with certainty. Depending on the design and variables it may take trial and error to reach you goals.

Yes....no secondary bevel. Maybe I will try some80crv2 then.  The pics I have google the grind only goes up the blade an inch or so on most of em.

 

cleaver3.jpg

Edited by Kreg

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That pic does look like there's a secondary bevel on it. Most people just refer to it as the edge or the cutting edge.

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The ones made in Almazon Spain have 2 bevels. They are extremely heavy and extremely sharp. They use them for everything from cracking rib bones to dicing vegetables. I would do as they have done. 

A blade about .18- .20" thick and maybe 3 1/2" tall at the choil area with 2 bevels  that come about 1" or so up the blade.

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Posted (edited)

From the look of the photo, the bevel seems around an inch wide if the blade is 3.5". For an inch wide bevel with a 3/16" thick blade, that would make a 10.8° primary.

After a second look it seems closer to 3/4" wide...so 14.5°

Screenshot_20180619-194245.png

Screenshot_20180619-194519.png

Edited by Joël Mercier
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More complex steel like 52100 are a little hard to get the best out of without a regulated high temperature oven to use in heat treating.  The 80CrV2 is probably not a bad choice from what I've read.  From the steel that I have used for a chopper 5160 would also be good.  Both the 80CrV2 and the 5160 are easy to heat treat of a gas of solid fuel forge.  The 5160 might not hold a edge as well as the 80CrV2 but it might be just a tad tougher and easier to sharpen.

Doug

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Thanks guys....that calculator is interesting Joel. I have been  trying to avoid secondary bevels and have been making some razor sharp blades...but maybe a secondary bevel is in order here.

Maybe I should have asked what would you guys grind a cleaver at.....my initial thought was 10* per side with no secondary.

Its for my ex fiance's oldest boy....told him I would make myself one and then talk price.

You guys have talked about this brass rod test. I was envisioning smacking the spine of the blade with a hammer to cut the rod in half.

Just so happens while watching FIF last night they did a "brass rod test"

Jason Knight took a swing at some vertical brass rods....is that what you guys were referring to?

Also can some one tell me where to look for that recent 80CrV2 thread? It looked like Wes got some pretty incredible grain with his recipe.

 

cleaver4.jpg

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The real brass rod test, (disregard FIF) involves putting the sharpened blade down on a brass rod, held in a vice or fixture, as if it were a sharpening stone and pushing down on the blade until the cutting edge flexes. If it stays flexed then the blade is too soft. If it chips then the blade is too hard.

Not a dramatic as whacking the brass rod but a lot more useful and consistent.

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The brass rod test is actually done both ways by different makers.  If you do try to drive the blade into a brass rod don't use a hammer.  Use a wood mallet or a club.  If you were refering to the show from last night, 6/19/18, then I believe that Mr. Knight was hammering the blades into steel bolts; total overkill.  I use 1/4" brass rod backed up by a board.

Doug

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Last night there were several episodes, some from the first season IIRC, including both whacking bolts and brass rods.

I have to question the usefulness in chopping a brass rod as being any consistent measure of value. There would be issues of alloy content of the brass, how it was clamped and how much extended, variable amounts of force. Even if it were clamped as in the flex test there are too many variables. It actually could be seen as a test of the brass rod. It one knew the alloy of the steel and it's Rockwell hardness that is actually what it would be.

The flex test on the other hand is completely a measure of the blade itself and the reaction of the edge to the pressure needed to flex the cutting edge. It actually could be done with any grade of brass or a material other than brass since it is only the steel being tested. Brass is convenient and the edge of the blade digs into it to prevent the blade skating down the rod.

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Posted (edited)

There were multiple episodes on at my place last night. Not sure if this was a re- run or not.

They looked to be about 1/4 brass rods....then right after Doug sliced some sushi =)

Edit....looks live Vern tree'd me.

Edited by Kreg

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Pretty sure the katana was from first season.

Waiting for Doug to say,

"Your knife will.. filleeet "

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On 6/20/2018 at 12:01 PM, Kreg said:

Thanks guys....that calculator is interesting Joel. I have been  trying to avoid secondary bevels and have been making some razor sharp blades...but maybe a secondary bevel is in order here.

Maybe I should have asked what would you guys grind a cleaver at.....my initial thought was 10* per side with no secondary.

 

 

cleaver4.jpg

What do you mean when you say "secondary bevel"? I thought you were talking about a second flat grind instead of a single. that makes a sabre grind I believe. The Almazon knife is a sabre grind I think.

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Posted (edited)

If the bevel below the texture is flat and ends at the cutting edge I'd be inclined to call it a "scandi" grind. If it's flat and has a secondary I'd call it a sabre, if it isn't flat and has no secondary I'd think of it as closer to a convex grind. Of course the lines tend to blur a bit leaving some of the distinctions in the eye of the beholder. 

In that first closeup I can't tell but it looks like, from the heel partway to the tip there is a secondary but it transitions to a "scandi" as it gets close to the tip.

Edited by Vern Wimmer

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Ahhh, I think you're right Vern. 

I think this blade is a scandi. I guess. 

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Guess I will start trying to remember the scandi and sabre dealio. When I said secondary I guess the proper term would be sabre.

I will probably go with 5160....I dont have parks 50 or equivalent yet.

I am gonna try and wrap up a few blades before I start this one.

I have a big bowie thats going on handle number 3 or 4. Gonna attempt a frame handle this time.....think thats the proper term.

 

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80CrV2 is a deep-hardening steel that requires a medium speed oil, just like 5160.  Parks 50 would risk cracking it, it's too fast.

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9 minutes ago, Alan Longmire said:

80CrV2 is a deep-hardening steel that requires a medium speed oil, just like 5160.  Parks 50 would risk cracking it, it's too fast.

Thanks for the catch....makes me leary of googling anything...or fb for that matter.

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 At the risk of sounding like a salesman, that is one of the great things about this forum. Right here you have professional metalurgists, knifemakers of all types with experience full time, part time, some with every piece of equipment you can imagine and others with the most basic. Between them there is little that hasn't been done or tried. This place, while not as trendy as a lot of sites and other internet options, has real answers to almost any questions you can think of regarding forgable carbon steel and general knifemaking. It may not deal with a lot of folders or the latest and greatest stainless steel but the focus on 'smithing gives it a more down to earth quality.

Now, deliberately sounding like a salesman, I think that 80CrV2 has great merit in the world of knife making that we live in. It has been used in Europe quite a bit and now even Case is using it in the Winkler/Skinner collaboration and yet we, the individual can use it to good result with the basic equipment we use for other steels. It is even comparable with inexpensive, relative to industrial quenchants, Canola oil. What more can you really ask for? 

I think, based on experience dating to the late 70's that we are in the best era of knifemaking that I have ever seen. We have people on this forum that do things, routinely, that were considered "avant-garde " experiments years ago and they share their experience freely.

We have more tools, and the parts and designs to build them than ever before and right here we have the people who have done it to help someone else along the path.

The moral is " if you hear about it elsewhere, on the internet, on a TV show, in a bar or a barbershop. Check here before you do it. Somebody here probably knows about it firsthand.

Sorry if it sounds like a sermon from the church of Holy Forge with an anvil as a pulpit.

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Amen, Brother Vern!  :lol:

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Posted (edited)

You guys are great...for the record the thread I googled  on the 80crv2/parks  50 was from here from 2016.

This particular individual got some great grain....but then I am pretty sure he could make a great looking knife out of gum wrappers =)

Thanks again...

 

 

Edited by Kreg

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For the record the quenchant hs nothing to do with the quality of the grain. That has already been established by the heat treating/thermal cycling. The quench just quickly cools the steel to jump over, as much as possible, the pearlite stage of cooling., to get to the martensite stage when the austenite created by the hardening temperature, converts to matensite.

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10/4 I will use canola when I get to that point. I was just stating where I got the info that I thought I needed parks or similar.

The cleaver looks like a bit of grinding.....dont care to do it twice. lol

 

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Heat the canola to the point it's uncomfortable to keep your finger in, or 120-130F if you aren't into the whole "organic holistically influenced" your body is a tool, movement:D

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