Blade height/thickness suggestion for stock removal method

einsteinjon

einsteinjon

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I am interested in purchasing some CPM 3V direct from Crucible and got a quote today. But I need a little advice first as far as stock width goes. I plan to use the stock removal method and end with about a 2" blade height on a 3/16" and/or 1/4" chopper, each about 18" OAL with about a 12" blade length. When grinding, will using a 2" wide piece of stock work? Or will some of the width be lost to grinding such that I should start with 2-1/2" wide stock? And for the record, I probably won't make it for awhile, but want to buy the 3V now "just in case." :p

Also if anyone has suggestions for blade thickness on this size (3/16" or 1/4"), I'd love to hear about it. I'm kind of interested in making one of each, but then I'd have to buy twice the stock, which can get expensive. I was also thinking about going half and half on the stock with someone else if I buy both (18" lengths each of whatever I choose)...just to throw that out there.

Thanks! :thumbup:
 
Crucible can sell you a mixed batch but they will be in 36" length. At least that is what I always buy. As far as the height you will lose a bit of material when shaping and grinding to finish but how minimal it is depends on your experience, approach, finish, and design. Personally I would recommend getting it a bit wider at 2.25 or even 2.5" providing you have access to a bandsaw or a grinder with a decent motor to hog of the material to shape your blank. This is of course if it HAS to be finished at a 2" blade depth. However, I would draw your design out first and take measurements and then buy accordingly but remember it is easier to take steel away providing you have the tools but putting it back.... not so much. You may find it a little difficult to force your design into the billet you ordered. Also, being new you will make mistakes so I urge you to practice on another more affordable steel or material first whether working with files or a grinder. As far as the thickness goes I think 3/16" is enough. Heck I think 5/32" is fine for a wide 12" blade. It also depends on your grinds and desing; flat, hollow, convex, full height, full tang, etc. I get tired swinging heavy blades but that's just me.
 
Ok that is making sense. I do already have the blade drawn out...I'll try to take a pic of the drawing later. I also have bought some pieces of wood that I am going to practice on. I plan to buy some cheapie steel from the hardware store for the step after that too.

So I guess the question may be a little difficult, but I'd say I'd rather have a slightly taller than 2" blade than shorter. So if I were to start at say 2-1/8" (I should be able to cut that down from 2-1/2" ok), there is decent chance I will end at 2"? Basically if I really want it toward the 2" height, starting it at 2.25" or 2.5" might yield too much height and I'd have to thin it out to get it down to 2"...ok now I'm just thinking "out loud"...feel free to chime in. Thanks!
 
Technically as long as your drawing can fit in a 2"X18" box it will be fine. The differences may be negligible but I know most of us noobs make mistakes so I try to compensate a little. Also, I just personally prefer more breathing room and recommend it for other beginners. Common mistakes for beginners can be grinding the edges too thin, too thick, and grinding into the spine. Sure, there's more mistakes we can make but these will keep you busy. Good idea on practicing on the wood and mild steel. I may have a 2" wide 18" long 1/4 incher billet around somewhere for you. I'll have to check but I would try 3/16" in another material first. Your grinding and chosen grind heaights will definitely affect the overall weight. What equipment will you use and how will you grind it (flat, hollow, etc)?
 
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lets just say that the first time i ground out a blade, the knife started as 1" wide....lol, and the end product only ended up 1/2" wide ! Not on purpose of course !
 
A friend of mine has a bandsaw that I'll be able to shape it with, and I recently got a Craftsman 2x42 belt grinder. I'm thinking of doing convex.

And I'd definitely be interested in hearing if someone has a billet in the size I'm shooting for (3/16" or 1/4"), like Murdok said :thumbup:
 
Here's a pic of what I'm thinking if it helps for anything. I realized after taking it that putting a ruler next to it may have helped, but like I said before it's 18" OAL, 12" blade length and 2" blade height.

HPIM1388.jpg
 
Definitely try some desings on other materials (steel, wood, etc) before grinding on the 3V. It will help determine what is more comfortable for you and help you perfect your grinding. Also try some smaller blades and work your way up to this one. It will help A LOT. I would still recommend getting something just a bit wider than 2" so you have some breathing room and when you profile the blank leave the edge at least 1/16" or so wider than desired just to be safe and depending on your skill level (more skill you can cut closer to your to the desired specs). Also, so you know you will catch some heat for the trademark Busse talon hole near the choil. Definitely finish some smaller blades in cheaper steel and work your way through and go slow.
 
Murdok72605 said:
Definitely try some desings on other materials (steel, wood, etc) before grinding on the 3V. It will help determine what is more comfortable for you and help you perfect your grinding. Also try some smaller blades and work your way up to this one. It will help A LOT. I would still recommend getting something just a bit wider than 2" so you have some breathing room and when you profile the blank leave the edge at least 1/16" or so wider than desired just to be safe and depending on your skill level (more skill you can cut closer to your to the desired specs). Also, so you know you will catch some heat for the trademark Busse talon hole near the choil. Definitely finish some smaller blades in cheaper steel and work your way through and go slow.
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I didn't know that was trademarked. Thanks for the head's up. I don't know that I would ever sell anything, but if I do in the future I'll get rid of that. Ok it sounds like if I pick up some stock I'll go with the 2-1/2". I don't plan on grinding on it right away, but I'd like to have it laying around.
 
I think 3/16 is plenty thick enough for a chopper, you should draw in your plunge line, I personally would skip the convex and go straight flat grind. or you may mean flat with a convex edge??

If you have a 2" blade height it looks like you got a bit of handle sticking above the blades and some steel below the blade. Draw two parallel lines 2" apart and see it ti fits.
 
Also If I may add. With your 2 inch blade according to your drawing your handle will only be about an inch wide. just seems kinda thin to me. just my 2 cents.

Bennie
 
Patrickknives said:
I think 3/16 is plenty thick enough for a chopper, you should draw in your plunge line, I personally would skip the convex and go straight flat grind. or you may mean flat with a convex edge??

If you have a 2" blade height it looks like you got a bit of handle sticking above the blades and some steel below the blade. Draw two parallel lines 2" apart and see it ti fits.
Click to expand...

I was actually thinking full convex. How come you are suggesting flat grind? Is it easier?

The handle does stick up above the blade, I was planning on tweaking it if I went with a 2" billet. I cut out a 2"x18" strip of cardboard and put it on top to see. Same problem with both ends of the handle. I'll probably go with 2-1/2" anyway though.

heatheninthehills said:
Also If I may add. With your 2 inch blade according to your drawing your handle will only be about an inch wide. just seems kinda thin to me. just my 2 cents.

Bennie
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The handle is about 1" wide at the front and almost 1.5" at the back. That was on purpose b/c I didn't want a belly...personally I find this more comfortable for chopping. Do you think it just looks funny or do you think there may be a performance issue?

Thanks all!
 
I've managed to go edge to edge losing only about 1/32" in width on a piece of CPM S30v bar, but I would not recommend it.

The problem I've had with CPM stock is that the sides of the stock comes rather pitted (due to the particle metallurgy process and whatnot) and so when you plan to have a knife that's .130" thick, which is on the line of being to thin, you end up having to make it thinner in sanding it down flat.

In any case, as far as stock removal steel goes, CPM steels are the best
 
White Rabbit said:
I've managed to go edge to edge losing only about 1/32" in width on a piece of CPM S30v bar, but I would not recommend it.

The problem I've had with CPM stock is that the sides of the stock comes rather pitted (due to the particle metallurgy process and whatnot) and so when you plan to have a knife that's .130" thick, which is on the line of being to thin, you end up having to make it thinner in sanding it down flat.

In any case, as far as stock removal steel goes, CPM steels are the best
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The sales rep I talked with at CPM said the 3/16" stock comes in at .207"-.227" and will finish down to 3/16". Is that accurate?
 
einsteinjon said:
The sales rep I talked with at CPM said the 3/16" stock comes in at .207"-.227" and will finish down to 3/16". Is that accurate?
Click to expand...

I ordered a bar recently from US knifemaker supply that was supposed to be .130" and I measured it with calipers before sanding and it was .136", so its pretty close. It usually comes down to about .125" or so by the time I'm done with polishing and stonewash.

I've never used their .188 stock before but I'm sure it'd be about the same. Its not a huge issue, it just bothers me a little to have an edc blade thiner than .125".
 
einsteinjon said:
The sales rep I talked with at CPM said the 3/16" stock comes in at .207"-.227" and will finish down to 3/16". Is that accurate?
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Yes it is pretty accurate. If anything you may have it finished just a bit above 3/16". At least that has always been my experience.
 
Cool, I'd rather have it above 3/16" than below...that's kind of what I thought since if I got a piece that was .227", I can't imagine losing so much that I get knocked below .187". Although I have no experience yet :)
 
Answere your PM reguarding flat vrs convex grind

I have limited experience with a convex grind but I think on a 2" blade it will be very difficult to do without some sort of jig to hold the belt on each side the same.

By hand a convex grind is done on the slack part of the belt. The angle or curvature of the grind will depend on the width of the blade and the pressure on the belt. The belt will want to grind the top and bottom edge before it grinds the middle. I guess you would chase the curvature up the blade from the edge.

A flat grind is done against the platten and you have a angle that can be repeated on each side, the pressure will not change the grind. For that reason I think a flat grind is easier.

The reason I really like the flat grind over others is it leaves some metal in the mid section of the blade which I feel is stronger, less flex. and can be taken to a narrow edge depending on what you want the knife to be used for. I would suggest about 0.04" edge for a chopper from such a prime steel.



Patrickknives said:
I think 3/16 is plenty thick enough for a chopper, you should draw in your plunge line, I personally would skip the convex and go straight flat grind. or you may mean flat with a convex edge??

If you have a 2" blade height it looks like you got a bit of handle sticking above the blades and some steel below the blade. Draw two parallel lines 2" apart and see it ti fits.
Click to expand...
 
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