Bladesport chopper

[worldwood]

I doubt that's what he meant. Perhaps he was just saying that obsessing over a percentage of a degree of angle isn't very productive - that's my opinion anyway. Of course others feel differently... there are cats in MT&E who spend hours and hours comparing a 5-degree .002" edge to a 5.5-degree .003" one and vice-versa.

Overall geometry and whether or not the knife can take the beating you dish out is what probably matters most, followed closely by weight and balance. All those factors work together in any knife, large or small.

You'll find that some of these comp guys don't sharpen their knives exactly the same all the way down the blade anyway. It may be a good deal thinner and more acute near the tip for fine cuts than it is near the middle or heel for chopping. That pretty much throws math formulas out the window.

Something as specialized as a comp cutter seems a lot like a high-end guitar to me. I can buy an exact replica of Tony Iommi's favorite axe, but that doesn't mean it's going to be comfortable for me or make me sound like him.

It's awesome to have guidelines from experienced cutters and makers, but at some point you just have to work with your knife in your hand and see what happens. If the edge doesn't cut well enough, thin it out some. If it's weak, thicken it back.

That makes sense the way you put it... The way he put it.... not so much LOL

 

[JG Custom Metal Works]

I doubt that's what he meant. Perhaps he was just saying that obsessing over a percentage of a degree of angle isn't very productive - that's my opinion anyway. Of course others feel differently... there are cats in MT&E who spend hours and hours comparing a 5-degree .002" edge to a 5.5-degree .003" one and vice-versa.

Overall geometry and whether or not the knife can take the beating you dish out is what probably matters most, followed closely by weight and balance. All those factors work together in any knife, large or small.

You'll find that some of these comp guys don't sharpen their knives exactly the same all the way down the blade anyway. It may be a good deal thinner and more acute near the tip for fine cuts than it is near the middle or heel for chopping. That pretty much throws math formulas out the window.

Something as specialized as a comp cutter seems a lot like a high-end guitar to me. I can buy an exact replica of Tony Iommi's favorite axe, but that doesn't mean it's going to be comfortable for me or make me sound like him.

It's awesome to have guidelines from experienced cutters and makers, but at some point you just have to work with your knife in your hand and see what happens. If the edge doesn't cut well enough, thin it out some. If it's weak, thicken it back.

That makes sense and i appreciate that. The reason I am looking to figure out more precise angles is to shorten the learning curve. A lot of long time knife makers learned by making mistakes and years of honing their craft. They've reached a point that they can take a blade and freehand grind perfect bevels. I'm not at that point. Hell, I'm a long ways from that point. By figuring out the bevel angles and precisely defining the variables in the equation then I can improve repeatability with performance.

As far as performance is concerned, I have no illusions. You can crunch all the numbers you want but until you get out there and start chopping shit up you aren't going to know. Nothing can replace the feedback and experience you get from utilizing the tool. That doesn't mean all the propeller head stuff needs to go out the window. I'm a long time hunter(coyotes and predators mainly) and I've hunted with old school guys who have their 06' with a Bushnell 3-9x40 on it, with cheaper hunting loads, who can pull up their rifle and plug an animal on the run at 200+ yards. I prefer to load my own ammo, know the velocity/ballistics, and how to range/dope with my optic so I can make the REAL FAR shots(500yds +). Like when prairie dog hunting, talent will only take you so far. Eventually you have to work math into the mix if you want to make hits. If you can understand what's happening with the math it makes for better repeatability. It's easier to figure something out when it goes wrong and the correct for in the future. I'm trying to apply the same principals with knife making.

I'm wondering, does the link I posted(with the FFG chart) jive with your guys' findings?

 

[worldwood]

I'm wondering, does the link I posted(with the FFG chart) jive with your guys' findings?

Im a complete newbie to all this, but from what i have learned speaking to Dan, if i was making a comp knife id personally shoot for .32" thick stock, and 5.5° per side going down to about .020" at the edge.

I spent quite a while running numbers myself trying to learn a little about trig and how it works, Dan also helped explain some of it to me and i also used a college tutor to help make me understand it... I still never quite understood it fully though honestly.

Like mentioned i have one of Dan's comp knives, and i have used it quite a bit, i also have another practice comp knife in 3V at around .22 thick. I have used both a LOT now and have been able to notice plenty of differences in performance... Both are great blades, but that extra thickness gives way to better geometry at the same blade height. Now if i was going camping and was just going to be cutting firewood i may use the 3V blade more because its a couple hundred grams lighter.. But in a competition id definitely grab the Keffeler.

I got a chunk of 52100 in .265" thick stock and i learned starting at .26" you reach .020 in 1.35" at 5.5°.. I know i want .020" at the edge before sharpening and i know i want 5.5° per side.. SO i would have to use a saber grind to keep the 2" blade height.

But if i start at .31.32" it would take 2" (blade height) to reach .020" using 5.5° per side. Sounds perfect to me. So using a thinner stock but wanting the same angles mean less blade height or using a high saber grind.

Again, im new to this so dont quote me... But this is what i have gathered, it may be of use to you as well.... But Dan can really explain things way better, and he is very willing to share what he has learnt. He has got the video camera out in the past and showed me how to use online calculators and everything. I suggest giving him a call sometime. Just keep a pencil and paper close LOL

 

[dphillips]

I doubt that's what he meant. Perhaps he was just saying that obsessing over a percentage of a degree of angle isn't very productive - that's my opinion anyway. Of course others feel differently... there are cats in MT&E who spend hours and hours comparing a 5-degree .002" edge to a 5.5-degree .003" one and vice-versa.

Overall geometry and whether or not the knife can take the beating you dish out is what probably matters most, followed closely by weight and balance. All those factors work together in any knife, large or small.

You'll find that some of these comp guys don't sharpen their knives exactly the same all the way down the blade anyway. It may be a good deal thinner and more acute near the tip for fine cuts than it is near the middle or heel for chopping. That pretty much throws math formulas out the window.

Something as specialized as a comp cutter seems a lot like a high-end guitar to me. I can buy an exact replica of Tony Iommi's favorite axe, but that doesn't mean it's going to be comfortable for me or make me sound like him.

It's awesome to have guidelines from experienced cutters and makers, but at some point you just have to work with your knife in your hand and see what happens. If the edge doesn't cut well enough, thin it out some. If it's weak, thicken it back.

Just wanted everyone to know, I'm still watching this thread. My methods agree with what James says here, so I don't have any helpful input on the trig questions. Since I grind on a free handed on a work rest I don't think I have the precision needed to get involved with the trig.

This has been a very interesting thread though, and I have enjoyed it. There has been some good questions and some good insight on here.

Thanks,
Donavon

 

[JG Custom Metal Works]

Just wanted everyone to know, I'm still watching this thread. My methods agree with what James says here, so I don't have any helpful input on the trig questions. Since I grind on a free handed on a work rest I don't think I have the precision needed to get involved with the trig.

This has been a very interesting thread though, and I have enjoyed it. There has been some good questions and some good insight on here.

Thanks,
Donavon

I concur, my "trig" is going to consist of putting an angle finder against my platen and tool rest lol. I've talked with Jose Diaz and, as with all the Bladesport guys I've talked with so far, has been very helpful. I'm gonna get the chopper in the works soon.

 

[JG Custom Metal Works]

Sorry to drag this back up but I used that flat grinding chart(that I put up on post #96) tonight to figure out the angle for one of my knives and it worked great. It was a 3/16in thick, 1.5in wide, and the chart called for a 3.6 degree angle(I used 3.5). It was right on the money.

I should be starting the chopper the beginning of Sept.

 

[JG Custom Metal Works]

Alright so my first Bladesports style chopper has begun. Jose Diaz is generous enough to sell me one of his Cane Toad Chopper blanks and I wanted to do this one as a practice before I start that one. Knife steel is 0-1 and it's .25in thick. I have the handle most of the way shaped and just need to figure out where I want to set the plunge and how i want to contour the "tip." I also might need to figure out where I want to put the front lanyard hole.

If anything jumps out to you guys as things I might want to change please let me know. The actual blade profile has not been formed yet as I was going to see what you gents had to say about it. There's a little wiggle room on the handle for grinding but obviously can't add back on. It fits my hand pretty good but has a decent amount of room on it to. Should i skeletonize the handle? Also, does anyone one have any recommendations as far as a target HRC hardness for when I send it for heat treat? I had planned to send it to TruGrit(I usually use them and I get 50% off on my next batch) but am wondering if I should break down and send it to Peters because they work with Bladesport knives a lot...

Anyway here are some pics, let me know what you think.

 

[JG Custom Metal Works]

double tap

 

[james terrio]

Should i skeletonize the handle?

Probably... Grind the blade the way you want and temporarily put handles on it so you can see what the balance is like. Then if it's not tip-forward enough you can start drilling/skeletonizing/tapering the tang until it feels right.

 

[JG Custom Metal Works]

Good advice James, thanks. I will do that.

Do you have any recommendation as to what hardness I should shoot for with this guy? I've done O-1 choppers around 58 hrc in the past but I wonder if I should aim a little higher being that it will need the edge retention.

 

[M forge]

It is hard to tell from the picture how tall the handle is. I can tell you from experience I had this weekend not to make the handle of a chopper too round. The handle I designed was a little short so I made it more round/fat. It did not chop well at all.

Listen to Dan, he know what he is talking about. Donavon Phillips is also a very good source.

I too am very much a rookie at this but the guys that are the experts have been very willing to help.

 

[james terrio]

Do you have any recommendation as to what hardness I should shoot for with this guy? I've done O-1 choppers around 58 hrc in the past but I wonder if I should aim a little higher being that it will need the edge retention.

I think that's right, but I can't prove it. Ask Brad at Peter's HT, or Dan or Donavon.

 

[JG Custom Metal Works]

It is hard to tell from the picture how tall the handle is. I can tell you from experience I had this weekend not to make the handle of a chopper too round. The handle I designed was a little short so I made it more round/fat. It did not chop well at all.

Listen to Dan, he know what he is talking about. Donavon Phillips is also a very good source.

I too am very much a rookie at this but the guys that are the experts have been very willing to help.

It is hard to tell from the picture how tall the handle is. I can tell you from experience I had this weekend not to make the handle of a chopper too round. The handle I designed was a little short so I made it more round/fat. It did not chop well at all.

Listen to Dan, he know what he is talking about. Donavon Phillips is also a very good source.

I too am very much a rookie at this but the guys that are the experts have been very willing to help.

I designed the handle after the handle on this knife. The one on this bladesports chopper will have more angle in the handle though:




I've been researching a lot into designing this blade and you're right Dan, Donavon and other bladesports guys have been awesome in providing their insight. Here's a great video from Dan about handle shapes:
https://www.youtube.com/watch?v=1K5US5a68lI&noredirect=1

Does anyone know what type of edges guys are using on these knives? I would think flat bevels with a convexed edge would work great but I wonder if guys are using flat ground edges to more precisely control the angle...

I should be grinding the pre-heat treatment bevels tonight. It looks like, for a full flat grind, I will need to grind them at around 4 degrees. I'm planning on doing a 15 degree(30 inclusive) edge from there and then possibly convex the shoulder of the edge bevel a bit.

 

[M forge]

As far as the edges go it seems some guys use a hand sharpened V edge and some guys use a convex belt polished edge. Donavon uses a V edge hand sharpened to 1200 grit on a DMT and stropped on an 8000 grit diamond paste strop. Other guys do a full polish on a belt and I'm sure there are other ways also, that is just the ones I know. I think it would also depend on the steel and HT used. I do not have tons of experience but CPM M4 will take a crazy sharp edge. W2 also take an insanely sharp edge at least for what it is. Again that is just my limited experience.

I do not know what angles they use for sharpening, I know Donavon uses his eyes and feel and doesn't measure the angle. The blades I've seen and handled will easily and quietly cut newsprint, and even cut curves and shapes in it.

 

[JG Custom Metal Works]

As far as the edges go it seems some guys use a hand sharpened V edge and some guys use a convex belt polished edge. Donavon uses a V edge hand sharpened to 1200 grit on a DMT and stropped on an 8000 grit diamond paste strop. Other guys do a full polish on a belt and I'm sure there are other ways also, that is just the ones I know. I think it would also depend on the steel and HT used. I do not have tons of experience but CPM M4 will take a crazy sharp edge. W2 also take an insanely sharp edge at least for what it is. Again that is just my limited experience.

I do not know what angles they use for sharpening, I know Donavon uses his eyes and feel and doesn't measure the angle. The blades I've seen and handled will easily and quietly cut newsprint, and even cut curves and shapes in it.

Dan had a thread up a while back(I found searching) where he stated he does a 30 degree inclusive edge on his competition cutter. I bet it was m4 steel though. I'm wondering if I can get away with an edge that acute with O-1.

 

[james terrio]

I'm wondering if I can get away with an edge that acute with O-1.

Just like any other knife, there's only one way to find out If it chips or lays over on the 2x4 chopping, grind it back a couple thousandths to thicken it up a little and try again.

 

[JG Custom Metal Works]

Just like any other knife, there's only one way to find out If it chips or lays over on the 2x4 chopping, grind it back a couple thousandths to thicken it up a little and try again.

LOL good point.

I finished the pre-heat treat bevels last night, here's a couple pics.





I still have a little profile work to do and will probably put in a sharpening notch. IIRC bevels were right at around 3.8 degrees and went just under full height. I'm thinking I will probably cut some holes in the handle to lighten things up.

ETA: Pre-heat treat work is done:

 

[M forge]

James is right on, chop with it and see what happens. I have a Benchmade M4 chopper that was graciously loaned to me, and I have a W2 chopper I made. The W2 knife holds up well but I have to put a little more angle on it than the M4 knife.

Try it out, sharpen it, try it again. To me that is part of the fun and you will probably need practice sharpening these beasts to get what you want from it.

 

[JG Custom Metal Works]

I've hit a little bit of a snag guys. I planned on using horse stall mat for the handle but I'm wondering what to use for pins. I spoke with Jose Diaz today(my Cane Toad Chopper is getting shipped tomorrow) and he said that rubber O-ring material works good for pins. The problem is that I already drilled the pin holes out to 1/4in thinking I would just use stainless steel pins. The only O-ring material I could find was 3/16in.

Another issue is that with the Cane Toad Chopper Jose is sending me the entire tang is skeletonized aside from a lanyard hole and a 1/2in(I think) hole towards the front. I'm not sure if I should even bother with pins or just use a tube for the lanyard and a bunch of G-Flex. Here's a pic of it:



Anyone have any ideas as to what I should use for pins? Hell, I think some of the guys might not even use pins. If i use hard pins I wonder if it will effect(create a hot spot) the grip when it's squished?

 

[dphillips]

Glad to see your project is moving along. Looking good.
Bladesports requires at least one pin through the handle. As far as the hot spot you mentioned, the rubber I use doesn't compress enough for the pin to be felt. I put two in mine. One at the front for a lanyard and one about 2/3 the way down the handle. And I use 5/16" tube for both.

Hope that helps.
Donavon