O1 Chopper - EDIT 6/24: finished pics added!

Sam Dean

Sam Dean

Joined
Aug 3, 2012
Messages
1,434
Hello everyone! First time posting here, but a long time lurking...

First of all, many MANY thanks to all of the contributors here. I've learned a lot!

I'm making my first real knife from O1 and I have a question about the hardness for a good working blade.

It's 18'' long, 5/16'' thick and about 2-1/4'' at the widest point. Go big or go home, right? I'm going for a good branch chopping, yard clearing camp knife.

Anyway, I've ground the shape, bevel & swedge and heat treated per the manufacturers specifications. After the first tempering draw (500 deg. for 2 hours), I checked the hardness (I have a calibrated tester at my work).

Right not it's right at Rc57.5 ±0.5

What do you all think - should I draw it at a higher temp. and get the hardness down around 55/56, or is this low enough to not worry about being excessively brittle. I know there's lots of stock, but that also means more potential for high shock loads and fractures. I plan on doing 1 more draw at 500, unless I hear some other recommendations.

Any and all comments are appreciated!

Thanks,
Sam

Oh, here's some pics.

Preliminary sketch:

O1 Model 1 Sketch by mysdnc, on Flickr

After first draw (turned it a cool purple):

WIP O1 by mysdnc, on Flickr


WIP O1 by mysdnc, on Flickr
 
Last edited:
Go ahead and do another temper cycle at 500F for 2 hours right away.

Then sharpen the edge and do some testing to see how it holds up on the stuff you want to cut. If it's a little chippy, either draw the blade again at 25 degrees higher, or thicken the edge (just dull it back and resharpen it).

57.5 is a very good balance of hardness and toughness, and O1 is a good tough steel anyway. I suspect if your edge geometry is right (mostly meaning not razor thin), you won't have to mess with the hardness much.
 
Thank you James - I appreciate your experience!

I'll go ahead and do a second draw this evening and sharpen it up tomorrow. My edge is right at .040/.045''; do you think this is a decent compromise? I'm just going by what looks right, but don't have any good working experience to judge with (yet, anyway..).

Thanks!
Sam
 
01 tempered at 450, which gives you 59 HRC or about that is not too hard with the geometry you have on this blade. 01 is used to make punches and dies, tools you can pound on. Its geared to be tough. 500 is good also; the second cycle is a good idea as suggested.

Fred
 
That's actually too thick.;)
onespdfrk said:
Thank you James - I appreciate your experience!

I'll go ahead and do a second draw this evening and sharpen it up tomorrow. My edge is right at .040/.045''; do you think this is a decent compromise? I'm just going by what looks right, but don't have any good working experience to judge with (yet, anyway..).

Thanks!
Sam
Click to expand...
 
I finished the second draw tonight, 500 deg for 2 hours - then started the finish sanding and cut out handle slabs from some hillbilly micarta I made from old jeans & t-shirts. I think my edge will finish right at .030 when I'm done. I was worried this would be too thin, but maybe not!

My goal is to get the knife finished this weekend and start on the sheath. I think I'll force a mustard patina for protection. I saw one applied with a sponge and it looked really nice. I guess you could also use PCB etching solution? I've used it to re etch Damascus blades with good results.
 
Fred.Rowe said:
01 tempered at 450, which gives you 59 HRC or about that is not too hard with the geometry you have on this blade. 01 is used to make punches and dies, tools you can pound on. Its geared to be tough. 500 is good also; the second cycle is a good idea as suggested.

Fred
Click to expand...

Yep. I temper 01 choppers at 450 and get 59 60 all the time.

IMO, you should grind the edge down a LOT from there. Remember if its 0.030 at the very edge before the edge bevel, then at the top of the finished edge bevel it is much thicker than that. You're going to have a very wide edge bevel, which is a pita to sharpen and looks like hell. I'd take it to 0.015 or 0.020 minimum. Likely I'd go down to .010" or less like I try to do all my knives. 01 is tough stuff.
 
Fiddleback said:
Yep. I temper 01 choppers at 450 and get 59 60 all the time.

IMO, you should grind the edge down a LOT from there. Remember if its 0.030 at the very edge before the edge bevel, then at the top of the finished edge bevel it is much thicker than that. You're going to have a very wide edge bevel, which is a pita to sharpen and looks like hell. I'd take it to 0.015 or 0.020 minimum. Likely I'd go down to .010" or less like I try to do all my knives. 01 is tough stuff.
Click to expand...

Thank you - I obviously have a way to go in figuring out the little details! I'll stick with my plan and shoot for .030 or less, and follow your advise on the next. I calculated that a 20 deg (per side) edge on my grind starting at 0.030'' on the edge will give me an edge bevel 0.054'' wide. I'll start there and thin it out some more if it doesn't perform well. I'm going to follow the advise of many and stick with O1 until I get a good feel for this material.

By the way, your designs are fantastic! I really like the laminated handles; very classy!

Sam
 
That's your first knife?!?!? :eek: Dang. :)

Kudos for designing the knife you wanted and then finding the stock to make it from. 99% of new makers (and some that have been making for many years :foot:) get the steel first and then see what shape will fit between the lines. And the resulting knife always shows it too.

Your blade has a very nice, flowing design with clear intentions. On your next chopper, you might want to think about a "dog leg" handle shape. It keeps the knife from ratcheting out of your hand while chopping. That's just $0.13 worth of advice, not a criticism. :)

As to your OP, it sounds good and I agree with the advice the guys have posted.

IMHO, a knife like this will perform optimally if you flat grind down to about 0.015" and then feather in a convex grind down to an edge. It will be a thin edge that wants to bite into whatever it touches, but will have enough meat behind it to support it.


GREAT WORK, I am excited to see this one done, and your next knife as well! :) :cool:
 
What Nick, Andy, Joe and Fred said :thumbup:

I just want to say that it's refreshing to see a new maker who's clearly done his homework and is asking smart questions. Sam, you're off to a great start, keep up the good work. Kudos! :)
 
NickWheeler said:
That's your first knife?!?!? :eek: Dang. :)
Click to expand...

Wow - Thanks Nick and James!

That's great advise about the convex edge on a chopper - I'll try conventional first, then try the convex and see if I can find any performance difference.

I have to confess, I'm an engineer at a company that manufactures metal cutting (milling) tools. I've got a pretty good understanding about tool steels, just not when it comes to knives. I do, however, have lots of equipment at my disposal, from the CAD programs to mills, lathes and multiple heat treating ovens. I finally decided to take advantage of the situation and try my hand at making something.

Thanks,
Sam
 
I had a sneaky suspicion that this wasn't your first foray into the metal-working realm :) That's great! I'm sure you know many things that I don't, and I welcome your input!
 
OK, I wrapped this one up over the weekend. What do you think? I ended up forcing a patina with yellow mustard and ferric chloride.

I've learned a whole lot of things from this process, and I'll apply that to the next one:

1. Thin the edge! I was nervous about having an edge that it too thin and might distort from the heat treat & quench. Wow, was I wrong. I think roughing in around 0.015'' to 0.020'' would have been the way to go.

2. Do as much finish work as possible before heat treat. Soft metal is a lot easier to grind away than hard. Also, the finish should be as smooth as possible. Any scratches before heat treat will be there after, and a LOT harder to grind out!

3. Plan, plan, plan. I thought I went into this with a good plan, but there could have been more. Simple things like handle fasteners and the right adhesive should be worked out (and in hand)before any metal is cut.

4. The steel is tougher than I think it is. This could have easily been made out of thinner stock without any performance loss. However, I still think it looks good with the thick (5/16'') stock.

5. Make a wood/cardboard mockup. I would have modified the handle shape slightly (made it about 1/4'' taller) if I would have made a mockup to test fitment.

Thanks for any and all input, good or bad! I'll start making a sheath out of veggie tanned leather this week, and try it out on a camping trip next week.

Sam


O1 WIP by mysdnc, on Flickr


O1 WIP by mysdnc, on Flickr


O1 WIP by mysdnc, on Flickr


O1 WIP by mysdnc, on Flickr


O1 WIP by mysdnc, on Flickr
 
For hillbilly micarta, those colors worked out great- nice patina, as well. This chopper will only look better as it weathers. Good job!
 
Thanks guys!

I went out & chopped up some limbs & random things this evening. It was OK, but I think if the stock was a little thinner it would chop better. OTOH, it splits wood like a champ!

On to the next one!
 
Very nicely done. I like it a lot.
 
You must log in or register to reply here.
Back
Top