CNC Knife

Macchina

Macchina

Joined
Apr 7, 2006
Messages
5,215
Just wanted to update for all who are interested. I cut the knives last week. I used a 1/4" 4 flute bullnose (.060" radius) carbide endmill to do the roughing then the finishing. I left .005" stock, and finished it with a .005" stepover (perpendicual to the length of the blade) program with the same cutter. I then drilled setup holes, put bondo in all the areas that I cut and surface ground the bondo flat. I flipped over the bar, repeated the programs, and cut out the handle perimiter last. All in all, they turned out pretty good. I would have left about .005" more stock per side to bench out all of the cutter marks, but I got most of them. I left the edge at .020" thick and heat treated the blades with an acetylene torch in a steel forge I made. I quenched them in used motor oil once they got to non-magnetic. The handles I rough cut out, leaving a little stock on the sides, and screwed them to the knives. I then sanded all around to make the scales match up to the knife perfectly. I did most of the edge work with a power sander, and spent 30 minutes with my stones to get them perfect. I made the sheath out some HDPE we had lying around the shop and a heat gun. I had a great time, and got them done in about 25 hours. Here are a few pictures:
DSC01291.jpg

DSC01295.jpg

DSC01297.jpg




Here are some pictures out of AutoCAD for my first real knife I'm making. It will probably take me longer to cut it out on the CNC than by hand, but I want to make it right the first time, as I do not have the time/money to invest in making many knives right now (the wife gets her job in the spring, then it's off overtime for me:D ). I'm making it out of 0-1 steel ($15.22 for a Starret precision ground piece 3/16 x 2 x 18 at Enco!) and green G-11 handles. I was wondering if anyone knew of any smiths that would be willing to heat treat this the right way for me? I don't any equipment to heat treat it, and would like this knife to have a good heat treat. Here are some pics, I will post some more latter.
Knife1.jpg

Knife2.jpg

Knife3.jpg

Please give me all the advice
 
My advice would be to cut one out of wood and make sure it feels the way you want it to feel. It's one thing to design something that looks nice. It's virtually impossible to CAD something up that feels just right on the first go.

Nice CAD work, and nice design! It sure looks like it will be a great knife!

Dave
 
I draw my knife designs out on paper and then glue them to a piece of 3/4" plywood and cut/sand it out to shape. Let's me see how I think they'll feel. (the idea of putting them on the plywood was not my own but one I got from the Graham Brothers)

Looks like a very nice knife design.

Charles
 
Nice. Looks kind of Busse-ish.

Rather than wood, you could have it solid-modeled in one of those plastic-model "printers." If you don't have access to one, you can probably find an adult school that teaches SolidWorks or something that has one and pay 'em a few buck to zap it out for you.
 
Maybe someone with more experience then myself can chime in on this but...
Isnt getting cnc'd bevels perfect really heard? I know it can be done but only a few makers I know of cnc machine the bevels into there knives and I have always understood that it is because on top of a high end cnc machine one need to spend alot of time tweaking the programing to produce even a normal blade bevel. Guys like R.J. Nartin who do faceted blade bevels with cnc have said the time investment to get it right is insane. Not tryin to discourage but if you only have a small amount of steel you may want to try and hand grind your bevels instead of trying to dial in a cnc program.

Again, someone with more cnc experience can hopefully confirm/deny this. This is just my understanding of cnc'ing bevels.

Jcaswell, I was under the impression those 3d models cost close to 1k to produce, have the machines gotten cheaper? Just a 3d scanning bed is pretty expensive.
 
I can understand where it may be difficult, but I do this kind of stuff every day. Not to brag, but I've machined parts that are used in live missles in Iraq (+/- .0005" tolerances). It just takes some expirience to know how to draw your surfaces, write your cutter path, etc. This is the first knife I'll be making, so I'll post pictures of how it goes. About those 3D models, they are very expensive, I doubt that any schools have a 3D printer.
 
Another question to you makers: How much material thickness should I leave at the edge before heat treat? I just read my last post, I'm not trying to be a Jack-Hole, I'm just saying that I don't think it will be that difficult to cut the bevels. Where did you hear that it would be difficult? I'd like to read about that before I start to cut.
 
I used to be a student at the University of Alaska, Fairbanks and they had one of those 3d printers. I'm not sure how much it cost to make the "prints" but I do know that only a few students got to use it.

They are really neat though but for the time I'll just cut out the silhouette in plywood first. :-)

Charles
 
The price of those 3-D printers has dropped a lot. You're finding them in schools and there are quite a few floating around at design outfits, at least here in SoCal.

I have a friend doing a model truck body. It's costing him about $300, but like I said, find a school that has one and you might have them do your thing as a sort of project--especially if you pitch a few bucks for 'supplies.'
Right off hand, I know there is an 'adult education facility in Ventura now that teaches Solid Works. There's a room full of top-line computers, a 3-D printer and all the other latest stuff.
 
There are ways of using CNC mill for cutting bevels.
Angus Trimm (Albion is doing it this way too) cuts swords from a solid bar of 5160. He cuts one side then the other while it's still connected at the edge to the rest of the bar. The sword is eventually freed from the bar with bevels, fuller, etc complete. Here is a link to the Albion site. The last picture on this page shows a sword in a milling center being carved out as described.

http://www.albion-swords.com/swords-recreated.htm

Of course if you know what you're doing, you could probably do a simpler project, like knife bevels, in numerous other ways.

You could also just send it out to a CNC blade grinder, or the more popular route: learn to use the belt grinder.:D
 
I am not shure what thread it was but R.J., Hinderer and someone else all chimed in about using cnc. I would consider them both to be top notch machinists. If you are used to aerospace tolerances then I'm shure you will manage. :D Also they are world class knife makers so it may be they were bieng picky and wanting a specific outcome that was harder to get than a plain flat grind bevel. Like I said I had just heard the programing and initial set up for a knife with cnc'd bevels was steep and was thinking if you didnt want to go through a few blanks. I know no matter what I managed to do to my first knife I couldnt start over, I had to finish it. But it sounds like you know your way around a cnc mill well enough that you should do just fine. I was hoping someone who cnc'd bevels would post, but they still might.
 
BigJimSlade said:
I was hoping someone who cnc'd bevels would post, but they still might.
Click to expand...



Big Jim,

Yeah, milling the bevels isn't too bad, but it is slower than you're probably thinking because it isn't done all in one pass. I had to make a few of these, so CNC was a good choice. Set it up, and walk away.

This is what it looks like when I design and build a blade the "new fashioned" way.

http://www.metalworking.com/dropbox/blade.jpg

http://www.metalworking.com/dropbox/blade4_making_blade.jpg

That is a 10" hollow "grind". That one ended up being a test blade to test heat treat and grind thickness. To answer one of the original questions, that edge was .010" before oil quench and it didn't warp, but the blade design was pretty clunky. BTW, the decarburazation (instead of turning the gas down after purge, I accidentally turned it off!) was deep enough I had to move the edge back some to get back into hard steel. The real blades didn't look like that after hardening in argon.

The finished blades are okay, but a real ground blade looks better. And a hand ground blade is a work of art. With that said, I think there is a place for CNC amongst your other tools if it suits you.

I'm curious what the purists think about this.
 
edge thickness, some people like up to .04 inch others like Nathan go thiner down to .01. the main thing is that it is not sharp first off so when doing the heat treat one does not get cut the other big issue is decarb. im not to savy on this but from my understanding depending on the exact way it is heated (propane, vs coal, vs electric, and then if its wraped in foil or not) matters now thin you can really take it. since you wont be doing the HT your self, ask who ever you are going to have do it how thick they say it needs to be.

i like the design the only thing i would add is the notch at the base of the blade (blade ricasso junction) but thats probably more of a personal preferance (its supposed to prevent sharpening stones from beign damaged and helps get a consistant blade to the edge. i think it helps personaly)

hmmm going back and looking it at the way you cliped the point looks just a little off to me (probably just my personal preferances). i think what would look right to me is if the was not cliped as far down and/or a rounded clip point (like the circular cut in, hmmm this whole multiple cuts for the same name is confusing). or maybe like i think you had mentioned the lenght as well.

over all it looks very good, i really hope the machine can produce you vision becasue if it does you'll defianly make some money if you do runds

-matt
 
I think I can get two knives out of the same 18" length of steel, so I designed up a smaller one today. This one I am going to get the blade thickness down to .125 (leaving the handle .1875) and probally cord wrap it. I think I'm going to heat treat the knives myself with an acetylene torch and some heat bricks that I have at work. Can you give me any advice on how to properly heat treat the blades so that I do not warp/crack them. Also, does 01 reach critical temp @ nonmagnetic? I can't wait to get to work on Monday (never had this feeling before). My steel will be waiting for me at work, and cutting will begin at lunch.
CNCKnife1.jpg

CNCKnife2.jpg

CNCKnife3.jpg
 
They look great. I'm actually amazed that they turned out so well. Congrats!
 
nice job man. they look great. your making me want a CNC now. you have any other designs that you are going to do next?
 
Nothing in the near future. I don't have much freetime right now (between work and bladeforums :D ), but I do plan on making a few quality pieces over the summer. I don't like fancy knives at all, I plan on making some real quality users, maybe something thick and long that I can chop with.
 
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