Making bevels in a knife factory?

Storm Crow

Storm Crow

Joined
Apr 12, 2006
Messages
2,506
After perusing Youtube for months and not turning up much at all, I was wondering if anyone could tell me about the kinds of equipment used in factories to put bevels on blades.

In particular, I'm looking for options in ways of putting a flat grind on a line of mid-tech stock removal blades that minimizes the requirement for skilled labor. I know a good number of the newer low-and-mid-level production companies are using CNC machines to mill the bevels, and it is an option I'm considering. I would love to see what other setups are out there. I have some ideas, but if you can learn from what other folks have already done, I think it's a good idea to do so. :)

About the only thing I've turned up on Youtube other than the CNC option is equipment that grinds edges on straighter planer blades. I'd really love to see what Kershaw is using to grind their Camp 18 bush sword blades. :cool:
 
I would say a facility with a Kuka robot, or something similar, would be ideal...

[video=youtube;1gkFVfRqkgQ]https://www.youtube.com/watch?v=1gkFVfRqkgQ[/video]
 
Woooow ... wow.

Thanks for sharing that. I wondered about their Asian knives and if they were simply copying traditional shapes. Really cool to see how they differ from their European style blades.

Wonder if there's a robot for making sheaths. :D
 
Look up Berger grinders. Not sure if my spelling is correct so try different variations if nothing pops.
 
Interesting question. I'm planning a move to mid-tech for next year, and am looking at Wire EDM rather than grinding for doing my blade bevels... This is an idea that's still in it's infancy, but I'm planning on subbing out a prototype or two early next year, and then evaluating the possibility of getting a Wire EDM for my shop to do the bevels. Second-hand machines are surprisingly affordable...

The general idea would be to hold a knife blank, edge up, in a fixture that's set at the angle of the desired blade bevel. The wire EDM machine would then move it's wire through the blank to carve off the bevel in a fashion similar to moving a cheese wire through a block of cheese. Wire EDM machines are very cool, primary advantages are that they're very accurate as it's a non-contact machining process, they don't heat the workpiece up at all, and that they're perfectly happy machining hardened steel. Downside is basically consumables cost, which will very likely be higher than for a grinding solution.

A fixture would be required for each side of the blade, as well as CAD/CAM for defining the path the wire will take through the blade blank. Tooling and consumable cost will definitely be higher, but it's offset by the fact that it's a hands-off process.

Like you, I have also been searching for automated blade grinding solutions. Haven't seen much outside of solutions that involved industrial robotic arms, and that's a solution that will likely always be far too costly for a smaller business.
 
aarongough said:
Interesting question. I'm planning a move to mid-tech for next year, and am looking at Wire EDM rather than grinding for doing my blade bevels... This is an idea that's still in it's infancy, but I'm planning on subbing out a prototype or two early next year, and then evaluating the possibility of getting a Wire EDM for my shop to do the bevels. Second-hand machines are surprisingly affordable...

The general idea would be to hold a knife blank, edge up, in a fixture that's set at the angle of the desired blade bevel. The wire EDM machine would then move it's wire through the blank to carve off the bevel in a fashion similar to moving a cheese wire through a block of cheese. Wire EDM machines are very cool, primary advantages are that they're very accurate as it's a non-contact machining process, they don't heat the workpiece up at all, and that they're perfectly happy machining hardened steel. Downside is basically consumables cost, which will very likely be higher than for a grinding solution.

A fixture would be required for each side of the blade, as well as CAD/CAM for defining the path the wire will take through the blade blank. Tooling and consumable cost will definitely be higher, but it's offset by the fact that it's a hands-off process.

Like you, I have also been searching for automated blade grinding solutions. Haven't seen much outside of solutions that involved industrial robotic arms, and that's a solution that will likely always be far too costly for a smaller business.
Click to expand...

Funny you'd mention that. I run two EDM wire machines along with two CNC milling centers at work and about a month or two ago I was discussing doing bevels on the mill with my boss and he suggested he felt doing them edge up in an EDM wire burner would be an easier setup than a milling set up. Basically in a wire machine all you'd need for a fixture would be stainless small machinists vise. I even considered burning all my blanks on the machine and putting in all my handle holes then moving to a second bevel operation. Very simple and very economic. I think even makes more sense than milling them.

Jay
 
Antlerhog said:
Funny you'd mention that. I run two EDM wire machines along with two CNC milling centers at work and about a month or two ago I was discussing doing bevels on the mill with my boss and he suggested he felt doing them edge up in an EDM wire burner would be an easier setup than a milling set up. Basically in a wire machine all you'd need for a fixture would be stainless small machinists vise. I even considered burning all my blanks on the machine and putting in all my handle holes then moving to a second bevel operation. Very simple and very economic. I think even makes more sense than milling them.

Jay
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Nice to hear that someone with exposure to wire EDM thinks I'm not crazy!

I agree that doing all the operations between a wire EDM and a mill could be a very nice solution. My tentative plan right now is that I'd have the blanks rough-shaped on a waterjet by the steel supplier, then do profile clean-up and hole drilling on a CNC mill, then heat-treat, then use wire EDM to machine the bevels. This is all very much in the 'pie in the sky' stage, but I'm definitely interested in pursuing it further.

If the cost of consumables for the wire EDM machine turns out to be acceptable then I think that could be a very neat overall solution.
 
Take a look at this video we made earlier this year. You can grind machine grade flat edges that are as sharp as you want to make them. The Bubble Jig can be adjusted to produce just about any edge angle and they are truly flat. It just takes a steady hand. I'm 70 now and i can put the initial edge bevel on in less than ten minutes.
As seen in the video, following with the ERU makes the edge as clean and sharp as anyone could want.

Fred

[video=youtube_share;iFzVjH8DXYo]http://youtu.be/iFzVjH8DXYo[/video]
 
aarongough said:
Nice to hear that someone with exposure to wire EDM thinks I'm not crazy!

I agree that doing all the operations between a wire EDM and a mill could be a very nice solution. My tentative plan right now is that I'd have the blanks rough-shaped on a waterjet by the steel supplier, then do profile clean-up and hole drilling on a CNC mill, then heat-treat, then use wire EDM to machine the bevels. This is all very much in the 'pie in the sky' stage, but I'm definitely interested in pursuing it further.

If the cost of consumables for the wire EDM machine turns out to be acceptable then I think that could be a very neat overall solution.
Click to expand...

With the newer machines the wire is much cheaper. The two machines we have are a 20 yr old Charmilles and a two year old AccuTex. The newer machines wire is about $80-$100 a spool but I believe the Charmilles spool are also $100 but for 1/2 the amount of wire. On our AccuTex you could probably do hundreds of bevels per spool.

I agree that with larger runs water jet may be the way to go. I'm just doing singles to maybe 1/2 dozen blanks at a shot so just throwing it in the burner works good for me.

Jay
 
Ok, the wire EDM sounds very cool. Gonna do some more research on it, but I've located a local shop to consult with if I decide it's something that might work for me.

I have some grinding setups that would be used with a 2" x 72" floating in my head that aren't quite concrete yet. Something that would hold the tang and then move the blade across the belt and angle it as appropriate. I saw Travis Wuertz demonstrate a setup on his surface grinding attachment that did similar, but can't remember how he had it worked out. Anyone seen something like that used in a low-level production setting?

I'm on the fence about keeping as much of the process in-house as I can and farming out processes when they make sense. Like I said, gauging options. I already have the first batch of blanks waterjet cut.
 
I definetely just learned something about how production blades are manufactured....
 
Antlerhog said:
With the newer machines the wire is much cheaper. The two machines we have are a 20 yr old Charmilles and a two year old AccuTex. The newer machines wire is about $80-$100 a spool but I believe the Charmilles spool are also $100 but for 1/2 the amount of wire. On our AccuTex you could probably do hundreds of bevels per spool.

I agree that with larger runs water jet may be the way to go. I'm just doing singles to maybe 1/2 dozen blanks at a shot so just throwing it in the burner works good for me.

Jay
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Interesting! I'm very interested to learn more about consumables costs on wire EDM machines. Honestly even if it was $5-10 per knife in consumables it would still likely be worth it to get even an older machine. Having that process be hands-off would be a huge help. Sounds like the newer machines could do it very inexpensively though. It would be fascinating to see how far you could go with just a modern machine, given the tolerances those things can hold you'd be able to machine even critical parts for folders with ease. Profiling and beveling for fixed blades would be a 'cake walk', at least from the machine's perspective.

Waterjet is definitely a good option for roughing profiles for larger runs. If I had a wire EDM with hole drilling and auto threading though I'd likely take the extra precision that EDM brings and give up the relative cheapness of waterjet. I still have to re-finish every surface that comes off the waterjet, whereas there would be much less work (if any) on parts that came off EDM. That said I really don't think I'll ever be able to afford that kind of machine, I'll likely be dealing with the old machines that the 'real' machine shops are getting rid of. Stuff made in 1985 that still has a tape drive :)

The option to outsource is always there. Not sure I can bring myself to do it though. I got into knifemaking partly because I wanted cool 'toys' in the workshop, and I love getting to use awesome machinery. Outsourcing stuff kinda ruins that, not to say anything about what it does for lead times, quality, etc...

This is an interesting thread, I don't see this type of discussion happening much anywhere, and I for one welcome it very much!
 
The feed rates on wire EDM are quite slow. The process is usually used for cutting the hardest of materials such as carbide or cutting profiles like square slots which are not practical or economical by conventional means such as cutting, grinding, milling, turning, etc.. If you are trying to EDM wire cut through the full width (1+ inch) of a blade to cut a bevel, it won't be fast. Considering the cost of the machines, I'd think this is best done on a production basis by investing in a used (or even new) CNC mill.

To me, the best production scenario for 25+ blades seems to be having the profile cut by water jet; machine holes, bevels, and tapers via fixtures and CNC mill programming, cut scales and machine them in the same manner as the blade, and then assemble by "screw and glue". This requires production runs and tooling/fixture costs, but I think it would provide much more throughput than wire EDM. Time is money.

The mill or EDM can be replaced by a robotic grinder too for maximum output, but I don't think anyone besides the largest production makers of knives could consider this as an option. Even so, these factories still rely on CNC milling for a large majority of the process. I'd bet that they are water-jet cutting their blanks too.

I hope that more informed persons chime in now.

Mike L.
 
You know, the old Brown and Sharpe oil slinger cam action automatic screw machines could turn a profile as fast or faster than a modern day turning center.

I need to build a cam follower grinder attachment for production grinding bevels on a regular 2X72 grinder. It ain't rocket surgery...
 
Nathan the Machinist said:
You know, the old Brown and Sharpe oil slinger cam action automatic screw machines could turn a profile as fast or faster than a modern day turning center.

I need to build a cam follower grinder attachment for production grinding bevels on a regular 2X72 grinder. It ain't rocket surgery...
Click to expand...
Says the guy who could actually make a cam follower grinder attachment for production grinding bevels and could probably build the Starship Enterprise.
 
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