Waterjet? Plasma? Laser? What is best to cut out blade blanks?

Delta Handmade Knives

Delta Handmade Knives

Well-Known Member
Good morning folks. Hope everyone is having a good day.

Here is the deal: I have had more than one experienced knife maker tell me that laser or plasma cutting are not good for knife making. They tell me that waterjet is the way to go.

Question is simple. How do you feel about this? Is it true? What are your thoughts on laser or plasma cutting versus waterjet cutting of steel for the purpose of making high quality knives?

Thank you!
 
I have had some water jetted...was more expensive than I'd hoped. A very small EDC blade was $6. At the time I was worried about the "recast" of laser or plasma.(because of what I heard also...I'm now calling BS on that..lol) Really not an issue I think...any re-welding of particles is very thin and will be ground away easily....I think the laser and plasma are faster? maybe cheaper then...

experienced knife makers may have opinions that may not actually be based on fact. If you called a laser or plasma Mfg company and asked specifics about your own process they would most likely give you solid info that would show that any concerns a knifemaker has may be unwarranted. I would use the cheapest of the three without batting an eye personally.

I now cut mine out on 25 year old cnc machines...and it is slowwwwwwwwwwwwwwww...lol. And carbide endmills aren't cheap...! But the machines are paid for and I have more time than money!

Hope this helps!
 
I've used all 3...

Plasma wasn't very accurate... Laser was really accurate with the least kerf (so less wasted material), but it created haz (I think that's the term) where the edges got hard. Not a problem when you are grinding away but it was a huge pain for holes that you wanted to drill out later. So yeah, waterjet is my preferred way now...
 
Of the 3 mentioned, waterjet is the only way to go in my opinion.

With any heat based cutting method on the steel types used for blade, you have to deal with a "heat affected" zone, that can range from about .020" to .125" or more. Whatever it ends of being, it's something that must be dealt with... usually by grinding it away. This does not occur with waterjet cutting. The key is finding/using a source for waterjet cutting that knows what they are doing. You'll pay a bit more, but the accuracy and the fact the accuracy provides for less waste, is worth it. Waterjet outfit vary wildly on what they charge, and how they charge..... some by job, some by time, and some by the piece. Most will charge you a "setup" fee, and may also charge a fee for converting your sketch or drawing into a CAD format.

Now, there are a TON of outfits who are offering waterjet cutting these days..... and chances are you will not find a local source. Educate yourself, and ask others who they recommend.
There is a HUGE difference in the quality of the parts you get, based on the knowledge, experience, and caring of the waterjet outfit you choose. Most offer what is called "cut quality".....and it's often coarse, medium, fine, or very/super fine. And even the quality of each of those can vary for one outfit to the next. Some, like the company I use, that only cuts knife blanks and knife parts, only offers fine and super fine. Personally, I never go less then "fine" cut quality, simply because it usually gets me more parts from the same amount of material versus coarser cut quality.

All of the waterjet cutting I have had done, is a source across the country from me.... so I buy the titanium or steel, have it drop shipped to the waterjet cutter, and then pay for the shipping from the cutter to me. Most of what I have done is folder parts from Titanium, but occasionally I will have blades waterjet cut too. Generally, the smaller the job, the more it costs, depending on the method used to charge (by the piece, by time, or by job)....so have as much cut as you possibly can at a time. It's common for my jobs, including material, to cost $1K+ depending on the material I'm having cut. But when you consider it only takes a couple of straight knives or folders to pay for that....it's very fair for the time/labor/consumables it saves.

NO CONTEST.....WATERJET ALL THE WAY! :)
 
Last edited:
It really depends on how you want to make your knives, and a lot will also depend on the quality of your CAD files as well as the vendor who's going to run them.

The HAZ (heat affected zone) is something that can be worked around pretty easily if you use carbide tooling. With ANY of the three methods, I would leave a little extra material for cleaning up the edges, holes, etc...
You should "spot" your holes so that you can drill and/or ream to final dimension anyway, especially if you're cutting folder parts or similar. If it's just pin holes for a handle on a fixed blade, then that's less important, but I still like to drill and ream to final.

Waterjet and laser will probably get you closest to final dimensions with minimal cleanup, but they're going to be pricier than plasma for sure. That said, being able to click "submit order" and have 100 blanks show up in a couple of weeks is worth the price of admission to a lot of makers. Just make sure you've got everything dialed in as well as you can!

While these things can save you a ton of time, they can also waste a lot of time if you (or the vendor) gets something wrong. Best to pay a little extra up front for a couple of prototypes before you pull the trigger on larger numbers. Some vendors will "one off" a proof for you for pretty cheap, just to make sure everything is kosher. Others will charge you based on "economy of scale". So one might cost you $25, but if it works and you want to order 50 more, then the price will drop to $5 per or something like that.
 
EdCaffreyMS said:
Of the 3 mentioned, waterjet is the only way to go in my opinion.

With any heat based cutting method on the steel types used for blade, you have to deal with a "heat affected" zone, that can range from about .020" to .125" or more. Whatever it ends of being, it's something that must be dealt with... usually by grinding it away. This does not occur with waterjet cutting. The key is finding/using a source for waterjet cutting that knows what they are doing. You'll pay a bit more, but the accuracy and the fact the accuracy provides for less waste, is worth it. Waterjet outfit vary wildly on what they charge, and how they charge..... some by job, some by time, and some by the piece. Most will charge you a "setup" fee, and may also charge a fee for converting your sketch or drawing into a CAD format.

Now, there are a TON of outfits who are offering waterjet cutting these days..... and chances are you will not find a local source. Educate yourself, and ask others who they recommend.
There is a HUGE difference in the quality of the parts you get, based on the knowledge, experience, and caring of the waterjet outfit you choose. Most offer what is called "cut quality".....and it's often coarse, medium, fine, or very/super fine. And even the quality of each of those can vary for one outfit to the next. Some, like the company I use, that only cuts knife blanks and knife parts, only offers fine and super fine. Personally, I never go less then "fine" cut quality, simply because it usually gets me more parts from the same amount of material versus coarser cut quality.

All of the waterjet cutting I have had done, is a source across the country from me.... so I buy the titanium or steel, have it drop shipped to the waterjet cutter, and then pay for the shipping from the cutter to me. Most of what I have done is folder parts from Titanium, but occasionally I will have blades waterjet cut too. Generally, the smaller the job, the more it costs, depending on the method used to charge (by the piece, by time, or by job)....so have as much cut as you possibly can at a time. It's common for my jobs, including material, to cost $1K+ depending on the material I'm having cut. But when you consider it only takes a couple of straight knives or folders to pay for that....it's very fair for the time/labor/consumables it saves.

NO CONTEST.....WATERJET ALL THE WAY! :)
Click to expand...
Ed, what are your thoughts on the people that claim HAZ is not an issue at all because it will be taken care of during the heat treat.

I think $6 a blade is dirt cheap when you consider the price of belts, your time and the material saved by a good nesting of your parts.
 
J. Hoffman said:
Ed, what are your thoughts on the people that claim HAZ is not an issue at all because it will be taken care of during the heat treat.

I think $6 a blade is dirt cheap when you consider the price of belts, your time and the material saved by a good nesting of your parts.
Click to expand...
At the risk of ruffling feathers..... I totally disagree that it's "taken care of during heat treat". Now, having said that, it is a matter of degrees.....as in, the immediate area where the plasma or laser cuts, is simply beyond repair.... that can be a couple thousandths...or it can be a lot more, depending on the person doing the plasma or laser cutting, how the machine is set, and even how new or worn the nozzles/tips are. How do I know? Because I've tried saving the HAZ on both plasma and laser cut parts, and seeing if I could reverse the damage..... sending samples off for testing proved it.....nope! Only way to be 100% sure/safe, is to grind away the HAZ.... or better yet, use waterjet and not worry about it. That was many moons ago, and I have not used anything other then waterjet since.

If folks wanna use plasma or laser, I'm not going to try to deter them, unless I'm asked (as you just did). I find that often times with this generation of knifemakers..... trying to convince them that the popular thing.....might not be the best thing.... Is like trying to teach a pig to fetch. It's a waste of my time....and it just annoys the pig. :) If folks don't want to listen, and take shortcuts anyway....then its on them. I still find it interesting that the "hive mind" of the internet can take fallacy and make it "fact".
 
EdCaffreyMS said:
Is like trying to teach a pig to fetch. It's a waste of my time....and it just annoys the pig. :) If folks don't want to listen, and take shortcuts anyway....then its on them. I still find it interesting that the "hive mind" of the internet can take fallacy and make it "fact".
Click to expand...

I've taught a pig to fetch and to sit! Lol, kids do it for their 4H project.
 
The $6 blades I had water jetted was for a batch of 72 blades. Definitely got the value pack. He would have let me do different designs on the same sheet of steel with no extra cost. so $432...plus shipping (don't remember how much but 72 blades aren't light). Blades were 1/8 thick. (blades I'm doing right now are about 4x the periphery and 2x as thick so would that be $40 to blank out? Dunno...)

One thing that nearly bit me was file translation....I gave him step, igs., and dxf(very industry standard files)....his machine did not import anything was remotely close to my cad with its proprietary software. it took three iterations before what he saw was what I wanted. Fortunately the first go 'round was goofy enough looking that he called me otherwise I would have scrapped the lot.

I also am sure I did not get the finest setting on the machine as it took some machining to clean up the angle of the cut. The holes were fairly accurate as I told him I was tooling off of the front pin and the lanyard hole. I reamed them on a drill press after and they all fit my fixture perfectly.(the holes did look much better than the profile....and reamed easily...which laser or plasma would not do...)

My apologies shooting from the hip earlier....I was not trying to ruin your blade! My sense was that you often see the material laying in water but not much steam and these plasma cutters moving so fast that heat build up "looks" minimum...which is why I suggested calling a machine MFG and ask them per your needs....I know that as often as internet lore gives the nod on a faulty process it also can use dated understanding to nix a technology that has put to bed some of its growing pains...but the MFG pretty well has to stand by their stats...the end user has a lot to do with how well the end result works also...'cause time is money.
 
I've seen some real good laser work that wouldn't cause issues with HAZ. Industry has to deal with this, too, and it is possible to get essentially zero bad material. But you're talking about processes that are worked out for a specific material for a specific purpose. And there are a few outfits that do it for knives, and they do it very well. BUT, your local fab shop will most likely not have 31 varieties of knife steels and thicknesses worked out, so maybe could get some very bad HAZ. Water jetting is a much safer choice when you're not dealing with someone with specific expertise (and desire) to make a knife blade.
 
doug adams said:
This is a bit off topic. How much haz would you have to grind off if you cut a blade out with oxy/acetylene torch?
Click to expand...
It depends on how good an individual is at Oxy/Acty cutting. Based on my experience, no matter who good an individuals it, the HAZ will be much larger on parts cut with Oxy/Acty versus Plasma or laser. Just a rough estimate, but from what I've seen, you're looking at 1/8"+ for an average Oxy/Acty cut, versus thousandths for a very good CNC controlled plasma or laser job. I have both Oxy/Acty and a 3/4" capacity Plasma in my shop, and frankly I am horrible at cutting with either, but the HAZ is always significantly less with the Plasma then the Oxy/Acty. However, there is still a significant amount of grinding needed to get rid of HAS from either.

I think what many don't realize is that grinding away the HAZ means you have to factor in the loss of materials on the profile of a knife, meaning you need to oversize it to begin with, then there's the belts, and the time required for grinding/HAZ removal..... all the things that simply are not there if you just choose to waterjet cut your blades/parts. I have had many folks tell me.... "But it's always cheaper to have my blades plasma/laser cut!" But is it really? Just sayin. ;)
 
EdCaffreyMS said:
It depends on how good an individual is at Oxy/Acty cutting. Based on my experience, no matter who good an individuals it, the HAZ will be much larger on parts cut with Oxy/Acty versus Plasma or laser. Just a rough estimate, but from what I've seen, you're looking at 1/8"+ for an average Oxy/Acty cut, versus thousandths for a very good CNC controlled plasma or laser job. I have both Oxy/Acty and a 3/4" capacity Plasma in my shop, and frankly I am horrible at cutting with either, but the HAZ is always significantly less with the Plasma then the Oxy/Acty. However, there is still a significant amount of grinding needed to get rid of HAS from either.

I think what many don't realize is that grinding away the HAZ means you have to factor in the loss of materials on the profile of a knife, meaning you need to oversize it to begin with, then there's the belts, and the time required for grinding/HAZ removal..... all the things that simply are not there if you just choose to waterjet cut your blades/parts. I have had many folks tell me.... "But it's always cheaper to have my blades plasma/laser cut!" But is it really? Just sayin. ;)
Click to expand...
Thanks Ed. How much haz would you think you have when you cut one out with a cutting disk on an angle grinder?
 
This post interests me much, I have a plasma cutter that I used during my bumper builds for jeeps and off-roaders ten yrs ago. It is 13 yrs old and is a hassle to hook up to compressor and an import version. The time it takes to hook up I will have two blades cut-out with my portaband. Glad I never used it for blade profiles.
 
You must log in or register to reply here.
Back
Top