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How thin can you really go?

Posted by KWB 
KWB
How thin can you really go?
July 15, 2016 07:18PM
Making some micro knives out of .078 and .050 stock. And I keep wondering how thin and how low of a primary can I really get while maintaing edc usability. I was thinking either a narrow blade and .02 at the edge or a wide blade and .010 at the edge. I want to see how close I can come to a laser really.

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Re: How thin can you really go?
July 16, 2016 04:17AM
Alvin Johnston made blades out of 0.055" stock, hollow grinds, < 0.005" at the edge, <10 dps. They were usually very narrow blades but he did make wider skinners on occasion.

The stock thickness really isn't an issue because for most cutting lateral forces are really low. I ground a blade out of a 0.025" thick piece of hawksaw blade, 3" long, works fine as a utility knife.

Look at Havalon for example and other scalpel type blades. Just take one and see what it takes to crack it off. It isn't hard of course, but it isn't going to happen just cutting normal materials.
KWB
Re: How thin can you really go?
July 16, 2016 06:21AM
I dont think lateral force will be an issue either especially since they are 2 inches long or so.

My main concern grind angle and edge thickness, for ex- if you had .050 stock, 1 inch wide, and 2inch long, .005 at the edge and .025 in the middle of the grind this should produce a decent cutting blade, certainly not the limit but for edc tasks I dont know if any thinner would be wise.

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Re: How thin can you really go?
July 16, 2016 06:34AM
i have made some test knives of 1/32"(0.03"/0.8mm) of O1 at Rc63-64. they are exceptional slicers of meat and vegetables, but the hardest thing i have tried to cut is carrots.


4" cutting edge, 1 1/4" wide, weighs 2oz. the blade is fairly rigid and i have had no issues with the blade wandering during cuts. works well as a fillet knife for small fish, for making thin slices of meat from a larger cut(whole pork loin or beef knuckle), and slicing fresh bread or pastry with tearing.



3" cutting edge, 1 1/2" wide, 2.3oz(most of the weight is the oak burl handle. again blade is rigid and doesn't wander when cutting. blade shape allows vertical push cuts without your knuckles banging the cutting board. i am usually only cooking for 2 or 3 and this blade will do 98% of the cutting i need to do.
I don't think steel this thin could be used for anything other than a slicer. I have tried a bit of cutting wood and they do well when making very thin cuts of clear(no knots) oak or pine. I have had no issues with the blades chipping, but i have been careful to only cut on wood or polyethylene boards.
If interested in trying some, this link is for 3 pieces 1/32"x2"x18" of Sheffield O1 for $25 delivered [www.ebay.com]

scott
[www.etsy.com]



Edited 2 time(s). Last edit at 07/16/2016 07:06AM by oldsailorsknives.
KWB
Re: How thin can you really go?
July 16, 2016 08:38AM
How high are the grinds on those knives? Edge thickness?

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Re: How thin can you really go?
July 16, 2016 11:35AM
top knife: at the spine 0.020", 1mm from edge is 0.005", grind is about 0.365(3/8) high.
bottom knife: at the spine 0.035" 1mm from edge is 0.006" grind is about 0.38" high.
most of the edge work done on a norton crystolon coarse/fine, then a 4 sided diamond stone from harbor freight.

scott
[www.etsy.com]
cKc
Re: How thin can you really go?
July 16, 2016 08:04PM
With really thin steel the secret for me is to grind the edge first like a scandic at desired final outcome then start grinding the bevels after. Less flex while doing by he edge

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KnivesAndStuff (YoutTube)
Re: How thin can you really go?
July 17, 2016 06:10AM
i wonder on steel this thin if an edge bevel more than 3/8" to 1/2" high makes any difference in cutting ability. on both knives above, the thickness at the spine is 0.035" or less, over an inch from the edge.

scott
[www.etsy.com]
Re: How thin can you really go?
July 17, 2016 09:20PM
This is a little chef knife I did. .077" thick at spine, almost a full flat grind. I didn't measure super carefully, but .009" or less at edge, 15* per side. Has been holding up well in the kitchen, lost its edge very gradually.



Some of the Opinels are similar to what you are doing, for a few bucks you could destroy one to have a data point.



Edited 2 time(s). Last edit at 07/17/2016 09:24PM by Any Cal..
KWB
Re: How thin can you really go?
July 18, 2016 04:07AM
Any cal- what is the blade width?

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Re: How thin can you really go?
July 18, 2016 10:19AM
1.5"
KWB
Re: How thin can you really go?
July 18, 2016 07:30PM
I just made one with similar blade width, stock. [www.instagram.com]. I am not sure how its going to work with edc but we will see. The lateral stability concerns me a bit, as I have twisted grinds before. My normal cutting was shown on my youtube channel for.reference while that is the upper limit it does happen. I cant say my .124-.136 blades dont perform well I just want to see how good it could be.

I think I am just going to have to test as one thing to take into account is a person strength making a blade for me is not the same as making a blade for horse shoe, nail benders and wrestlers. If I experiment a bit I can see at what point my strength overcomes the steel and just raise the primary a tad.

Two ways to approach really go insanely thin like- .050, 1.5 in wide, .005 at the edge and cross your fingers ever time you make a hard cut or make it just strong enough that you cant ripple the grind.

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me2
Re: How thin can you really go?
August 01, 2016 11:42AM
Quote
oldsailorsknives
i wonder on steel this thin if an edge bevel more than 3/8" to 1/2" high makes any difference in cutting ability. on both knives above, the thickness at the spine is 0.035" or less, over an inch from the edge.

I have a RADA cutlery knife that I reground down to 3 dps on the full thickness (0.03"winking smiley. Edge bevel is 7 dps and 9 on the apex bevel. It has trouble making cuts deeper than the bevel width, which is between 1/4" and 3/8" wide. I've compared it to the Scalper on apples and such, and it seems to bind. It could just be the handle feeling like more force is being required, as it's quite narrow and somewhat uncomfortable on deep/hard cuts.
Re: How thin can you really go?
August 03, 2016 05:22PM
i think you can go a lot thinner than you think you can. I ran into this question a couple years ago, and what I found works best for me is to take 3 measurements of each knife. at the shoulder of the edge {this can vary a lot due to the angle that you sharpen, but in my mind makes more sense than what you ground the edge to prior to sharpening}, the spine of course. and then the measurement I added in the middle an don't see very many makers listing, and that is 1/4" back from the very edge. the anvil on my micrometer is 1/4" diameter, and so its a very easy measurement to take, but tells you a lot about the grind. and I really wonder if it is the most important measurement. and it doesn't really matter what the grind is, 1/4" back is 1/4" back. and I believe it tells the customer a lot about what they can expect out of the knife.

I like to tell folks that the shoulder of edge measurement will tell you how easily the blade will get into the work, the 1/4" behind the edge will tell you how easy the blade will pass through the work, and the spine will give you an indication of how strong the knife will be. there is more to it of course, but that is my simplest explaination. now I would think that each steel type that you work with plus your heat treat will be huge factors, but I know that by keeping track of those 3 measurements, I have learned each of my steels a lot more.

I think the most extreme knife ive ever ground is my personal 8" santoku. I took it to .004" at the shoulder of the edge, .016" 1/4" back from the edge, and it probably finished out at .080" or so at the spine. now it took a couple sharpenings to stabilize the edge, or that could have been me learning the knife, and it is definitely not for bones, but ive cut mostly frozen meats with it with no edge damage, and it is a lot tougher than I had expected.

here are my 3 latest neckers, ive used each for 6 months or more as an edc, and am not very nice to them, they are all the same carter pattern necker that I make.

current one is a 70ish layer 1095 and 15n20 random pattern with one twist, I left it a bit thick as it is the first Damascus knife ive made and I wanted a bit more meat just in case .013" .040" .080"

the prototype 440c necker .020" .035" .070"

1095 .020" .030" .060"

all 3 have about a 3 1/4" blade, 7"ish OAL

all 3 have been ground back quite a bit through repeated sharpenings id say at least 1/8" has been removed from each in width, and ive "layed the edge back" at least a couple times on each. I remember that the 440c has at least 2 antelope, and the Damascus one has 2 sheep under their belts. I dont remember the 1095, as that was over a year ago, but it probably saw some game also. I also want to say that each was around .010" at the shoulder of the edge when they were new. but my knives are the best testers, and so they get beat up pretty bad.

Performance above all else!!!
CaltonCutlery.com
CaltonCutlery@yahoo.com
KWB
Re: How thin can you really go?
August 03, 2016 08:57PM
Thanks Joe, I typically do the same as you are doing. A lot of my work with aeb-l has shown I can go really thin but on very heavy push cuts like pvc pipe I can ripple the grind. This has happened rarely and the cuts were near max force I could apply without breaking something (on myself). Not sure how much force that is but my use with a torque wrench leads me to believe in excess of 30ft lbs. I will have to measure in at some point.

I would guess this matter is all pretty subjective as the biggest variable is a person strength and skill. I think my best bet is to make some knives and just run through some tests, I match my max strength cuts with the grind, stock etc and go just a fraction above for everyday cutting tasks and try to balance it all out. No point in making a knife for heavy cuts when the heavy cuts occur less than five percent of the time (although when they do and fail it a bummer.)

I think my leanest one to date is a recent one which is .050 stock, 1.25 wide, and .002 pre edge, I want to carry this and see how it performs. I would like to have a little 1-1.5 inch blade that cuts like a laser.

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Re: How thin can you really go?
August 04, 2016 07:11AM
Kyle,
I know you are talking about making knives, but have you thought about using utility/razor/box/replaceable knives (havalon piranta, outdoor edge edc knives) and their replacement blades for comparison?

---------------------------------------------------------
Stone Sharp Edges
[www.youtube.com] [www.facebook.com] [www.instagram.com]

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
KWB
Re: How thin can you really go?
August 04, 2016 06:25PM
I have yes, that is what Cliff has suggested. I am just super cheap and have not bought one yet.

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cKc
Re: How thin can you really go?
August 05, 2016 04:29AM
Quote
KWB
I have yes, that is what Cliff has suggested. I am just super cheap and have not bought one yet.

I think its an interesting point though.. because when asking how thin can you go.. well AEBL and many other steels are made for razors, and disposable razors.. so the answer is extremely thin..

but as you pointed out.. it wont cut a pvc pipe anymore than a razorblade.. so the question is how thin can I go to do a particular task.. thats a very different question.

I make aebl kitchen knives that have 0.001 - 0.002" edges, and are 0.005" a long way up the blade and they work great for veges... just not bones because of the cross section.

I finally got around to putting this in the mail to cliff




but this is my most extreme grind.

compare the 0.0095" thickness of a swissarmy, and this kitchen knife (OPEN IN NEW TAB TO SEE FULLY)
new tab


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KnivesAndStuff (YoutTube)



Edited 1 time(s). Last edit at 08/05/2016 04:36AM by cKc.
Re: How thin can you really go?
August 05, 2016 07:18AM
i guess i should order a piece of 1/64" O1 and see what can be done.

scott
[www.etsy.com]
Re: How thin can you really go?
August 05, 2016 09:42AM
cKc-
Nice, can't wait to see Cliff's work with it. Might answer some of Kyle's questions also at the same time.

---------------------------------------------------------
Stone Sharp Edges
[www.youtube.com] [www.facebook.com] [www.instagram.com]

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
KWB
Re: How thin can you really go?
August 05, 2016 10:41AM
I have a basic idea, but as you said how thin for a particular task. Ive found once you have to really bare down on stuff to get through it such as pvc schedule 40, thick copper wire etc. Yhe cross section has to be just right or the grind ripples.

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Re: How thin can you really go?
August 05, 2016 10:44AM
That's crazy thin Kyley. I bet you could shape and sharpen that in one pass each on the right stones.
Re: How thin can you really go?
August 05, 2016 11:18AM
Quote
cKc
...this is my most extreme grind.

compare the 0.0095" thickness of a swissarmy, and this kitchen knife...

That's a great illustration. I just mic'd the depth to 0.0095" on my Herder k3 and while it's impressively thin, it's not that thin.

-Nate
cKc
Re: How thin can you really go?
August 05, 2016 02:55PM
Quote
Ryan Nafe
That's crazy thin Kyley. I bet you could shape and sharpen that in one pass each on the right stones.

if Cliff took that knife to his 24 grit stone, he'd probably take 1/4" off the height of the blade in 1 pass.. its so easy to flex that you need a very light touch on the stone, and a very good cutting stone.

The reason I like my edge bevels to only be truely microscopic is because I'm a lazy sharpener.

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KnivesAndStuff (YoutTube)
Re: How thin can you really go?
August 05, 2016 03:17PM
Quote
cKc
its so easy to flex that you need a very light touch on the stone, and a very good cutting stone.

... where does he get all those amazing toys ... J (to silent Bob)
cKc
Re: How thin can you really go?
August 05, 2016 06:07PM
Its been so long since I've seen silent bob that the reference is going over my head grinning smiley

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[data.gearbastion.com]
KnivesAndStuff (YoutTube)
Re: How thin can you really go?
August 05, 2016 06:27PM
J says it in MallRats which is an homage to Batman, it recreates a scene from the first Keaton Batman. Silent Bob uses the Batman "rule of cool" inspired Batman grappling gun.

I was just referring to the knife.
Re: How thin can you really go?
August 05, 2016 06:36PM
Kevin Smith's birthday was a few days ago......

---------------------------------------------------------
Stone Sharp Edges
[www.youtube.com] [www.facebook.com] [www.instagram.com]

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
Re: How thin can you really go?
August 06, 2016 08:33AM
Quote
cKc
Quote
Ryan Nafe
That's crazy thin Kyley. I bet you could shape and sharpen that in one pass each on the right stones.

if Cliff took that knife to his 24 grit stone, he'd probably take 1/4" off the height of the blade in 1 pass.. its so easy to flex that you need a very light touch on the stone, and a very good cutting stone.

The reason I like my edge bevels to only be truely microscopic is because I'm a lazy sharpener.

I agree about the lazy sharpening. Once I started using knives that I reground to zero or close to it (~ <0.005) I sort of stopped regularly carrying my other ones.

What stone do you think would work best? I would think that if it's that flexible you would want a stone that's at least 500 grit, something that would be relatively smooth feeling. I don't really have much experience with higher grit stones though, aside from Spyderco rods.
KWB
Re: How thin can you really go?
August 06, 2016 11:18PM
I wish thin grinds like that could hold up to heavier cutting tasks, but anything beyond regular edc that most people have the edge chips, grind ripples, or apex folds over. While the last is easy to fix not something I like to deal with continuously.

Two options as I see it- carry 2 knives one like a laser and another more hd. Or flat grind with a blended transition grind. I have done the transition grind on a small 5160 blade .220 thick 2 in high grind, zero grind with transition grind 1/4" above the edge. I actually tried something I have never done which is blended the transition grind in very slightly convex to zero then buffed the knife to form a edge. Im not sure the durability of this edge but boy does it cut. No aggression in any form pure push cutting, but as far as that goes it matches my normal edc .125, 1.5" grind, .010 tho edge. On cardboard and beat it on hard wood push cuts I think this is due to the extremely low edge angle as it bit into the wood half way up the grind then stopped dead. Surprisingly though it chopped seasoned wood with no significant damage. But the bummer to all this is to keep that geometry you would need to sharpen it that way each time as well as the lifetime of the particular would be short lived. High performance and high maintenance.

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