Help skool me regarding blade thickness.

H

HARDBALL

Joined
May 6, 2001
Messages
923
Hi all,

I readily admit, I am LOST when it comes to Math, especially fractions. That said, I have been trying to figure out, just how much THICKNESS is truly needed on a given Knife.
I have been looking/researching different Knives types (and their blade thickness) today. I have looked at my Spyderco Para Military 2, a Canadian #1 Belt Knife, a several Mora Knives for example.
Now, if you happened to see the thread I have on my Thrift Shop (50 Cent) knife, that lil' knife has a blade that is VERY thin and cuts/slices beautifully. The blade is the same thickness of a U.S. Penny being 0.061 (1.55mm) thick (or thin if you will). I suspect this is a pretty darn thin blade (even for a short bladed knife). I later learn that a DIME is .045" (1.35mm or approx. 1/32") thick.
I understand that many CUSTOM knives are often made 3/32" thickness. Now, I have a MORA Companion Heavy Duty F (Orange) which has a .126" (about 1/8th. inch) thick blade. It's a nice knife but, I did NOT like it for "Food Prep" as the blade is too thick for cutting IMHO. That being said......what then is a good comprise for a blade length of about 3" to 4" with a bit more strength
(than the Penny thickness blade) yet still be an excellent slicer ? Is 3/32's the correct answer ? Thanks for any help/suggestions.

Regards,
HARDBALL
 
I use both 3/32" and 1/8" for my culinary knives.
I can make a serviceable culinary knife out of 3/16" if the blade is tall enough with a full flat grind to the spine.

Go with 3/32" and then adjust from there after you have made and tested your desired knife of 3-4"
 
The problem you are having with your Mora for food prep is the Scandi grind not the thickness.
When you try to cut carrots or other veggies with a Scandi grind, the blade gets about half way through then snaps the rest of the way.
With the proper edge geometry, a 1/8th inch thick, full height grind blade can be a great slicer.
 
Hi guys,

Thanks for the replies. FTR, yea, I was wondering if that in fact might of been part (if not the entire) problem. OK....Rhino.....so now 3/32's to 1/8th. inch thick. Is there something (common) in between I need to consider ? Something LESS than 3/32's ? Something MORE than 1/8th. or is somewhere around 3/32's to 1/8th. the best bet ?

HARDBALL
 
OAL thickness plays second fiddle to OAL geometry IME. If a knife is done right, a 1/4" thick knife can slice onions pretty darn well. Not as well as a well done 1/16" thick knife but well enough you won't have much of a problem "working around the knife" so to speak. Most knives I've seen can't accomplish this though because these are "super, cut through cinder block" knives and have edges ground accordingly. So it really depends on how well the edge is ground.

That said, I would say a good all around knife that doesn't need to do any light prying would be in the 3/32"-5/32" range going thinner if you're easy on your knives. Thicker side of the spectrum if you're a bit rough with them. As far as the scandi, you've nailed the problem with them. Thick scandis are next to useless for anything but woodworking. Thin scandis on the other hand are great tools. If you want a scandi and you want it to use it in the kitchen get a 3/32" or less thick knife. The Mora Companion MG is sub 3/32" thick and works pretty well in the kitchen. I use mine as a paring knife.
 
Esee 3 - 3.5 inch blade, 1/8th inch thick, full flat grind - slicing demon
 
Hi Shotgun,

Thank you for the information you provided as it is most helpful. No doubt "Geometry" of blade is VERY important and I have a LOT to learn about blade grinds. I've recently been on kind of a "thickness" kick as I have acquired a BUNCH of old "Butcher" style knives this Summer. I find it interesting that so many of these older knives are rather thin. One knife for example is a L.E. Wood Cuterly Co. North Hampton MASS. which I suspect is around one hundred thirty (more or less) years old (the Company was founded in 1865). This Knife has three pins Wood handle, a poured Pewter Bolster and a
5.75" blade that is the same thickness of a NICKEL (1.95mm/1/16th.inch) which is 0.0767717 inch (also know as "thick as a Nickel"). This old knife feels quite sturdy for not being a 1/4" thick! However, the blade still has a bit of flex. Perhaps if the blade were shorter, it might be more sturdy/stiff. Oooh, much to my surprise, a NICKEL is thicker than a Quarter.
Thinnest (of course) is a DIME, then, the PENNY, a QUARTER and then the NICKEL. I stopped after 41 cents lol.

Regards,
HARDBALL
 
Man, I just read a TWELVE page discussion on Knife Thickness at BushCraftUSA. My Head is spinning! Lots of good info!
Almost the entire Monday Night Football Game (PHI & WSH) to read.

HARDBALL
 
1/16" for slicing, 1/8" for utility, 1/4" for hard use.
Work around in between these for higher or lower bevels.
Work around in between these for broader or narrower blades.

Even a thick saber grind can get shaving sharp. Not as easy to get that sharp edge angled properly towards the work as it is a razor.

Your steel and your heat treat will also affect how long the edge will last.

Everything else is just practice! :)
 
Take your average production folder and/or fixed blade.

Cut their spine thickness in half.

That's about how much you need.
 
HARDBALL said:
Hi guys,

Thanks for the replies. FTR, yea, I was wondering if that in fact might of been part (if not the entire) problem. OK....Rhino.....so now 3/32's to 1/8th. inch thick. Is there something (common) in between I need to consider ? Something LESS than 3/32's ? Something MORE than 1/8th. or is somewhere around 3/32's to 1/8th. the best bet ?

HARDBALL
Click to expand...

hardball,
I purchase most all of my steels from Niagara Specialty metals in NY. You can buy 1/8" and have it ground down to what you wish. As other have stated, Blade geometry is just as important or more.

I like Full Flat grinds to the spine on all of my culinary knives with a few chisel grinds being hollow ground on the inside.

I started with hand files & sand paper along with a large can of elbow grease. You are welcome to PM me if you have any questions that I might be able to help you with?
 
Hi guys,

Thanks for all your help and suggestions. Esav.....1/16" for slicing, 1/8" for utility, 1/4" for hard use.....I like that! Sort of sums it up. Good.....yea, I was looking at my Para Military 2 and thought.....that's a pretty thick spine! I'd bet I could get away with HALF the width and still be good. Rhino.....I will contact you in the future about one of your beautiful PARING Knives. Oooh, I lived in "Studio City" for sixteen years.

Regards,

HARDBALL
 
Hardball,
There is a trend in knives these days to be on the THICK side to put it mildly! Stick around for a few years and you will see this sharpened pry bar pocket knife trend go back to something a little more reasonable.
There are many aspects of knives that follow trends just like fashion of ladies dress lines, Heels etc or rocket fins on a car for another example. There are new and innovative ideas in knives now as well. You will learn the diff as you learn more.

For starters, Look at, fondle and use all of the different kinds you can, to get a true hands on feeling for the different kinds of knife designs. Those old butcher knives you mentioned sound great!
 
Remember that the stiffness of a blade goes up very quickly as the thickness increases. Going from a 1/16" thick to a 1/8" thick blade, all else equal, give you a blade that has 8 times the stiffness. In 3 to 6 inch blades, once the thickness gets to about 1/16", you shouldn't have any trouble with the blade flexing too much during hard cutting. I have a 6" blade kitchen knife that is only 1/32" thick, and on very difficult cuts, like turnips or such, it can be too thin. For an outdoors blade, a 1/8" thick blade with a 75% height flat grind works well as a balance.
 
Hi all,

Rhino.....you said a mouthful. Trends come, trends go. If I were a Knife maker, I would try to be ahead of the curve and start making "thinner" bladed knives as what goes round comes around.
me2.....good point about the 1/8" blade being eight times the stiffness of the 1/16th. blade. On the whole, I'm thinking 1/8" thick blades is (for most situations) about as much thickness as I'll need.
From what I am reading, it seems to strike a good "overall" balance of weight/strength/etc. Still, I try to keep an open mind. I have no doubt the Becker BK-2 has it's place for certain situation.

HARDBALL
 
evilgreg said:
So much truth.
Click to expand...

So much confusion.

Spine thickness effects lateral strength of the blade but has little effect on cutting efficiency without respect to blade-height.

Edge thickness effects cutting efficiency and also edge-durability. A blade 1/4" thick at the spine can be just as fragile as a 1/16" blade at the edge, making it unsuitable for chopping into hard objects despite superiority in lateral strength. Similarly, a 1/4" blade can cut with the same efficiency as a 1/16" blade if they sport the same thickness behind the edge, depending on the cutting resistance of the material and the depth of the cut.

For benchmarks, use a standard box-cutter blade for thickness. If you need more lateral strength (i.e. prying), move up in spine thickness but grind as needed to keep edge-thickness the same. If you are not sure where to measure edge-thickness, it should either be where the primary bevel meets the secondary (edge) bevel (the shoulder) OR just measure 1/16" back from the apex (a common edge-bevel width).


Good general use cutting geometry = <1/16" wide edge bevel, <0.020" thick (<15-dps), followed by <5-dps primary bevel to the spine of whatever thickness. My $0.02
 
Good information Chiral. Spine thickness is also for weight in a chopping blade, but again, blade height has to be taken into consideration. A blade that is 1/4" thick and 2" wide with a full flat grind has the same edge geometry as a 1/8" blade 1" wide, which is somewhere between 3.5 and 4 degrees per side. The former is a good width for a chopper, as the extra width and spine thickness adds weight, while the latter is a good all purpose cutter, but won't have the weight to be an effective chopper. I do a lot of chopping with a 12" blade that's only 3/32" thick, but the edge geometry is about 4.5 degrees per side with a width of about 1/2" to 5/8". However this blade is also 2.5" or more wide, so gets weight from that. It's not as good at prying as a 1/4" or even a 3/16" thick blade, but I've not bent it in use, which includes batoning, throwing, and prying up keystones around the flower beds.
 
This is one of the best cutters I have. Ron Flaherty model 1 .200 thick A2 deep hollow grind. I was supprised at its cutting ability. The geometry is perfect.
IMG_20130618_222744_360_zps53529f79.jpg
 
You must log in or register to reply here.
Back
Top