# Whan is a blade too thin



## Ploppy Blobby (Apr 1, 2020)

Hi, am looking for a bit of sense checking, think I may have ground the distal taper too much. Carbon steel( HRC~61, 105WCr6 /1.2419) 2.2mm at the heel 1.65 halfway and 0.9 just before the tip.
Thing is I can flex the blade easily, see pic, and am worried this has wreaked the blade too much.
Any advice would be appreciated
Thanks, Phil 
Oh, it's a santoku 50mm blade height


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## MartinJ (Apr 1, 2020)

Hey, 
No maker here, just user. 

I don't see any problem here, if the ht is done right, those kinda steels are pretty flexible when ground that thin.


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## Benuser (Apr 1, 2020)

Not much to worry about. Have a look at vintage Sabs with their crazy fragile tips. 
Anyway, with a santoku the tip is very low. 
Rule of thumb for a general purpose chef's knife, max values: 0.2mm behind the edge, 0.5mm at 5mm from the edge, 1mm at 1cm.
See where the 0.5 and 1mm lines are along the blade.


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## Matt Zilliox (Apr 1, 2020)

no way, if it doesnt break its perfect! As long as th HT is right ill bet is rocks. but if you are unsure, kindly send it for testing and ill make sure it wont hurt anyone. do you know how hard it is to convince makers to go that thin?


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## milkbaby (Apr 1, 2020)

IMHO that's fine. Some knives are very stiff, others more flexible. People may have different personal preferences. Best thing is to finish it and test it, see what you like or don't like about it and apply that knowledge to your future work.


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## ian (Apr 1, 2020)

For reference, I recently reground a Wat 180 gyuto so that it’s

.93 mm at 2 cm from tip
.68 mm 1cm from tip

I love it this thin. However, it’s stainless clad blue #2, with the core at 64 HRC, so I’m not sure how good of a comparison it gives.


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## Benuser (Apr 1, 2020)

ian said:


> For reference, I recently reground a Wat 180 gyuto so that it’s
> 
> .93 mm at 2 cm from tip
> .68 mm 1cm from tip
> ...


Is it me, or are stainless cladded ones stiffer than plain carbons?


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## ian (Apr 1, 2020)

Benuser said:


> Is it me, or are stainless cladded ones stiffer than plain carbons?



Don’t know. Mine’s pretty stiff even at the tip, though.


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## Beau Nidle (Apr 1, 2020)

That's fine. If the heat treat is good then there's no issues. I have a couple of knives that are 0.75mm at 1cm behind the tip and they're fine. Just don't go cutting any bones with them.


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## Ploppy Blobby (Apr 1, 2020)

Matt Zilliox said:


> no way, if it doesnt break its perfect! As long as th HT is right ill bet is rocks. but if you are unsure, kindly send it for testing and ill make sure it wont hurt anyone. do you know how hard it is to convince makers to go that thin?


 be happy to but the shipping cost from the UK may be a leeetle high, not to mention that its is only the 4th blade have made and am not sure how my poor fragile ego could cope


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## Ploppy Blobby (Apr 1, 2020)

MartinJ said:


> those kinda steels are pretty flexible when ground that thin


True, very similar to spring steel i guess so yeah, as long as you are not cutting bone should be fine. I'll sharpen it (badly) and give it a go.........


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## Matt Zilliox (Apr 2, 2020)

you should show us more pictures of the blade! ive never made a knife, id be proud to just create one!


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## Ploppy Blobby (Apr 3, 2020)

Matt Zilliox said:


> you should show us more pictures of the blade! ive never made a knife, id be proud to just create one!


Okily dokily, overall length 300mm, blade 170mm, weighs 147g and the handle is made from a French oak wine barrel (I work in the wine trade so have made a few like so) treated with tung oil. Overground the middle left side hence the odd 90 degree grind marks to fix.


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## milkbaby (Apr 3, 2020)

Nice job! Keep it up!


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## Ploppy Blobby (Apr 4, 2020)

milkbaby said:


> Nice job! Keep it up!


Could not stop if I tried  got 14 on the go


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## M1k3 (Apr 4, 2020)

Did the handle smell nice when you sanded it?


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## soigne_west (Apr 4, 2020)

How’s it cut?


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## Ploppy Blobby (Apr 4, 2020)

M1k3 said:


> Did the handle smell nice when you sanded it?


Oh yes, but not as nice as a whisky barrel i cut in half for planters


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## Ploppy Blobby (Apr 4, 2020)

soigne_west said:


> How’s it cut?


As the man off the TV says 'it will cut' 
https://www.instagram.com/p/B-jmFtYpxEx/


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## SilverSwarfer (Apr 6, 2020)

Hey, nice looking work there! I’m all stirred up to try and make knives some day. If only I had any funds or space to build a shop... until then I continue living vicariously through others. So thanks for that.


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## Matus (Apr 6, 2020)

Don't try to make the distal taper linear from handle to the tip. If you forge, then you can have a lots of taper right in front of the handle, then make it slow to to about last 5-7 cm at the tip and then make the tip as thin as you find fit. That will give you less flex as you are showing. If you are doing stock removal then obviously (unless you start from a very thick stock) you will not have that strong distal taper in front of the handle, but you can still make the tip as I mentioned. Btw - 2.2 mm at half length sounds pretty reasonable (give or take of couse - depending on the knife style and whether it should be a laser or workhorse).


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## gregfisk (Apr 6, 2020)

Nice work on the knife. How thick of stock did you start with? I’ve been making my knives with 1/16” stock so they are very thin to begin with. They flex a fair amount but I don’t see it as a problem


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## Ploppy Blobby (Apr 6, 2020)

Matus said:


> Don't try to make the distal taper linear from handle to the tip. If you forge, then you can have a lots of taper right in front of the handle, then make it slow to to about last 5-7 cm at the tip and then make the tip as thin as you find fit. That will give you less flex as you are showing. If you are doing stock removal then obviously (unless you start from a very thick stock) you will not have that strong distal taper in front of the handle, but you can still make the tip as I mentioned. Btw - 2.2 mm at half length sounds pretty reasonable (give or take of couse - depending on the knife style and whether it should be a laser or workhorse).


Thanks, still amazed at how generous everyone is with sharing their knowledge.


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## Ploppy Blobby (Apr 6, 2020)

gregfisk said:


> Nice work on the knife. How thick of stock did you start with? I’ve been making my knives with 1/16” stock so they are very thin to begin with. They flex a fair amount but I don’t see it as a problem


Thanks you, still learning, so much to learn still. Stock was 3/32 and the flex when using is fine but sharpening worries me. Finding it more difficult to keep the blade, um, aligned, straight, correct. Well, it flexes and that feels like the angle moves about.


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## Matus (Apr 6, 2020)

Ploppy Blobby said:


> Thanks, still amazed at how generous everyone is with sharing their knowledge.



That is at least 50% of why I stick around  If you check out the link in my signature you may then find an article on my blog about a design of a gyuto. As long as you do not take is as some ultimate truth, but rather a food for thought, you may find it helpful.


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## Ploppy Blobby (Apr 8, 2020)

Matus said:


> That is at least 50% of why I stick around  If you check out the link in my signature you may then find an article on my blog about a design of a gyuto. As long as you do not take is as some ultimate truth, but rather a food for thought, you may find it helpful.


Nice blog, lots of thought and work has gone into it, brain started aching about halfway through  REALLY wished i had read the part about non-linear distal taper before making a 240 gyuto - its rather whippy


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## Matus (Apr 8, 2020)

I am happy you found it useful


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## mlau (Apr 28, 2020)

Looks great to me! How did you get it so thin?

Sort of reminds me of a Herder K2.

I'd like to get into knife making to make thin enough paring knives that feel nice.


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## Ploppy Blobby (Apr 28, 2020)

mlau said:


> Looks great to me! How did you get it so thin?
> 
> Sort of reminds me of a Herder K2.
> 
> I'd like to get into knife making to make thin enough paring knives that feel nice.


Thanks!
A mate wants to make something similar but for cutting squash, think I need a much heavier blade for that.
That's full flat grind which I find relatively easy with the belt grinder, food really sticks to that style of grind. 
Been trying to put a slight convex grind on the more recent efforts


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## Benuser (Apr 28, 2020)

Ploppy Blobby said:


> Thanks!
> A mate wants to make something similar but for cutting squash, think I need a much heavier blade for that.
> That's full flat grind which I find relatively easy with the belt grinder, food really sticks to that style of grind.
> Been trying to put a slight convex grind on the more recent efforts


Adding some asymmetry, moving the edge to the left if you happen to be a right-hander, perhaps?


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## Ploppy Blobby (Apr 28, 2020)

Benuser said:


> Adding some asymmetry, moving the edge to the left if you happen to be a right-hander, perhaps?


Funny you should say that, was just putting distal taper on the next toy (210mm gyuto) and had decided to try that. Probobly get confused and make a lefty. Much research on the horizon


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## Benuser (Apr 28, 2020)

Ploppy Blobby said:


> Funny you should say that, was just putting distal taper on the next toy (210mm gyuto) and had decided to try that. Probobly get confused and make a lefty. Much research on the horizon


We all went through the same...





A Basic Explanation of Asymmetry


A Basic Explanation of Asymmetry Way back when I began sharpening I remember reading through many forum threads about asymmetry in double bevel knives and having no idea what was going on. All this talk about 70/30 and 80/20, "You should be doing this and shouldn't do that", but no real...




www.kitchenknifeforums.com


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## Ploppy Blobby (Apr 28, 2020)

Benuser said:


> We all went through the same...
> 
> 
> 
> ...


 that's exactly what I was just reading


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## mlau (Apr 28, 2020)

I'd love to see your mate's face if you made this a single bevel for a leftie.

Being an accidental ambi, sometimes I forget to be a righty.
It's a weird feeling to use your left hand for doorknobs, etc.


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## Kippington (Aug 18, 2020)

Ploppy Blobby said:


> Hi, am looking for a bit of sense checking, think I may have ground the distal taper too much. Carbon steel( HRC~61, 105WCr6 /1.2419) 2.2mm at the heel 1.65 halfway and 0.9 just before the tip.
> Thing is I can flex the blade easily, see pic, and am worried this has wreaked the blade too much.
> Any advice would be appreciated
> Thanks, Phil
> Oh, it's a santoku 50mm blade height View attachment 75622


You gotta remind anyone that sharpens this knife that the tip is flexible - It behaves differently from what many people are used to on the stones. I've seen enough messed up knives with thin tips because people don't adjust their sharpening to the flex... The profile goes from black to red.


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