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Thread: Grinding the Kanna Blade
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22nd December 2016, 03:25 AM #1Novice
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Grinding the Kanna Blade
I recently received a kanna that I got on that auction site and noticed that the blade has a sizeable chip in it. Luckily I didn't pay much so not a whole lot lost.
What is the best way to remove material without negatively affecting the cutting edge?
I know I will have to tap out the blade (ura-dashi)? once the material is removed.
I guess if nothing else this is a good learning opportunity.
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22nd December 2016, 11:14 PM #2
Good choice in purchasing a cheap Kanna if you FUBAR it then no major loss.
You can use a bench grinder to grind out a chip. Its just a matter of a very light touch and constant cooling.
Lightly grind the blade across its width then dunk in water and repeat
Because the blade is laminated you must not only be concerned with drawing the temper but also causing a de-lamination.
So go easy.
However if you have a diamond plate, you can increase the bevel angle easily, this will remove the chip and will increase the edge durability and reduce the chance of edge chipping in future.
Just remember that the bevel angle must be a few degrees less then the bedding angle of the dai.
Just freehand sharpen the blade lifting the blade a little so more pressure is on the front of the bevel and work until you remove the chip.
You do not need to achieve a complete flat bevel first time out.
As long as you have a clean sharp edge, then over time you can broaden the micro bevel to a more traditional full face broad bevel.
Tapping out is relatively simple affair, the only advice is that slow and steady is best. A single gentle tap is better then ten hard thumps. You only need a tiny flat even 2mm is plenty. Do not try to achieve a wide flat on the ura. A narrow & even ura is always better. Look for symmetry when tapping out.
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25th December 2016, 08:16 AM #3Novice
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I appreciate the information. I was worried about using a grinder to remove the material. Also what is the best way to remove the thicker rust? (not just the surface patina type rust) Should I just use some steel wool?
I am also on the hunt for a ~3mm chisel to work on the oshi-mizo? for the other plane that I have.
Kanna_Chip_2_Sm.jpgKanna_Chip_Sm.jpg
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27th December 2016, 10:43 PM #4
Cracker, can I suggest that you very lightly polish the ura side as described by Des King (see link below) or So in one of the first postings on this forum. Do just enough to indicate the width and shape of the ito-ura. Then take another photo and show us the result.
From what I can see from the above photos you may have less to do than you think.
Don't worry about rust removal at this stage. I can suggest a methods for dealing with that when you get to that.
Ito-ura and problems | D & M King | Blog ::
Stay sharp!
NeilStay sharp and stay safe!
Neil
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30th December 2016, 04:29 PM #5Novice
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Here are the pictures after a light polish. I also did the face of the blade to better show the chip.
The ito-ura is not completely visible since the chip is higher than the surrounding steel.
Also how should I store my planes? There are large humidity swings in my garage (20-70%) through the year. I have noticed that the first day I received this particular plane I was able to get the blade to protrude from the bottom of the dai as it should. Today I was not able to repeat that. I have stored the kanna with the blade in, but inside where it stays less humid overall. I hope I have not ruined them just by storing them inside.
I do appreciate the help. You can do all the reading on the internet as one can but without some guidance it can be a bit of a challenge.
Blade_Edge.jpgBlade_Edge2.jpgBlade_Edge3.jpg
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30th December 2016, 07:28 PM #6
When I do not use my kanna I make sure to withdraw the blade from the dai. That way I do not have a stuck blade nor is there a chance that the blade may split the dai. If there is a huge shift in humidity.
Shifts in humidity is to expected and the dai may need adjustment however this is pushing my limit of knowledge. When, how and by how much I do not dare to say.
It is hard to tell from the photo what is exactly going on. Does the blade have a crack in the lamination?
Could you use a coarse stone to clean up the back and the bevel so its more clear?
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30th December 2016, 07:36 PM #7
crackerkorean is just noticed that your username has Korean in it, are you Korean? If so you you must have a wealth a knowledge found in native Korean speakers. The Koreans seem to traditionally use more Japanese tools then Chinese.
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30th December 2016, 11:28 PM #8Novice
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Unfortunately I am not a native Korean speaker so that is not a source of information that I could use, I wish it was.
The first picture shows rust between the laminations where they have separated.
The second photo you can see where how far the laminations have separated up the back of the blade. (You can see a line where the piece is separating from the rest of the blade.)
Hopefully these pictures are a little more clear as to whats going on.
20161230_073351.jpg20161230_073306.jpg
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30th December 2016, 11:39 PM #9
That's a mighty big rip in that blade. I'll be interested to see how it goes. I suspect lots of grinding back and tapping out!
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31st December 2016, 09:17 AM #10
Yes massive rip and delamination.
You have one option grind.
I would not try to grind a 30 degree bevel.
I would grind it square at 90 degree until you grind out the chip & the split.
Then grind you 30 degree bevel angle.
Why square? it is faster when you need to remove 6mm pls without risking burning a thin bevel edge during such a long grind.
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31st December 2016, 11:12 AM #11
The light grind has revealed some serious problem with your blade, Cracker.
As others have observed, the delamination being the most problematic. Depending on how far that goes back into the blade will determine if the blade can be rescued. The delamination is the primary reason for the crack. Any attempt at ura-dashi is likely to extend the crack or create a new one if that cannot be eliminated.
The other issue that your light grind has revealed is the large size of the ito-ura and the thinness of the hagane layer. The ura side of this blade has been substantially ground down. I wouldn't expect to see this until the blade was much shorter. The thinness of the hagane layer would have also made it more prone to cracking.
I'm starting to think that this blade may not be worth the effort required to get it back into working order, but trying to see what you can do with it will be a valuable learning experience.
Cracker, what is the width of that blade? I may happen to have an old blade that may fit your dai block.
Stay sharp and stay safe!
Neil
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31st December 2016, 12:31 PM #12Novice
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Thanks for the help guys.
Good thing it was cheap. I will work on it and see if it might be recoverable.
I did get this thinking might as well learn on trying to "restore" one vs just purchasing one. Seems I am getting a bit more than I thought which is good, I am happy with any opportunity to learn and understand my tools.
I would also like to get my feet wet with before I go out and get something from one of the few online places that I have found.
Once I get the blade sorted out, then itl be onto fitting the dai to the blade. I need to get a couple of things before I start working on that. (file and 3mm chisel)
BTW width of the blade is 65mm.
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31st December 2016, 12:55 PM #13
Worst case scenario - the blade is FUBAR and not usable. You can still use it to practice freehand sharpening, and tapping out and fitting to dai, With no concern about breaking it.
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31st December 2016, 03:18 PM #14
I have one (see blade No 2 in photo) that is 63mm near the cutting edge and 65mm near the top of the hagane boundary.
IMG_20161231_100245.jpg
As you can see, plenty of rust, but may be a good blade once cleaned up. The ito-ura is OK-ish close to the cutting edge, which is a plus for it. However, it does widen a bit about 25mm up from the edge, but you would be years away from that becoming an issue for you.
And the price is good too, it is a freebie for you.
Let me know if you would like it.
Stay sharp!
NeilStay sharp and stay safe!
Neil
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10th January 2017, 01:42 PM #15Novice
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Hoping to get to the grinding this week now that we will have warmer temps after the snow.
Would just the grinding stone that came with the grinder be good enough or should I order a special stone?
I plan on recording the whole restoration process of this plane for any other beginners from a beginner.
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