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 Post subject: Nubatama sharpening set philosophy ?
PostPosted: Sat Jun 22, 2013 8:49 pm 

Joined: Fri Mar 22, 2013 12:44 am
Posts: 161
Location: Northern Virginia
Hi Mark, Ken, et al,

I am interested in the philosophy behind the stone selection in the Nubatama sharpening set given the seriously huge selection of stones available from Nubatama?

Why 150 / 1K / 5K instead of any number of other 3 stone combos possible?

Many thanks.

 Post subject: Re: Nubatama sharpening set philosophy ?
PostPosted: Sun Jun 23, 2013 2:06 am 
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Joined: Mon Apr 23, 2012 4:45 am
Posts: 1461
Excellent question!

Well we needed a coarse, medium and polishing stone and something that had wide applicability to a variety of steels, knives and styles of usage.

So let's start at the 150 Bamboo. It's coarse, fast, and yet still fine enough to leave a good finish. Unlike other series that end at say 400 or 500 grit, I choose this because coarser stones would be too coarse for general use. The finish is pretty fine for a 150, just slightly coarser than say a Beston 500 or Chocera 400. In many instances, you can skip and intermediate stone like a 400 Bamboo, which you can add later if you wish. I could have started with a 400 or 320 grit stone, but the 150 is just so fast that even if you already have another series of stones, the 150 will improve your work using them too. And it's the fastest thing out there for erasing scratches from an Atoma 140 or DMT XXC.

The 1k Ume. The Medium hardness is applicable to a wide variety of blades and blade types. Not so soft as the 1200 for instance. And not so hard as the Ume double hard 1k. The 1000 Black Ume is a larger brick and more costly so a smaller stone seemed a more affordable choice. It is just slightly softer than the 1k Bamboo gold.

The 5k Bamboo - Well it's right in the middle of two 4k stones and two 6k stones, works outrageously nice on carbon steels yet works very nicely on stainless too.

I fully suspect that more advanced sharpeners will add to this starter set as they refine their needs. Basic sharpeners may find that these three stones more than meet their needs.

It is entirely reasonable to add say a 10k Bamboo or 400 Bamboo to this set or even a 60 grit Ume for major repairs and reprofiling. If I were concerned with kasumi finishes, I might choose to add a 2k or 3k Bamboo to this with the 5k Bamboo being a nice followup.

I know this combo won't meet everybody's needs. But that's why there's more than 3 stones in the Nubatama line :)


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 Post subject: Re: Nubatama sharpening set philosophy ?
PostPosted: Sun Jun 23, 2013 5:43 am 

Joined: Tue May 29, 2012 12:29 am
Posts: 945
I would like to share my experiences as not only a user of Nubatama stones but someone that uses these stones more in a day than most will use them in 1 year.

To give a idea of just how much I use them, on a average day I will sharpen 100+ knives with about half of those done by hand. Literally I spend 8 hours a day sharpening knives. I have developed new calluses and worked my sharpening muscles to the point of cramping and next day soreness.

I use a 3 stone set-up to sharpen most knives (traditional knives are a different story) and that consist of a bamboo 180 grit, 1k gold, and 5k. These stones have proven their worth but also shown me the value of a diverse set of stones. I have learned that while these stones work extremely well for my needs the other Nubatama offerings will be able to better suite my needs and ill explain why.

Starting with the 180 bamboo,

This stone is the stone that starts the whole process, when I get a knife its in the worst possible shape 9 out of 10 times. Several chips, rounded tips, and the edge... the edge is just a rounded section where a edge was once located. I will typically go straight to the belt sanders to set a edge profile and make my work just a bit easier. A belt only gets me so far though, defining the bevel geometry and making a nice pointy tip are just part of the shaping process.

The 180 bamboo is a finer coarse stone, meaning it has a little less drag on the blade and wears a bit slower but cuts quickly and leaves a very defined bevel. It's mud production is very fine and somewhat silky. Unlike the 120 or 220 pink brick which are very aggressive and IMO more geared to single bevel knives due to how they work. I really like its feedback and how fast it cuts but with the volume of knives I sharpen my 180 stone is now half the thickness it once was and will soon be nothing more than mud in the bottom of the sink.

So, for my needs having several low grit stones to pick from is becoming a huge advantage as I figure I would wear through 3-4 180 stones per year :O

The 1k bamboo gold stone has been a awesome middle grit stone and those who have tried this stone have all been amazed by its insane cutting power. It quickly removes the coarser grind marks and establishes a 1k burr while producing a nice dark mud and not loading on the surface. While this stone is slow wearing its not slow wearing enough for me and I would guess I could consume 4+ 1k gold stones per year. Yes, you are reading that right.

So for 1k stones I have been considering the hard or x-hard Ume 1k stones.

On to the last of my progression, the 5k bamboo.

The 5k bamboo has been a bit of a trick stone for me to fully understand. It's so slow wearing yet somewhat soft that it has great feedback but is probably going to outlast all my other stones. It does not build much swarf and most of the time no mud but when you inspect the bevel its quickly removing the 1k scratches and applying a polish that at times has a hazy appearance. Besides all of the above its greatest feature IMO is the ability to make a edge that's clean and crisp with little to no burr, sometimes I don't even need to strop the finished edge thanks to this somewhat unique feature.

As a little test I used to Tojiro gyutos in a head to head race. The race consisted of two 3 stone sets, the first was the chosera stones in 400, 800, and 3000. The next set was my bamboo stones 180, 1k, and 5k described above. Using the chosera stones I completed the sharpening in 8 minutes and 1 second including stropping on 1 Micron diamond strop to remove the remaining burr. Using the Nubatama stones I completed the sharpening in 6 minutes and 49 seconds while only needing a few strops on a bare leather strop as the burr was much smaller.

I considered it a solid test with un-bias results because I was not only putting the stones to the test but also myself. Than and my boss also agreed the edge quality from the bamboo stones was noticeable better. Yeah yeah 3k vs 5k but remember one of those seen a abrasive coated strop...

 Post subject: Re: Nubatama sharpening set philosophy ?
PostPosted: Sun Jun 23, 2013 5:47 am 
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Joined: Wed May 16, 2012 4:42 pm
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JB <> Informative post. Thank you...

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 Post subject: Re: Nubatama sharpening set philosophy ?
PostPosted: Sun Jun 23, 2013 5:56 am 

Joined: Tue May 29, 2012 12:29 am
Posts: 945
Your welcome, I figure with the amount I use these stones I can give others a good idea of the strengths and weaknesses of specific stones.

Currently I am thinking of replacing the 180 bamboo with either a 150 bamboo or 220 Ume green brick as my needs for a very coarse stone are not really needed. I figure a slow wearing 220 would be a solid choice. As for the 1k, I figure a harder stone should wear a bit slower needing fewer replacements per year.

For me its not so much a matter of if they will work (because I know they will) but how long they will last.

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