Andrew Pritchard

Equivalent grit numbers

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With my birthday coming up, I've decided to investigate an upgrade to my sharpening for my hand planes and chisels

 

Currently I'm using the "scary sharp" method, with a block of granite and series of sandpapers. I can currently get up to 2000 grit sandpaper. I'm sure there are higher grits papers I can get - I've heard of diamond lapping films, but they are rather expensive and I'm not so sure I want to go down that route.

 

Anyway, my question is this: Is 2000 grit sandpaper the equivalent to 2000 grit stone when it comes to wet stones?

 

I'm thinking of getting a 4000 and 8000 stone, but I'm wondering if the 4000 is necessary or whether in fact I should ditch the scary sharp for the upper grits all together.

 

Has anyone here moved from scary sharp to stones - and is there much of a learning curve?

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2000 grit wet/dry is really fine grit wise. Probably at least as fine as an 8000 grit stone, maybe finer than some. Not trying to disuade you from getting stones. I quickly grew to dislike scary sharp.

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Scary sharp might be hassle for a pro or very prolific amature. But for the weekend hobbyist, it is a pretty good way to go. I find 2000 grit paper provides a mirror finish, then stropping with white rouge to be a good final touch. Frequent touch ups on the strop will reduce the need to drag out the sandpaper by a considerable amount.

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depends if it's 2000 on the P or F scale... The former is about 10u and the latter about 1u. The grit on a stone is based on a separate set of standards and will depend on several different factors: Oil or Waterstone; Natural or Synthetic; Clay-matrix or Ceramic-Matrix; and quite a bunch of other stuff.

 

For example, if we assume you want to purchase an inexpensive synthetic clay-matrix Norton waterstone: If it's P2000 paper, then it would equate to about an medium stone, say 1500g on the J scale. It it's F2000 paper, then it would equate to a fine stone, say around 8000grit on the J scale.

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With my birthday coming up, I've decided to investigate an upgrade to my sharpening for my hand planes and chisels

 

Currently I'm using the "scary sharp" method, with a block of granite and series of sandpapers. I can currently get up to 2000 grit sandpaper. I'm sure there are higher grits papers I can get - I've heard of diamond lapping films, but they are rather expensive and I'm not so sure I want to go down that route.

 

Anyway, my question is this: Is 2000 grit sandpaper the equivalent to 2000 grit stone when it comes to wet stones?

 

I'm thinking of getting a 4000 and 8000 stone, but I'm wondering if the 4000 is necessary or whether in fact I should ditch the scary sharp for the upper grits all together.

 

Has anyone here moved from scary sharp to stones - and is there much of a learning curve?

 

No need to stop at 2,000 grit paper.  Try 6,000 grit 3M paper:

 

http://www.amazon.com/6000-Grit-Mint-Polish-Paper/dp/B00K2V8XI8

 

It's expensive but you won't need to change sheets very often.

 

The Chris Scharz chart that stops at 2,500 grit sandpaper has been out of date for some time.

 

Here's an assortment that goes up to 10,000 grit sheets:

 

http://www.foredom.net/a5969-5962.aspx

 

Need something really fine?  How about .05 micron (NOT .5 micron but .05...) this is 100,000 grit equivalent

 

http://www.amazon.com/Monkey-Pinewood-Derby-Axle-Polish/dp/B005FXYPNA

 

Powders to 200,000 grit are available from here in bulk:

 

http://www.gravescompany.com/polishin.htm

 

A 10,000 grit waterstone is close to being a joke if you're on a quest for fine abrasives (not that you need anything this fine for woodworking tools but since you asked....)

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No need to stop at 2,000 grit paper.  Try 6,000 grit 3M paper:

 

http://www.amazon.com/6000-Grit-Mint-Polish-Paper/dp/B00K2V8XI8

 

It's expensive but you won't need to change sheets very often.

 

The Chris Scharz chart that stops at 2,500 grit sandpaper has been out of date for some time.

 

Here's an assortment that goes up to 10,000 grit sheets:

 

http://www.foredom.net/a5969-5962.aspx

 

Need something really fine?  How about .05 micron (NOT .5 micron but .05...) this is 100,000 grit equivalent

 

http://www.amazon.com/Monkey-Pinewood-Derby-Axle-Polish/dp/B005FXYPNA

 

Powders to 200,000 grit are available from here in bulk:

 

http://www.gravescompany.com/polishin.htm

 

A 10,000 grit waterstone is close to being a joke if you're on a quest for fine abrasives (not that you need anything this fine for woodworking tools but since you asked....)

 

The thing is that 6000 grit is 2 micron.  By some of the other scales that is coarser than the 2000 grit papers.  Then of course even micron size isn't everything, is it max or average?  What is the distribution of sizes?  What are the cutting properties of that abrasive vs other abrasives?

 

How about this http://www.amazon.com/661X-Diamond-Lapping-Film-White/dp/B00FW6YNE6/ref=sr_1_1?ie=UTF8&qid=1410443470&sr=8-1&keywords=diamond+lapping+film

 

.5 micron diamond lapping film

 

Or this 

 

http://www.leevalley.com/US/Wood/page.aspx?p=68943&cat=1,43072

 

.1 micron diamond lapping film

 

But as people have shown previously you can't entirely depend on grit numbers as there is more than one scale.

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2000 on which scale? If 'F' scale, then F2000 = about 1u = about J8000... Right? If so, then +1.

 

My rule of thumb: the harder you whack a chisel, the less honing required. The higher the Janka, the higher the hone. The lower the bevel angle, the higher the hone. Paring chisels = highest hone...

 

For example:

Mortising chisels: J2000

Bench chisels that are struck:J4000

Bench chisels that are not struck (or at least not often and lightly): J6000

Paring chisels (J-white): J-Nat shiage-to (finishing stone)

Dovetail paring chisels: J8000 low Janka, N-Nat high Janka

 

Dovetail procedure: bulk waste with fret saw, remaining course waste striking bench chisel and fine waste/fitting with dovetail pairing chisel... Almost all drawer stock is low Janka.

 

Plane irons: J8000

Japanese white steel: J-Nat

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OK, let's measure it by microns.  The Monkey Jam axle polish is .05 micron as are some of the loose grit powders.  That's not five tenths of a micron but five hundreths of a micron.

 

One micron is coarse grit by comparison.

 

I say all of this for the sake of trivia and not much more.  One certainly doesn't need these very fine grits.  They didn't have them in the18th century and don't appear to have been hindered one whit:

 

www.ronaldphillipsantiques.com

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They did have fine media back in the day, just in a drastically different form than we do today They stropped and used various compounds that where sub micron in size.

 

 

 

 They didn't have them in the18th century and don't appear to have been hindered one whit:

 

www.ronaldphillipsantiques.com

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Rottenstone, chromium oxide and various Rouges come to mind, not to mention the leather itself has an abrasive property. The Japanese also have super fine natural stones that they have been using forever.

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Good stuff Dan.  I was aware of pumice and rottenstone but hadn't really given the earth pigments (the basis for rouge) much thought.  And some leather does have silica I believe.

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Good stuff Dan.  I was aware of pumice and rottenstone but hadn't really given the earth pigments (the basis for rouge) much thought.  And some leather does have silica I believe.

 

Various amounts of chromium oxide was/is used in the tanning process as well.

 

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As for in the past, there are fine natural stones from all over the world.  Belgian Coticles, German Esher and Thuringian hones.  Plus there were synthetic straight razor hones for over a hundred years.

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Various amounts of chromium oxide was/is used in the tanning process as well.

 

Of course it all makes perfect sense.  Hand woodworkers in the 17th, 18th and early 19th centuries could not have accomplished what they did with lousy edges resulting from grossly substandard sharpening media.  European ecclesiastical carving of the relevant periods alone seems proof enough to me.

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The video is a little misleading, his actual blog post is a lot better.

http://paulsellers.com/2013/11/sharpness-mean-real-terms/

 

What I think he was trying to say, but didn't really do a good job (he alludes to it in the blog post) at, is sharpen for the task at hand.

 

Mortising chisels and scrub planes don't need to be taken to a super fine grit, because they are rough tools. Even if you do put a super keen edge on them it won't mater after a minute or two because of the type of work they do. If you are going to go strait from a #3 or 4 to a finish, then you will want a higher grit. If your going to sand  after you plane, there is no point in going to a higher grit.

 

I would go as far as saying the current batch of woodworking pundits try to over simplify stuff to much.

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More times than not I go fine India and then to a hard rubber strop with AlOx powder understanding that this is essentially a proxy for a very fine stone.  My black Ark has slowed down a whole lot and I just don't use it that often. 

 

The India removes bluntness, the strop takes care of rag and imparts a surprising amount of polish in a few seconds' worth of work.

 

I don't usually strop jack plane irons and chisels which are being used for chopping in that particular session. 

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I question stone ratings. Do stones always fracture at identical sizes? Is there not a chance that media slurry becomes a blend of sizes with the largest scoring bits at the rated size? Is this not why Seller's can get an edge to work with that stone? Is the result not a touch higher polished that the equivalent sandpaper media that strips off the paper before it grinds? How does this slurry/wear factor into the discussion? Is it a non-issue, a minor issue, or an ignored issue?

One more: what is the cutting effect of a slurry loaded stone, even if the slurry could be rinsed away?

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Slurry of swarf?  Many stones don't generate much slurry, especially things like oil stones.  Slurry being abrasive media while swarf is removed metal.  These are fundamentally different things.

 

As for a slowed down black ark, why not lap it a bit to restore a new surface?  Stones need maintence like any tool after all.

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