Flattening a Fine India

[Russell Cook]

Hi all,

Today I checked the flatness of my Coarse/Fine India stone, and found the Fine side is not flat, kind of humped in the centre by ca. 0.5mm.

I have some P80 sandpaper at home (this is very coarse, coarser than coarse crystolom), and was thinking of gluing this to some glass to do the job, with water as a flushing agent.

Sound like a good plan?

[Bill Haumann]

I've flattened some india stones with sandpaper on granite. It worked fine, there was some gumminess from the india, not sure what might help with that.

[Tony Zaffuto]

The "gumminess" may be because (depending upon manufacturer) the stone may be impregnated with oil.

[David Weaver]

coarse diamond hone or loose silicon carbide. You can use sandpaper if it's all you have and see how it holds up, but diamonds or loose grit will do a better job. I wouldn't glue it to glass, you might need more than one sheet.

[Chris Griggs]

Loose silicon carbide is the best solution I've found (I assume loose diamond would work too). You can put it on glass, or granite, or a flat cinder block. The loose grit will wear the substrate as well though so don't go putting it on an expensive inspection plate or anything like that. Loose is the key work here. Oil stones whether india for natural destroy sandpaper, and can shorten the lives of diamond plates.

[Jim Matthews]

Could the same be done on a smooth cinder block, with only water?

I understand some auto supply shops still sell carbide "valve lapping" compound
but you would want one that's without any grease or suspension, I suppose.

Diamond plates are expensive, but they should last most of your lifetime.

[Chris Griggs]

Could the same be done on a smooth cinder block, with only water?


Yes, but the I find putting the Sic on the cinder block makes is cut much faster. My results on just a wet cinder block were mixed.

[David Weaver]

If anyone can't find loose silicon carbide locally, you can always find it at lapidary supply places *cheap*. I would get 60 or 80 grit for india stones or any stone flattening. Even with shipping, it shouldn't be more than about $10 for a pound.

330959395745 (no affiliation)

Same with al-ox, i've gotten that from soap supply places (i guess people put it in soap) for $10 shipped for a 2 lb tub of it. It only gets to sucker price levels when it's sold by woodworking retailers or other specialty places where the buyers wouldn't go through it fast.

[David Barnett]

It only gets to sucker price levels when it's sold by woodworking retailers or other specialty places where the buyers wouldn't go through it fast.

Ain't that the truth

Panadyne Abrasives (http://www.panadyneabrasives.com/Home_c1.htm?page=all) offers brown or white aluminum oxide, black or green silicon carbide, cerium oxide, boron nitride, boron carbide, zirconia and more—no chromium or iron oxide, though—and they're happy to sell one pound at a time, and for the more spendy materials, even smaller amounts.

Nothing wrong with that eBay seller, of course, but variety is the spice of life and sometimes it's convenient and cheaper to order several lapping materials and grits at once.

[David Weaver]

sometimes it's convenient and cheaper to order several lapping materials and grits at once.

Most definitely agree with that.

(thanks for the link!)

[Russell Cook]

Hi,

Had a go today with some SiC grit on glass (36-60 grit) and it's better than it was but there's 2 corners are still about 0.3mm out of flat. I'll continue a different day.

Have to say it's a bigger pain than doing waterstones eh. The oil is messy and the gunk from the fine side has got all over the coarse side, so I'm thinking I may need to give it a thorough clean once it's flat. Can't help wishing Norton had got the Fine side as flat as the Coarse side and saved me this bother ...:)

[Steve Friedman]

Ain't that the truth

Panadyne Abrasives (http://www.panadyneabrasives.com/Home_c1.htm?page=all) offers brown or white aluminum oxide, black or green silicon carbide, cerium oxide, boron nitride, boron carbide, zirconia and more—no chromium or iron oxide, though—and they're happy to sell one pound at a time, and for the more spendy materials, even smaller amounts.
David,

Thanks for that link. Looks like a great resource. I have a ton of black SiC in various grits, but wondering if it makes sense adding any of the other types. Is there anything (in English) that describes the difference between the various materials and when you would use each? Also, I see they sell diamond powder. Do you recommend them for that as well?

Steve

[David Barnett]

Thanks for that link. Looks like a great resource. I have a ton of black SiC in various grits, but wondering if it makes sense adding any of the other types.

You're welcome, Steve.

If you mostly use silicon carbide for flattening stones or blade backs, I'd stay with that. Sharp blocky silicon carbide's excellent for that, is cheap and it's easy to change grits on cast iron laps. I mostly use aluminum oxide, Linde A & B, and other oxides such as cerium, chromium and tin for polishing certain gem species, but aluminum oxide works well dry on strops for edge tools and is popular with carvers.

I haven't any idea what diamond powders PanaDyne sells and for how much, having bought my powders in bulk before finding PanaDyne. For small amounts of diamond powder for sharpening, one can find bargains on eBay (http://stores.ebay.com/TechDiamond/Diamond-Powder-/_i.html?_fsub=5464275015&_sid=79834605&_trksid=p4634.c0.m322), and other reliable dealers such as David Clayton, sell on eBay (http://stores.ebay.com/Diamond-Tools-International) and directly (http://jadecarver.com/). There are other online lapidary abrasive suppliers, of course, and selections vary. Kingsley North (http://www.kingsleynorth.com/skshop/product.php?id=46489&catID=189) sells chromium oxide where PanaDyne does not, for example.


Is there anything (in English) that describes the difference between the various materials and when you would use each?

Most everything I have explains abrasives in context of the materials they're intended to alter, which is to say gem species rather than tool edges, and how certain crystal habits and abrasive shapes interact with the crystalline makeup of intended target surfaces.

Although at first appearance daunting, much can be learned from Aggregation and flow of solids; being the records of an experimental study of the micro-structure and physical properties of solids in various states of aggregation (http://archive.org/details/aggregationflowo00beilrich), by Sir George Thomas Beilby.

While it doesn't cover modern superabrasives, nor the still newer nanoabrasives, nor all the tribological advances of the last few decades, it's still worth a look for those deeply interested in lapping and polishing, and it is free.

Here's a table that gives abrasive shape and character as well as Knoop microhardness, showing finer gradations than the simpler Mohs scale.





ABRASIVE PROPERTIES



HARDNESS





ABRASIVE
MOHS
KNOOP
SHAPE
CHARACTER
REMARKS










Quartz
7
820
Lt. Wedges
Soft, friable.
Silicon Dioxide


Garnet
7 - 8½
1360
Lt. Wedges
Medium soft, friable.
Complex Mineral


Emery
8½ - 9

Blocky
Medium soft, friable.
Impure Al2O3


Corundum
9
1635
Varies
Med. hard, friable.
Natural Al2O3


Alumina
9
2000
Varies
Hard.
Synthetic Al2O3


Aluminum Oxide
9
2100
Hvy. Wedges
Hard and Tough
Synthetic Al2O3


SPC Aluminum Oxide
9
2100
Disk-like
Hard and Tough
Synthetic Al2O3


Ultra Alumina
9
2100
Hexagonal
Hard and Tough
Synthetic Al2O3


Silicon Carbide
9
2550
Blocky
Hard and Sharp
Synthetic SiC


Boron Carbide
9
2880
Slate-like
Very Hard
Synthetic B4C


Diamond
10
7000

Hardest
Natural / Synthetic





If I think of a survey or listing more focused on sharpening and polishing steel, I'll post it. Right now, though, I'm drawing a blank.

[george wilson]

I have an old sandstone wheel I use with some water to flatten stones. I haven't tried a fine India,but very quickly flattened a black Arkansas. I don't see why it wouldn't flatten an India.

P.S.: Now that I recall,I know it would work because I learned that trick from old Mr. Sims,whose tool box Roy Underhill had on his show. He used India stones and flattened them that way.

I was in the Gunsmith Shop back in the 70's (in williamsburg). A young guy was trying to flatten their black Arkansas stone with 600 grit wet or dry wrapped around a file!! I Took their grindstone out of the trough and laid it flat. We had the Arkansas stone flat in about 5 minutes. I think it would have taken him about 20 years to flatten it the way he was going about it!! The young guy was an excellent craftsman. He just needed some old tricks.

[Steve Friedman]

David, thanks for taking the time to do that. Very helpful.

Steve

[David Barnett]

My pleasure, Steve. :)

[Russell Cook]

Hi all,

I've got the stone flat now, using SiC grits 36-60 on glass.

However, some of the gunk that came off the fine side got into the pores on the coarse side.

I washed it in soapy water and rubbed the coarse side with my hand, quite a few times. It got a lot better, and it cuts OK still, but some patches are still not totally clear.*

What could I do to clear the pores out a little more? Dishwashing detergent with a toothbrush? Vinegar and toothbrush? Please don't say boil it!

[David Weaver]

boil it....oops. Not sure what to suggest. If you use the stone often, you'll end up using it somewhere between it's coarsest cutting and no cutting at all, because it will consistently stay at an in between level, but keeping it cutting as fast as it did as perfectly new is a pretty labor intensive endeavor.

[Russell Cook]

Cheers for the reply, David.

Well, I used it this morning to prepare a new chisel for use (my set of chisels did not come ready to use!) and it worked well, so I'll think I'll stick with it as is for now.

I have the vague idea of once every year or two boiling all the oil out, re-facing both faces, and then refilling it with oil.
I found lapping it with oil still inside to be a bit of a pain.

[David Weaver]

If you use a very liberal amount of oil on the surface of it once in a while (and hone while it's like that) it should stay in good shape indefinitely and be very useful, even if it doesn't cut as fast as they do when they're freshly agitated. That fresh speed is too fast cutting for me, it wastes off too much steel.

I have a little bit of a problem with stones of just about any type (as in I buy them when I don't need them) and to a T, when I get a group of stones and a bunch of india stones come with them, they look like they have been very lightly used and then discarded once they're loaded. There must be machinists (or must have been) who used those common stones until they were loaded and then let the company buy a new fresh one.

[Steve Voigt]

That fresh speed is too fast cutting for me, it wastes off too much steel.

Yeah, me too. I'm a recent convert to India stones.I love the "fine" stone, but after hollow grinding, it only takes about 6 strokes to put a nasty huge burr on a blade. I've actually been thinking about getting a soft Arkansas and trying that for the first step off the grinder (btw, really like that black arkie you sold me).


I have a little bit of a problem with stones of just about any type (as in I buy them when I don't need them) and to a T, when I get a group of stones and a bunch of india stones come with them, they look like they have been very lightly used and then discarded once they're loaded. There must be machinists (or must have been) who used those common stones until they were loaded and then let the company buy a new fresh one.

I don't know if my experience is typical, but in my old machine shop we didn't use stones at all. We ground almost everything on Baldor dry grinders with grey wheels, then honed a secondary bevel with a fine diamond wheel.

[David Weaver]

I think you're probably correct, the india stones that I've gotten in bunches are hard and old, and experience with newer ones (that are a little more friable, especially the silicon carbide side on combination stones) and lots of old ones (that are bone hard all the way around) makes me think they were loaded up and discarded many many decades ago. I can imagine people would've used them on carbon steel and HSS cutters, but I can't imagine anyone would use them on carbide tooling, or even HSS once diamonds became relatively affordable.

Glad you're pleased with the stone. Norton's black stones are a bit different than the other brands I've tried. They have some tooth, but that may disappear in time. Some of the perceived toothiness of norton's fine stones probably has a lot to do with how they finish the surface of the stones, though, and I never did use that one enough to find out where it would end up. It's only probably a clinical disorder that's given me enough curiosity to buy and fiddle with all of this stuff, but I still love to try different stones no matter what they are.

[Russell Cook]

Cheers for all the info,.

Btw, I'm also quite fond of my India combo stone. My introduction to sharpening was Leonard Lee's book, in which oilstones in general are reviewed very unfavorably, but I've been happy with how it works.