Fettling Arkansas Stones

[John Crawford]

Hi Everyone:

I hope you'll tolerate another sharpening thread, for someone who is working through the learning curve.

I had been using sandpaper with decent results, but thought I would go in the oilstone direction. From one of the reputable online dealers, I picked up (1) a soft Arkansas (novaculite) and (2) a hard Arkansas, and was planning on finishing off with a green-stuff on my MDF strop.

I'm sharpening vintage stanley plane irons, chisels, and so forth. No fancy steels.

So, my questions are:

(1) I'm having a hard time getting the soft Arkansas to cut well. Both stones needed some flattening, which I took care of with 60/90 silicone carbide on a granite plate. For sharpening, I'm using mineral oil mixed with mineral spirits. It takes me about 500 passes to raise a bur (on a microbevel) using the soft Arkansas. That seems too many, am I right? Any thoughts on how I might get it to cut faster? Or is this not the first stone that one should use? (I'm just talking about ordinary re-sharpening here, not establishing bevels, shaping, etc.)

(2) In terms of coarseness, the hard Arkansas doesn't seem much different than the soft. (It is indeed much harder.) Is this to be expected? I flattened the hard Arkansas using the same 60/90 silicone carbide grit. Would going finer here do anything?

Thanks again for your help! I thought stones would be easier than sandpaper, ha ha ha. I'll be proud when I get this up and running.

[Andrew Fleck]

I don't know a lot about oil stones, but 500 passes seems about 490 too many to me. Someone will be along shortly to help you out.

[David Weaver]

It should take three or four passes with a freshly ground iron or chisel to raise a burr with a soft arkansas. Who made the soft and hard arkansas stones you're using?

Soft arks are almost always coarse (dan's brand stones aren't, but their softs can be avoided), hard arks can be any number of different things depending on when they were made and what brand. A vintage hard is the same thing as a black or translucent stone (if labeled hard by pike or norton). If they're off brands or current make, hard arkansas stones are just less porous soft types that are more dense, but they are not the same as what Dan's sells as true hard, black or translucent (those stones of Dan's make are excellent, unlike the soft, and are better or at least as good as anything newly mined).

As time goes on, a good soft and hard ark will separate themselves from each other. A good soft will continue to cut while a good hard will raise a very small wire edge and do more polish than cut.

For right now, you might try liberally smearing the soft ark with mineral oil and abrading the surface of it with something just to flush out any stuff that may have settled in the pores when lapping.

It'll be a little while of honing before you get a good feel for what the stones are. What I'm saying by that is that the hard should settle down a lot. Straight off of silicon carbide grit, and it might still be fast cutting. A freshly sawn translucent or black stone that hasn't been lapped finely will cut very fast and harsh until it's settled in some, and then it will never cut that new fresh fast again, because that new fresh is essentially a bunch of tiny saw marks from a diamond saw - the surface of the stone is more or less serrated.

My opinion is that you want to grind often with oilstones so that you can let them settle in and not work much metal with them - that's when they are a real treat. If you don't want to grind by machine, a medium crystolon stone is the best thing you'll find for grinding bevels on chisels and irons.

[John Crawford]

Thanks for the info, David. These stones are from Natural Whetstone Co. (I'm not intending to say anything bad about their stones, I'm just learning to use them....)

I do tend to grind less often, such that the micro-bevel isn't very micro any more....

I'll play around with all this and see what happens.

If you others have advice, let me know....

[Steve Voigt]

Couple thoughts:
- Abrading your stones with the 60/90 loose grit is definitely a great way to go, but I don't think I would use it on a granite substrate. For one, why kill a nice piece of granite like that? But also, it may be too hard to give the best results. The normal practice is to use a piece of glass, and that works great for me.
- If it's taking you 500 passes to raise a burr, something is wrong. Where did you get the stone? On Dave's advice, I got a soft Ark from natural whetstone, and I really, really like it. However, it is not what I use straight off the grinder, because it's not coarse enough. The soft ark is best as an intermediate stone--I use it when a tool has gotten dull, but has no damage. It normally takes me a half-dozen to a dozen strokes to raise a burr, then I move to the hard black ark.
- However, when a tool has just come off the dry grinder, or has some very light damage that's too light to bother with re-grinding, I start with a fine India, which cuts a lot more aggressively than the soft ark. If I haven't ground all the way to the edge on the grinder, it would take too long to raise a burr with the ark.
I suggest that you get a fine or medium India to use as your first stone. They are about $17 from TFWW. Also, I suggest that you take a tool that you know is sharp (sharpen it your old way, with sandpaper), and use it till it's dullish, but not terrible. Try raising a burr on the soft ark. If you can't do it in a reasonable amount of time (say a dozen or so long strokes), then I'd think the stone is at fault.

Edit: Just saw you posted that your stone is from natural whetstone. As I said, I really like that stone, so maybe the problem lies elsewhere, unless you just got a dud…

[John Crawford]

Thanks Steve, I'll do some testing this weekend.

[Noah Wagener]

I get the same feeling that they are all the same coarseness. On Dan's website they actually say as much. I can not get a black that i believe is a Dan's stone to polish beyond the softs i have. The edge of all of them seems to perform pretty well though.

I lapped a soft or Washita of some sort with water because i wanted to try it with water as some here had said that is how they use theirs. It seemed faster to me. Oddly though there was zero swarf i could see while with oil it had raised a black mess real fast. It is white with a little greyish puprle and i find it faster than the ones that stain yellow.

[David Weaver]

That should be a good fast cutting stone. I've noticed more variation between mines/cutters than within, so I'd imagine that your soft is a lot like the soft I had at one time (I still have the hard, they're fairly similar - I think you said that - and the NW hard doesn't bear a resemblance to a vintage hard).

Noah's comment about the particles is pretty much correct. There might be some variation, but the determinant in sharpening speed is how large the pores are and how fresh the surface. If there are large pores with sharp edges around them, the stone cuts fast.

At any rate, the challenge with all soft arkansas stones is to have something on hand that can get them to cut as fast as they cut off of the diamond saw, and to be honest, I don't really know of anything that does that. A 400 grit diamond hone, esp if worn in, will grade the surface of the stone to a finer cut. silicon carbide will do the same if it's broken down, and grading the surface of the stone, esp. if the pores get clogged, will make it cut like a finer stone.

The medium and soft india stones are great bargains. Their vitrified bond is so hard that you will suffer some of the same fate when flattening them (when new they will cut faster than they ever do for you again), but they will always cut fairly well and are probably more appropriate for fine tool sharpening when they've settled in some, anyway.

I'd suspect that your NW stone is a little bit clogged, they are not dense as far as hard and softs go and have a nice open pore uniform pattern. Use it with mineral oil for a while and see if the surface cleans up. What do you plan to grade it with/ lap it with in the long term?

[Sean Hughto]

500! Something's way wrong. The obvious answer would be that you were not presenting the bevel at a high enough angle, so you had to grind away a lot of steel before the actual edge reached the stone and could manifest a burr. You sound like you have sharpening experience, and state that you were trying to raise a microbevel, so this obvious answer does not seem to be likely. So I would suggest it has to be the stone (not coarse enough) or the state of the stone (clogged).

[Matthew N. Masail]

I ordered a soft and hard from Natural Whetstone. and got a new black Dan off the auction site from a seller that is apparently selling originals. will be interesting when I get to try them for a while.

David, how about a small piece of this stuff to prep the stone, maybe still too fine?
http://www.toolsfromjapan.com/store/...oducts_id=1613

[David Weaver]

That's probably a good thing to use, a full large hone isn't needed, just one to rough up the surface of a stone.

Atoma's diamonds are probably the most durable of the budget hones, and 140 is probably a good grit size, esp. since atoma bunches their diamonds instead of just spraying a coating.

Last couple of strokes with the hone should be perpendicular to the direction the tools will go if you want the stone to cut fast.

[Matthew N. Masail]

Thanks, that's really cool. If the soft ark doesn't cut well enough, I'll might try it. funny though how stones seem to cut better once you get better at using them.... hidden stone secret maybe.. "only thee who is worthy may experience my full rath!"

[Tony Zaffuto]

David,

Where do you get a soft india stone?

Thanks,

T.

[Matthew N. Masail]

tools for working wood have india stones or
sharpeningsupplies.com

a 8X3 india any grit is 19$..... quite funny acually and I feel a little silly not buying one but I think they need oil to work well.

[Noah Wagener]

I used a diamond blade on an angle grinder to take down some high spots and tried the stone and those spots were rapid but i do not think that would be a routine i'd want to continue. Maybe the sidewalk roughs it up.