What is your "signal" to flatten a stone?

[Ron Kellison]

My current sharpening set is made up of Sigma II stones in 1000, 3000 and 10,000 grit and a 325X DiaSharp for shaping and flattening. I really like the stones...they are everything they are cracked up to be! However, I suspect that I am flattening the stones more often than actually needed. What are your cues to flatten a stone?

Best regards,

Ron

[Adam Cruea]

I flatten my 240 after every sharpening, and sometimes during sharpening.

For the others, I watch the outer corners of the blade. If I notice that going from one stone to another leaves them untouched, it's time to flatten the previous stone.

All in all, though, you start to get accustomed to when you flatten your stones. For example, if I sharpen my jointer irons, I'll run my Atoma diamond plate over my 1000, 6000, and 13,000. Just take a pencil, swipe across the stone. When the pencil is all gone, the stone is flat.

[Chris Griggs]

I used to flatten my stones what I now think is way too often. Literally every couple honings. Now unless I'm doing an inordinate amount of work on any given stone (e.g. rahabbing a blade), I just flatten my stones when I enter the shop, and leave it at that for the shop session. I don't really have a sign for when they need flattening, I just know flattening at the beginning of a shop session works for me. If I used a guide much still, I'd probably flatten them more often, but I free hand, mostly honing sideways, and try to work the whole stones surface, so maybe that lets me get away with flattening less. Truth be told sometimes, when I just pop down to the shop for what will be a short amount of time I don't even flatten during that session. Technically I probably should, but I've gotten progressively laxed about it hasn't seemed to hurt anything.

I don't neglect flattening them, I just don't obsess over perfect flattness the way I used too. Basically, I know that if the stone takes more then about 30 seconds I probably shouldn't go quite as long between flattenings next time.

[george wilson]

My diamond bench stone,and Spyderco black and white ceramic stones never need flattening. I honed the white one flat with the diamond stone initially,to get rid of slight out of flatness and "fuzzy" spots on the white stone. I'm not sure that they surface stones as well now as they used to,though. I've seen pictures of the white stones with circular grinding marks left in them.

[Jessica Pierce-LaRose]

For me, using my Naniwa Super Stones (less so with my one Sigma stone) , the signal is often less one that says somethings not flat, and more that I'd like the surface is a little more fresh to cut a little faster. I flatten less now than I used to - I flattened a little less when I moved to freehand sharpening, and flattened a little less as I got better at freehand sharpening.

Certainly, however, if I flatten for flatness and didn't need it, I see that pretty quick, and stop. If I've got a low corner for some reason, a quick stroke or two with the flattening stones helps me figure that out quickly, drawing contrast to it, and helps me avoid it if need be.

[Derek Cohen]

I take a diamond stone to the surface whether the stones need to be flattened or not. Most of the time I am not concerned about flatness anyway, but that the surface is loaded and the stone is not cutting optimally (and sometimes poorly) is left to get black. Both Sigmas and Shaptons are the same. I spritz with a little detergent in the water, which helps keep them clear, but only for a short while.

I imagine that ultra flatness is only important for those that rely on a honing guide, but freehanding a blade allows one to follow any slight hollows. Keeping the surface clean is more of an issue for me.

Regards from Perth

Derek

[Terry Beadle]

I use a pencil. I rub with my DMT. If the pencil marks are removed, it's flat enough. If the stickem level of the DMT is high, I'm really sure it's flat.

Water stones need to be check every 5 min of work or so. If it's a higher polishing stone, like 4000 and above, then more frequent flattening is usually needed as the stones are softer, however
the amount of flattening time required is less than a lower grit stone requires.

It's always better to keep them flat. The time required to flatten a stone plus the time required to correct what a non-flat stone can do to a chisel or plane blade, is too much to off set the cost lost of stone material by too frequent flattening IMO.

So every 4 ~ 5 min of work, check it for flat. You'll soon see how often the stone ( what ever grit ) will need to be re-flattened. The harder the steel and the more pressure you use
on the target blade will also affect how often you need to re-fresh the stone.

Flat, .... it's where it's at ! Hoot!

[David Weaver]

I don't flatten as much as derek mentions, but when I do, it's for the same reason - because I want uniformity of the cut and the speed a fresh surface provides.

There is a conondrum in the world of stones - stones that stay flat well benefit from being abraded just for freshness, and stones that don't need to be refreshed because they're friable don't stay very flat.

I never flatten a finishing oilstone, though.

[Jim Neeley]

+1, I consider my Shaptons to be a consumable.. very slowly consumed but a consumable nevertheless.


I use a pencil. I rub with my DMT. If the pencil marks are removed, it's flat enough. If the stickem level of the DMT is high, I'm really sure it's flat.

Water stones need to be check every 5 min of work or so. If it's a higher polishing stone, like 4000 and above, then more frequent flattening is usually needed as the stones are softer, however
the amount of flattening time required is less than a lower grit stone requires.

It's always better to keep them flat. The time required to flatten a stone plus the time required to correct what a non-flat stone can do to a chisel or plane blade, is too much to off set the cost lost of stone material by too frequent flattening IMO.

So every 4 ~ 5 min of work, check it for flat. You'll soon see how often the stone ( what ever grit ) will need to be re-flattened. The harder the steel and the more pressure you use
on the target blade will also affect how often you need to re-fresh the stone.

Flat, .... it's where it's at ! Hoot!

[Larry Fox]

I sharpen with Shaptons so I flatten every grit every time with the plate before I start sharpening a tool. Unless things are really bad I don't flatten a particular grit more than once while using it for a tool. Like Jim, I consider them to be consumables and want them to be flat while using them. With the Shapton setup its just too easy to do and it adds a lot of certainty to your work which I really like.