Extra-coarse-grit stone recommendation requested.

[inferno]

I have a very specific question that seemed better to ask here than to start a new thread. I'm planning to buy a course Crystolon to flatten the Pro 120. They should be close to the same grit, or the Shapton might be slightly finer based on what I've read. Will the tough oilstone binder plus SiC hold up to the weaker magnesium binder plus AlOx, or will I eventually need another solution to flatten the Crystolon? I'm trying to avoid dealing with SiC powder if possible

i have not used my 100 grit Sic stone on the 120 pro. but i have used it on the 220 and up and there it works very well! you have to flatten the Sic stone too some times with loose grit. you could also simply sprinkle loose grit between the SiC stone and another stone. that works very fast.

i recommend using loose grit on the 120. coarse stones are picky with the surface condition to cut well. also using loose grit to flatten stones is extremely fast. i would not sacrifice an atoma for the 120. you will ruin it.

 

[DHunter86]

Atoma and DMT Dia-flat would be better.

I've tried those too, but sadly the surface of the SP120 won't be back to factory finish, i.e., it cuts much slower than it ought to. One alternative that I've yet to try is to use the very edges of the Atoma 140 plate to scratch the surface after flattening. This tends to leave a coarser surface on JNats and is beneficial as conditioning for some harder stones; this should work here as well.

Not sure about the Nanohones as I've yet to try them. I went with the cheap Diamond plates as they're way less messy than SiC powder, which works but is messy. I do agree that these plates wear much faster than Atomas though, but once they wear, they make nice diamond nagura for naturals.

 

[Kawa]

SiC powder is messy, and for me it takes more time to set up then a flattening stone.

But if one of your problems is that the SP120 isnt factory finish after flattening, loose SiC powder is the solution.
Sadly, once you felt the original coarseness after SiC powder again, you realize that that original feeling wont hold for a long time. Most of my coarse stones are getting slick again during one knife session.

So I do something like this: if I need a 400ish stone, I can take my lapped pro400. After one session I won't see it as a 400 anymore. So untill lapped again, I move it up one gritt in my mind, using it as a medium 1000ish kinda stone.

 

[spaceconvoy]

I have a very specific question that seemed better to ask here than to start a new thread. I'm planning to buy a course Crystolon to flatten the Pro 120. They should be close to the same grit, or the Shapton might be slightly finer based on what I've read. Will the tough oilstone binder plus SiC hold up to the weaker magnesium binder plus AlOx, or will I eventually need another solution to flatten the Crystolon? I'm trying to avoid dealing with SiC powder if possible

Replying to myself, lol... but if anyone's curious, the Pro 120 beats a coarse Crystolon. The abundance of blue mud was the first indication, confirmed by the marked difference between the two sides of the Crystolon after about 30 sec of lapping. Oh well.

But damn the Pro 120 is beastly. As a home user I don't need this much power. I'll probably stick with the GS500 for my coarsest stone, mainly because it means the Atoma 400 becomes a nice all-in-one flattening solution for all my stones. Y'all ultra coarse people are crazy, but in a good way.

 

[Cliff]

I have an 80-grit diamond plate to flatten coarse stones. I'm a fan of the SP 120.

 

[Qapla']

If it's for the SP 120, it'll laugh at the diamond bonding of the plate, slowly. Atoma and DMT Dia-flat would be better. The Nanohone ones should hold up also. They are expensive too.

How would you compare the Atoma, DMT and Nanohone plates? I notice that the Dia-flat and the Nanohone Lapping Plate are far more expensive than Atoma's are.

220 Nubatama Platinum

What steels have you used it with, and what else can you tell us about it?

 

[M1k3]

How would you compare the Atoma, DMT and Nanohone plates? I notice that the Dia-flat and the Nanohone Lapping Plate are far more expensive than Atoma's are.


What steels have you used it with, and what else can you tell us about it?

Nanohone > Dia-flat > atoma
Basically in succession of price.

Honestly for super hard stones, loose SiC or sandpaper is the way to go. It'll lengthen the life of any diamond plate tremendously.

 

[Qapla']

For those who do use loose SiC powder, how do you most often use it? (Things like the Shapton Naoru are quite expensive.)

 

[DHunter86]

Ideally I'd like to get float glass, but I've been using them on tiles.

 

[Ben.G.]

For those who do use loose SiC powder, how do you most often use it? (Things like the Shapton Naoru are quite expensive.)

I called a glass shop near me. He cut and beveled a 12”x12” piece of glass for $10.CAD. it works great.
I also bought some thin foam stickies to keep it from sitting directly on the countertop. I made sure they were very thin and placed them all over the bottom with little space in between. I feel like this is more stable than placing it on a towel and doesn’t allow any chance for it to have stress points where it could break under pressure.

 

[ian]

I'm a little confused about using float glass. I mean, isn't the SiC going to abrade the glass anyway? Does it abrade slowly enough that the initial flatness of the glass is very important? Is glass harder than tile?

 

[spaceconvoy]

I'm a little confused about using float glass. I mean, isn't the SiC going to abrade the glass anyway? Does it abrade slowly enough that the initial flatness of the glass is very important? Is glass harder than tile?

Yeah I don't get it either, and I wonder how long the people suggesting this method have used it for. Years ago when I didn't want to shell out for a diamond flattening plate I tried flattening stones on the back of a granite tile, until I noticed the stones were no longer getting flat. There are no miracle materials, and everything abrades.

 

[ian]

To me, it just seems like an alternative to the 3 stone method, but maybe where the tile/glass abrades more slowly. So, still potentially effective, but you may have to be careful to be flattening the entire glass/tile and not just rubbing in the middle. I've never tried it though.

 

[spaceconvoy]

But it's only a two-stone method unless you rub your stones together as well. I think the only advantage is probably surface area. It'll take a while to become dished enough to notice, but it will dish eventually

 

[ian]

But it's only a two-stone method unless you rub your stones together as well. I think the only advantage is probably surface area. It'll take a while to become dished enough to notice, but it will dish eventually

Yea, true. Probably one should just do this with the cheapest flat surface (per hardness) possible and replace it frequently.

 

[inferno]

glass in an amorph material. its not crystalline as a stone for example. it lasts quite long. but if you want it to last as long as possible you will have to use the whole glass plate.

just like using coarse stones, use the whole surface.

i think stefan wolf on youtube gets about 6 months out of 1 side of glass. and it seems to be his main method for flattening.

i only use the glass when i have several stones needing to be flattened, and to experiment with surface roughness. for stones above 1k i use diamonds or my 100 grit sic stone. it basically becomes a project as soon as the glass plate comes out so i make sure i have a few things to do on it when its time.

i have recently tried just sprinkling sic powder between my sic stone and the stone needing to be flattened, it works. i did the coarse side of an india type stone, put the texture back in a very short time.

 

[kayman67]

Yeah. If it's big enough, will last a while. On the other hand, trying to use a small(ish) one made it useless after the third session (3 stones, same day).

 

[pennman]

I flatten my stones on my belt grinder. Gets out the worst dishing on the coarsest stones. Can refine the surface up to 3000 grit if necessary. I actually get the dish out with a 50 or 80 grit belt then put it on 120 to smooth the surface. Then I use my flattening stone to make a slurry. Never had a stone crack or overheat because they have all been soaking or I spray the belt with water and use a slow speed. Here is an economical grinder that will do the trick for most everyone. I have one of these and it works well. Use the belt and not the disc

 

[spaceconvoy]

I spent some time this afternoon reprofiling and thinning my new Sukenari to reduce the belly to a nice shallow curve. Ended up shortening the length by 4mm and reducing the weight by about 2.5g, mostly done with the SP120.

After a while I stopped bothering to refresh it with either a JKI 150 diamond plate or coarse Crystolon, since they didn't seem to make much difference. If I rinsed it off it would feel glazed at first, but then the cutting power would slowly return as the swarth built up. With the right amount of water and swarth it would find its groove - you can tell when the surface slightly bubbles and froths with each stroke. @M1k3 you're right about it not needing resurfacing with stainless cladding, but I wonder why.

The weirdest part was there seemed to be no discernible dishing, except some gouges I made with the spine. Even though it felt almost completely abrasion resistant when thinning the bevels, doing work on the spine made it crumble. What exactly is this demonic beast of a stone?? The worst part is the scratches aren't quite removed by my GS500, so I gave up on the finish until I can order a variety pack of sandpaper.

It was pretty sweet to feel a noticeable difference in cutting a potato after a dozen strokes (side note: a potato is the most useful sharpening tool besides actual stones). I take back what I said earlier about not needing this much power. Still can't imagine using it more than once a year, so I'm going to epoxy it to my GS500 as a base, raising the height to match my other stones until its terrible power is required once more. Recommended

 

[M1k3]

Stainless cladding is soft enough to catch the abrasive while being abrasion resistant enough to pull the abrasive out.

 

[inferno]

View attachment 105298
--snip--

you have just found out how to correctly use your coarse stone.

with all coarse stones there seems to be a sweetspot in how much slurry you should keep on the stone to keep it cutting fast.
its the same with the 220 pro too. i have found its sweetspot and it pretty much refreshes itself as i go. and usually you dont actually need a truly flat stone either. so the stones become quite low maintenance too. i just try to work more at the high spots when i see dishing. its flat enough

 

[Qapla']

Looks like you all convinced me; I'll be giving my Shapton Pro 120 another shot when the sandpaper arrives. Until then, I'm going to see if I can replicate that water-bubble and stone self-refreshing effect with the Nubatama Black 180. I might have also been badly misunderstanding coarse-grit stones as well; most of my stones (especially medium-grit stones) I just use without creating slurry ahead of time unless there's no other way, and when slurry/swarf builds, I use it as is.

The Shapton Pro 120 does in fact dish, but quite slowly. I've resurfaced mine many times by now. Granted, with single-bevel knives there's a much larger surface area on the stone being used at a given time. IME clogging has been the much greater issue.

 

[M1k3]

Regarding clogging on SP 120. I've made small grooves across the surface. Sort of like when the Japanese knife makers make grooves in the giant water wheel.

 

[inferno]

i have a small boron carbide "norbide" stick. i will try to put grooves in my 120 with that too.

the norbide sticks are made for truing SiC and alox wheels, only diamond and cbn is harder.

 

[M1k3]

i have a small boron carbide "norbide" stick. i will try to put grooves in my 120 with that too.

the norbide sticks are made for truing SiC and alox wheels, only diamond and cbn is harder.

A junk knife works also
Use the spine at the tip.

 

[daveb]

A junk knife works also
Use the spine at the tip.

TFTFTFTFTFTF

 

[M1k3]

TFTFTFTFTFTF

My apologies, I misspelled TFTFTFTF

 

[ian]

Regarding clogging on SP 120. I've made small grooves across the surface. Sort of like when the Japanese knife makers make grooves in the giant water wheel.

Huh... this helps with clogging? That's real interesting.

Btw, I've rediscovered the SG 120 for crap stainless. Works really well imo. Doesn't clog at all. Doesn't wear fast. Is not screaming loud like Sigma 240. Is flattenable with an Atoma, even.

Kinda wish I'd actually used your SP 120 some when you sent it to me. Maybe I'll buy one at some point if I get an appropriate flattening method. Although I probably don't need one right now.

 

[M1k3]

Huh... this helps with clogging? That's real interesting.

Btw, I've rediscovered the SG 120 for crap stainless. Works really well imo. Doesn't clog at all. Doesn't wear fast. Is not screaming loud like Sigma 240. Is flattenable with an Atoma, even.

Kinda wish I'd actually used your SP 120 some when you sent it to me. Maybe I'll buy one at some point if I get an appropriate flattening method. Although I probably don't need one right now.

It helps release grit. Especially useful for simple carbons or mono stainless.

Sandpaper. Coarse sandpaper used like someone else is paying for it. 3m Cubitron.

 

[ian]

It helps release grit. Especially useful for simple carbons or mono stainless.

Sandpaper. Coarse sandpaper used like someone else is paying for it. 3m Cubitron.

I thought I tried that and it was completely ineffective. Maybe I was using crap sandpaper, can’t remember