Extra-coarse-grit stone recommendation requested.

[daveb]

Perhaps seal the top as well and use it in your garden?

 

[M1k3]

i did a 1h session on the sigma 240 yesterday. i had 3 aus8 blades to sharpen and remove small chips from.

this is quite a ****** stone to be honest.
*even though i had sealed it, it does not hold water well at all. you constantly need to add more water.
*it wears about 2-3x faster than it should imo. (for the material it removes)
*its not fast. yeah this is not a fast stone.

comparing it to my fav in this grit range the 220 shapton pro.
*sigma is much slower.
*sigma can't handle high pressures to get **** done. because it will simply wear away even faster then.
*the shapton holds on to its water a lot better.
*the slurry it forms is simply better than sigmas.
*shapton wears a lot slower, even though its a very fast wearing stone.

now i'm thinking about simply filling the whole stone up with 1comp polyurethane glue. maybe that will make it last longer and hold on to its water?

Odd. Opposite of my experience. Except for the water thing.

 

[Benuser]

http://glasspolishshop.com/diamond-hand-pad-15003
Surface Shapton Pro 120 and all those glazing SiC coarse stones with this. It's 100x faster and better than a brand new Atoma 140.

Thanks a lot for the suggestion, @kayman67 !
Got the 60 grit and it works great in very short time. My coarse Shaptons have recovered their initial coarseness.

 

[Cliff]

http://glasspolishshop.com/diamond-hand-pad-15003
Surface Shapton Pro 120 and all those glazing SiC coarse stones with this. It's 100x faster and better than a brand new Atoma 140.

Does this flatten or just clean up the stone?

 

[ModRQC]

Odd. Opposite of my experience. Except for the water thing.

It is odd to me. Don't have experience with SP220 but Sigma is fast and not very dishy. Can support pressure - that works better if sealed though water management gets a bit easier.

I think I know @inferno problem though: when the Sigma dries its mud clumps fast and the stone dishes just as fast. It really likes water a bit too much so its speed is cut down some by extra management - but still fast.

 

[ModRQC]

Does this flatten or just clean up the stone?

It's a pad therefore soft therefore won't flatten properly.

 

[spaceconvoy]

Odd. Opposite of my experience. Except for the water thing.

I wonder if you're using different types of steel. I recently switched from carbon stainless and had to replace a stone that no longer worked for me. It would be nice if mentioning steel type when talking about stone performance became standard practice, though I often forget to do this myself.

 

[M1k3]

I wonder if you're using different types of steel. I recently switched from carbon stainless and had to replace a stone that no longer worked for me. It would be nice if mentioning steel type when talking about stone performance became standard practice, though I often forget to do this myself.

Whatever is used in the stainless wokshop #2 cleaver, Wusthof Pro and Grand Prix II, A2 variants, VG-10, Shirogami, soft stainless cladding, etc.

 

[GorillaGrunt]

I used the Sigma for sharpening very dull or chipped/damaged knives, mostly factory stainless, and preferred the result if not the process over other stones. I didn’t do much thinning of good knives on it and don’t remember ever having a good result with that compared to other stones; however I’ve since messed mine up with the wrong sealant.

 

[inferno]

It is odd to me. Don't have experience with SP220 but Sigma is fast and not very dishy. Can support pressure - that works better if sealed though water management gets a bit easier.

I think I know @inferno problem though: when the Sigma dries its mud clumps fast and the stone dishes just as fast. It really likes water a bit too much so its speed is cut down some by extra management - but still fast.

no. its just slow. and overly dishy.

 

[Benuser]

It's a pad therefore soft therefore won't flatten properly.

Looks like a pad, is absorbant, but stiff. By the way, my purpose is to restore the stone's texture. For flattening you may use the three-stones trick.

 

[Cliff]

I have a coarse diamond plate for that, but they're expensive. I've used an Atoma 140 as a kind of nagura, but it sounds like this is a better idea.

 

[ModRQC]

Looks like a pad, is absorbant, but stiff. By the way, my purpose is to restore the stone's texture. For flattening you may use the three-stones trick.

Stiff yes and I understand what you want, was answering the other query by @Cliff...

and since you know what it takes is it stiff enough to flatten?

 

[ModRQC]

no. its just slow. and overly dishy.

So it’s impossible that @M1k3 and myself get different results?

I’ll take this with a grain of salt.

 

[ModRQC]

I wonder if you're using different types of steel. I recently switched from carbon stainless and had to replace a stone that no longer worked for me. It would be nice if mentioning steel type when talking about stone performance became standard practice, though I often forget to do this myself.

I used the Sigma to thin SK5 and to thin an old Victorinox, as to use extremes. Also on White SS clad, VG-10, and what else... I think Masahiro VC well all simple carbons either mono or SS clad. Endured an hour of full pressure thinning of Victorinox I’m not sure it even lost 3mm of thickness after all that and flattening as needed. It’s not as fast on SS I think but pretty aggressive still.

 

[inferno]

So it’s impossible that @M1k3 and myself get different results?

I’ll take this with a grain of salt.

are you saying that you and mike have a stone conspiracy going on?

i have absolutely no idea how you use your stone and therefor its impossible for me to judge the results you are getting. and i have no idea about what reference frames you have.

i still got the results i got. you might get other results. and thats ok with me. if you think its a good stone. cool for you. i think its so-so stone at most.

i got these results when i weighed how much steel they removed for an equal amount of work. sigma 340mg, shapton 390mg. also aus8 but clad.

 

[ModRQC]

are you saying that you and mike have a stone conspiracy going on?

i have absolutely no idea how you use your stone and therefor its impossible for me to judge the results you are getting. and i have no idea about what reference frames you have.

i still got the results i got. you might get other results. and thats ok with me. if you think its a good stone. cool for you. i think its so-so stone at most.

i got these results when i weighed how much steel they removed for an equal amount of work. sigma 340mg, shapton 390mg. also aus8 but clad.

Yes I remember that thread and thought you were sourcing your interpretation there. Still the stats says slower but nowhere near slow, and dishy more than a Shapton I don’t doubt it any second but far from really dishy stones like Cerax.

And BTW I also think the Sigma is so so. I’d rather spend more time with a stone I like better even if slower. Sigma gets the cheaps and the daunting thinning work.

But Sigma slow and dishy the way you’re saying it I never would agree.

 

[Benuser]

Stiff yes and I understand what you want, was answering the other query by @Cliff...

and since you know what it takes is it stiff enough to flatten?

Yes, if you don't too much pressure. Have used tonight to cleanup and chamfer my Chosera 2k, after cleaning and restoring my coarse Shaptons. Please be aware though it's only half the size of the stone, or an Atoma. If the stone is seriously dished, I don't know if it will work. Use a light hand. As others here, I'm reluctant to use the Atoma with a 220 or a 120, but they easily get smooth.

 

[kayman67]

Does this flatten or just clean up the stone?

It's not big enough to start with, but any high spots can be removed much faster and you can use something else after, just to level the surface. Definitely can take some pressure of a regular diamond plate. I just did this today with a 220 SiC stone.

 

[ModRQC]

I like the idea very much. Will try and get some of these for sure.

 

[inferno]

i have a 100 grit SiC stone for flattening. after a few stones you need to resurface it on powder.
its cheap and it just works. make sure you dont get a stone presoaked with oil!

as a sharpening stone i found it pretty useless. lost its bite after maybe 1 min.