naniwa superstone 400 problem

Having a problem with Naniwa Superstone 400. Using clamp on guides for a pretty edge...no angle changes at all.

First, to establish bevel I use DMT XC, not apexing. Almost apex not quite. Move to C DMT and apexing, creating minimal burr both sides, then finishing off the edge as if this were my final stone. Will easily shave hair and bite into nail.

Wanting to refine diamond scratches I move to Naniwa Supertone 400. This stone makes my edge duller. Apex is no longer crisp. Will not shave at all, barely bites into nail.

Frustrated, I use the DMT Fine, and this brings the edge back. Easily shaves and bites into nail. I progress from there, Shapton 1000 Pro works in the diamond line up quit well. What a stone that is! (See I misspelled "quite", but I left that in there just for Rick! ... and my eclipses too ... )

So no matter the steel, and using an angle jig, the Naniwa Superstone 400 basically kills my edge, but any diamond or waterstone after wards works fine.

This happens every time, no matter the angle or steel.

I've heard those stones are softer, maybe it's rounding off apex? Doesn't feel like that tho when I am using it. I've never had issue using water stones in a diamond line up before, until this stone. Even using the Naniwa in an exclusive water stone line up, it seems to do the same. Yes, freshly lapped, and very flat. No mud either, just splash and go. Metal shavings suspended in water on top of stone. The Shapton Pro 1000 in a diamond line up works very well.

Any thoughts as to what might be going on with this stone?

Side note....last night decided to thin down a Kershaw Leek 13C26 (AEBL). Sigma Power Select II 120!!! Wow! (Keep under running water...it loads instantly) to thin, almost apex. Shapton Pro 1000 at about 14° per side to establish bevel on an edge that barely reflected light. Then Spyderco Fine Ceramic, then 0.3 micron film. WOW!!! Sharpest I've ever made a knife! EASILY would split my arm hair lengthwise, while still on my arm. The sharpest I've ever made a knife!
 
Don't you love those timeouts!

I don't own the Naniwa SS, but my rule of thumb for all stones that feel even remotely soft is to finish with a few trailing passes once I've raised and removed the burr most of the way. A hard stone might turn up a new burr after a few passes, but a softish stone will refine nicely. Used with a leading pass it erodes the edge. This type of stone can usually be ID'd right off by the small or non existent burr that is created for the amount of steel removed.

The other thought is that it seems a lot of the softer stones are made to be run in a series - they aren't intended to make super sharp edges at low to medium grit, just to shape the edge and keep the (soon to be) apex from accumulating any dud metal or deep scratches so the polishing hones can do their job easier. IMHO the Nortons are like this - a nice edge can be coaxed out of the lower grit stones with some extra time and care, but they really seem to be made specifically to set the edge up for the 8k.
 
The Naniwa SS are soft so it's going to round out the apex at coarser grits. No much you can do about it.

Clean crisp edges at coarse grits require much harder stones.
 
Thank you so much for replying. You two guys are very knowledgeable. Last night I messed around with it a bit more, and I think for sure the problem is how soft the stone is, and it is rounding off the apex. Especially coming off the diamond plates....not sure if the contact of the edge against diamonds that "protrude" up from the substrate, is not compatible with the contact of the edge against a dead flat waterstone. Just a theory...when I use that clamp on guide my angle is exactly the same, and that imperceptible difference in abrasive "height" when using an exact angle on two different stones simply rounds off the apex. That may be all hogwash tho.

Last night I had a shop knife in 52100 that I thought I'd mess around with on the Naniwa. Started with the Naniwa 400 and easily had a hair shaving edge....but when it was proceeded by a diamond plate yesterday it did nothing of the sort. Moved up to the Shapton Pro 1000 (again...lovin that stone), it was noticeably sharper. Then moved to the King 4000....and I had the problem again. It was no longer sharp, would not bite into nail, would not shave.

Experiment....so I decided to go back and start over. Put a layer of blue tape on the part of the guide that contacts the stone. Went back to the Naniwa 400 and made shaving sharp edge, then the Shapton 1000. At this point I removed the tape, essentially lowering the angle just a tiny tiny fraction so the apex doesn't quite make contact (we're talking barely not making contact....I think you can visualize what is going on), and then went to the King 4000. This allowed the softer King stone to basically start polishing/sharpening just a smidge behind the apex, and then work it's way up to it. MUCH better results.

Lesson learned.
 
Next time get the Chosera/Naniwa Professional 400 if you don't make the switch to Shapton ;)

They are the hardest stone Naniwa makes and it creates a much crisper edge at coarse grits. That said, the Shapton pro 320 although a bit muddy produces a much nicer coarse edge and is followed nicely by the 1k.

Overall I wouldn't worry about making the edge too sharp on a coarse waterstone. Coarse waterstones are for shaping bevels while the 1000 is your workhorse where final edge geometry and the beginnings of sharpness are created. Make the best edge you can with the 1000 stone so that your 4000 stones more easily produces a sharp edge. Also, with your 4K stone use edge trailing strokes, it's a soft stones and will produce a better edge with this method.

All soft stones will be a bit problematic but with proper technique they can work as intended.
 
I don't even use the King 4K with a leading pass at all unless for cosmetic reasons. Normally I'd come off the 800 or 1k and just do a few light backhone passes on the 4k at a slightly higher angle, essentially making a very shallow microbevel. This is how I most often use the Norton 8k as well. By varying the number of passes one can make an edge with all kinds of character.

If I am going to polish a wider bevel I do as you described only without the tape - I recalibrate often by slightly lowering the spine so I get the feel off the shoulder and then elevate slightly to stay on the bevel without rounding it over. The feedback on these softish polishing stones is so minimal it is extremely easy to begin rounding the edge. Once begun, they then lack the abrasive potential to make much in the way of corrections at the original angle and the edge quality just slides away as you work.
 
Quality slides away as you work....yep, that's what I get sometimes with the soft King stone. I will try edge trailing strokes with that stone. Funny, tho, I use that one quite often after a Norton 1000, edge leading, and have gotten good results. Maybe I'll get GREAT results edge trailing. Jason.....the Shaptons I am REALLY digging. I haven't used any of the glass stones at all, so no input there (although I understand them to be the bee's knees). But the Shapton Pro 1000, a ceramic stone, I LOVE. Seems like I get much better results with hard stones...diamond, ceramic. I guess that's to be expected.
 
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