sharpening s90v... hope this is the correct sub-forum...

sloth357

sloth357

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Hi.. I've been doing lots of re-profiling and sharpening of different knives the past year especially.. and lately found I am struggling getting s90v as sharp as other steels.. cpm154cm sharpened up quick and eye bleeding sharp! s90v gets sharp, but then stropping to finish seems to never get any sharper.

Perhaps I need to learn more about my steels, but is s90v too hard for simple CrO compound??

I mainly uses stones for sharpening, then lightly use a black arkansas stone and then go to black compound stropping and green (CrO).. the cpm154cm gets mirror polished very nicely and sharp as SH!T, the s90v not so mirrored, not so sharp.. 1095 easy... A2, great mirror and sharper than s90v... even s30v seems to get a bit sharper.. is it the vandium I'm struggling with?? technique?

Some tips would be helpful, otherwise I will continue to experiment and read whatever I can find that might give clues, thanks much!

edit: Oh and 3v is getting very sharp and mirrored as well.. just this damn s90v!#$!#$ :)
 
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Try using various diamond compounds for stropping, as these will cut any carbides in the steel much easier & cleaner than chromium oxide.
It is most likely the huge amount of vanadium carbides that has been giving you trouble.
 
I use a Silicon Carbide based polishing compound for stropping. It is a course grit at 600 but leaves a very aggressive and polished edge. Silicon Carbide is the material Norton India stones are made from and will cut the Vanadium carbides efficiently, not saying diamond won't work either. I get S90V to whittle hair with this compound before shipping a knife.
Good Luck
Chris
 
norton india are aluminium oxyde, norton crystolon are SiC.

what stones do you use ? the arkansas wont do anything to s90v, the chromium oxyde will polish but too slow to be practical. the best for this steel will be all diamond setup from start to stropping, SiC will work too as cbn.

on the other hand ive tried sharpening s90v on waterstones with great success, even if alumOx isnt supposed to cut vanadium carbides perhaps because of how waterstones works getting always fresh abrasives out of the matrix.
 
I use an old Washita Mountain Whetstone Company triple stone set, then the Black Arkansas, and then strop with either black or green, then suede.

The triple stone set did a great job of reprofiling the s90v, but it left deeper scratches that took quite a while to get mostly out..

CBN?? help me there :)

I'll check out those norton's your mentioned, and perhaps some diamond sestup.. thanks for the ideas guys.
 
If you google Phil Wilson knives, he has a pretty detailed article on sharpening, specifically what he prefers for the "super steels" like s90v, 10v, etc. It's very similar to what Big Chris recommended and very cheap also compared to many solutions.
 
imho theres at least one stone in his set thats synthetic, the coarsest i guess, that would explain why he struggled so much getting the scratches out, as only the coarsest stone was able to cut the steel decently.

honestly if you want to stay cheap buy a norton crystolon, the combo one, some diamond pastes for your strop, not too fine as the fine crystolon isnt that fine and you'll be set for all your knives.
 
S90V is what pushed me to buy diamond compounds.

I use diamond plates to sharpen all high wear steels, I only have problems when I attempt to use other types of stones/abrasives on them.
 
pwet said:
imho theres at least one stone in his set thats synthetic, the coarsest i guess, that would explain why he struggled so much getting the scratches out, as only the coarsest stone was able to cut the steel decently.

honestly if you want to stay cheap buy a norton crystolon, the combo one, some diamond pastes for your strop, not too fine as the fine crystolon isnt that fine and you'll be set for all your knives.
Click to expand...

Aha, that makes sense. I was thinking he had an all arkansas tri stone set. If he's got synthetics in his set then one of them is probably silicon carbide. If its a good stone he shouldn't need to get a norton crystolon.
 
Sloth 357. It kind of depends on what you want to cut. If you want to whittle hairs then the polished edge with diamond paste and the water stones work the best. If you want to cut abrasive material like cardboard, rope leather animal hide ect then a courser edge works best. Use a Norton silicon carbide (crystalon) medium stone and lubricate with windex or equal. take off the wire edge if there is any with a strop embedded with diamond paste or SC slurry off the stone. Just a few stokes will do it. Remember a very fine edge is going to be very thin where it contacts the cut material. Very thin means weak since there is not much material to back it up and it is going to roll when pushed hard. With these high carbide, high RC grades, a courser edge at a moderate angle will hold up better over the long run at least IMHO. Phil
 
It's the Vanadium that will effect sharpening with the more normal CRO stones mostly.

One can do a few things that I found to work well on the more wear resistant steels.

As Phil Stated Silicon carbide is really a must at the min as it will cut those hard Vanadium Carbides and makes pretty short work out of setting the bevel.

One can get a Med and Fine Norton Silicon Carbide stones if they sharpen freehand.

There is also those Congress Mold Master Silicon Carbide stones for those who have an Edge Pro or Sharpmaker and they work very well, I finish with the 400 grit.

Also the Standard Edge Pro stones work well on steels like S90V once the bevel is set with the 120 Grit stone.

Ceramics work extremely well for touch ups as does a Strop loaded with Silicon Carbide.

The most important part is to get that bevel set and correctly then it's not too bad after that, but it will take longer than something like VG-10 or ZDP-189.

I use an edge finish in the 14-16 Micron range as it gives a good balance of semi polish, aggressiveness, and edge retention.
 
Thanks for all the good information. I believe the triple stone set is silicon oxide. I did just order the norton crystolon set. I will check out a diamond paste here soon.

No I didn't try to reprofile with black arkansas... lol Just tried to finish with that and CrO stropping, which seemed to do very little compared to how it behaved with cpm154cm and 3v or 1095.

Phil, I wanted to bring it to what you call hair whittling, but then next time around more coarse for various utility uses around the shop and garden. Push cutting small gauge rope, small branches, cardboard. I was just surprised at how much harder s90v is than the other steels I was working with and now want to attain that shiny sharp as heck edge before I call it good :)

Oh and the stone sets with 2 crystolon and 1 india, will the india do anything to finish on s90v?

Again thanks for the reponses.
 
Yes Silicon Carbide (Crystalon) is harder than Alum. Oxide (India). India will work to take off the burr and will give some polish but does not cut as clean as the SC. On the South Fork the hardness is RC 60 +/- measured on the flat near the guard. That is a true 60 as compared with my certified test block from Wilson Rockwell Instrom. This steel is also somewhat quench rate sensitive so depending on how it cools most likely the edge area of the blade will be a little harder that the flat where I measured. The surface has to be perfectly flat to get a good reading so it is not possible to check the cutting edge itself now without a micro hardness test. There is about 10% Vanadium Carbide in CPM S90V. VC is about RC 85 so the dense hard carbides resist the stone so that is why it feels harder than it really is. I get a good working edge by hand and eye off the stone but if you want the" hair whittling edge", which is a noble goal you have to use one of the mechanical aids as described by Ankerson. Good luck, Phil
 
sloth357 said:
Thanks for all the good information. I believe the triple stone set is silicon oxide. I did just order the norton crystolon set. I will check out a diamond paste here soon.

No I didn't try to reprofile with black arkansas... lol Just tried to finish with that and CrO stropping, which seemed to do very little compared to how it behaved with cpm154cm and 3v or 1095.

Phil, I wanted to bring it to what you call hair whittling, but then next time around more coarse for various utility uses around the shop and garden. Push cutting small gauge rope, small branches, cardboard. I was just surprised at how much harder s90v is than the other steels I was working with and now want to attain that shiny sharp as heck edge before I call it good :)

Oh and the stone sets with 2 crystolon and 1 india, will the india do anything to finish on s90v?

Again thanks for the reponses.
Click to expand...

You can get hair whittling edges off the Norton stones as long as the edge is clean and the bur is removed. :)

Although if you are going to use the knife that level of sharpness will be gone very quickly.

It's the added wear resistance from the Vanadium carbides that makes S90V somewhat harder to sharpen than say CPM 154.

But make no mistake those High percentage Vanadium steels can get screaming sharp, it just takes more time to get them there.
 
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