CPM S30V finish difficulty

Frank Hunter

Frank Hunter

Well-Known Member
I am working with some CPM S30V and have read elsewhere that the final finish on it is difficult. In my experience so far it seems about twice as hard to finish grind after HT and on hand sanding it's more like six to eight times the labor. I'm working to 1200 grit right now and with a little research on the problem, it's apparently dislodging carbides that are really boogering up the finish with 400 grit size scratches. The steel is incredibly resistant to even my sisal buff and white compound. It also appears to have some significant pits which might be related to the carbide issue. Any suggestions or experience with this steel and high or mirror polishes?
 
Frank,
Yep! S30V & S35VN are tough:s7888: and don't give up easily!! I personally pass on doing over 400 Grit and then a scotchbrite progression through Brown,Maroon Blue because it doesn't ever seem to want to really shine!

I save the 600 and up work for 440c & CPM-154. These steels appreciate and get a liquid mirror finish.

I am trying to think if I have ever seem a bright finish on any of the production knives in my store that have S30V or it's sisters? Just too tough to finish!

Laurence

www.rhinoknives.com

www.westsidesharpening.com
 
I suspect that with the right combination of pressure and grit I can get it mirrored. Not going to be cost effective at all, though. And as for the pits, I'm going to experiment with finishing the grinds somewhat and if they're clean evidently the flats just have slightly deeper surface inclusions. I'll let you all know how it goes...I'm going to give it another eight hours or so but after that it'll be time to start putting a handle on it.
 
Here's an update on this large 7" CPM S30V hunter I'm working on. The mirror finish isn't going to happen...I put the whole next day into hand finishing and although I can get some areas of the flats absolutely clean of scratches the steel itself is very milky with a pretty evident although fine orange-peel grain. It takes hours to chase an inch or two all the way to 1500 and get it buffed and occasionally I see a large heavy scratch show up from seemingly nowhere due to the carbide issue. So going back over those and chasing them off the edge is so time consuming that I'm going to go the scotchbrite route and buff appropriately.

The pits I was finding were able to be resolved by taking another .010 off with the flat platen. They were just a little deeper than the surface boogers I've seen in CPM154CM and 440C I suppose.

At any grits higher than 320 with the sanding block it feels like I'm trying to sand a piece of glass the steel is so tough. And in addition, this progress is on the flats only...I'm not going to try to take the hollow grinds past a 16x finish followed by the super-fine scotchbrite.
 
I had missed that thread by Bruce. I've got a great deal of the steel remaining and with subsequent knives I'll get some cork belts and give it a shot. Thanks!
 
Yep, be sure to do all you can on the grinder and go to cork belts and finally buff. Buffing won't remove any scratches so if you see one simply go back on the corks and buff again.
 
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