Getting started for high alloy knife steels

[Setarip]

Hello!
I just purchased a Tormek T8. I am upgrading from a KME sharpener. The kme was ok, but since I am a knife maker and use "high alloy" stainless steels at 60+RC, the kme often took 3-7 hours (!!!) to sharpen from no edge to acceptable sharpness.

My questions about the tormek are: is the SG-250 stone acceptable for steels such as AEB-L, CPM-154, and other chromium carbide and vanadium steels? Or should I skip that and buy the SB-250?
My other question is about the leather honing wheel. My thought was to buy a couple of them and load them with diamond pastes ranging from 2000 grit to 8000 grit or higher. Does that sound like a waste of time? With the kme I usually sharpen up to 1500 grit with a diamond stone, and then strop with diamond from 3000, all the way up to 100,000 for a mirror finish and roughly 140-ish BESS. Any help is greatly appreciated!

[John_B]

Here is an excellent post on sharpening the super steel alloy knives. CBN or Diamond wheels are the only ones that will effectively grinde the vanadium. Other wheels will remove the surrounding material leaving the vanadium untouched.

https://forum.tormek.com/index.php?topic=3614.0

[cbwx34]

Hello!
I just purchased a Tormek T8. I am upgrading from a KME sharpener. The kme was ok, but since I am a knife maker and use "high alloy" stainless steels at 60+RC, the kme often took 3-7 hours (!!!) to sharpen from no edge to acceptable sharpness.

My questions about the tormek are: is the SG-250 stone acceptable for steels such as AEB-L, CPM-154, and other chromium carbide and vanadium steels? Or should I skip that and buy the SB-250?
My other question is about the leather honing wheel. My thought was to buy a couple of them and load them with diamond pastes ranging from 2000 grit to 8000 grit or higher. Does that sound like a waste of time? With the kme I usually sharpen up to 1500 grit with a diamond stone, and then strop with diamond from 3000, all the way up to 100,000 for a mirror finish and roughly 140-ish BESS. Any help is greatly appreciated!

You could consider just setting the edge with the Tormek, and finish with the KME,... should cut the time considerably.

[Setarip]

The KME is gone. Lots of negatives for the few positives that system brought. I guess my question can simply be: silicon carbide or just move up to CBN/diamond? I typically use AEB-L and CPM-154 for my knives so there is no vanadium carbide present, but I also have a large slab of CPM-Magnacut that I will be trying out and that has 4% vanadium. I moved to the tormek because I want to use water cooling for my edge setting and sharpening rather than my belt grinders. Larrin at knifesteelnerds has a great article about sharpening without water cooling and how that effects edge life.

[Peter Eaton]

The steels I use for my knife making are Elmax @ 60-61HRC, Vanax, AEB-L , 52100 and 26c3.

Steels like Elmax and Vanax which are third generation powder steel alloys are incredibly wear resistant. Elmax for example is used in the North Sea on oil pipe lines , food processing machines and high pressure injection moulding. They and other alloy tool steels without doubt are best sharpened on CBN wheels as they are designed NOT to wear. I contacted Vadim and he gave me loads of advice and I also bought his software / book on sharpening...both are excellent.

CBN also outperform diamond apparently due to how they break down in use.

AEB-L is not in the same league as the super steels and although it has a fine gain structure it is not a powder steel.  Yes its a great steel but if you grind out a hardened knife blank of AEB-L it feels totally different and feels 'softer' for want of a better term than Elmax. AEB-L is far easier to hand finish , Elmax and Vanax are punishing on the arms as they just don't wear easily when hand sanding.

Note I said hardened blanks as hardened blanks cut faster on ceramic belts. Basically 'hog out' 90% of your steel on 36 or 60 grit as those grits run cooler. Then the remainder of the bevel can be done on finer grits....but with all grits dip in cool water every pass, or as I do keep your thumb of the blade for rest assured your thumb will let you know how hot that steel is wayyy before it reaches its tempering temperature. In the case of the last batch of Elmax I had heat treated it was a 500c tempering cycle 

Now back to your original question, CBN wheels are they way to go for sure, I have a 600 and 1000 grit on my T8 and then it is onto paper honing wheels/diamond. I doubt the original stone will do anything where these high wear steels are concerned, also not sure about the diamond paste on the Tormek leather wheel and what effect it will have.

But even before CBN I grind all my blades down to just above .5mm on 2 x 72 inch ceramic belts, obviously cooling the blade every pass. Then that edge is bevelled at 17.5 degrees or lower. Only then do I go to the CBN wheels which sometimes takes 20 -30 mins to refine the edge to 1000 grit.  The final stage is paper honing wheels with diamond paste....both the CBN wheels and honing wheels use Vadim's software / homemade jig stands.

[Setarip]

I appreciate your response Peter! Yes I am not too concerned about AEB-L anymore. I actually have used the sg-250 wheel with nitro-V and CPM-154 (both at approx. 61-62RC) and they sharpened like nothing. So I am pleased with that. I do have some CPM-Magnacut that I have yet to use which has 4% vanadium so that steel may not sharpen as easily on the standard stone. I will wait and see. For now my plan is to use the SG-250 and then buy CBN for the higher wear resistant steels.