Recommendation? The daily grind: before or after HT?

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Cushing H.

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I know there has been a lot of general back and forth on this in terms of preferences... but i would like to ask for a specific discussion on the pros and cons of grinding bevels before versus after HT. i know some have mentioned exclusively grinding after HT as being “easier”, whereas some have said that grinding after HT, especially for really hard steels, just chews up belts. Others have, alternatively, said they do a partial bevel grind before HT, then finish the bevel after HT. My assumption is that this reduces the use-rate of belts, with maybe a trade-off of risk of warpage (maybe dependent on type of steel, and definitely dependent on thickness of grind prior to HT?)

most of my previous grinds have been done post HT ... but am considering trying partial grinding pre HT on my next set of blades (steel is CPM 154). What say all of you on this?
 
I do partial, easier to work with before HT. After is just finishing and cleaning for me. (I usually do 1095 with hamon)
 
I do my kitchen cutlery out of .074 15n20. I like to do all the grinding at once and take it down to the point that its ready to sharpen. I just never saw the point of grinding, leaving enough meat on the edge to prevent edge burning, then straightening the inevitable warp and going back to the grinder. There isn't a whole lot of steel there to begin with!
 
Firstly, I don't use a lot of wear resistant steels. The steels I mostly use include 14C28N, RWL34, O1, 52100, 80CrV2, 1095/420, 1095/15N20, O2, 8670 and some Niolox from time to time.

I used to grind the bulk of the bevels before HT and then finish up the grinds after. But over the years I've put a lot of effort into optimizing my knife making processes. And the topic at hand is one of the things I've changed since. Nowadays I heat treat all blades without any grinding on the bevels, they've only been profiled and drilled.

I like it this way because,
  • I only have to grind one time - from start to finish
  • My plate quenches works much better
  • I can easily surface grind the blades after heat treat which also helps with the hardness testing
With the steels I use there's not a big deal grinding a heat treated blade, I use fresh quality belts, grind wet, pretty high SFPM and lean into it. It'll get the job done pretty fast, no matter if it's a small petty or a large bowie.

Unlike a lot of knifemakers I have no concerns about throwing away used belts. :D
 
I only grind wear resistent stainless steels (S35VN, Nitro V, M390). I grind the bevels down to .010 edge pre heat treat. Post heat treat is very hard on belts.
 
Cushing H. said:
Can I ask the reasoning behind that cut-off?
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One of the BIG reasons usually mentioned for grinding post HT is less issues with warping. The thicker blades (over 1/8", or perhaps 3/16"?) don't usually warp anyway with plate quenching. Thin blades (<.100") will have more issues with warp. Grinding post HT helps with that. Make one pass on one side, dip in water, make next pass on opposite side, dip in water. I've use .040" AEB-L without too much problem with warp. When I pull blade from plate quench, I'll clamp between 1/2" X 2" aluminum bar for the Dry Ice soak before temper for really thin AEB-L to help prevent warp.
 
I take my profiledAEB-L, 440C PM Stainless blades, grind about a 33% on the two sides of the edge to .010 send to HT & Cryro, using fresh 36, 60, 120G VSM Ceramic Belts I finish grinding the Bevels. Then Taper the Tangs. I’ve used roughly $10-15 or so in belts for a finished knife I sell for $400.00 Plus. I have no issue with a cost of belts “Consumables” like that. Try it! You’ll like it! ;-)
 
No matter the flavor of steel thicknesses less than .11 get profiled and HT then ground to help keep warping to a minimum. And over .125 they are all rough ground pre HT. Between those I will HT then grind Damascus and rough grind mono steels pre HT. Then reground after HT to remove decarb and get the edge down to where it needs to be for the knife being made.
 
i do all grinding post HT now because i mostly do tapered tangs. the tangs always needed to be reground after coming back from peters ht to get rid of warp. better to do it once than twice. with 3m cubitrons, i do not notice any difference grinding pre or post HT with cpm-154.
 
john april said:
i do all grinding post HT now because i mostly do tapered tangs. the tangs always needed to be reground after coming back from peters ht to get rid of warp. better to do it once than twice. with 3m cubitrons, i do not notice any difference grinding pre or post HT with cpm-154.
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I am also thinking doing it this way, but how do manage the heat? Do you have a water sprinkler or you just dip in water?
 
looney, i just dip in water when doing bevels and clips. ( when doing tapering on the surface grinder attachment, they do not get hot enough to ruin the temper). another thing to remember is higher grits cause more friction and heat. a blade will get hotter a lot faster from a 400 grit belt than a 120 grit. higher grits, dip more often. grinding with no gloves will let you know when the blade is getting hot. i grind with gloves but i dip every 2 passes.
 
Thank you for the advice, I will try this in my next batch, I totally forgot about the small warping after heat treat :eek:
 
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