KNIFE MAKING
Grind before heat treat, or after? The question filled another long thread on the forums. The answer is both. The skill is knowing what belongs on each side of the quench — because getting the order wrong costs you blades, belts, and tempers. Yours included.
KEY TAKEAWAYS
- Do the heavy grinding before heat treat. Soft steel grinds fast and cheap.
- Stop at a dime-thick edge before hardening. Thin edges warp and crack in the quench.
- Drill every hole before the steel gets hard. Your bits will thank you.
- After heat treat, grind cool. Slow speed, sharp belts, water close by.
- The last thing you make is the edge. Always.
BEFORE HEAT TREAT: MOVE THE METAL
Annealed steel is soft. It grinds like it wants to be a knife. This is where the profile gets cut, every hole gets drilled, and the bevels get roughed in to about 80 or 90 percent. Fresh coarse belts eat soft steel with light pressure. Save your money grits for later — this stage is about moving metal, not making it pretty.
One number matters here: leave the edge about the thickness of a dime. Around 0.030 inches. That margin is what keeps the quench from turning your work into a potato chip. It also leaves room to grind past decarb — the soft skin the fire puts on your steel.
WHY YOU STOP EARLY
A finished edge going into the quench is a bet you will lose. Thin sections cool faster than thick ones, and uneven cooling means warps at best and cracks at worst. The full walkthrough lives in our heat treating guide, but the short version is simple: hardening punishes whatever you thinned too soon.
AFTER HEAT TREAT: FINESSE, NOT FORCE
Now the steel is hard, and the rules change. Hard steel grinds slower and heats faster — and past a certain temperature you are quietly un-tempering your own blade. So the pace changes. Slower belt speed. Sharper belts. Lighter passes. Dunk the blade in water more often than feels necessary.
This is the stage where variable speed stops being a luxury. Finishing bevels at full speed on hardened steel is how edges burn before you ever see the color change. It is also where equipment that supports repeatable results earns its keep — a grinder that tracks true and holds its settings lets you take the same pass twice.
Work through your grits, then put the machine down. The last refinements are hand work — our hand sanding guide covers the method. Sharpening comes at the very end, after handle work. The edge is the last thing you make.
THE ORDER, ON ONE LINE
Profile. Drill. Rough bevels to dime-thick. Heat treat. Finish grind, cool and slow. Hand sand. Handle. Sharpen. That order has built a lot of good knives, and it will build yours. It is also a big part of why the 2×72 saves so much time — one machine handles both sides of the quench, if it has the speed control to do the second side right.
THE MACHINE SIDE OF THE EQUATION
Any solid 2×72 with variable speed can run this order of operations all day. That is what the NOVA was built for — maximum machine, minus the weight. And if you want a proven machine at closeout money, the original Torus 2×72 Steel is $845, fully assembled, while stock lasts.
Whatever you grind on: respect the order. The quench divides your build into two different jobs. Work them like it.
Ready to set up the machine side? Start at toruscnc.com/shop.
