Why Small-Batch Heat Treatment Matters
Precision Heat Treatment
A woodworking tool is only as good as its heat treatment. Even the finest steel cannot reach its full potential without a carefully controlled process. At Roberts Fine Tools, every blade is heat treated individually using methods chosen to maximize the performance of each steel.
Every blade begins in a digitally controlled Evenheat heat treating kiln, where temperature and soak times are precisely controlled. Consistent temperature is essential for achieving the desired hardness and microstructure.
Immediately after leaving the kiln, blades are plate quenched between two 1.25-inch thick aluminum plates with forced-air cooling. Aluminum rapidly removes heat from the steel while helping maintain excellent dimensional stability and reducing distortion.
The blades are then transferred as quickly as possible into liquid nitrogen for cryogenic treatment. This rapid transition minimizes retained austenite by transforming more of it into martensite before tempering. The result is a more complete heat treatment that contributes to improved hardness, wear resistance, dimensional stability, and edge retention.
Finally, every blade receives a double temper, relieving internal stresses while developing the ideal balance of hardness and toughness for demanding woodworking use.
Because every blade is processed in small batches, I can carefully control each step rather than relying on a large production process.
Benefits of Small-Batch Heat Treatment
Small-batch heat treatment allows every blade to receive individual attention throughout the process.
Rather than processing hundreds or thousands of parts at once, each blade is monitored from the kiln through quenching, cryogenic treatment, and tempering. Rapid transfers between each stage help ensure the steel follows the intended heat treatment cycle as closely as possible.
Research by Dr. Larrin Thomas has shown that for air hardening steels , rapid plate quenching combined with immediate cryogenic treatment can produce measurable improvements compared with slower industrial gas quenching and delayed cryo under the conditions tested. This also allows our steel to have higher hardness to toughness ratios and less variance in HRC than industrial batched heat treated steel. A2 appreciably benefits and MagnaMax greatly benefits from precise small batch heat treatment/ plate quenching .In practice this means less sharpening and less chipping for a given hardness. My process is designed to follow these principles while maintaining consistency from blade to blade.
References
https://knifesteelnerds.com/2026/06/01/magnamax-industry-vs-custom-heat-treatment/
