My question is when you harden the blade you do it over a three day span. Letting it cool for 24 hours in the oil before you harden it again. Have you tried doing it without the time span? If you have what were the results? I'm 54 and I still can't wait. Ray

I have played with the time delay between quenches, and have found dramatic differences on knives that were only left in the oil to cool for an afternoon versus ones that remained overnight.
With that in mind the best quess I can give you is something beyond the 8 hour mark. I have noticed also that the blades that are left to cool when it's really cold outside (10F or less), will perform better than blades that are cooled in the oil during warm weather months. My solution to bring both on equal footing is the liquid nitrogen quench. Once it's done, the blades will cut identical.
It may sound strange, but the slow cool down in the oil helps to refine the grain as if you where annealing the blade. My personal view is that the grain refining process continues with each quench/cool cycle. I sent several blades off for spectrographing, and found that there was a reduction in grain size with each successive quench/slow cool cycle. The grain in a single quenched/cooled blade was .9 micron larger than the grain in a blade that was quenched/cooled three times. .9 micron doesn't sound very significant, but it adds up in real performance to about 20% more cutting ability. That's enough to make me take the extra time and effort to do it.

What is the temperature of the oil when you do the quench? I try to get my oil 120 to 150 degrees before the quench. I'm going to forge one more blade in the morning and then give my new toy a try. Really do appreciate your advice and I'll let you know how they turn out. Thanks, Ray

Your in the correct range for the oil temp. I like to quench blades when the oil is in the 150-160F area. Just be careful that you don't go above 180F. Oil this hot will not get the blades cooled quickly enough, and you will get hard and soft spots rather than a good even hardness. I'm off to the forge too! Got several billets that are screaming for the hammer! :)