Step 3- Surface Grinding

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Now that I have profiled the knife blade, the next thing to do is to surface grind the steel to bring it down to the desired thickness.  In this case, I am making a knife approximately 3/16 of an inch thick… that's about .187 of an inch (or 4.8 MM). That's one beefy knife. 

The steel comes from the mill a bit oversized. In this case it is about .206 of an inch. It is also "mill ground", meaning it is not perfectly flat or uniform. That means I need to take off some steel and get it down to the right size. Actually, I will leave it a bit thick – say .191" which then allows me to take off a little more after heat treating. 

The surface grinder is a very precise machine. New surface grinding machines are still made, but I like the old, big, monster ones which were made in the USA to very tight tolerances. For those interested, I use a hydraulic Brown and Sharp 618 Micromaster surface grinder. Weighing over a ton and requiring 15 gallons of hydraulic fluid, it is currently the largest single machine in the shop. It was recently rebuilt and certainly gets the job done!

Essentially the surface grinder works by passing the steel back and forth under a grinding wheel that spins at around 3600 rpm. The steel is placed on a magnetic chuck that holds the piece down flat. After each pass under the grinding wheel, the steel is moved over slightly and then ground again. This process repeats itself until the entire surface has been ground. We then move the grinding wheel down about .001" and repeat the process. 

This is whole process is repeated until we have removed about one half of the desired amount has been removed. We then remove the steel, clean it off, flip it over, and then grind the remainder off the other side in the same fashion. 

You may ask how I achieved this before the surface grinder. Well, I accomplished it by using a large magnet and holding the steel flat against the platen of one of our regular grinders. Although not as accurate, that method served me well for a number of years. Once mastered, the surface grinder made the process faster and more accurate without taking anything away from the custom process.

Some knife aficionados ask if I taper the tang of our knives. Some folks hold the tapered tang as the mark of an expert knifemaker. The answer is that in some instances we do, however, one of our trademarks tends to be the brawny look of the thick steel on our knives. Our customers tend to want to look down and see all that steel. It also gives me more of a canvas for my file work. Balance can be an issue, so we normally remove weight in the rear of the knife by drilling out additional stock (leaving plenty behind to still have complete overbuilt structural integrity). This is not because we "can't do" a tapered blade - it is simply our choice. And by the way, a tapered blade on a normal grinder is something we used to do. However, if one uses a surface grinder such has ours, it can by created fairly quickly with a couple shims. There is no real secret there. It just takes a bit of additional time. 

With a normal surface grinder, all three axis are manual. In other words, one handle is turned by the user to make the table (with chuck) move back and forth, from left to right. Another handle then moves the grinding wheel closer or further away. And the third moves the grinding wheel up and down. Our surface grinder is hydraulic, meaning the first two axis are automatic leaving the user to only control the vertical motion of the blade. The Micromaster feature allows us to lower the grinding wheel in exceptionally precise increments.

Once ground to the correct thickness, I verify the results with a micrometer and then get ready to bevel grind the blade.