DAY 3
Today was a fun day for me because the instruction was highly technical with enough variance to allow my inner artistry to be satisfied. Today we would learn how to remove steel stock using “control lines" or "plunge lines". These refer to the lines where our blade's bevel meets the ricasso (the blunt part of the blade near the handle and they play a role in the knife's aesthetics and function and in some cases providing a grip or a transition point from the handle. Today we would also get to use the drill press for the first time.
STEP 4 – Scribe layout lines
To get started we had to scribe layout lines that we would use when grinding the shape of our knives. These lines consist of a primary bevel line, horizonal control lines and vertical control lines. I have put forth my best effort to document each of these layout lines, but my notes were taken in a fast a furious manner and I did my best to capture the exact technical specifications and details.
STEP 4A – Primary Bevel – The 2 primary bevel control lines are used during the initial grind to establish an approximate 30° bevel. To create these layout lines, the width of the steel was measured at the blade edge with digital calipers, 0.030” was subtracted from the blade width and that result was divided by 2 to yield the amount of steel that would be taken off each side of the steel. For my knife, the calculation looked like this: (( 0.170 - 0.030 ) / 2 ) = 0.070” from the blade edge. The image below shows the 2 primary bevel control lines with a 0.030” gap between them.
STEP4B – Horizontal Control Lines – Two (2) horizontal control lines are used in both the initial grind and subsequent grinds to build on the primary bevel. These layout lines need to be scribed now before starting the primary bevel grind so that enough steel is present to accurately mark the 60-grit grind line and the top horizonal grind line. The 60-grit grind line was scribed at 0.375” and the top horizonal grind line was scribed at 0.500” as depicted in the image below. These measurements were provided by our instructor.
STEP4C – Vertical Control Lines – The vertical control line is used in all the blade grinds and establishes a clean and crisp transition between the ground bevel and the unground portion of the blade. For my knife, I measure 0.250” (¼”) from the tip of my choil towards the tip of the blade and scribed that line 90° from the blade edge to the top horizontal grind line that was already laid out. This measurement was provided by our instructor.
STEP4D – Handle Pin Holes = The instructor asked that each of us use at least six pins to attach our covers to the knife. To lay out the handle pin holes, the rule of thumb that our instructor follows is to locate pins no more than 3-times and no less than 2-times the thickness of the pin. In our case we are using 1/8" (0.125”) pin stock of 416-stainless which would make the rule-of-thumb layout lines no more than 0.375” (( 0.125” x 3 ) = 0.375” ) and no less than 0.250” (( 0.125” x 2 ) = 0.250” ). For my knife I measured 2.5 times the thickness of the pins for my handle pin holes, set the digital calipers to 0.3125” and scribed a line on 1 side from the edge of the steel. I then measured the distance from the choil to the end of the handle (4.00”) and evenly divided that by 3 and scribed 3 tick-marks on the blade edge handle hole pin line. I then used a straight edge to mark the corresponding 3 tick-marks on the spine edge handle hole pin line. The image below depicts the layout of both the vertical control line and the handle pinholes.
STEP 5 – Grind to the 30° primary bevel
I learned quickly that beveling is by far the hardest part of crafting a blade so far. Creating a perfect bevel is a skill that requires many hours of practice to master and watching our instructor show us how it’s done proved that point. Bevel grinding entails applying pressure to your knife at an angle to create an angled blade edge. Ensuring the grind lines are crisp and clean when beveling would be impossible without layout lines. We were taught that one of the many tricks to beveling is to ensure you’re grinding smoothly from one side of the blade to the other. If you hesitate or try to correct a grind as you’re moving from side to side, you’ll likely dig into the material and create a wobble in the grind line. It’s better to commit and keep your movement steady as you grind from one side to the other. Smooth movements equate to a smooth blade.
STEP 6 – Grind to the 60-grit horizontal control line
The next thing I learned when beveling is ensure you’re grinding from the edge towards the spine of the blade and not the other way around. It’s best to slowly move the workpiece towards the belt and allow the edge of the metal to lightly kiss the belt before applying your angle and pressure. If you press too hard initially, you could cut the cutting edge too far. Again, I was reminded that slow and steady is the key.
The plunge line for my bevel could either be crisp and sharp or softer and more rounded in appearance by modified by adjusting the belt tracking. I found that if the belt edge matches up with the edge of the platen then it leaves a crisp plunge line but if I adjusted the tracking so the belt hangs off the edge of the platen that it creates a smoother transition between where the belt is cutting hard and where it’s not cutting at all, which I used to attempt a soft rounded plunge line.
STEP 7 – Drill and countersink the handle pin holes
To keep the steel from wandering when the drill bit touches the steel, each of the 6 handle pin holes was center punched to create a small, conical depression that served as a guide for the 1/8” drill bit and ensured greater accuracy in the placement of the holes. Our instructor said that the key to success with the drill press is to lower the drill bit gently into the steel and apply consistent pressure. We were taught to avoid excessive pressure and not force the drill but instead let the bit do the cutting and that excessive pressure can cause the bit to overheat, dull, or break and even change the temper of our steel. When drilling my 6 holes I periodically lifted the drill bit out of the hole to clear out chips to prevent clogging. I reduced pressure as the drill bit approached the end of the steel to avoid sudden breakthroughs and potential damage to my knife.
Since the countersinks are simply an aid to installing the pins and are concealed by the covers, they didn’t need to be at a precise depth. I mounted a ¼” (0.250”) drill bit and while loosely holding the steel I slowly lowered the drill press just enough for the drill bit to center on the 1/8” hole and I countersunk all 12 holes (both sides of the knife). The image below shows one side of the knife with 6 holes countersunk.
STEP 8 – Saw jimping lines on the spine
Jimping is small notches that are cut into the spine of the blade in the area between the sharpened edge and the handle. Its primary purpose is to enhance grip, especially in wet or slippery conditions, and provide a more secure hold by increasing friction between my fingers and the knife. This wasn’t something that everyone in the class was doing but I felt that it would allow for better finger placement and leverage for delicate tasks like carving or detailed cutting with my knife. I also felt that my sheep foot style blade could be used with greater precision thereby leading to cleaner cuts and finer results. Beyond functionality, I also felt that jimping on my knife would add a touch of visual appeal and that the geometric pattern created by the grooves would complement the overall design of my knife, making it a pleasing combination of form and function. The image below shows my knife at the end of day 3.
To conclude our day 3 class, the instructor provided us with a vision of the way forward to complete our knives. Next week we will be completing our 60-grit grinds to the top horizontal grind line and transitioning to 120-grit to complete the pre-heat-treating grinds. We will then be heat treating our blades in preparation for final finishing. We once again ended the class in fine fashion, cleaned up the shop and I left the campus with a piece of steel that was starting to look like a knife.
