Day 4
I arrived at my class about 10 minutes before the start ready to complete our 60-grit grinds to the top horizontal grind line and transitioning to 120-grit to complete the pre-heat-treating grinds. I was a bit concerned about the weather being over 90° F today at 8:30AM and heat treating our blades in preparation for final finishing at about 2,000° F but as soon as our instructor arrived, we were told that we wouldn’t be heat-treating today because of the extreme weather. I think this was a good call given the average age of the class is at least 60 years of age, possibly more. The instructor looked at my top horizontal grind line and felt that my blade was ground enough for heat treating which he would be doing on our behalf this coming week at his home studio so I didn’t get to spend any time at the grinder today.
STEP 9 – Finish jimping lines on the spine with a file
I used a file to finish the rough-cut saw jimping that I started last week. Filing my jimping involved using a triangular file which for those that don’t know is a hand tool with abrasive teeth, to shape, smooth, and remove material from steel. I believe it’s a fundamental metalworking skill that could be used for a whole bunch of tasks like creating straight edges, shaping curves, and refining surfaces like my jimping. The instructor taught me the fundamentals of filing which include:
- Choosing the Right File: Files come in various shapes (flat, half-round, round, triangular, square, etc.) and sizes, each suited for specific tasks. Flat files are good for general shaping and smoothing, while half-round files are useful for concave surfaces.
- Securing the Workpiece: The workpiece should be securely held in a vise or with a clamp to prevent movement during filing with the work area outbound of the vice.
- Proper Filing Motion: The files that I was using only cut effectively on the forward stroke, so I was taught to apply pressure while moving the file forward and lift it off the workpiece on the return stroke to avoid dulling the file.
- Using Two Hands: I watched my instructor use both hands to control the file, applying even pressure to ensure a consistent cut and a smooth surface, I simply copied what he was doing masterfully.
I came to learn that long, slow strokes help create a smoother surface and prevent the file from overheating. I also found that too much pressure could damage the file and lead to uneven filing and consistent movement prevents the file from digging into one spot on the steel and creating a ditch. Just like on the grinder, I used my body weight to push the file, rather than relying solely on my arms to maintain consistent pressure.
STEP 10 – Create a heat-treating pouch
Creating a single-use heat-treating pouch (also known as a tool wrap or heat treat foil) is a common technique for protecting metal parts, especially tool steel and blades, from oxidation and decarburization during heat treatment. Our instructor taught us that this helps to minimize scaling and maintain the integrity of the material's surface properties. To get started we used a specialized foil that the instructor provided that is made of 0.002” thick Alloy #321 which is a titanium-stabilized austenitic stainless steel known for its excellent corrosion resistance and high-temperature strength that can withstand the high temperatures required for heat treating our 440C bar steel which calls for 1950° F for 45-minutes.
Step10A - The lengthwise fold - The flat specialized foil was cut to a length 4” longer than our knives and folded in half creating a joined end. The foil was then folded 90° at the joined end and when uniformed across the length of the foil, folded flat the remaining 90°. The foil was again folded 90° at the folded joined end and when uniformed across the length of the foil, folded flat the remaining 90° creating a double fold the length of the foil. This double seam was tightly sealed with the light tap of an ordinary carpenter’s hammer.
Step10B - The first width-wise fold - The foil was then folded 90° at one of the open ends and when uniformed across the width of the foil, folded flat the remaining 90°. The foil was again folded 90° at same open end and when uniformed across the width of the foil, folded flat the remaining 90° creating a double fold the width of the foil. This double seam was tightly sealed with the light tap of an ordinary carpenter’s hammer and a pouch is formed to accept the knife steel.
Step10C – The second width-wise fold - The knife steel is then inserted into the pouch so that the end of the knife steel is touching the double seam on the width of the pouch. Starting from the closed end of the pouch and working towards the open end, air is evacuated by lightly forming the foil around the profile of the blade. Once evacuated, the foil was then folded 90° at the only open end and when uniformed across the width of the foil, folded flat the remaining 90°. The foil was again folded 90° at same end and when uniformed across the width of the foil, folded flat the remaining 90° creating a double fold the width of the foil. This final double seam was tightly sealed with the light tap of an ordinary carpenter’s hammer and the heat-treating pouch is finished.
Our instructor told us to handle the specialized foil carefully as the edges are very sharp. I would suggest wearing gloves if they are available when handling this specialized foil; it’s razor blade sharp. The goal is to create a sealed pouch to minimize oxygen exposure during heat treatment and make the pouch snug but not so tight that it's difficult to remove the part, especially for oil quenching. I guess we’ll see next week how well we did towards meeting that goal.
STEP 11 – Prepare covers
STEP11A – Generate 2 book-matched covers - I chose black canvas micarta for my knife covers which simplified the process of generating 2 book-matched covers. Book-matching is a technique used in where two adjacent surfaces are arranged to create a mirror image, resembling an open book. This is achieved by cutting a single piece of material into two slabs, then flipping one slab to create a symmetrical pattern. With natural materials like wood, this is important because the finished knife will show the same grain lines at the same place along the knife tang on both covers when finished. With synthetic material like Micarta, this is not as important because the material has no grain to match.
To generate my 2 covers I drew a horizontal line 1-1/4” wide along a 12" side of the black canvas Micarta and drew a vertical line at the 6” mark creating 2 covers that are 1-1/4” wide., and 6” long. The covers were cut on the band saw.
STEP 11B – Layout master side cover - One of the covers was hand aligned to the knife steel so it extended ½” beyond the ricasso and completely covering the cover side of the knife steel. Once hand aligned, the two pieces were clamped together using Vice Grips with multiple reminders from the instructor that ONCE IN THE VICE GRIPS DO NOT TAKE THEM APART UNTIL TOLD TO DO SO. Our instructor said that this is critical to ensure proper book-matching of the covers which is a hallmark of any custom-made knife. Once clamped, the outside of the cover is scribed with an “X” to identify it as the “Master” cover.
STEP11C – Drill pin holes in clamped master side cover - Using an 1/8” drill bit, I lowered the drill press through the countersunk hole in the knife steel and through the canvas Micarta. Once all 6 holes were drilled, I ran the clamped cover and knife steel combination up and down a stationary drill bit to clear the hole to a full 1/8”.
STEP11D – Scribe master side cover to the blade profile - The blade profile is scribed in the cover material to create a rough-cut line. We were now told to remove the Vice Grips that were clamping the master side cover to the knife steel. More than one student asked a second time to be sure THAT WE WERE BEING TOLD TO TAKE THE VICE GRIPS APART.
STEP11E - Drill pin holes in the clamped matched side cover - The master side cover and the matched side cover were then clamped together using Vice Grips and the pin holes in the master side cover are used as a template to drill the matching side cover pin holes. The ends of both covers are now marked with an “X” using a Sharpie to maintain proper bookmarking. Once all 6 pin holes were drilled in the matched side cover, I ran the clamped covers up and down a stationary drill bit to clear the hole to a full 1/8”. We were now told to remove the Vice Grips that were clamping the master side cover to the matching side cover.
STEP11F – Cutout scribed master side cover - The master side cover was cut on the band saw up to be leaving the scribe line.
STEP11G - Scribe matching side cover to the master side cover - The master side cover is now used as a template to scribe the profile of the covers.
STEP11H – Cutout scribed matching side cover - The matching side cover was cut on the band saw up to be leaving the scribe line.
STEP11I – Connect master and matched side covers with pins - The master side cover and the match side cover were aligned using the “X” created in Step 11E to maintain proper bookmarking and 2 pins were inserted to connect the two covers.
STEP11J – Scribe, cut, and finish sand the ricasso end of both covers - The ricasso end of both covers was scribed to mark the end of the covers on the knife steel. The mark could be domed, cupped, straight, or flowing to accentuate the profile of the blade and/or covers. I chose to keep my vertical cover line straight to meet the spine of my knife at a 90° angle.
To conclude our day 4 class, the instructor told us that next week we’d be installing our covers with pins through the knife steel and start to shape the covers. Additionally, the finish grinding will commence and any fine bench work like jimping or file-work. We once again ended the class in fine fashion, cleaned up the shop and I left the campus without my piece steel but with a pinned set of covers that looked like they belong on a knife.