•What makes Ban Tang Knives stupid sharp?
• What is a “Stupid Sharp” knife and how is one made?
• But WHY is it Stupid Sharp?
• What steels do you like to work with and use? Why?
• General Heat Treat info?
• Why do you like putting chisel grinds on your knives?
• Titanium knives with carbidized edge: What are they, why are you making them, and how are they made?

 

Q. What makes Ban Tang Knives stupid sharp?

A.First I choose the right steel for the job. I grind the most optimal geometry into each blade based on its intended use and design. Then I heat-treat or temper each blade to meet the demands of the intended use of the knife. Each knife is then carefully sharpened one at a time using my proven method. I don’t cut any corners when it comes to sharp.

Q. What is a “Stupid Sharp” knife and how is one made?

A.The following is my usual process in making a knife:

1) Profile the blank (I’m currently doing only stock removal, and I don’t see that changing any time soon)
2) Drill holes for handles
3) Clean up the surface of the blank
4) Using a belt grinder, I grind the main bevels by progressing from a 36 grit belt to a 220 grit belt
5) Carefully wrap the knife in stainless foil and triple fold the edges
6) Heat treat the knife in an oven
7) Plate quench the knives when the critical temperature is reached 8) Let the knife cool to 150F, and then return knife to the oven for the first temper
9) Remove knife, and let cool to room temperature
10) Dip in liquid nitrogen filled cryo tank over night
11) Finish second and third temper
12) Clean up flats and ricasso from 80 to 120 grit
13) Regrind the main bevel from 80 grit to 220 grit
14) Roughly sharpen a V edge with a 120 grit, and refine edge up to a 320 grit
15) Frosty satin the entire knife, etch logo and clean up the etch, clean up the spine and bevel the corners for a smooth spine
16) Tape up the entire knife blade and ricasso, then clamp the blade tang to whatever handle material I’m using (usually micarta)
17) Drill holes into the handle material using the clamped tang as a template, and scribe the outline of the tang onto the handle material
18) Rough cut the handles on a bandsaw
19) Pin and clamp handle set together and clean up the front of the handle slabs on the grinder
20) Temporarily pin and glue the handle scales onto the tang, remove pins and shape the handle scales on the grinder
21) Hand sand the handle scales to smooth out contours and finish
22) Countersink the handle material
23) Cut rivet tubing (oversize) with a hacksaw and grind tubing to size
24) Flare tubing
25) Grind entire spine one last time to clean up spine and ensure that the handle scales are flush with the tang
26) Remove tape and apply Stupid Sharp edge (discussed further below)
27) Clean entire knife with Simple Green, and pat dry. That’s all there is to it, now the Stupid Sharp Knife is done!

Q. But WHY is it Stupid Sharp?

A. A friend once told me my knife was “so sharp, it’s Stupid!” We jokingly called it “Stupid Sharp,” and it just kinda stuck with me.

The answer here is edge geometry. Effective and efficient knife performance absolutely depends on how well the geometry of a blade’s edge matches the task in which the knife will be employed.  Edge geometry is a combination of both primary and secondary bevels. The primary bevel/grind forms the transition from the spine of the blade to the edge. Primary bevels are typically flat, hollow, convex, chisel, and/or a combination. Secondary bevels form the edge itself. These bevels are typically either V or convex. I prefer a convex edge to a V edge because I feel the convex edge is stronger, cuts better, and is easier to maintain. While both of these bevels should be appropriate for the knife’s intended use, how smoothly a primary bevel transitions into a secondary bevel is also a critical factor underlying cutting performance.

There is no single perfect geometry that can be used in all applications. This is why matching the geometry to the task is crucial in getting the highest performance possible out of a knife. For instance, on a chopper, I generally prefer a robust full convex geometry (full convex grind into polished zero convex secondary) or full flat geometry (Full flat primary into a polished zero convex secondary). On medium-sized knives that might see a variety of uses, I generally prefer a gentle convex or full flat primary into a polished zero convex edge. On small knives, I often prefer a chisel grind that also transitions into a polished zero convex edge. But there are no hard and fast rules, and I have been known to experiment with geometry to test out performance characteristics.

Q. What steel do you like to work with and use?  Why?

A. In no particular order

Carbon: CPM-3V, CPM-M4, A2, D2, 10V

Stainless: AEB-L, M390, CPM-154, CPM-S35VN, Elmax
I also like Titanium (6Al-4V) knives with a carbide edge (further discussion below)

Generally, I like A2 and M4 for working knives that’ll see field time. I like A2 for its toughness, ease of field touching-up, and decent wear resistance. CPM-M4 is a “high speed tool steel” and is some good stuff. It takes a fine edge, holds it like a pitbull, while remaining relatively tough. At higher RCs (63-64) it holds an edge for a looooong time. If it were more stainless, it would be my new favorite steel.

In the kitchen, I’m a big fan of AEB-L or Titanium knives with carbide edges. AEB-L is very corrosion resistant, sharpens up easily, and holds a great edge for typical kitchen work. It’s actually designed as a razor blade steel. Its super fine grain structure allows it to take ultra sharp high polished edges that are ideal for push cuts. As for the titanium, I think the rust-proof nature combined with the decent working edge provided by the tungsten-carbide edge makes for an excellent every-day, negligible maintenance, kitchen user. Of course, new steels are always popping up, so I’m always experimenting with new stuff. While these are what I favor now, that might change down the line.

Q. General Heat Treat info?

A. Heat treatment can vary with each knife, depending on steel used and the knife’s intended application. I generally heat treat my knives to around 59-61RC. Sometimes I’ll go higher if the steel performs better when harder while giving up some toughness (say, CPM-M4 heat treated to 63-64RC for slicers, skinners, etc..).

Q. Why do you like putting chisel grinds on your knives?

A. I like chisel grinds on defensive blades because it allows me to get some very acute edge geometry. It also gives the appearance of nice and deep pronounced grind lines. With really thin stuff it is almost impossible to do flat grinds without significantly weakening the blade. Some argue that the chisel grind is easier to grind. Maybe…Maybe not… I don’t really care. I prefer it for the above reason.

Q. Titanium knives with carbidized edge: What are they, why are you making them, and how are they made?

A. Most people think of Titanium knives as novelty items that hold very little practical value unless you are a diver (recreational, professional/commercial, EOD, etc). For the most part it is true. Titanium is soft, relative to steel, and it won’t hold an edge like a good heat-treated steel blade will. However, to the average civilian user, titanium offers a high strength-to-weight ratio, superior corrosion resistance, and a tough and ductile edge (so chipping shouldn’t be an issue).

Now, add some tungsten carbide to the mix and things start to look even more favorable for the titanium blade. Tungsten carbide is extremely hard; it’s a 9 in the Moh scale. A measurement of hardness on the Moh scale does not readily convert to the Rockwell C measurement most of us are familiar with, but I think it would be roughly in the mid 80′s. If we apply a tungsten carbide edge to a titanium blade, we end up with a very low maintenance (effectively rustproof) piece of cutlery that can hold an edge just as well if not better than most quality steel edges. When a titanium blade is given a decent edge geometry, the carbide allows the titanium to hold a good edge and cut well.

The carbidized edge is a toothy hair scraping sharp vs a higher polished hair splitting sharp of a steel edge.  I’ve been able to slice slivers of paper easily with a polished carbidized titanium blade. While it could no longer easily and cleanly slice paper after about 25-30 cuts through cardboard, I know it could have kept cutting cardboard for much longer without a problem. I have had a few guys put their carbidized Ti knives through the ringer, and all of them are amazed at how well the edges hold up and how easy they are to maintain. One guy used his knife to cut and lay up a yard full of sod. Needless to say the knife was dull afterwards from all the sand and various other grits in the soil, but it required minimal work to bring the edge back to working order. People have reported their Ti knives functioning well in a variety of tasks, including food prep, dressing game, working with wood, and taking apart abrasive packaging materials (e.g. cardboard).

I, and others, have noticed that the carbidized edge will still cut very well even when it feels dull. In fact, the carbide edge can almost be considered self-sharpening: since the carbides are only applied to one side of the titanium blade edge, more carbide is exposed as the titanium wears away on the other side. This is similar to the self-sharpening phenomenon observed with the teeth of beavers. Actual sharpening of a carbidized titanium edge is very simple. See the sharpening and maintenance questions further along in this FAQ for more detail.

So why carbidized Ti knives? I think these knives should work well in the kitchen, where they would be cutting relatively soft, non-abrasive, material (veggies, fruit, meat) in a wet and corrosive environment. Titanium’s superior corrosion resistance, coupled with the easily maintained carbide edge, makes these knives perfect for every day kitchen duty. I also suspect that carbidized Ti knives will catch on with the ultralight hiking/backpacking crowd. A strong, lightweight, and very low maintenance knife sounds ideal for the ultralight backpacker – someone who typically isn’t out there doing heavy duty work or doing things that require a fine edge.

Titanium also works great for smaller defensive blades.  The lighter weight and low maintenance is a huge plus.  The carbidized titanium edge is plenty sharp for defensive purposes.
How do I get the tungsten carbide onto the titanium? I currently use a Carbidizer very similar to the Rocklinizer. This tungsten carbide applicator electronically embeds the carbides into the titanium substrate. You can sort of think of it as a micro-weld.

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Q. Do you make custom knives?

A.Yes, I do on occasion make knives to a customers personal specifications.

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