Wednesday, September 19, 2012

Modified Kobun

I've been looking for a fixed blade EDC and self defense knife for a while, especially after starting Pekiti-Tirsia Kali (that's another post).  I've tried out a few different knives, but I was pretty surprised at how much I liked the Cold Steel Kobun after ordering it from Amazon, especially because I only paid 35 bucks for it with tax and free shipping.  This is how it looks from the factory, measuring in at 0.1" below the legal limit for carry in Texas.

Anyways, being who I am, I couldn't just leave it alone, so I decided to make a few mods to the knife.  First off, the knife is very slim, and that's one of the reasons I liked it for a carry knife, but I still felt like I'd prefer something a little... extra in the handle.  The day that I got it in, the first thing I did was cord wrap the handle, to give it a little more thickness and improve my grip.

Here's how it looked after the wrap.

Right side:

Left side:

Right side:

I'd been thinking about how little I like the modern tanto shape with the very angular yokote on the kobun even before I purchased it.  I saw a few other posts where people had reprofiled modern tantos, ending up with something approaching a Rick Hinderer type spanto type point.  So with that inspiration I sat down with my whetstones and reprofiled the yokote.  Here's what I ended up with, and I think I like the profile a LOT more than the factory grind.

Even being careful while wiping off the filings, I lightly marred the finish, so I'll have to go over it with some high grit wet/dry sandpaper eventually, but in the meantime, it'll do just fine.

Let me know what you think


I'm working on my first kiridashi.  The blade material is an old file I purchased in a lot of 20 files on ebay.

I got a gift of firebricks from my friend a while back, and this is the first chance I've had to put them to use in my shop.  Prior to now, I've been using a Mapp gas Benzomatic torch for annealing and heat treating, which is far from optimal.  Using the firebricks, I put together a very simple forge (in the spirit of Wayne Goddard's one brick wonder).  Basically, I placed one brick flat, then used the sides of two bricks to form a chamber about 1", maybe 1 1/4" wide.  Then I laid another brick on top to hold them in place and form a roof, and set another brick down flat behind, with a last standing on its side to direct the hot gas flowing through out to the sides and up.

Just using the Benzomatic, it got hot FAST.

Here's how it looked during my heat soaks before annealing:

With torch on

Looking into the forge

The blade removed for photo-op

In that last, I removed the blade quickly and snapped a photo, and then put it back in the forge.  I'm really happy to be able to get a relatively large area heated to critical with just a benzomatic.  I've already purchased hoses and a burner for a more permanent setup, but haven't picked up a propane tank yet.  I'll also note... it doesn't look that pink in person, it's much more of a bright orange, something must be off using my cell phone camera.

After annealing, I really got into the zone with cutting out and profiling the blade, drilling holes for the eventual cord wrap, and cutting out the inside of the handle, and I didn't even think to take pictures of the process.  By the time I remembered, I was already in the heat soak for hardening (probably because I was reminded of taking the photos during the annealing process). Here's another photo of what it looked like:

Right after quenching in oil, this is the blade profile

Sorry for neglecting to include anything for scale.

Ok, so here's how it looked after polishing on my bench stone and up to 220 grit.  I left the majority of the blade at this low grit because I want it to have a "used" look.  I think I might play around with giving it a nice patina with mustard or vinegar.

Here's the blade polished and sharpened.  The secondary bevel was polished and sharpened to 2000 grit on wet or dry sandpaper on top of glass.

I cleaned the blade, and did a base wrap using black paracord sheath.  You can see here, during polishing, I left the file marks on a small visible portion of the blade's flat, just as a reminder of its origins.

After the base wrap, I played around with more paracord sheath, and ended up with the following pattern.

I'm not sure how much I like it, I may pull it off and do the crossing cords on every wrap, or something else entirely.

Here's the final blade

Let me know what you think!