In this tutorial I will show you how to make mekugi which are the retaining pins used to secure the tsuka to the nakago of a katana, wakizashi, and tanto. The following method is appropriate for any modern production Japanese style sword.
Mekugi are typically made from susudake, a smoked and seasoned piece of bamboo which is very strong yet not brittle. It is also flexible and very resilient to snapping, making it good for absorbing pressure.
The fibers of the bamboo plant have a natural elasticity and are very tough and even when crushed, they resist breaking. But only when cured properly.
The bamboo used for these retaining pins is of high quality, smoked and cured and not to be confused with the cheap and weaker bamboo used for take out food chopsticks and other more fragile wares.
If the katana blade is the soul of a warrior and the habaki is the heart of the sword then the mekugi are certainly the anchor. These little pins are crucial to the functionality and safety of this weapon and it would be quite useless and extremely dangerous (to the wielder or random onlookers) without them, especially on the one-size-fits-all assembly of some budget katana. It is very important to make sure your mekugi are of good quality and fit properly so remember to check them often and replace them when necessary. It is not worth it to use cheap material like chopsticks to replace them with because after all, this is what will keep that 3 foot razor from becoming a horrible trip to the hospital or worse.
Pieces of susudake can be purchased from sellers like Nihonzashi and Namikawa among others for about $10-$25 and will yield roughly 10-15 mekugi depending on size.
Mekugi can sometimes also be made of other materials like buffalo horn. Buffalo horn is not recommended for a katana but have been used on wakizashi and mostly found on tanto since it is not as resilient as bamboo and could crack under heavy stress.
Polyoxymethylene is also another material I use for making mekugi. here is a wikipedia excerpt –
Polyoxymethylene (POM), also known as acetal, polyacetal and polyformaldehyde, is an engineering thermoplastic used in precision parts requiring high stiffness, low friction and excellent dimensional stability. As with many other synthetic polymers, it is produced by different chemical firms with slightly different formulas and sold variously by such names as Delrin, Celcon and Hostaform.
Typical applications for injection-molded POM include high performance engineering components such as small gear wheels, ski bindings, fasteners, knife handles, and lock systems. The material is widely used in the automotive and consumer electronics industry. The M-16 rifle’s stock and other parts are made of it.
Delrin can be purchased in blocks, slabs and rods. I use 1/4″ rods since they are already cylindrical and require much less shaping. The rods are usually about $5 each and can be found on ebay. I find Delrin to be a very good material for mekugi since they are very tough yet flexible and crush rather than splinter or crack. They are also easy to shave and grind.
Coping saw, or piercing saw, or dremel cutoff disc, other small bladed saw, or anything you have that will neatly cut the bamboo
Sandpaper in different grits
Drill press or portable drill with adjustable chuck
Ruler, measuring tape or calipers
Wood stain (optional)
The first thing I do is measure the thickness of the finished tsuka to see how long the mekugi should be. If your tsuka has two mekugi, you might need a slightly longer one for the top (near fuchi) as this area tends to be thicker than the bottom. You should also be aware of the diameter of the mekugi-ana in your nakago to make sure you aren’t starting out with a piece too narrow. The mekugi-ana in both the nakago and the tsuka should be tapered or larger on one side than the other to prevent the mekugi from passing all the way through.
You might not find this to be true on some mass produced swords but find instead that the holes are uniform. The tapered mekugi you make will still work but the fit just won’t be as good as if the holes were tapered. On many nakago you will also notice that the mekugi-ana are very wide requiring a very large mekugi which is unnecessary and annoying but since you can’t make the holes smaller, you just have to fit them the best you can. Ideally, the mekugi should fit tightly in the nakago mekugi-ana about halfway through.
Then you transfer this length plus an additional 1/8″-1/4″ to the delrin rod or piece of susudake and mark it off.
Now place the rod in a vice or other stable clamp and cut on the mark with your saw. I use a piece of leather or shop towel to protect the rod or piece of bamboo from getting marred by the vice. Be sure not to tighten too hard or you can crush it.
When you cut from the susudake, you will be cutting a rectangular piece a little longer and thicker than you need for the final mekugi.
Place the end of the rod in the chuck of your drill and carefully tighten just enough to hold it firmly. When using bamboo, be very careful not to crush it. I use a small piece of fabric or leather to protect it in the chuck.
Place the side of the rod against the file at a slight angle and start to rotate the drill. Your goal is to create a conical shape. If you are using a drill press, hold the file up against the side of the rod/bamboo making sure to support the opposite side with something like a piece of leather or wood block.
Keep spinning the rod against the file applying light pressure while also sliding the rod back and forth along the file to increase the friction. You will notice the plastic dust building up so just clean it off once and awhile. Same with the bamboo.
An alternative for shaping the mekugi would be to use a very sharp knife to carefully whittle the piece to the same conical shape. Go easy with the knife so you don’t shave off too thick of a slice at a time. It will start to look like this in a while
If you notice, one side is tapered more than the other
Once you have the shape close to what you need, you can switch to using sandpaper which will remove less material than the file. Also at this point you want to start checking the fit in both the tsuka and the nakago-ana to make sure you don’t make the mekugi too thin where it just slides right through the hole.
I use a piece of leather to back the paper so it doesn’t get too hot to hold.
Keep checking the fit frequently.
Once the mekugi is very close to the final shape, you can then choose to give the ends more of a polish for aesthetics by switching to higher grits of paper.
I like to add a high sheen to the exposed ends of my mekugi for aesthetic reasons. I do this by polishing with progressively higher grit paper finishing off with 1000-2000. After this I apply a little renwax and buff with a cloth. You can also stain the bamboo if you want a custom color or even apply a little polyurethane if you like. These additional steps are completely optional.
After I polished and buffed it with renwax
That’s it, easy!
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