Friday, February 10, 2017

Chainsaws, or gender

Telling you the truth, until I joined the Lovers of Niiharu Citizen Forest, I was not sure how to use saw, sickle, hatchet, etc. Last month, I have passed the first anniversary as a member of Lovers organization. I can now say something about the usage of them with a swelling chest with pride … er, as a first-year student, actually. There are several senior Lovers members who are carpenters or have business in landscaping. Pros. The environment in Niiharu Lovers is ideal to learn how to use the tools with instructions from professionals, free of charge ;-) So, I tell you for sure Japanese hand-saw can cut the object when we pull. Also, I learned Japanese believe Euro-American tool does the job when they push … Oh, what a wonderful contrast to ponder cultural differences … By the way, I don’t know if this Japanese understanding for westerners is true. (Are they?) The other day, the chairman of Niiharu Lovers, Mr. Ohkawa, taught us why Japanese hand saw operates like this, together with the mechanics of blades. I was impressed. Behind the tool, there is a robust idea of designers whose knowledge has been transmitted for hundreds of years. Gosh.

To cut a tree in a safe manner,
the first strike for a socket should be horizontal.
The other day, an instructor used a level
to show us forest instructor trainees
the ideal angle for horizontal position.
This is how I thinned a forest.
(“I did it, I did it, I did it!”)

Here is what I have learned from the lesson. First, a blade of a saw is not a single row of blades, but practically 2 parallel rows. Two blades face each other and make one set for operation. Second, 2 rows are made of one steel. The edge of steel is cut jugged, then each ridge is ever-so slightly bent outwards in alternate directions. It creates a tiny valley between 2 ridges whose function is to scrape out crumbs when the saw cut material. Third, a ridge of a saw has 3 blades, 2 for each side, and one at the tip. The blades of the tips are sloped in a uniform angle, which determines the timing when the saw cut. Japanese saw has tips facing to the top of a saw. This direction is for the tool to cut when we pull, and I guess western saws have the blades of tips facing to the handle. (… Do they?) Fourth, when we saw wood, the tips first hold the material, then the blades of two rows cut into the object simultaneously. It means an opening is in fact made of two parallel slits. As we saw deeper, some crumbs of two slits fall between the two rows of blades and the valley structure pushes them out. Clever! Fifth, for Japanese saw, the slits are made when we pull. During the pushing, the tip blades are practically sharpened. So do the blades of the side ridges. When we use only a part of the saw, the used parts are sharpened and their steel wears down, but the rest will be left untouched. Eventually, the blades of a saw lose straight line and it becomes difficult to maneuver. That’s why it is important to use the entire blades always. A-ha.

The blades of my saw
The 2 blades have a structure like this.
The mechanics of sawing
When we sharpen a saw, we have to have 7 steps for one ridge. Sharpen 2 slopes of a ridge; deepen the valleys of both sides to recover the wear-down; adjust the distance of 2 ridges when they open too wide; sharpen the tip; and finally keep even the height of all the ridges. … Sounds difficult. Hence, normally we use disposable hand saw blades. Mr. Ohkawa said, “The same thing cannot be said for chainsaws as their blades are not cheap. Though, the design of chainsaw blades is same as hand saws. We just use special measure for improving blades of chainsaw thoroughly after every use.” My mainly-male seniors told us the job is not so popular. “You know, when we know there are beers after this sharpening things, we unconsciously cut corners of the tedious stuff … look, this part of blades has a strange angle. Ha, ha, ha.” Mr. Ohkawa was not so happy. “Blades cost money, and our organization is not so rich. Damaged blades call us sooner for replacement. We have to be careful about this.” The students of Mr. Ohkawa’s lesson this time happened to be 2 ladies, Ms. F and I. We practiced the filing of chainsaw blades, one by one, in silence.  We found it a fun! Ms. F rejoiced to see the result of her labor. “Naomi, look! They are shining! I’m sure they can operate very well.”

7 stages of blade sharpening for a saw. We push a file always against the blades.
Both have parallel blades structure.
Attaching a measure to improve blades of a chainsaw
All the blades of a chainsaw
should be sharpened in 45 degree.

We have also learned the basic procedure for operating chainsaws. A machine has 2 tanks: one for gas (or actually a blend of 25 parts of gas and 1 part of engine oil), another is for chain oil. When chain oil does not come out smoothly, the saw easily heats up and the machine stops. It’s important to check the injection of chain oil before cutting. After starting the engine, open the choke valve completely and let the engine to turn fully AND continuously. “Don’t rev it up discontinuously as you do for motorbikes. The power of chainsaw engine is not so big, and stop-go roars could stall it. Besides, it wastes gas more.” Hmmmmm. “Then, listen, it’s important. Chainsaw is to cut woods easily. You don’t have to push the blades on woods, but simply touch it by situating the safety cover of the machine along the curvature of a wood.”

The proper positioning for chainsaw

We gingerly proceeded to the practice. Squeezing the handle, we opened the choke valve to rev up the engine.


A wood was cut just like tofu … To sum-up our experience, a word from Ms. F would be the most exact.



… It’s a common saying that operating chainsaw can change a person’s character … One of my new year’s resolutions for 2017 is preparation for chainsaw license. In Japan, unless you hold the license, no accident with chainsaw will be covered by insurance. In a worst case scenario, it can lead to a criminal investigation. Naomi is a good girl.

By the way, do you know Jason had never used a chainsaw even when it was Friday the 13th?

If you find a problem in Niiharu Forest, please make a contact with

Office for the Park Greeneries in the North 北部公園緑地事務所
Yokohama Municipal Government Creative Environment Policy Bureau 横浜市環境創造局
Phone: 045-311-2016 (I guess in Japanese only)
FAX: 045-316-8420 (I hope there is somebody who can read English …)

Niiharu Administrative Office / Satoyama Exchange Center 新治管理事務所・里山交流センター
Phone: 045-931-4947
Fax: 045-937-0898

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