Introduction

I decided to make a Japanese Scraper Plane called a Tachi Ganna. Why?

I do a lot of handing planing with a regiment of different planes like the Jointer, Jack, Smoother, Bock, etc. etc. I really like making sure that my stock is square and flat before going into a project. However there are times when really perfect bottom flatness is required especially when you are making wooden planes. When you make Japanese pull planes absolute dead flatness is required on the bottoms. There are areas on the bottoms that are also relieved to minimize friction while planing as well. Japanese scraper planes are essential in achieving dead flatness.

Key Aspects of the Tachi Kanna/Ganna:

Purpose: It is a Japanese scraper plane primarily used for fine finishing, smoothing hardwoods, or treating difficult grain where a traditional blade might tear the wood.

Blade Orientation: Unlike regular Japanese planes (hira-kanna) with low-angle blades, the tachi has a vertical or nearly vertical blade, essentially acting as a scraper.

Usage: It is often used to sharpen or "scrape" the sole (dai) of other Japanese planes to keep them flat and functional, ensuring perfect contact with the wood.

Alternative Name: It is sometimes referred to as a scraper plane or sometimes associated with Dinaoshi-ganna.

Essentially, tachi kanna (vertical plane) and tachi ganna refer to the same specialized, high-angle scraping tool used by Japanese craftsmen for precise finishing.

Summary: A scraping plane with the blade set at 90 degrees to the sole, this plane micro scrapes instead of shaving the wood.

Ideal for: Planing very hard wood and soles of plane blocks (dai)

Tips: Plane across or diagonal to the grain

The Prototyping Process

There are several different ways to make a Tachi Ganna. You can mortise out the bed cavity or you can do lamination style. In addition, blade orientation from top view: can be skewed or straight and from side view: straight up and down or leaning at a small angle. I decided to play around and make some prototypes so I could determine which meets my needs.

In this first prototype Fig 1 (looking from the side), the bed cavity is leaning towards the rear by 5°. This effectively puts the blade's cutting edge in a very slight cutting / scraping mode. A wedge is made to secure the blade between the bed and and a cross pin which I made from a 4” long 1/4-20 hex bolt. Note the position of the blade cutting edge (red arrow)

In this second prototype Fig 2 (looking from the top), the bed cavity is straight up and down but rotated by 5°. This effectively puts the blade's cutting edge in a very slight skewed scraping mode. A wedge is made to secure the blade in a mortised cavity that is stepped in from the sides preventing forward move while wedging (see red arrow).

After making and trying out the two prototypes per Fig 1 and Fig 2, I decided that making another one where the bed cavity is leaning towards the front by 5° per Fig 3 might be best. This effectively puts the blade's cutting edge in a very slight but more effective scraping mode. The blade bevel is 45°. A wedge is made to secure the blade between the bed and and a cross pin like I made in Fig 2 above.

Testing

I decided to do some scraper testing on Pine , Oak, and Maple. I scraped a block of Maple per Fig 4. I placed pencil lines on the before view. Then scraped.

I was quite pleased. It scraped extremely flat. Look at the fine shavings on the top of the vise. (see red arrow)

Check out this video of me trying it in action.

Finish

I gave three coats of 2 lb blonde shellac on the top and the sides. I left the bottom bare. For the wedge I did the same but left the face bare that faces against the blade.

Thanks for looking!

Cheers!

MrRick

Thanks for the explanation of use and structure of this plane. Found it interesting a plane made to smooth other planes. I have a question. Thought Japanese planes worked on pull stroke but in video it appears to be a push?

It is a pull stroke plane. It cuts on the pull.

Are you making your own irons or is there a source you use?