Popular Woodworking 2007-10 № 164, страница 47

H \ have been reading these pages during the past few years, you have been introduced to the traditional spokeshave. I'm going to show you how to make your own. This means making everything from a shaped, hardened and tempered steel blade, to making the tool's wooden body with a micro-adjustable mechanism, right in your own shop.

History of the Spokeshave

The traditional wood-bodied spokeshave has a blade that lays flat to the work surface, or sole, ofthe plane. It cuts in fine, smooth strokes that rivals or surpasses its cousin, the angled blade of the metal-bodied shave.

The spokeshave receives its name from wood wheel making, where it is indispensable to the wheelwright in planing the transition from the square hub end of a spoke to the round. And, you can fit the wood sole of the plane in tight recesses if needed -j ust increase the angle of wood in front of the blade.

How Tool Steel Works

The project starts with making your blade, which will become the template for carving the wood body. Tool steel for the blade is an alloy that changes properties when subjected to heat. The 01 (oil-hardened) stock is a good steel for general applications, and has rather forgiving parameters when heat treating.

There are three stages through which you take the steel. It is manufactured in lengths Vs" x ⁵/s" x 1s", enough for four blades. The cost is less than $10. (I suggest ordering parts for several shaves while you are at it.) Tool steel is annealed when manufactured, meaning that it is soft enough (Rockwell 45) that it can be cut with a hacksaw and drilled.

The second stage is where the steel is hardened. Here, you play blacksmith and heat the blade red hot in your shop-made furnace. The temperature of steel when it glows red is between 1,450° Fahrenheit (F) and 1,700° F. The duller color of cherry red is the desired temperature range of 1,450°F to 1,500° F for 01 tool steel. It is now subject to abrupt cooling by quenching in oil. The 01 steel gets its name from being formulated to require the shock that happens when it is immersed in oil that

boils at 325° F. Some other steels are designed for a water quench that is a more severe temperature drop to 212° F. The blade is now super hard at Rockwell 75, but also very brittle; it will shatter if struck with a hammer.

To restore the desired toughness, or ductility, the blade is then tempered in an oven that heats to 425° F, and then it is slowly cooled. This will be done in your own heat-treat oven, aka toaster oven. The shiny surface of the steel at this temperature has a light straw color which is the first of a rainbow of surface patinas from yellow to bronze to blue as the steel is heated to 625° F. The final hardness is determined by the amount of heating. Light straw heating will result in a blade of Rockwell 60 hardness that possesses adequate toughness for long edge life.

Making the Blade

The steps for blade making are:

1. Lay out the shape and holes on the 01 steel.

2. Center punch the location for holes and drill with a #21 or ⁵/32" drill, and tap the 1032 threads.

3. Hacksaw the blade to length and notch the ends.

4. Cut two pieces of 10-32 threaded rod to 1V4" long, which will serve as handles while grinding. Grind the bevel of the blade, leaving a small flat on the leading edge.

5. Harden the blade by heating the sharpened edge to cherry red (1,450° F - 1,500° F) and quench in oil.

6. Temper to light straw (425° F) in your toaster oven.

7. Sharpen edge and flatten the back of the blade on the belt sander.

8. Use the new blade as the template for making the wood body.

9. Attach the threaded rod permanently to the blade with cyanoacrylate (CA) glue.

You can follow these steps as illustrated in the drawings and photos. While 01 annealed steel is soft, that is relative to its hardened state. So you will find that starting with a new 24-tooth blade in your hacksaw is helpful. If you have not used a tap before, be careful; they are brittle and easily broken. As you start cutting threads, retract a quarter turn for every half-turn advance. That technique, plus a drop of

Tap first. An 18" length of 01 tool steel Vs" x ⁵/s" will make four spokeshave blades. Black magic marker is used to highlight layout lines to locate holes for 10-32 threaded rod posts. Here a tap and tap wrench are used in a setup on the drill press using a spring-loaded center (taken out of the drill chuck for viewing purposes) to keep the tap straight while threading.

LEAD PHOTO BY AL PARRISH; REMAINDER OF PHOTOS AND ILLUSTRATIONS BY THE AUTHOR

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