Woodworker's Journal 2006-30-2, страница 23

In this photo, the author uses a skew chisel as a straight-ended scraper to shear scrape the profile of the outside of the bowl.

high point to the tow point for all elements.

For bowls, rough out the initial shape using a large bowl gouge. (Roughing gouges are meant for spindle turning!) On the outside of the bowl, cut in an uphill direction, from the base of the bowl to the rim. On the inside, cut from the rim towards the center. It is possible to cut either uphill or downhill on the inside of a bowl, but in general, uphill will give you a better cut.

Cutting with a gouge is done with the flute pointing in the direction of the cut, the tool traveling in that direction, and some portion of the lower half of the cutting edge contacting the wood. Those are the three "rules" of cutting or shear scraping with a gouge.

'l"he steepness of the bevel is of some importance for achieving a good cut and for controlling the tool. A steeper angle, one closer to 30 degrees, will be challenging to control, but it will give you a cleaner cut. A bevel closer to 70 or 80 degrees will be easier to control, especially when working on the bottom of a bowl, but the cut will not be quite as clean.

Adjusting the Bevel for Clearance

If your lathe can only handle bowls of small diameter and your tools have long handles, you will find that the bed of the lathe gets in the way when cutting on the inside of bowls. Here are three solutions: 1) buy a larger capacity lathe; 2) use tools with shorter handles or cut off the extra length from your long-handled tool; 3) grind the angle of your gouge more towards 60 or 70 degrees. That will allow the tool handle to be lifted high enough

Woodworker's Journal April 2006 23

to clear the bed of the lathe yet still make a cut-

Shear Scraping

Shear scraping can be done with scrapers or with gouges. To shear scrape with a scraper, make sure the cutting edge is sharp and has a slight edge to it. This can be achieved either straight off the grinder or by raising a very slight burr on the cutting edge. Instead of holding the scraper flat on the toolrest and horizontal (as for scraping), lift the handle slightly so the cutting edge of the tool is pointed slightly down. Next, lift the side of the tool and present the cutting edge to the wood at an angle. Take a light cut. Shear scraping is meant to take off only a slight amount.

To shear scrape with a gouge, the profile of the gouge should be that of a fingernail grind. Present the cutting edge directly to the wood, ignoring the bevel. Place the cutting edge of the tool at a slight angle to the wood. The tool handle will be at a more vertical position than for cutting. Pull the gouge in the direction of the cut. Use a good portion of one side of the tool's cutting edge. Using a long section of the cutting edge helps create a smooth-flowing curve.

To shear scrape between a bowl and headstock, you can hold the tool with the flute open upward and the tool handle down. Try pulling the tool to cut in difficult areas.

The advantage to shear scraping is that you can achieve a very fine cut, especially with difficult-to-turn woods. It's the only way I can get a good cut on cherry, for instance. Also, shear scraping is sometimes the only method for accessing difficult-to-cut areas, especially when turning the outside of a bowl when it's mounted with the opening facing the tailstock. The small clearance between the back of the bow! and the headstock often makes it difficult to remove wood from the back and bottom. Shear scraping not only allows you access, it lets you cut in the direction needed for a cleaner cut

I realize that word directions are difficult to follow. We are visual people. Study the photos accompanying this article. Practice. If you don't have a catch or dig-in, you're not extending yourself or learning new methods. For safety's sake, always take a light cut and keep your toolrest as close as possible to the wood. Turn at moderate speeds until you are proficient to keep those catches minimal. And by all means, please keep on turning, and have fun! JP

Betty Scarpino is Woodworker's Journal's woodturning columnist.

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