Turning Archive 2005

Subject:
Shear Scraping and End Grain Problems

Wally Dickerman
>End grain tearout is a problem that plagues new turners, and sometimes experienced turners alike. It needn't be a problem.

My first advice is to cut with the grain whenever possible. Cutting against the grain will tear out the unsupported wood fibers, resulting in a very rough surface that is difficult to get rid of.

Shear scraping is a great way to eliminate a lot of sanding, expecially with heavier grits. There are dedicated shear scrapers on the market, but I usually prefer to use my bowl gouge. The gouge should be side ground, Ellsworth style, and be very sharp. Basically, it's done with the flute facing the wood, the top cutting edge almost touching the wood, and scraping with the lower cutting edge. drawing the tool handle first. On the outside of a bowl, scrape above center with the handle lowered. The tool should be cutting at an angle of 20 to 40 degrees. For best results, cut with the grain, and take very light cuts. You should be getting small feathery shavings.The damaged wood surface, end grain tearout, etc. should disappear. Inside a bowl, draw the tool toward the rim. Guard against letting the top edge get too far from the wood, or the tool will dig in. Adding oil to the wood makes the process even more effective. I use Danish tung oil, the same oil that I use for finishing, but mineral oil can be used. After shear scraping, I almost never use sandpaper any heavier than 150. I often am able to start with 180 or 220.

A better and easier job of sanding can be done in a shorter length of time when using oil. Just apply the same oil to the wood as was used for shear scraping. Some turners use oil with all grits, but I only use it with the heavier grits. A plus when using oil is that there isn't any sanding dust in the air.

Wally

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