Mastering Shear Scrapers

Crown Tools left and right
skewed shear scrapers

Overview

One of the most useful techniques you will ever learn as a woodturner, is shear scraping. Often confused with traditional scraping (which is a totally different technique), shear scraping is a woodturner's best friend. It's your go-to technique for fairing the curves on your projects, eliminating torn grain and refining the quality of the surface prior to sanding.

Shear scraping is one of the simplest and easiest ways to clean up any tear out, or bruised grain areas on your woodturnings... Instead of using your 60-grit gouge! Shear scraping is an elegant process that sweetens the surface and reduces the total amount of sanding required on your projects. Although it's used primarily with bowls, platters and hollow forms, shear scraping can also be adapted to certain spindle turning projects.


Traditional vs. Shear Scraping

Shear scraping is vastly different technique from traditional scraping. Although the tools used for shear scraping may be the same as those used for traditional scraping, the way the tools are held and presented to the surface of the timber are very different. One of the great advantages of shear scraping is the ability to move in either direction, with or against the grain. When used properly, the resulting shear scraped surface is equivalent to a 320-grit sanded surface.

This technique allows you to eliminate labor intensive sanding with course abrasive papers, saving you time and money. You can shear scrape a surface to 320-grit faster than you can sand it from 80-grit to 320-grit. Another benefit of shear scraping is that it can be performed with several different types of tools, including Irish ground bowl gouges, traditionally ground scrapers, skewed scrapers and dedicated shear scrapers.


Shear Scraping with “Irish” Ground Bowl Gouges

One of the many benefits of the popular Irish Grind on bowl gouges is the ability to use the long swept-back wings for shear scraping. The long swept-back wings on the side of the bowl gouge are perfect for shear scraping the outsides of bowls, platters and hollow forms. Irish ground bowl gouges cannot be used on the interior of vessels when used for shear scraping however, because the long wings cannot match the interior curves on bowls.

Interior surfaces must be shear scraped with dedicated bull nose (full round nose), or half round (radiused) shear scrapers. Also note that small bowl gouges less than 1/2" do not perform well as shear scrapers. The larger 1/2" and 5/8" bowl gouges offer the best performance when used for shear scraping. Smaller 3/8" and 1/4" bowl gouges tend to vibrate excessively when shear scraping, due to their lack of mass in the shaft of the tool.


Shear Scraping Protocol – Irish Ground Bowl Gouge

Note: Your gouge should be freshly sharpened before shear scraping. Think of shear scraping as a finesse technique. Shear scraping removes tiny amounts of wood only. You will be producing shavings as fine as goose down. It cannot be used to perform gross profiling work. If you need to remove large amounts of wood on the profile, you should use your bowl gouge in the traditional fashion. Once all of the profiling work has been completed, you can begin shear scraping to refine and perfect the surface.

To use your Irish ground bowl gouge for shear scraping, simply rotate the flute of the tool upside down and orient the shaft of the tool into the optimum shear angle of 45 – 50 degrees.


Bowl gouges ground with the popular swept back Irish grind

Your best shear scraping performance will be achieved with the cutting edge held at 45 to 50 degrees, up to a maximum of 55 degrees. Although you can shear scrape at other angles, 45 – 50 degrees seems to be the overall sweet spot, for the best performance and efficiency.

For example, if a bowl is mounted in a chuck (foot nearest the headstock) and you need to shear scrape the outside curve of the bowl (small diameter to large, or foot to rim), turn the gouge over and place the right wing lightly against the surface of the timber. The left wing should be rotated very close to the surface of the wood (within 1/8" to 1/16" from the surface), but not touching. Only one wing (in this example the right wing) will touch the surface of the wood.

With the wood rotating, lightly touch the right wing against the wood surface, close the left wing down near the surface and orient the handle at 45 – 50 degrees. Lightly stroke back toward the rim in light, smooth strokes. You should be producing shavings that look like delicate goose down. If the shavings are large and thick, you are not shear scraping.

You can also move from the rim toward the spigot, using the opposing left wing. In this case, you would place the left wing against the wood, move the right wing to within 1/16" of the surface (but not touching), orient the handle at 45 – 50 degrees to the surface and lightly move from the rim towards the foot. Once again, you should be producing shavings that look like delicate goose down.

With certain forms and shapes, using your Irish ground bowl gouge for shear scraping can present significant challenges, due to the length or size of the gouge. In these cases, you should use a set of dedicated shear scrapers, which are much easier to maneuver in tight quarters.

If you're new to shear scraping, I recommend that you use a set of dedicated shear scrapers, instead of your Irish ground bowl gouge for shear scraping. This is because dedicated shear scrapers are much easier to use than an inverted bowl gouge and produce results as good as, if not better than Irish ground bowl gouges when used as a shear scraper.

Once you become proficient with your Irish ground bowl gouge, you can begin to experiment using it as a shear scraper. The easiest time to practice shear scraping is when you're turning green wood rough outs. If you happen to make a mistake, you can simply turn the piece a little smaller, or adjust the profile slightly. Once you begin practicing your shear scraping skills, it will become second nature to you very quickly.


Shear Scraping with Dedicated Shear Scrapers

Henry Taylor Tools skewed shear scrapers

Dedicated, or purpose built shear scrapers are much easier for most woodturners to use than an Irish ground bowl gouge for shear scraping. This is especially true if you have very little experience using an Irish ground bowl gouge. Dedicated shear scrapers look like traditional scrapers; however the ends are ground with a skewed angle on the end, instead of straight across, or rounded.

Dedicated shear scrapers are used slightly tilted on the tool rest, using the angled end to lightly stroke the surface of the wood. Because the optimum shear angle is already ground into the end of the tool, you simply position the tool in the area that you want to shear scrape, and stroke the tool back towards you as you sweep it across the surface.

See Shear Scraping in Action: To view two short video clips of shear scraping the outside and inside of a bowl using shear scrapers, click here.

Kel McNaughton's shear scraper has the correct shear angle ground into the shaft of the tool. Unlike most shear scrapers, this tool is used flat on the tool rest, producing superb results

The pre-ground skewed end of the scraper keeps the tool cutting in the optimum shear angle (45 – 50 degrees) to produce the best results. Dedicated shear scrapers are available in left and right hand skewed configurations. One is made for moving left to right across the surface and the other, from right to left. Another style of dedicated shear scraper uses a round end, or a slightly radiused end ground on the tool. These must be manually held in the 45-degree position during use.


Shear Scraping with Traditional Scrapers

Traditional full round and half-round scrapers can also be used for shear scraping when held at the proper shear angle

A traditionally ground flat (straight across), round, or radiused scraper can be made to produce a shear scrape by moving the tool up off the flat surface of the tool rest and into the 45 degree shear cutting position. This will create the desired angle of cut, with the cutting edge addressing the wood at a proper shear angle, producing those goose down shavings we all love so much.


Benefits of Shear Scraping

A Lot Less Sanding! – Shear scraping, when properly done, is capable of producing a surface that can be sanded starting with 240, or even 320-grit abrasives. Yes, you read that right. It’s much easier and faster to shear scrape to 320-grit than to start at 60, or 80-grit and work your way up to a 320-grit surface. Of course, you will probably sand higher than 320-grit on your projects, so shear scraping will not totally eliminate sanding, but it can substantially reduce your overall sanding on a project.

On some areas on your project, you might not be able to shear scrape due to size limitations, or proximity to adjacent design elements. Even so, you'll be better off shear scraping the areas that you can and sanding the rest of the areas in the traditional fashion.

Damage Repair – Shear scraping is one of the best ways to remove torn, or bruised grain areas on your project prior to sanding. Yes, you could just whip out your trusty 60-grit gouge and have a go at these problem areas but let's face it; few things in woodturning are as universally disliked as sanding. Most of us will do almost anything to sand less if we can achieve the same surface quality by some other means.

Fairing The Curve – Shear scraping is the fastest and most efficient way to make subtle changes in the profile of your project, without making another bevel rubbing pass with your gouge. If you have a small flat spot on a curve, or perhaps a full curve, you can easily shear scrape the curve into the correct shape. This saves timber (vs. making another pass with your bowl gouge) and it allows the correction to be made in the specific area that needs adjusting. If necessary, the overall profile can then be blended into one harmonious curve.

Less Heat - Shear scraping is a more elegant process than sanding, producing substantially less heat on the surface of the wood. If you are working with any of the newer alternative materials or with heat sensitive exotic woods, the reduction in heat on the surface achieved through shear scraping can be an important consideration.


Additional Tips for Shear Scraping

  • Your tool must be freshly sharpened, straight off the grinder wheel before shear scraping. Some turners prefer to hone the edge, removing the burr before shear scraping, but this is not necessary to achieve excellent results.
  • Once you have made a few strokes on your project, stop and resharpen your cutting edge. Just like with traditional scrapers, the cutting edge on a shear scraper will not last very long.
  • The optimum angle to remove the wood fibers is 45 – 50 degrees, up to about 55 degrees. Be sure to orient the tool’s cutting edge to achieve this optimum shear angle.

Final Thoughts

Learning the proper techniques of shear scraping is not very difficult, just remember the basic set-up and keep your tools sharp. Once you become proficient at shear scraping, it will become one of the most valuable tools in your skills "toolbox." Both green and dry wood can be shear scraped with excellent results. If you are just learning to shear scrape, practice on some rough blanks, or on your green wood rough outs. It takes a bit of practice, but your efforts will pay big dividends for many years to come.


Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.


Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

Steve is also the current and founding President of the Lone Star Woodturners Association, Inc., an AAW member chapter. The LSWA is a 501(c)3 non-profit educational organization dedicated to teaching and demonstrating the art and craft of woodturning.

Steve is also a featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his articles covering technical topics, or project based articles in an upcoming issue.