Correct Position For Shear Scrape

RIGHT: Rotating gouge keeps tool rest and reducing the risk of catches.

CORRECT POSITION FOR SHEAR CUT under cutting edge, supporting cut

FORCE Of ROTATING WOOO

supported cutting edge

Continue to rough out the profile, using a combination of body and hand movements to move the edge of the gouge through the wood. For extra support, keep the tool handle tucked into your side and move your body with the tool. Use your upper hand to pull the tool leftward along the rest, as you swing your body— and hence the tool handle—right toward the lathe bed. For this cut, only the edge of the gouge contacts the wood; the bevel does not. This technique quickly gives you the rough form you want, but the surface will be ridged and some end grain will tear.

You can also make roughing cuts using the deep-fluted gouge rolled horizontal with the flutes facing away from the lathe bed. And the cleanest cut of all is the back cut, using the full round shoulder on the inside edge of the tool. (Sec photo 1 still get a buzz from this back-cut, even after 23 years, because when you get it right with the right timber, a continuous ribbon of wood flows into the base of the flute and up the other side to hit you in the face or, if you move your head, whoever is craning over your shoulder!

You will need to stop the lathe frequently as you rough out in order to move the rest closer. Always spin the blank by hand to make sure it rotates free of the rest before switching on the lathe again.

Trueing the Base

Before finishing the profile, you must true the base so it will sit flat when you reverse the bowl blank for hollowing. Start by flattening the perimeter of the base. Do this by using a shear scraping cut, which is a refined version of the profile roughing cuts. Roll the shallow gouge almost on its side (see photo then squeeze your upper hand to pull the edge into the uneven surface and cut until the "tick-tick" noise disappears, indicating that you have a true surface. Once you've established a flat area, you can reverse the tool so the bevel rides on the flat, and then shear cut toward center. (See photo *6.)

For very precise control when shear scraping, have the thumb of your upper hand push against the tool, resisting pressure exerted on the blade by the fingers of the same hand. (See photo *2.) The tension created allows you to move the edge exactly where you want without the tool bouncing on the wood.

This shear scraping cut allows heaps of precision, and you can also x use it to remove any small ridges on I your profile curve, or on patches of f twisted grain. If you take several 1 passes that just stroke the surface, » you can make little ridges and torn § end grain vanish. I

FIG. 2: MAKING CLEAN CUTS

Direction of shear cut

Fibers will shear cleanly when wood below supports cut

Shear Scraping

To establish hole depth, author bores with a hand-held twist drill. Scribed marks on the drill help him determine the exact depth off the hole.

To finish the profile of the bowl, use the shallow gouge, held nearly horizontal, and lightly shear cut from the bottom to the top off the bowl.

When reversing the bowl for hollowing on a screw chuck, glue the base off the bowl to a waste block, then screw the block to the chuck.

To establish hole depth, author bores with a hand-held twist drill. Scribed marks on the drill help him determine the exact depth off the hole.

To finish the profile of the bowl, use the shallow gouge, held nearly horizontal, and lightly shear cut from the bottom to the top off the bowl.

When reversing the bowl for hollowing on a screw chuck, glue the base off the bowl to a waste block, then screw the block to the chuck.

To hollow the interior, cut from the larger to smaller diameter, using a shear cut with the flutes facing toward center.

To prevent kickback when starting a cut from space, bring the tool down through an arc into the wood by lifting the handle and pivoting the tool on the rest.

How you turn the base will depend on how you intend to mount the blank for hollowing. If you want to glue the blank to a waste block and mount that to the screw chuck for hollowing, then turn the base dead Hat. If you own a three-jaw or compression chuck, you won't need to use a waste block, so leave the base slightly concave and turn a foot in the middle for gripping.

Finishing the Profile

To finish the profile, you need to use a light cut to shape a smooth and flowing curve. Hold the shallow gouge nearly horizontal and pointed in the direction you're cutting, with the bevel rubbing the wood. (See photo *7.) Now you have control of the cutting edge, because the bevel shoulder provides a secondary fulcrum from which to control the precise path of the edge as you cut.

To hollow the interior, cut from the larger to smaller diameter, using a shear cut with the flutes facing toward center.

Starting this cut as you comc in from space can be tricky. Pin the tool blade firmly down onto the rest using your upper hand and then, with the flute of the shallow gouge rotated away from the wood at about i5°, bring the point of the tool down through an arc into the wood by raising the handle with your lower hand. The instant that the nose of the tool enters the wood, you have a supporting surface for the bevel. With practice, you can keep the bevel rubbing and carry right on to cut the whole curvc in one go.

Caution: Merer attempt to use an unsupported inside edge of a shallow gouge in this situation. It will catch. (See Fig. I.)

It would be good to stop here for a moment and offer a bit of general turning advice: Problems arise in woodturning whenever you push the tool too forcefully into the wood. The smooth surface you start from is a point of reference against which the bevel should rub rather than press. If you get a bumpy surface, chances are that you started your cuts with the bevel pushing against an uneven surface. To eliminate bumps, you need to go back to the base of the curve and start again, aiming to go through the ridges and over the dips on a curve of your choice—not the wood's. Don't let the tool wander into the valleys, or you will magnify the problem.

Now back to our bowl. Once the surface is as good as you can get shearing with a gouge, any little ridges can be shear scraped using the shallow gouge on its side.

Don't sand at this stage, because if the job runs out of true when reversed, you might have to re-turn the profile and resand.

To prevent kickback when starting a cut from space, bring the tool down through an arc into the wood by lifting the handle and pivoting the tool on the rest.

Finish the interior with a large scraper, swinging the tool in broad movements.

Hollowing the Bowl

If you intend to reverse the bowl onto a screw chuck, glue a waste block onto the bowl base, using the tailstock to hold the waste block in place until the glue dries. I find cyanoacrylate glue with accelerator (available from Craft Supplies USA, 801-373-0917) is fastest. Then turn the waste block to a cylinder and drill a hole in it at center with a hand-held twist drill as shown. (Sec photo »8.)

The part-turned bowl is now held by the foot. (See photo *9 ) Before you begin to remove the center of the bowl, true the face and particularly the rim. Then drill a hole at center to establish the internal depth. If the bowl is running slightly off cen-

Finish the interior with a large scraper, swinging the tool in broad movements.

ter, true up the profile using a very gentle shear scraping cut.

To shear cut the interior, you work from the larger to smaller diameter (see photo *10), using exactly the same gouge techniques as those used to turn the profile. Start hollowing an inch or so out from the center, and work toward the center. After you complete each cut, move farther out from the center and take another cut. Try to keep the cuts parallel to the lathe bed and pushing toward the chuck to limit the stress on the chuck. Use as little force or pressure against the wood as possible. Deep-fluted tools are favored here because of their superior strength as you work farther out over the rest.

When starting a cut from space, begin with the tool on its side, so the

SHOP-MADE CHUCKS (SECTION VIEWS)

Undercut rim jams tightly against chuck's shoulder.

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