The roughing gouge is likely the first and most often-used cutting tool in woodturning. This one rounded chisel is used for the initial turning when working on your lathe between centers, to round over the blank into a round piece of stock that can then be manipulated with other tools. It is also regularly used for hollowing out faceplate turnings such as bowls. Proper technique is essential to effectively (and safely) use the roughing gouge. Failure to follow the basic rules of using a roughing gouge can damage your workpiece, or worse, lead to an injury.
The first and foremost rule of using a roughing gouge is that the tool must be on the tool rest before the gouge engages the wood. After positioning the tool rest within a quarter-inch of the wood, place the heel (along the rounded outside edge) of the gouge on the rest, with the handle well below the workpiece. Raise the handle slightly, allowing the heel to engage the wood (but with the cutting edge well above the wood). On a piece of stock placed between centers that has yet to be rounded, this will lead to a bit of vibration being translated to the tool.
Place your off hand (likely your left hand if you're right handed) just under the heel of the gouge, with your forefinger against the base of the tool rest. This will help stabilize the gouge.
Ease the tool downward, keeping the heel in contact with both the tool rest and the wood, until the cutting edge of the gouge barely engages the wood. Angle the tool about 15-degrees in the direction you want the gouge to travel. In other words, if you want to ease the tool to the right, pull the handle of the gouge to the left about 15-degrees (while keeping the heel in contact with the tool rest and the wood).
Move the gouge, your off hand and your rear hand (on the handle of the gouge) evenly to the right and take off very minimal amounts of stock. Move only as far as the tool rest will allow. Stop just before the heel reaches the end of the tool rest (or when you reach the desired point on your stock). Return the tool to square to the wood (removing the 15-degree angle), and lower the handle to disengage the gouge from the stock.
Repeat the process until you reach the desired level of roundness of your blank. To test the blank for roundness, place your hand behind (opposite the tool rest) the wood and feel for round. Do NOT, under any circumstances, place your hand in front of the spinning wood stock, as it could easily pin your hand between the wood and the tool rest. This is one of the most common ways that woodturners are injured. If you must touch the spinning wood, it should always be on the back side of the spindle.
Also, never engage the gouge with the wood without having the heel firmly on the tool rest.
Forming Shapes with a Roughing Gouge:
A roughing gouge can be used for far more than roughing. It can be used for creating hollows or roundovers in a spindle quite easily. To create a hollow, simply rotate the heel of the chisel as it is presented to the wood (once again, with the heel firmly against the tool rest) and form the hollow as needed. Keep in mind that a roughing chisel cannot create a hollow of an arc smaller than the arc of the heel of the gouge. This is why there are so many different sizes of roughing (or spindle) gouges. Roughing gouges with a larger arc create sweeping arcs, while thinner gouges can create tighter arcs.
A roundover can be created by moving the roughing gouge in precisely the opposite manner used when creating a hollow.
As with all woodturning gouges and chisels, a sharp tool is truly safer (and will obviously cut better) than a dull one. To sharpen your gouge, use a grinding jig on a wet grinder to keep the angle of the bevel consistent. Rotate the tool along the jig as it is presented to the face of the grinding wheel to ensure a clean, even sharpening along the entire edge.