Powermatic 4224 - Manual (Page 14)

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there are dozens of chucks to choose from, the woodturner should first consider all the different types of turning that
will be done, and read reports or discuss with other turners who own chucks before making a decision. A chuck is
not a requirement but is handy when working on more than one piece at a time. Rather than removing screws, you
simply open the chuck and change workpieces. The most popular ones are four jaw scroll chucks with a variety of
jaws to accomodate different size tenons. Most also come with a screw chuck as well.
WOOD SELECTION
Firewood is the cheapest, most widely available stock to use while learning to turn bowls. Simply waste wood for a
while practicing turning techniques. Develop skill with each tool before attempting to make a finished piece. It is best
to start with dry wood, without worrying about drying or distortion. Once turning becomes comfortable, try green
wood which cuts very easily. As the turner gains experience, he or she will find extraordinary grain and figure in the
form of burls, crotches and bark inclusions.
CHECKS & CRACKS
Green wood will check and crack. For best results, leave logs in as long lengths as you can handle. As the material
starts to dry, surface cracks will develop on the ends of the log. Cut off two to three inches and you should find good,
sound wood. Also cut the log in half along the pith to avoid having it in the finished piece. Most checks radiate from
the pith. As you turn bowls from green wood, make sure you maintain a consistent wall thickness throughout the
piece. Leaving a piece thick in some areas and thin in others will cause the wood to dry unevenly and promote
checks and cracks.
DISTORTION
Distortion is a problem associated with turning green wood. It will vary from one type of wood to the next. Typically,
fruitwoods tend to distort more than others do. It also varies with the time of year the tree was cut and how the logs
are stored.
TOOLS FOR BOWL TURNING
The deep fluted bowl gouge is the most essential and versatile tool for most bowl and faceplate style turning. The
bowl gouge is heavier and easier to control than other types of gouges. It also allows removal of wood much faster
and with less vibration than other gouges. Most average sized bowl work can be accomplished with a 3/8" or 1/2"
bowl gouge. A 1/4" bowl gouge is best suited for smaller bowls and light finishing cuts. Larger 3/4" and 1" bowl
gouges are only used for extremely large pieces.
Large domed scrapers can also be used to help clean up the interior surfaces of bowls. A light touch with the scraper
slightly tilted will eliminate some of the ridges occasionally left by an inexperienced bowl gouge.
BOWL TURNING TECHNIQUES
TO SHAPE the OUTSIDE of the BOWL:
1. Odd shaped burls, crotches and other irregular shaped blanks require special preparation before mounting in a
chuck or onto a faceplate. Remove the bark, if there is any, from what appears to be the center of the top of the
workpiece.
2.
Drive spur center into the top of the workpiece with a mallet or dead blow hammer.
3. Slip the spur center into the headstock taper and bring the tailstock with a live or ball bearing center into
position. Lock the tailstock to the bed and advance the spindle in order to seat the cup center into the workpiece.
Tighten the quill lock.
4. Position tool support below the centerline and about 1/4" from the workpiece. (NOTE: For larger outboard
turning, an optional outboard turning stand is used to place the tool support; see your Powermatic dealer).
5.
Turn workpiece by hand to ensure proper clearance.
6. Start lathe at lowest speed and bring it up to the maximum safe speed for the size of work to be turned (see
table on page 9). If the machine starts to vibrate, lower the speed until vibration stops.
7. Rough out the outside of the bowl with the 1/2" deep fluted bowl gouge, holding the tool firmly against your hip.
For best control, use your whole body to move the gouge through the workpiece.
8.
As bowl takes shape, work on the bottom (tailstock end) to accomodate attaching a face plate.
9. Turn a short tenon (about 1/8" long) the size of the hole in the faceplate, Figure 10. This will allow centering the
workpiece when the faceplate is attached. (NOTE: If you plan to use a chuck, turn a tenon of the appropriate length
and diameter to fit your chuck.)