PART 11 HOW TO TURN AN ARC TYPE AND A CIRCULAR TYPE SPINDLE

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1 PART 11 HOW TO TURN AN ARC TYPE AND A CIRCULAR TYPE SPINDLE In the previous chapter, a conceptual model was described that helps one think about what to expect when turning a multi axis spindle. In a nut shell, there are two basic results or outcomes when changing the axes. The circular outcome results from turning the new axis to a cylinder and then cutting a profile on the new cylinder. #1 Alternatively, the arc type results form partially cutting into the new axes, resulting in 2 or more arcs that intersect. #2 The variables that can be used to create the desired result are 1) the profile or type of curve or line cut to create a design and 2) the placement of the axes. Axes can be parallel or twisted in relation to the center axis and/or each other, however the combinations of each type of axis placement are endless. #1 #2 profiles axes TOOLS AND TECHNIQUES The tools that are needed for this type of project are the same tools used to create a regular spindle: for me they are a detail or spindle gouge, and a roughing gouge (either a half inch bowl gouge sharpened like a roughing gouge, or three quarter inch spindle roughing gouge). There is no right or wrong about which tools to use. We all use the ones we were taught to use or the ones we have become most comfortable with. For me, the heavier half inch spindle gouge creates a more stable cut than a smaller spindle gouge. I keep the angle of the bevel of the spindle gouge at about 30 degrees. This gives the ability to cut sharp v-cuts and adds a consistency in approaching the wood. Many jigs and chucks have been developed that help keep edges sharp and angles consistent. Much of this work can be done between centers. The skills required to make multi axis turnings are the same skills needed to turn regular spindles. The bevel of the spindle gouge rides on the wood, keeping the tip high on the wood. When rolling to the right when making a bead, the right tip is used; and the left tip is used when cutting to the left as seen below. 1

2 The wood is cut with the tip. The bevel must ride on the wood to create the utmost control and success of the cut. When making a cut to the right of the bead, the spindle gouge must point to the right and the right tip of the tool is cutting the wood. When cutting to the left the tool is pointed to the left and the left tip of the tool is cutting the wood. SOME HELPFUL HINTS There are some factors that need to be in one s mind before the wood is turned. These strategies will help with a consistent and successful outcome. -First, turn the entire length of the wood to a cylinder. If the ends are kept square, it is difficult to turn them when the spindle is thin and fragile. -Next, decide the type of outcome you will turn, or at least have an idea of the axes you want to play with. Press the spindle between centers on those axes so that when the spindle is fragile, the holes are already there. -Number the axes not only on the ends but also on the outside of the spindle. I use a permanent marker which is dark enough to see the numbers. Also, decide on a numbering system and stick with it. If the numbers are the same on each end and twisted axes are used, either remember the progression or write it down for reference (like 1 to 2, 2 to 3, and so on). Even when not distracted, it is easy to get the axes confused. -Take notes on the project you are making so it can be recreated. Examples can be saved as a reminder of the outcome. -Sharp tools and the speed of the lathe are important factors when making a smooth cut. The slower the speed the more time the tool has in the air rather than on the wood. I use the fastest speed on my lathe which is 3,000 rpm s. -When making an arc type spindle and turning more than two axes, the depth of cut becomes critical. The tool rest can be used as a reference point for the depth of the cut. 2

3 -Sanding is a challenge, since the surfaces are curved and the edges are crisp lines. Cloth backed sanding paper is thick enough to hold while sanding these surfaces. It helps to sand each axis before moving on to the next axis. I do this so the lathe can hold the spindle while I sand it. The circular type can be sanded with the lathe on. The knuckles are in danger, so use caution. The arc type and any other non-round surface must be sanded by hand being careful to keep the edges crisp. My goal as a turner is to sand as little as possible. This means the cut must be as smooth as possible. -The types or outcomes that have been outlined can give ideas about forms that may have never been done. And some categories are more loaded with ideas than others. Also, the categories can be blended in many different ways. SAMPLE 1: Spindle that is an arc type with two parallel axes. The Drawing to the right shows the 2 parallel axes used. They are in the same plane. To make this spindle, first the rectangular wood is turned into a cylinder using a roughing gouge. This is the time to decide what axes are to be used. The distance of the axis from the center axis is important as well as the type of axis (either parallel or twisted). The holes are pressed into the ends between the head stock and the tail stock while the wood is not fragile since these spindles can become quite thin. It helps to write down the sequence of the axes that are being used and to keep the note on the lathe for reference. The spindle is placed in one parallel axis (that is the same direction and distance from the center axis) (1). A cove, a bead and a cove are then turned creating an arc shape in the wood. Note that the wood being cut is the air wood is since it is farther away from the new axis. The red line represents this new axis 1 3

4 2 The axis is then changed to the second parallel axis on the other side of the center axis. On this new axis, a bead, a cove and a bead will be turned (see magic marker, 2). I first turned a cove (3,4) and then a bead on either side (5). The photos show how this looks while turning the air wood This is the result (6,7). 4

5 SAMPLE 2: Spindle with twisted axes and a circular outcome This sample has 4 segments. Three axes are on one end and one is on the other end. The bottom and top segments are on the same axis. With a spindle roughing gouge, turn the 2 2 9" stock to a cylinder Press and number the axes. Mark references numbers on the side of the cylinder. (I always put the bottom of the spindle on the headstock end. There is no right or wrong way to number these; consistency, however, is important in all aspects of multi axis work. The segments (4,3,2,1,) AXIS 1 1 Put the spindle on Axis 1 (1). Turn the spindle by hand and set the tool rest before turning the lathe on, as is always done. With a ½" spindle gouge, turn anew cylinder and remove all the air wood. Now, turn a bead on this cylinder (2). 2 5

6 Sand the cylinder and bead smooth. Use care when sanding to avoid the air wood whacking your knuckles (3). 3 AXIS 2 Place the spindle on Axis 2 (4). The first bead is now part of the air wood. Now, turn the new cylinder on this axis and turn a second bead (5). Sand as previously described. 4 5 AXIS 3 Place the spindle on Axis 3 (6) and make a V-cut on this axis, removing stock all the way into solid wood (7)

7 AXIS 4 For the fourth segment, return to Axis 1 (8). To verify you re in on Axis 1, you should see the first bead clearly. Turn another V-cut on the tailstock (right) end (9)