Offset turning fundamentals – FineWoodworking

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Synopsis: If you mount the workpiece off-center so as to reduce solely a portion of the profile on every rotation, you may form elements on the lathe in virtually any geometry you may draw. You can also make elliptical types, similar to legs, and even tapered ellipses. You may flip a triangular form. After getting grasped the fundamentals of format for this highly effective method, the chances are spectacular.

I started exploring offset turning 25 years in the past after I was requested to make some cabriole legs. As a turner, I figured there needed to be a method to make them on a lathe. Positive sufficient, in an previous woodworking handbook I realized about offset turning, mounting a workpiece off-center so solely a portion is reduce on every rotation. Since then, I’ve experimented extensively with this highly effective method, which helps you to form elements in virtually any geometry you may draw. The stool within the picture reverse, made by a pupil of mine, has off-center-turned entrance legs which are elliptical in cross-section, and a again leg that’s triangular. This text exhibits how one can flip elliptical and triangular elements and likewise tapered variations of them. With this system, there’s no telling what you may make; one other pupil of mine carved an Inuit bear utilizing offset turning!

Format is foundational in offset turning

Begin an ellipse by laying it out on paper. You received’t be making a real ellipse, moderately two mating arcs. After tracing your sq. workpiece, draw traces from nook to nook of the sq. and draw a circle inside the sq.. Place each offset factors alongside one of many diagonal traces, equidistant from the middle. The nearer to the middle you place the offset factors, the rounder the ensuing ellipse; the farther from the middle, the skinnier the ellipse. With the format completed, switch it to each ends of the workpiece.

An ellipse on the lathe

You might mount your sq. clean off-center and start reducing the ellipse immediately, nevertheless it simplifies issues to first mount the clean on its centerpoints and switch it to a cylinder. Then cease the lathe and rotate the piece by hand till the diagonal format line that doesn’t have the offset factors on it aligns with the highest fringe of the instrument relaxation. Now use the instrument relaxation as a straightedge and draw a line from one finish of the cylinder to the opposite. Draw one other line on the alternative aspect of the cylinder.

Remount the workpiece utilizing one of many pairs of offset factors. Flip the cylinder by hand (it would now rotate eccentrically) and modify the instrument relaxation so there may be by no means lower than a 1⁄8-in. hole between it and the work. On the aspect of the cylinder that comes closest to the instrument relaxation, draw a sequence of vertical pencil traces from one horizontal line to the opposite. These will present because the piece is spinning. Once they disappear and also you attain the horizontal traces, the primary arc is completed. Remount the workpiece on the second pair of offset factors and repeat the method.

What I’ve described right here is the best sort of offset association. There’s way more to discover. Leaving one finish centered whereas the opposite finish is offset, you may create a chunk that transitions from spherical at one finish to elliptical on the different. I take advantage of offset turning to create necks for guitars, legs for furnishings, and a variety of vessels and bins. The probabilities are countless.

Lay out the ellipse

Start with the square. After carefully milling the blank square, Ireland traces it onto paper. — **Begin with the sq..** After rigorously milling the clean sq., Eire traces it onto paper.

Circle in the square. Find the centerpoint by drawing diagonal lines from the square’s corners, then draw the largest circle that will fit in the square. — **Circle within the sq..** Discover the centerpoint by drawing diagonal traces from the sq.’s corners, then draw the most important circle that may match within the sq..

A pair of arcs. Mark two offset points along the same diagonal line, placing them equidistant from the center. Then set the compass and draw a pair of mating arcs. — **A pair of arcs.** Mark two offset factors alongside the identical diagonal line, putting them equidistant from the middle. Then set the compass and draw a pair of mating arcs.

Transfer time. Transfer your layout to both ends of the workpiece: Draw the diagonals, then use dividers to transfer the offset points, and deepen those points with an awl. Draw the arcs with a compass. — **Switch time.** Switch your format to each ends of the workpiece: Draw the diagonals, then use dividers to switch the offset factors, and deepen these factors with an axe. Draw the arcs with a compass.

Turning a triangle

Offset turning a triangle is definitely simpler than turning an ellipse, although the format is a bit more complicated. On paper, draw a circle that represents the largest cylinder you may get from the clean. Divide the circle into three equal sections. You are able to do this by maintaining the compass set to the circle’s radius. Stick the purpose of the compass wherever on the circle and make a brief pencil mark throughout it; transfer the compass level to the crossmark and proceed on across the circle.

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From Superb Woodworking #299

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