Simulating Segmentation with the Scroll Saw

Simulating Segmentation with the Scroll Saw

In searching for new possibilities for scrolled bowls, I discovered two different ways to simulate the types of segmentation associated with lathe-turned bowls.

Examples of scroll sawn bowl cuts
The bowls on the left made good use of the remainder of the laminations that were created for the bowl on the right.

Both methods are easy to learn and far less demanding than traditional approaches. The first produces segmented bowls with solid sides; the second creates open segmentation.

Segmentation with Solid Sides

Drawn out scroll saw bowl segment pattern
This pattern created a bowl with segments of equal size.

My method for creating this type of bowl eliminates the need to cut many small pieces at precise angles. Instead, it relies on stack cutting, a standard scroll saw technique, to create the blank.

Scroll sawing bowl bottom pattern
The pattern number of each pair was transferred to both pieces when they were separated to ensure they would be glued in the correct order.

The basics are simple: two contrasting blanks, typically between 1/4″ and 1/2″ thick, are attached with double-sided tape. A pattern, consisting of a circle divided into a designated number of segments, is attached; the circumference and segments are then cut to shape.

Scroll sawn bowl with uneven segments
After the blank was completed, the small void in the center was drilled out and replaced with a decorative plug.

Once cut and numbered, alternate segments from each set are exchanged to form two multi-colored circles. Because all pieces are stack cut, deviations in any piece are compensated for by complementary deviations in the adjacent pieces.

Uneven bowl segment pattern
This pattern created a bowl with segments of unequal size.

The segments are glued at their edges to form two circles and sanded lightly once the glue has set. They are then glued together to form the blank.

Holding bowl segments together in a bowl press
Before glue-up, the blanks are rotated to determine the most attractive lamination pattern. The blanks are marked so that their orientation can be maintained, then glued together in a bowl press.

The blank can then be cut in the same way as any scrolled bowl, or rings cut from it can be used as decorative elements in a multi-blank project.

Open Segmentation

Segmented bowl blank pieces layout
Extra wedges are usually cut so the best matches can be selected, then ordered, for the most attractive appearance at the outer edge.

It was challenging to design a blank that would look like open segmentation when cut into rings, but the solution turned out to be quite simple. The blank is constructed from wedges cut from a circle, then glued evenly around a thin substrate.

Cutting segmented bowl rim with scroll saw
The rings are cut from the substrate side, which creates an attractive top rim. Although possible to cut from the wedge side, it’s far easier to do so from a stable surface than from a discontinuous one.

A pattern is attached to the substrate side and the rings are cut at predetermined angles. The cutting process creates rings with a regular pattern of slices and spaces.

Sanding bowl segments with a small sanding block
The segments are sanded after cutting, when it’s easiest to remove “fuzzies” from their sides and any glue that was not removed when they were glued into place.

Depending on size and purpose, the bowl can be cut so that the wall thickness remains uniform throughout, or cut so that the wall thickness increases slightly with each successive ring.

Scroll sawn bowl segments stacked together
When the cut rings are stacked and glued, the bowl looks like a lathe-turned open segmented vessel.

Walls of even thickness are ideal for smaller bowls, especially those that are primarily decorative, while those with increasing wall thickness have a greater gluing surface — a consideration for larger bowls or those intended for regular use.

Oval scroll sawn bowl segment pattern
To make evenly sized segments for an oval bowl, the pattern must take the circumference of the oval into account, as well as the number of wedges needed. Since only a few slices are cut from each wedge, the difference in segment length doesn’t matter.

Sanding of an open segmented bowl is standard, with two notable exceptions. First, care must be taken to avoid catching the sander on the edges of the segments; the slits at the bottom of the round inflatable sander are especially vulnerable. For this reason, I use the smaller of the two inflatable sanders: the openings in their abrasives resist snagging better.

Sanding scroll sawn bowl interior with small inflatable sander
The openings at the bottom of the small round inflatable sander are more resistant to snagging than those of the larger version, making it the ideal tool for sanding the inside of open segmented bowls.

Second, the center section of the blank, usually used as the base, has wedges on its underside. These must be sanded off for the piece to be used. If this is not feasible, cut a new base from the same wood as the substrate.

Variations to Explore

This versatile method for open segmentation can be used for rounded square and wavy bowls as easily as for round ones. With a slight pattern adaptation, it can even be used to make oval bowls whose segments remain evenly sized all around the circumference.

Once you’ve mastered the process for making a basic scrolled bowl, it’s an easy transition to variations that no one will believe were made with a scroll saw.

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