Spyrograph Rosette

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I needed a rosette that was both semi-fancy and easy to make for a bouzouki that I was making. What I ended up with was a rosette that resembled a spyrograph.

Spyrograph Rosette 

 

To achieve this, I drew two concentric circles, one representing the rosette’s inner edge with a diameter of 3 inches, and a larger one representing the rosette’s outer edge with a diameter of 3¾ inches. Then, I drew another smaller circle with a diameter of 1 inch (again, concentric with the others). It is this smaller circle that I used to define arching pivot points for my router. I used pivot points spaced 4mm apart.
Concentric Circles For the purposes of the picture I drew x's to illustrate the pivot points.

(Tip: If you’re experimenting with different sized circles it is helpful to remember the formula Circumference=3.14 x Diameter. Once you know the circumference of your pivot point circle, then you can easily divide it evenly to determine how far apart your pivot points should be.)

Because of the closeness of the pivot points, a rose cutter was made with a pin-point pivot and adjusted to 1¾ inches between the pivot and the cutter.

With the rose cutter’s pin-point inserted into the pivot points, I routed from the 3 inch circle to the 3¾ inch circle. Cut after cut I worked my way around the pivot points. Once all the arcs in one direction had been cut, I inlayed those channels and glued them.
Measuring the Second Round of Channels Once this portion of the inlayed wood had dried and been leveled, the second round of channels were cut in the opposite direction using the same pivoting technique.
Rosette Design without a Border It is possible to route an outer circle around the outside edge. If this is desired, then adjust the cutter to 3¾ inches and place the pivot point back in the center point of the concentric circles and route the outer perimeter circle. I chose to let the rosette spiral out without an outer border as seen in the photo.
Cutting the Sound Hole

Then I cut the backing. I adjusted the cutter to 4 inches using a traditional pivot and cut a circle from my backing material (not the soundboard) using a 3/16 or 1/4 inch pivot thickness. Then I drilled the center of the rosette with the same 3/16 or 1/4 inch drill bit. Then, I lined up the center pivot holes and glued the backing to the under side of the soundboard under the rosette. When the glue was dry, I adjusted the rosette cutter to 3 inches, and cut the sound hole. Binding the sound hole will cover the backing to hide it from view.

Enjoy!

Completed Spyrograph Rosette