solid wood rosette

Bespoke musical instruments from the North West of England

How to insert solid wood rosettes, using a router.

I recently saw a website, which one I cannot remember, but was impressed with the subtle use of wood rosettes. Whether these were solid or veneers was not clear. I had a commission is to make a Martin OOO style guitar and the client was looking for something eye catching but in a very understated way. He wanted none of this fussy and flash multicoloured, multilayered use of bindings and purflings. So this rosette style would compliment the IRW/ Spruce/Ebony body just perfectly.

So how was I to do it? I looked around in my scrap box and found a nicely figured and colour matched piece of IRW which when jointed and glued made a suitable blank to rout out the circle required. Did some dry runs with coloured paper rings to get a feel for the proportions and finally settled on a rosette ID of 105mm and an OD of 157mm.

First I needed to make a template big enough to create the hole in the SB to fit and insert the rosette.

I used a router plus 20mm collar and 40mm outer ring plus a 10mm straight two fluted TC cutter. This was a Perform kit from Axminster Tools. With a Trend Universal router base shown in the picture below. The red pen marks are to remind me which holes to use with my Bosch router.

The left hand photo shows the base with the collet for cutting the insert.

The right hand photo is with the 40mm OD bush fitted, for cutting the hole in the soundboard.

After a certain amount of head scratching and with pencil and paper, I worked out the template diameter needed to be a perfect circle of 187mm diameter. So using my router and trapeze circle cutter I made a template from some scrap 12mm thick MDF. Beware the dust, wear a mask and/or use a vacuum extract system. Note I should have marked the MDF with oversize cross hairs so that later I could locate the centre of the hole. Next time maybe.

A note of caution here about using cutters on MDF, remember MDF is very tough stuff and rapidly takes the edge of your cutters ; beware especially if you are going to use the same cutter to then cut your tonewoods. I was torn between using plywood and MDF for the template but thought the MDF would be more stable over time. But I had an old 10mm cutter anyway, which I used for this template cut.

A second note; you can never be sure whether the router guide bush is perfectly circular and come that, the collar as well. Therefore when assembling the router put an orientation mark on the bush and collar and align them the same way each time. Also when holding the router and moving around the template ensure you keep the same orientation to the work each cut you make. For instance I found if I held the router at a 9 and 3 o’clock position and kept it in that orientation during the cut, with the template marker pointing North, away from me, I could go around the template in one movement. Another way would be to orientate the router at 90 degrees to the tangent of the circle, and walk around the work to finish the cut. Which everway, be consistent and you should reduce the possibility of errors creeping into the process.

I then tested out this template on a scrap piece of 1/4 inch ply. The results were good but not good enough. When the insert circle was pushed into the hole created, it’s fit left a couple of very thin gaps.

The answer was to create two master templates. The first a straight 167 mm diameter, which was used for the sound board cut. The second identical to the first but then I used some 120 grit garnet paper on a suitable block and carefully went around the template ten times, keeping as even a pressure as possible on the MDF edge. This fractional enlargement of the second template gave me a template for the insert. The IRW insert when cut was just too big to drop into the hole created from the first template.

I sanded the inside of the spruce hole to give a slight taper . Then all that was needed was a little careful sanding to get the insert to fit perfectly. The rosette was pushed up from underneath the SB.

Speed was needed when I actually glued the rosette in place, as the aliphatic glue swelled the woods a little and the fit became very tight. Extreme care was needed not the crush the spruce and even the IRW could have been damaged. A sheet of clingfilm on top and one underneath the rosette, a suitable offcut of MDF and several kilos of weights on top stopped any warping of the SB and rosette. I left it overnight to dry.

Everything went well as can be seen in the photographs.

I reinforced the underside with spruce offcuts glued to cross the grain patterns and give extra strength.

My original idea was to then rout out circles, at half the SB depth, at the interface of the IRW and Spruce to insert a simple BWBW purfling. But I hope you agree that the simplicity of the IRW and Spruce contrasts sufficiently without any further ornamentation, especially as the bindings and tailpiece are simply ebony.

This was the top being glued onto serial number 009, but it shows the rosette quite well.