Rosette tools

[Will Reyer]

Awriiiiittt! Back in business – or at least closer. My first 4 guitars had plywood tops, didn't require rosettes, had soundboards and backs parallel, as they were based on resonator dimensions.

Now, however I want to step up my game, build the next two as actual orchestra models, with rosettes, deeper lower bouts, radiused fingerboards, headstock inlays – stuff like real luthiers.

Toward this end John Link gave me cedar billets for an actual two piece tonewood soundboard for #5, and Kjell Croce gave me same in spruce for #6.

Got #5, red oak, in mold with reverse-kerfed linings, head and heel blocks, side reinforcements. Got #6, quarter-sawn sycamore, in mold with head and heel blocks. Needed tools to make rosettes. Sent for inexpensive, up-cut, .250” shank, Chinese bit set in 1/16”, 3/32”, and 1/8”, from a luthier down near Ashville, NC. We'll see how these work.

I needed to make an adjustable base to use with a laminate trimmer for routing rosette grooves, and cutting out the sound hole. Had lots of red oak shorts, so used that. Would have liked maple better. Two-piece red oak base pivots on a piece of 1/4” drill rod. #8-32 UNC screw increases radius of cutter .015” per half turn. Two inches of travel, from 1.5” radius to 3.5”.

Suspect I will eventually have to do a version of this in aluminum. The PEM nut people make indexing pins and threaded studs that will install blind in thin sheet metal. A couple pieces of .125” 6061-T6 ought to make that work easily.

Then I needed to make wood purflings for the rosettes. Don't want to use plastic, I'm old and ornery. David, a friend here, said Stew-Mac had a YouTube on how to make wood purfling. Didn't see it. Found somebody on-line scraping wood strips to thickness between two pieces of .023” sheet-metal. Didn't see how that would help the burr on the scraper. Found another guy pulling thin wood down a plowed groove with a hand plane on top surfacing the strip. Taught all my Jr. Hi students to lay planes on their sides to save the projecting cutting edge, but suspect either method might have actually worked back in Torres' day, and he built splendid guitars.

Had an old Harbor Freight laminate trimmer with cracked base that would no longer adjust up/down. Mounted that behind a piece of scrap 3/4” plywood, and made a purfling plane. Table adjusts up/dn a little over 3/8”, overkill for what's needed. The vertical piece under table with the wing nut is plowed .250” x .750” to guide on a vertical fin. Feed, of course, is right to left. Height adjustment from bit to table set with feeler gauges. Band saw strips over-thick, plane one side of all, reset table, plane the other sides.

Outfeed (left) side has 1/4” drill rod for hold-down. Tangent at bottom of this pin needs to be co-planer or slightly higher than the bottom of the bit arc. I made clearance holes for the router base mounting screws so I could move bit up/down. Infeed hold-down is pine scrap sprung between two 1” drywall screws, retained by a clothes pin. Works good. Dust collection hose from vac will probably be co-axial with router bit, from the front.

Ken just posted a good fixture/method, Super Simple Rosette Maker at:
viewtopic.php?f=9&t=186

I've seen people not bothering with that but just pushing the purfling into the routed grooves and then gluing with thin CA. So y'all can chime in here and tell me your method, next, please. Do I want to wet or boil or bend these strips on my hot pipe? Will they bend dry at .025” thick? All suggestions welcome, since like one of my Texas bosses used to say, “All's we lack is finishin' up”, and I've still got a lot to learn.

[John Parchem]

Cool jigs!

I was taught to build classical rosettes right in the top by breaking them into workable sections, routing a slot for a section and installing. I have started to do that on a few of my rosettes. For example if I was going to have 4 colored purfling strips on the inside and outside of a rosette, I would route slots just wide enough to install the 4 purfling strips and install them into the top. I would then come back and route the inside sections and install as required. Everything stays nice and tight and I am only working with a manageable amount of strips.

I usually do not pre-bend thin purfling strips but I will pre-bend wood multistrip purflings and marquetry strips like harringbone or rope binding on a bending pipe so that they are close before installing.