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I want to make a rather complex rosette out of pieces of various woods.
My plan is to glue them together using CA glue on a backer board.
I tried a few experiments gluing the wood pieces together without a backer and the results are a bit fragile.
I have seen people using backers for this on the web but no mention of what type of wood they are using.
Seems like you want something about .06 to .06 inches that is stable but easy to sand off later.
I was thinking maybe 1/16 inch balsa as it's inexpensive, easy to find and easy to sand off.
Does this make sense? Any suggestions on what to use for this?

Thanks

What I use is regular old corrugated cardboard.
The cardboard is stiff enough to support a pivot pin for my circle cutter. The pin is mounted in a cheap cutting board.
When you are done, you can peel most of the cardboard off, leaving just heavy paper to be sanded.

A couple pics:
The inprocess one I found is spalted, but the process is the same. Here's the finished product, mosaic style. Walnut, cherry, spalted hickory in a redwood top, b/w/b purfling on the edges

The one time I made my own rosette I cut the channel in the top and laid the pieces of the rosette into it. It's a 24-sided polygon, and I cut the channel with a CNC router. You could take the same approach with a circular channel though.

Nix to balsa, too weak for the thickness. 1/64 plywood might work. This is all custom experimentation, and each person's processing the problem is unique. No copying what someone else did, there's too many unstated elements.

Thanks for the feedback. I think I should clarify what my issue is. I built a jig made out of plywood and plexiglass which holds down the wood pieces that are glued together with a pin in the center so you can cut out the rosette without a backing. The problem is that the resulting rosette is a bit fragile. It would help to add a backing. It doesn’t need to be too stiff as it isn’t used to hold the rosette against the force of the router bit. That’s why I’m thinking balsa wood might be good enough.

Scamp, experiment firstusing something other than the rosette you want to install. Once you're happy with the technique, transfer what you learned/developed to the real thing.

Peter

Great advice. Actually I already did what you suggested. I bought a cheap $10 spruce top, joined the two pieces, made a simple rosette and installed it for practice. Learned a lot. Feel much more confident with doing it for real.

Don't discard that inexpensive top. From what I've seen, there's worse out there.

I won’t. Actually I was very surprised at what I got for $10. I did a tap test and while I’m not an expert at this it did resonate quite well. The grain is also quite tight and straight. It has quite a few brown streaks but that’s OK with me.

Those brown streaks may have saved you a fortune! Grading is cosmetic untold numbers of tops with excellent acoustics go unnoticed.