Rosettes using flat sawn wood

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Dave M
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Rosettes using flat sawn wood

Post by Dave M » Tue Apr 25, 2017 6:30 am

I am part way through the build of a classical, falcate braced guitar, and for the first time I want to make my own rosette. There are some wonderful examples on this forum of patterns using what I have termed in the title flat sawn, by which I mean with grain running parallel to the top.
Clearly this is quicker to execute than the traditional Spanish rosette using end grain patterns. (intarsia?)

My concern is that the differential expansion of the top with pieces of wood looking like 20 or 30 mm of contrasting grain direstion may cause problems down the line.
Many people use burl timber which is more or less end grain so won't cause a problem.

My guess is that I am exaggerating this problem since there seems to be no reference to a problem in this area, but are there any builders out there who have experienced issues with rosettes of this type they installed a few years back?
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Allen
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Re: Rosettes using flat sawn wood

Post by Allen » Tue Apr 25, 2017 12:13 pm

My rosette material get's inlaid at 1.2mm thick. The purfling lines are 1.5mm deep. No problems at all.
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DarwinStrings
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Re: Rosettes using flat sawn wood

Post by DarwinStrings » Thu Apr 27, 2017 10:33 am

I still have one from twenty years ago, no problem.
Life is good when you are amongst the wood.
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mqbernardo
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Re: Rosettes using flat sawn wood

Post by mqbernardo » Fri Apr 28, 2017 8:32 am

I think you mean side grain, or perhaps face grain? I've done mostly those. No problems so far but I also inlay them on the thin side, like Allen, around 1,2 mm - maybe less.
If you inlay a material that doesn't move on a rebate of material that does move with humidity fluctuations you have different shrinkage ratios all the same, and so you still have potential for problems (knock on wood) ... or am I missing something?
When I inlay something like burl or crazy grain stuff I like to flood it with thin CA, on the (correct? False?) assumption it will help stabilise it.

Cheers,
Miguel.

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kiwigeo
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Re: Rosettes using flat sawn wood

Post by kiwigeo » Fri Apr 28, 2017 9:51 am

mqbernardo wrote: When I inlay something like burl or crazy grain stuff I like to flood it with thin CA, on the (correct? False?) assumption it will help stabilise it.

Cheers,
Miguel.
The segmented rosette on my current build is Cooba burl. The rosette was put together with superglue and I flooded most of the segments with glue during assembly. People also impregnate burls with epoxy (done under vacuum) prior to turning them.
Martin

Dave M
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Re: Rosettes using flat sawn wood

Post by Dave M » Sat Apr 29, 2017 6:23 am

Thanks people.
Yes Miguel I was looking for the right term. The point being that we have grain going in two directions with possible shrinkage/expansion problems. But I guess the pieces of wood in the rosette are relatively small so the contrary movement is not large. And as people have said the rosette is kept thin.

I have been working on a design using radial pieces and the big issue has been to get the angle of the taper right. It only takes a small error to make the pieces not lie in the right circle. My feeling at the moment is to do small corrections by hand sanding as I work round the circle.

I have been trying to come up with a design that can executed in a reasonable time while looking good. I do not want to spend as much time on the rosette as building the whole guitar which I think would be true of the traditional pattern!
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John J
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Re: Rosettes using flat sawn wood

Post by John J » Sun Apr 30, 2017 2:10 pm


Dave M
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Re: Rosettes using flat sawn wood

Post by Dave M » Mon May 01, 2017 5:29 am

John thanks for that it is really useful.
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Dave M
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Re: Rosettes using flat sawn wood

Post by Dave M » Wed May 03, 2017 5:20 am

Just for interest this is what I ended up with, using bits of technique from all over. It is in mahogany and sycamore - woods with similar hardness, but the white rings are in holly because I happen to know that this sycamore does not want to bend.
Attachments
rosette 2 small.jpg
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Dave

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