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I'm about to finish 3 guitars - one sitka, one engelmann, one cedar, using rosettes from LMI. I'm not sure if my circle cutter wobbled on the drill press, or if my channel was a little too big. But I have about a 1mm gap on the south side of each rosette which tapers off to near zero on the east and west sides. The rosettes themselves seem to have a uniform width around the circle, so I don't think they are the problem.

I'm not sure what's the best method of filling the gaps: a) wood dust & white glue, b) wood dust & cyanoacrylate, c) just a viscose cyanoacrylate, or d) a little marquetry inlay of the same wood in an attempt to match the grain. I think one way or other I can't hide it completely on close inspection. I'll be french polishing.

What works best for you? Many thanks

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"I must let my soul be my own judge."
6course.blogspot.com

So the tops are already braced with soundholes cut out, yes? I believe the preferred fix is to route a narrow channel around the entire rosette and add another purfling line, but that's extremely difficult to do later in the process. CA is not going to look good either by itself or (especially) with spruce dust.

Is the outside ring of the rosette black? Can you share a picture?

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Evan McCartney

Shellac to seal everything, then shove into that crack what ever you think gonna stay put.
Sand it down.

Personally my filler of choice (now don't tell anybody) is

B O N D O

with some colorant to help match the wood or fix.


blessings
Padma

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Audiences and dispensations on Thursdays ~ by appointment only.


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I can't for the life of me figure out that set up from your pictures. My brain hurts so I'll come back to it later after a few cups. But just looking at it, I don't see how you made a 'clamp' so to speak. The center bolt that fits to your router base looks like it comes through a rectangular stock of wood that braces the underside of the top to the router base. If so then how do you spin the router around to make the cut?

Try this...

http://www.luthiercom.org/phpBB3/viewto ... 103&t=1588

I also had trouble understanding the set-up until I realized the top disk is clear plastic.

Ah ha! Ok thanks I see it now too.

FWIW to the OP, if you have a systematic error in your rosette cutter where it's always just on the south side then maybe you can arrange it to hide it under the fret board. BUt actually 1mm is quite a gap so... er never mind.

For this group of guitars you are in 'repair mode'.
For next time: before looking at your rosette cutting jig for problems, have a good look at the pre-made rosettes. Even though they may be uniform width, I've found that off-the-shelf rosettes are seldom 'really round'. Cutting a bunch of test channels in scrap and dry-fitting the rosette can sometimes point out problems. Sometimes using hot hide glue and doing some 'massaging' of the rosette in the channel with a rounded tool can improve the fit of mosaic rosettes, though the 'rosette factories' may be using some waterproof glues these days.

And, while you have your scrap 1x8 handy, you can do some tests on your rosette jig as well.

Cheers
John

PS- I agree with the 'filler is not the answer' comments above. The rosette is one of the first spots that attract the eye of the 'inspectors' !

Were these classical rosettes? For future purposes, I have seen, don't ask where, one demo of soaking premade rosettes in water, until they become a little pliable, this lets you adjust, not only the size, but the fit of the rosette into your channel. You can either glue it wet or let it dry and glue it after it sets to the shape and size of the channel. I've never tried it, but it made sense to me. I'd test it before actually doing it!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Thanks for your suggestions, amigos. Here are close-up photos of two of the rosettes. As you can see, they are classicals using prefab rosettes. Up close, they don't look too good. I'm glad I'm not a bug. But on the good side, they look fine (to my eyes) at arm's lengths, and these two guitars are for my own use (the other is probably for my daughter).

Yes, my experience also is that the premade rosettes are somewhat out of round. But I have some spares of the same rosette, and I find that they are uniform when comparing the S side width to the E & W sides. So in forcing the rosette around the channel, the tension in the rosette perhaps causes it to pull upwards on the S side where the channel is 1mm wider. But the problem is definitely not the rosette, but my channel cutting.

I actually did do a test cut on a scrap piece of wood before cutting these channels, bud didn't think of wobble. Next time I'll be smarter, and measure the widths on the scrap. On my drill press by the way, I've found that overtightening a 1/16" bit causes wobble, so maybe that is also true of a circle cutter.

Anyway, thanks again for your thoughts. My preferred approach by the way, is to try to do some intricate marquetry work in the wider areas of gap, using some wood from the soundhole cut-out, some wood dust and white glue elsewhere, and some cyano for the really small gaps. Still very much open to suggestions though!

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"I must let my soul be my own judge."
6course.blogspot.com

I am using the EXACT same rosette on my first build and i noticed that they are not perfectly circular when i was checking dimensions. I was able to get around the issue by building and using a Wells-Karol jig for making my circle. I then adjusted the diameter i cut "on the fly" so that i could match the irregularities in the pre-made LMI rosette. Worked ok for me other than a bit of tear out because the directions i went when cutting. Chris has a very good youtube video on making one.

I'll add a picture of mine but its hard to notice the difference visually although as you can tell by yours when you cut the size to the larger diameter there is a decent difference in size.

Bill, you might want to consider building a Wells-Karol type circle cutting jig. It makes the process so much easier. It will allow you to cut perfectly round holes and you can easily sneak up on the final diameter a few thousandths at a time as Nate mentioned.

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Steve Smith
"Music is what feelings sound like"

Bill-
I'd keep it as simple as possible with any additions or corrections. Lots of 'traditional-looking' rosette treatments have solid dark lines or black/brown lines (sometimes quite thick) bordering the mosaic rosette.
Check out this discussion (previous and succeeding pages are good as well) for some ideas:
http://brazilianguitar.net/index.php?s=0a3967cb47bd702d73840235455304e5&showtopic=451&st=20

These days I fit my rosettes 'dry' and once everything is tight I add CA. It's quite a bit of extra work (sealing channel with shellac, etc..) but it does seem to work reasonably well. Having a good supply of veneer and fiber strips on hand helps a lot. Sometimes it just takes squeezing in one more .010" black fiber strip to tighten things up.

However, with a 'problem' mosiac rosette, I'd probably go to some sort of water-based gluing system, hoping to soften things up a bit. I believe Michael Thames uses heat to soften the white glue in his rosettes to 'adjust' the shape, both during construction (he makes his own rosettes) and installation, but I may have that info 'mis-remembered' !


Like Nate, I use a router jig to cut the channel. I tried the drill press but didn't like the speed and problems with holding down the work. Without the router jig, I'd opt for a hand tool. There are good builders who use only a blade driven through a stick, with a pin as axle, so lots of choices!
Edit: on Steve's suggestion on building a router jig.

Cheers
John

I have read that pre-made rosettes can be wet and adjusted to sound hole size. They become pretty flexible when wet, and swell a bit, closer to what they'll be when you glue them.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Long ago I gave a rosette jig of my preference to our Serge. It is the 7" Jasper circle cutter. Abound $25 USD and by using different size bits and some math, it covers the waterfront. I'll try to add a link in an edit. It even comes with its own very precisely made centering device. Mine is powered by a 310.http://www.rockler.com/gallery.cfm?Offerings_ID=10404&TabSelect=Details Hartville has them on sale for $20. They also provide formulae for the "hole" and the "wheel"-that is how it covers so many variations along with bit size.

My prefered method would have a gap around the rosette prior to installing, but I would always install the rosette prior to any other assembly. Some rosettes are constructed so that they will swell irreversibly when wetted, and some will swell but then contract back to original dimensions when drying. Each rosette must be tested, because even the first type might have been wetted accidentally at some time.

Try this test:

1) Cut off about 1/4" of the rosette where it will be under the fingerboard. If the piece splinters, do not try to glue it back together, because that will ruin the test. Just use it fractured but fit together.

2) Place the test piece on a scarp of flat wood and mark the base wood with a ball point pen extending past the two ends of the test piece.

3) Flood the test piece with water, cover it with Saran Wrap, and cover with a block of wood with a weight on it. Do not clamp it.

4) Lift the cover block briefly (not the Saran Wrap, though) after 10 minutes, 30 minute, one hour and observe if the test peice is expanding past the ink marks. Then wait two days for it to dry, and see if it remains expanded. On my preferred rosettes, I will get an irreversible expansion of almost 2mm, which will fill the gaps and conform to the circular channel, even if the rosette was not circular.

In practice, I use white glue to install the rosette, such as Elmers, but I still need to flood the rosette after placing it, because the glue starts to grab too fast. I have never tried fish glue--maybe that would work without adding the water to the outside surface. I had never heard about soaking the rosette before installing it. If you do that, there is the risk that it could expand too fast and you would not get it into the channel, but I do not know. I would not clamp the rosette, because a clamp can exert so much pressure at some points that it would prevent the rosette from expanding to fill the gaps. Just use a heavy weight over a board.

If you have one of the rosettes that expands when wet, but contracts when drying, you will likely have the rosette expand and conform to the channel, but then upon drying the interior will crack irregularly, leaving you with numerous gaps to deal with. I also find that some of these types of rosettes have colors that fade or run if soaked.

Many thanks again to all of you for the help you have offered. What a great forum.

For the future, I really like that Well-Karol jig, and those youtube videos will be really helpful. Looks a lot more precise than the attachment I made based on Bogdanovich, which I used for clearing out the channels. But I'll look more closely at that Jasper base too. And as much as I like the prefab design I was using, I think it's about time I started making my own. Nice how-to photos in that Brazilian forum thread!

And I appreciate your warning me twice John, about patchwork. I'll be careful, whatever I do. I like the idea of an outer black strip, but I'm doubtful that I could successfully pull off widening the circle by hand in order to inlay another strip, without creating a different kind of uneven circle. I'll have to think about that. Maybe with extreme care it'd be do-able. (And I assume the router jig shown in the rosette rescue forum is N/A on assembled guitars).

_________________
"I must let my soul be my own judge."
6course.blogspot.com

Thanks! Great tip which I will definitely use some day as I recently bought a pile of (identical) mosaic rosettes on 'clearout'.

Cheers
John

PS

When actually installing the rosette, do not lift the weight to peek and see if it expanded enough. First, there is nothing you can do if it did not. Second, the rosette will be trying to expand more than the channel will allow, causing it to pop up in the middle and pull loose from the glue. Likely, it will reattach if you put the weight back on, but it might not.

Although you can certanly look a day later with white glue, I like to just leave the tops stacked under weight for a couple of weeks to equilize moisture and reduce cupping.

Thanks again, all, for the advice you offered. I tackled the gap problem by adding a black strip on each of the 3 guitars around the installed rosettes. Cutting the line freehand with a knife was not as difficult as I had thought, although I went a little too wide in places, and still left myself with some very small gaps to fill. So the net result is an immense improvement, although not perfect. It will have to do. You can bet I will cut the soundholes cleanly next time - will make a Wells-Karol type circle cutting jig. Here a photo of the rosette area on the sitka guitar afterwards:

_________________
"I must let my soul be my own judge."
6course.blogspot.com