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This is a guitar based on Martin's Herringbone plans that I have. It is my first solo build. I am doing a French Polish finish on the guitar, had about 7 sessions done on the spruce top and noticed that I should have done a better job in the prep-stage as far as sanding the top. So, I took at my orbital sander and went from 120 through to 320 with Abranet discs. I avoided the side Herringbone as much as possible and unfortunately forgot about avoiding the Rosette.

You can see the lower section of the first Rosette line got too thin, in fact I hit a pocket in the channel because I must not have had it completely to the bottom of the channel when I glued it in. Now I am thinking about how to fix it, I have 2 ideas.

First, I ordered on of the Gramils from LMI last night, thought I might be able to use it to follow the sound hole arc and recut the channel just in the bad section, go right up to the "good" purfling ends and use a microchisel to get a nice sharp joint between the existing piece and the new piece.

Secondly, if the above fails, I was going to open up and make a larger hole and take out the bad ring, like the Clarence White model I guess. Do you think this is the right path or is there some other way around this?

Thanks,
Kurt

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

I've fixed several of these. Make a plug to fit the center with the correct sized hole for your circle cutter in the center. Reroute the purfling strip and replace it. If you didn't do the routing then maybe someone else might have another idea.

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Steve Smith
"Music is what feelings sound like"

Thanks Steve, the problem is I don't have a circle cutter, I did these free hand. Just kidding, I have that Disc Rosette cutter that you put the blades in and use the drill press. That's not to say I couldn't get a circle cutter, I do have the Dremel with the router base and I know Stew Mac has a circle cutter for it. Also, I save the "hole" so I will see how close it fits now. If it's loose I could probably shim it up with tape don't you think?

Kurt

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

Steve beat me to it, but I was trying to give the same advice. As you probably sanded the sound hole a bit before you started finishing, I suspect that while you are running the gramil around it will not follow the purfling line perfectly.

Also take care 120 on a RO cuts wood really fast. If you do get new purfling installed cut it flush with a scraper or a razor blade. I suspect you do not want to do anymore sanding in that area.

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http://www.Harvestmoonguitars.com

Yes I plan on staying away from the RO for the rest of this project. That's what I will do, get a circle cutter to be assured I have a proper radius and use a scraper to take the new purfling down.

Kurt

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

I make a new circular plug from a scrap of 1/2" plywood so that it fits very snug. Next I build up a platform inside the guitar under the sound hole using scrap wood held in place with masking tape. It's a pain in the butt to get everything the right height but when I'm done the plug drops in and sits flush with the top. After that you can re-route the groove but make sure your alignment is good all the around the circle before you cut anything. Good luck

If anyone knows an easier way jump on in.

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Steve Smith
"Music is what feelings sound like"

Good luck with that. It won't take very much off-center to end up with another issue. I would use a super fine bit and try to start in the center of the strip. Then cut for a wider strip. Also, what is the current thickness in that area? Do u have at least a tenth inch? A wells-karol (or similar) is essential for accurate positioning. And something other than a dremel.

Assuming that drill press cutter used a center hole for alignment, u should be able to get close with a plug. If u use a WK circle cutter, cut the plug just a bit big, then spin it on a drill and sand the edge till it just fits the hole. Most of these things work on a 1/4" center hole.

I had one of those drill press cutters once. It scared the crap out of me. Used once and sold it.

Steve,

Thanks for that, I was wondering how the heck I could get the original piece that I took out to fit back in the hole and find center again. That plywood plug should be much more stable. What if I were to get the plug to fit the hole exactly, and then laminate a really thin circular piece on top that was larger in diameter, say almost to my purfling line. Do you think that would be better than making a support from inside?

Thanks,
Kurt

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

To my thinking the only problem with that would be setting the depth of the cut when you reroute the purfling. It might work just fine but I haven't tried it that way. It's not all that hard to stack up scrap wood inside the body. Once you get close just use a caliper to measure the height and find/make a piece the correct thickness so that the plug is level with the top. If you try it the other way let us know how it works. Any way you do this it's going to take a while to get the setup right. After that it's pretty straightforward.

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Steve Smith
"Music is what feelings sound like"

When you've made the plywood (or whatever) plug/disc, preferably using a trammeling router, double stick tape the disc to the router base, then you don't have to mess with making a ledge for it inside the guitar. The cut depth can be set in the normal way. Would recommend using a decent laminate trimmer as your router rather than a Dremel or clone.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Here is what I came up with for the plug and support. I am waiting to see what circle cutter and router I will be using before I drill the final center hole, then I will glue the support to the bottom of the plug. It seems to fit pretty secure and the support hits the center strip in the body when the top of the plug is flush with the top.

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

One other question, the smallest router bit I have is a 1/16" down cut bit, the purfling I am replacing is a .060 W/B/W, so do I need to start with an even finer bit as Mike suggested, and where is the best place to get them?

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

Yes. And chances are, ur new chanel will be a bit larger, so study what perfling options are out there before u cut. A new perfling could be a bit wider, and you can fine sand it to fit. If everything is dead center, maybe u ok with original. Plan for both cases. If you top is thinner than 0.1", consider using a circle cutter to make a backup ring under the rosette, slightly larger in the inner diameter than the sound hole. Remove the 3 sound hole braces and use ring as brace.

I had a problem with a rosette once that I had made the purflings myself on, and they didn't go all the way down into their slot so I sanded through them. In addition, my attempts to "repair" the rosette by fixing just the bad sections were pretty pitiful.

I did the same thing, I made a tight plywood plug with a pin in it for my circle cutter.

I used the Stew-Mac rosette tool with a dremel.

I guess that "crappy" setup wasn't supposed to work, but it came out flawlessly.

I basically used the same circle cuter to make the plug as I did the rosette repair.

I didn't use an internal support as the whole thing was light enough that I didn't need it, plus I was doing the outer ring not the inner one.

Heres the Rosette fail


Here's how I made the plug:


Here's the plug in place:


Measured where I wanted to route:


And the fixed rosette! The outer lines were doubled to cover my crappy repair, but it gave the rosette a bolder look.

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Old growth, shmold growth!

Nice repair. Are there words hidden in that?

I should probably do that in the next one.

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Old growth, shmold growth!

I had to repair this rosette after sanding through the herringbone. I had been watching that part in the lower section and totally missed what I was doing to the spot at the top. This was also an orbital sander user error.


I made a plug using my stew mac circle cutter and Dremel. Its stepped so the top lip rests on the soundboard. It fit, but could be tighter so I wrapped some tape around the plug to get a nice friction fit.


It wasn't perfect with the previous herringbone so I routed the channel a bit wider and added some black purfling.

I finished the repair using the Wells-Karol circle cutting jig and Bosch Colt I got from Mike, worked really well. Looks pretty good to me, just put a wash coat of shellac on and will start French Polish process once again. Just glad I didn't end up with a larger sound hole in the end, which was my end of game alternative.

Thanks for the help,
Kurt

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

Looks good!! Hey Rod, that's the WK u made for me. Recognize ur signature? I upgrade to a bishop Cochran. That jig u built cut many circles for me.

I've done the disk thing once but using double stick tape is brilliant. One of the many things I wish I had thought of.

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Joe Beaver
Maker of Sawdust

I replaced a rosette on my 1st guitar after the guitar was complete. I used a stepped piece of MDF and held it up by putting a balloon inside the sound hole to hold the plug up against the underside. It worked well.

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Alain
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I was just looking at that, kind of scratching my head not being sure that I ever made one for Kurt....

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