Official Luthiers Forum!

I've done a bunch of searching and i'm getting confused.

I'm doing a fairly simple rosette on my 2nd guitar. It's a walnut ring, with a b/w/b fiber purfling around the outside and inside of the ring. This will be installed in a WRC top.

I have a bunch of different ways to cut the channels and rings and yet i'm not really getting the precision i'm looking for. I've practiced using a router with a little circle jig i made, that seems to work the best. I've also used the schnieder circle cutting gramil, which i like for scoring the wood to get less tearing.

Whati'm having trouble with is procedural:

Do you guys cut the ring out, glue the purflings to the sides of the ring, then scribe it and excavate the channel? Do you draw it all on using a compass and then match dimensions and get good results? Do you cut the channel for just the wood ring, then once that is in, cut the purf channels and try to lay those in?

thanks

_________________
brendan 3.0 new and improved, with better interpersonal subroutines

my method is inner ring first, level, then outer/inner lines.

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I cut practice channels in MDF scrap to make sure I get the correct size channel I want. I set the jig and make a cut, if it is good I will make the cut on the top, I then adjust the jig make the cut on the test piece. When I am satisfied with the test cut I will make the next cut on the top, and so on, until I am done. I have a matching channel cut in the MDF, to use as a guide, if I ever wanted to remake that rosette again.

I would try to install all of it at once, But you could use any method you like, either way will work.

Same as Tony. Install the wood ring, level, then router the purfling borders. That way you don't have to worry about how perfect the edges of the wood ring are. Plus getting the purfling strips to bend to the right radius is much easier if they're going into a tight channel. But you still have to be careful, I snapped one even though I wasn't pushing it in hard at all

I did one by cutting the wooden ring then gluing black fiber purfling to it. I made a kind of form to help. It got done ok but it was a real PITA. Now I do the same as Tony. Much easier and better results.

Don't know what kind of circle cutter you're using but do yourself a favor and consider building one of the Wells-Karol jigs if you don't already have one. They are an excellent tool for this job. If you use downcut bits you shouldn't need to scribe the channels before hand to get a clean cut.

_________________
Steve Smith
"Music is what feelings sound like"

For myself, I make the rosette prior to inlaying it.

You can see how I do it in the article I put on my website on how I make a classical guitar top.

http://www.guitaresmoisan.com/en/articles/04-2009.html

_________________
Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

I do the same as Tony & Dennis!
mc

_________________
Mike Collins

Here's what I do:

-route the outside edge of the wooden ring using a bit the same thickness as the purfling line
-move the router to the soundboard with the same radius as you used to route the wooden ring, and make that cut on the soundboard
-repeat the process on the inside cuts of the ring and soundboard
-hog out the area on the soundboard between the two cuts already made
-drop the ring in and press in the inside purfling line, which centers the rosette ring and leaves a purfling-sized channel around the outside of the ring
-press in outside purfling ring
-CA

I haven't tried this with a waterbased glue, but I suspect it'd be challenging given that it creates such a tight fit.

_________________
Evan McCartney

Yup, thanks to Coach Tony, I now do them the same way he describes.

_________________
My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I use the same method as Evan.
It helps to have a supply of veneer & fiber strips on hand in case you have to 'tighten up' things a bit before adding the CA.
I like fitting everything dry and using CA. A few experiences with rosettes and purfling 'swelling up' with water-containing glue and refusing to fit made me a convert to CA.
You do have to seal the channel very well with shellac to avoid some nasty CA stains into the soundboard.

Cheers
John

my method might seem a little willy nilly, but it works for me.
i use the stew mac circle cutter on a dremel to cut the wood rosette. i then cut a small slot out of the wood rosette so that it has a bit of flex to it. that slot ends up under the finger board extension, so no big deal.
i then center the wood circle, add a small piece of the purfling on the inside and outside so that i can mark where the finished inner and outer edges will be with pencil. these marks and all my 'testing' happen under the fingerboard extension.
i then start routing the channel from the center towards either the inside or outside edge. once i'm really close to the first edge i start moving towards the other edge. as i get close, each adjustment to the circle cutting jig just takes a very small cut, always testing the adjustment where the fingerboard will cover it up.
because i've got a cirlce with a bit of flex and purfling lines that will follow it, once my channel is wide enough for the wood rosette and the purfling lines to squeeze into my test are, i know that i'll have my channel right. if, for some reason, i end up with a channel that is too wide, i'll need to change my plan and add more purfs. but i've done about 6 this way so far and haven't had to resort to 'plan b' yet.
i use titebond and find that a pretty tight fit goes in well if you do it when the glue is really wet. give it a minute to start setting or getting gooey and you'd be in trouble.
hope this helps.
phil

Thanks a lot guys...

after i spent a long time trying to glue the purflings to the wood ring with poor results, i ended up recutting the wood rings, cutting channels to fit the rings perfectly, then rout the purfling channels after rings were glued. other than not really being able to get my schnieder circle cutter to do a channel deep enough for a .010 fibre line (because the angle of the knife wouldn't allow me to get it down far enough yet still keep the .010) it's coming along. a bit of excavation with a knife and it seems to be working quite well.

i did shellac the top and that has worked quite well.

thanks!

_________________
brendan 3.0 new and improved, with better interpersonal subroutines