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SoundHole Patch?...No Rosette (Read 4127 times)
mblue
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SoundHole Patch?...No Rosette
Mar 21st, 2009 at 2:34pm
 
I am guessing that a Rosette makes a soundhole patch more important, in that it reinforces the rosette channel cut in the soundboard. Is that true? How "important" is a soundhole patch when there is no Rosette?
Thanks...
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Zippyzingo
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Re: SoundHole Patch?...No Rosette
Reply #1 - Mar 21st, 2009 at 4:54pm
 
I'm not so sure that the sound hole patch is because of the rosette. I think it is because of the end grain that is exposed in edges of the sound hole. The top can easily split with the grain if this is not supported in some way. †If you are duplicating a successful design that has a patch, I wouldn't leave it out because I left out the rosette.

ZZ

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Matt Blacka
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Re: SoundHole Patch?...No Rosette
Reply #2 - Mar 22nd, 2009 at 12:31pm
 
Installing a rosette probably doesn't make that much difference in terms of whether or not you need a soundhole patch, after all the routed channel for the rosette is filled back in to the original thickness of the soundboard once you glue in the inlay anyway (just with inlay in the channel instead of soundboard).

The suondhole patch reinforces the soundboard, as by cutting a big hole in the soundboard for the soundhole, it is weakened significantly. As ZZ pointed out, the creation of a heap of end grain timber is also asking for a split in the soundboard, althouth the transverse braces above and below the soundhole help to reduce the likeliness of this happenning. Most acoustic guitars adopt small angled braces either side of the soundhole to reinforce the soundboard between the transverse braces, not a patch.

To avoid seeing the patch at the edge of the soundhole (and looking like a laminated top), just make the hole in the patch a little larger diameter than the soundhole, and then feather the edge of the patch where it approaches the hole.

Matt
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MAKAIO Ukuleles, Australia www.makaioukuleles.blogspot.com
 
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mblue
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Re: SoundHole Patch?...No Rosette
Reply #3 - Mar 23rd, 2009 at 3:02am
 
Thanks, ZZ and Matt...I can see that I guessed wrong about the soundhole patch being mostly related to a rosette.. And I can imagine how that unsupported end grain would be rather fragile.
I ordered too many plans, (all aimed at making high quality ukes), and one has the patch, and the others don't. So I guess it is one of those personal decisions... in this case related to strength and durability...
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Quine
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Re: SoundHole Patch?...No Rosette
Reply #4 - Mar 24th, 2009 at 3:15am
 
The sound hole patch is just the hana lima style of building. †I've seen alot of plans for ukes and guitars with different strategies around the sound hole. †I don't know
I just finished my first hana lima style uke. †It sounds pretty good to me, so I'd recommend sticking to the plan
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« Last Edit: Oct 16th, 2009 at 4:04am by Hana Lima Ia »  
 
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ukrazy
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Re: SoundHole Patch?...No Rosette
Reply #5 - Mar 24th, 2009 at 11:28am
 
Hi all, This is my first post, but I've been learning great stuff from this site for the past few weeks. Getting ready to start my first bubinga/spruce kit build. From the construction manual and good ideas from here, I've been working on jigs and tools.
†I too have wondered about the soundhole patch. I can't walk by a ukulele now without feeling around a bit inside. My plan is to not do a rosette on my first build. Two of my current ukes from different Hawaiian builders take the same approach. Both have top bracing pretty close to the top and bottom sides of the soundhole. Exactly like the Hana Lima plan. But instead of a full patch, each uses small strips of patch material on the left and right sides of the sound hole, about 1/4-3/8 in. back from the edge. Each strip is around 1/2 in. wide and is kept back about 1/8 in. from actually touching the bracing. My thinking, is the two braces are close enough to the soundhole edge to prevent end grain cracking and the two strips of patch stiffen the left and right sides of the hole. Wouldn't take much flex in that area to cause something to break. I'm thinking about routing in the two strips as I get closer to final top thickness. Will shoot for around .035 patch glued in. †Let me know if you think I'm crazy!
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Zippyzingo
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Re: SoundHole Patch?...No Rosette
Reply #6 - Mar 25th, 2009 at 10:19am
 
Hi Ukrazy,
One of the things that I love about this are the riches of options. †Most of what I do is repair type stuff. †An idea that is always in my mind when I do this is to do my best to keep things reversible which often translates into simple.

Not to disparage you in any way but if you are not up to routing for a rosette, you may have trouble routing for these braces too. Why risk it?

If you are concerned about the strength of the area after the bracing is installed, †I would suggest that you simply use slightly thicker bracing. †To my thinking it doesn't make sense to weakening the face plate by routing channels then trying to strengthen things again with an inset brace. †Just leave the face intact and use (slightly) thicker braces. †

Remember, as you think about this, that the top is supposed to be flexible. You don't want to keep it from moving. Changes from the plan may effect the final sound of the instrument. †

ZZ
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konacat
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Re: SoundHole Patch?...No Rosette
Reply #7 - Mar 25th, 2009 at 2:41pm
 
I really donít think the sound hole will effect the sound too much unless you made it really big and thick. The purpose of the patch is to support the end grain around the sound hole edge. It really shouldnít require much material. Most ukuleles that I have seen have two braces that run horizontal side to side one above and one below the sound hole. These braces would have much more impact on vibration than then a sound hole patch. The sound hole patch doesnít need to be very thick. Its job is to support the edge of the sound hole. You could take a very thin circle of wood and place it around the sound hole with the grain orientation opposite of the sound board. Make the patch I.D. slightly larger than the sound hole O.D. or feather the edge so the patch canít be seen through the sound hole.
You can also just run a couple of small braces vertical on either side of the sound hole.
I seen several ukulele with a sound hole patch the size of a  CD case except but of course thinner.

The bottom line is that I donít think a bridge patch has that big of impact on the finished ukulele. I might not put one on a soprano because it is a much smaller instrument plus a low string tension. I currently have 3 sopranos about done without sound hold patches and a guitar with the patch. Definitely, do not route a pocket for the patch itís not needed.

Have Fun

Philip


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