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 Post subject: soundhole disaster
PostPosted: Tue Jul 27, 2010 9:45 am 
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Mahogany
Mahogany

Joined: Thu Jul 23, 2009 4:54 pm
Posts: 96
First name: Devin
Last Name: Cox
City: Edmond
State: Oklahoma
Country: usa
Focus: Build
Status: Amateur
I cut my soundhole out lastnight and, despite my best efforts, the hole was not cut on-center with the rosette. What is the best course of action to repair this?

http://www.devincox.com/images/toprose.jpg

Also when the cutter cut through the back there was a bunch of tear out. What is the best method to repair this?
http://www.devincox.com/images/bottomrose.jpg

Thanks,
Devin


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 Post subject: Re: soundhole disaster
PostPosted: Tue Jul 27, 2010 10:28 am 
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Koa
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Joined: Fri Aug 19, 2005 4:02 am
Posts: 1706
Location: United States
What did you use, a plumbers hole cutter? That would be the wrong tool for the job. I cut my soundholes with my rosette cutting rig which includes a laminate trimmer, a router base and a homemade jig.

You can re-center the hole to the rosette by sanding material off one side. I would do that with a drum sander mounted on a drill press, or a spindle sander. Use the largest sanding drum that will fit in the hole.


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 Post subject: Re: soundhole disaster
PostPosted: Tue Jul 27, 2010 11:46 am 
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Brazilian Rosewood
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Devin-
When cutting for rosette or soundhole, it's important to clamp the top to a backer board-I don't know if you did this.

The 'guide hole' in the backer board is what keeps things centered; the top is too thin and fragile to give very robust support to a guide pin.

It's possible to double the thickness around the soundhole by gluing a 'doubler' to the underside - some builders do this on all their guitars. It's easier to glue the doubler in place before cutting the soundhole, obviously, but it could be done in 'repair mode' if you are careful.

If I were to sand the hole to correct the problem, I'd correct the soundhole shape/position by hand rather than with a powered drum sander. You can use stick-on sandpaper and offcuts of PVC/ABS plumbing pipe to make a sanding tool.

Welcome to the 'real world of woodwork' - we've all done something like this (numerous times) along the way.
;)

John


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 Post subject: Re: soundhole disaster
PostPosted: Tue Jul 27, 2010 12:05 pm 
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Koa
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Location: 8.33±0.35 kpc from Galactic center, 20 light-years above the equatorial in the Sol System
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Sand the hole back to center with a drum sander or you could file it back to center it round.

Regarding the tear out.
Sawdust and glue or you might even try the Padma's secret ingredient, is called Bondo.
Then slightly back bevel or round off the sound hole so the bondo don't show.

But Don't tell anybody that I said you could use

Bondo


As it really gets the "purists going"

Of course the "official" way is to tool the tear out area flat,
laminate on new wood and re thickness. Ya right!



blessings
be
duh Padma

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 Post subject: Re: soundhole disaster
PostPosted: Tue Jul 27, 2010 12:56 pm 
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Mahogany
Mahogany

Joined: Thu Jul 23, 2009 4:54 pm
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First name: Devin
Last Name: Cox
City: Edmond
State: Oklahoma
Country: usa
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I used this tool to cut it:
http://www.woodcraft.com/Catalog/ProductPage.aspx?prodid=4010&ss=33d7aff4-e879-4b4e-bb3d-20fdad2ac27d

clamped to a backer board on my floor mounted drill press. I used the wrong cutter though. uugh. I ground a cutter for the rossette channel and then didnt switch back to the cutter as shown in the pic/url above. Also, I did not cut the rosette channel and then the soundhole in the same setup. I cut the channel for the rosette and then removed the backer board and top from the press. I should have left it on the board. Lots a learning going on here.
I was hoping for something like sawdust and glue for the tear out, cuz I have lots of sawdust. (c:

ps. do I hurt the "spirit" of the guitar if I always cursing at it? (c:

Thanks to all who replied,
Devin


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 Post subject: Re: soundhole disaster
PostPosted: Wed Jul 28, 2010 9:48 am 
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I think what I would do is find a way to center the hole by cutting it over sized. Then come back and install a sound hole binding to reduce the hole back to what you want. It might need to be a fairly large binding, but it should make a mistake look like a design element. [:Y:]

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 Post subject: Re: soundhole disaster
PostPosted: Wed Jul 28, 2010 10:29 am 
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Koa
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devincox wrote:
...
ps. do I hurt the "spirit" of the guitar if I always cursing at it? (c:

Devin



Well Devin,

Some would defiantly say yes.

It may be an inanimate object. However it is an object that is designed and built to be sensitive and responsive to vibrations.

Many luthieres talk to the wood, telling it exactly what they want it to sound like and how to preform.

Sorta reminds me of a carved top me once built. That top was a real expensive tight grain block of lutz that opened up to reveal two pitch pockets, with twisted grain. Any one of them flaws are reasons for rejecting that billet. But for some reason me talked to the wood and carved her anyways. While carving I kept talking to her, telling her how sweet she gonna sound to some jazz picker and how her growl gonna supprise anyone who plays her. I talked to her the whole time I carved and built her box.

Gave her a name too, called her Grace. Couple of days after getting her strung up. Some young jazz picker walked in took one look and laughed his head off as he picked it up and started to play. He was blown away by her voice. Asked me how much. Without saying a word he opened his wallet and handed me the cash.

That top had three strikes against it, yet when I held and tapped that billet I could hear something inside her wanting to sing out....Maybe it was the wood, maybe it was me talking to her, telling her what I wanted her to sound like and maybe it was an anomaly or just the luck of the draw...you decide.

Now if you feel that you have instilled too much cursing in to your build, you may get lucky and oft the thing on to some acid head, hard metal picker. Gee you might even become rich and famous for building grunge metal axes full of piss and vinegar, you know "a whole new sound" kinda thing.

blessings
be
duhPadma

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 Post subject: Re: soundhole disaster
PostPosted: Wed Jul 28, 2010 11:39 am 
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Mahogany
Mahogany

Joined: Thu Jul 23, 2009 4:54 pm
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First name: Devin
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Country: usa
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ha ha. I guess I'll have to relax and leave the cursing for my electric guitar.


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 Post subject: Re: soundhole disaster
PostPosted: Wed Jul 28, 2010 3:04 pm 
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Koa
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devincox wrote:
ps. do I hurt the "spirit" of the guitar if I always cursing at it? (c:

This guy has some interesting pictures, I won't judge if it hurts or helps, but effect it, if you buy Emoto's work, then yes.
Rob
http://www.hado.net/watercrystals/index.php

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 Post subject: Re: soundhole disaster
PostPosted: Fri Jul 30, 2010 12:15 am 
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Cocobolo
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Posts: 372
I totally agree with Lance.
If you dont want to sand
fix your top securely to a backboard. be aware that pulling tape off spruce later can pull up splinters
using the hole plug and a compass or a piece of string or whatever
find the new centre and drill carefully for your cutter centre pin into the backboard.
There is no reason you cant lower the tool to the work with one hand on the press, and turn the blade with the other, never turning on the power. its only 2mm of soft spruce.Many light cuts super sharp You will also be able to check alignment before you cut..
then bind the hole and back fill the now invisible tearout

or do something like this!
Attachment:
hugedansoundhole.jpg


You do not have the required permissions to view the files attached to this post.


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 Post subject: Re: soundhole disaster
PostPosted: Fri Jul 30, 2010 9:40 am 
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Mahogany
Mahogany

Joined: Thu Jul 23, 2009 4:54 pm
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First name: Devin
Last Name: Cox
City: Edmond
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Country: usa
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Steve, thats a cool looking soundhole.
I think i'm gonna try and reshape the sound hole by hand. We shall see. (c:


Devin


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 Post subject: Re: soundhole disaster
PostPosted: Mon Aug 09, 2010 8:30 am 
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Mahogany
Mahogany

Joined: Thu Jul 23, 2009 4:54 pm
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First name: Devin
Last Name: Cox
City: Edmond
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Country: usa
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used a fine grit sandpaper and spindle on the drill press at 250 rpms and the rosette cleaned up very nicely. finished by hand. The tearout on the back side was mostly on the part that needed to be sanded away and thus was almost completely removed. I will finish it up with some glue and saw dust. I'm back on track and almost ready to glue up my braces.

Thank you,
Devin


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 Post subject: Re: soundhole disaster
PostPosted: Mon Aug 09, 2010 12:31 pm 
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Koa
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Just learn to hold the guitar at an angle so the hole looks centerred to the audience duh

I would just oversize the hole with sandpaper. Just keep the edge of the hole the same distance from the rosette and it should look ok. It will also remove some of the tear-out area.
Watchout if you use a drill press sander....it will go very fast through thin spruce


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 Post subject: Re: soundhole disaster
PostPosted: Sat Oct 02, 2010 11:44 am 
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Walnut
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Can you cut the hole bigger so it centers out?

How bout using a router with a circle template clamped on and a top or bottom bearing bit.

As for the bottom, after you center up the hole, can you cut a circular rabbet from the backside ( again
with an approriate sized circular template) and patch with spruce cutoffs from making the top?


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 Post subject: Re: soundhole disaster
PostPosted: Tue Oct 12, 2010 3:39 am 
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Koa
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I don't THINK anyone mentioned that when cutting the hole you should go halfway from the front, then flip the top over and cut the rest of the way from the back. no more tear out.

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 Post subject: Re: soundhole disaster
PostPosted: Tue Oct 12, 2010 3:20 pm 
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Works every time, Martin!

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 Post subject: Re: soundhole disaster
PostPosted: Wed Oct 13, 2010 9:11 pm 
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Koa
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I think Lance offered the most practical solution to re-centering and then re-sizing the sound hole. I was going to post it, but he beat me to it. He's a lot more experienced than I am, too, so don't listen to me. Listen to him.


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