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PostPosted: Fri Jan 19, 2018 9:03 am 
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Brazilian Rosewood
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I've never had such severe case of chip out before. I guess there is always a first for anything but this is seriously depressing. And as usual I went from something bad to worse then slightly better but in the end probably not acceptable. I'll have to see what it looks like under shellac. I'm thinking my only recourse is a retop...

But anyway the horse is already out of the barn on this one but what is the proper technique? My first attempt was to cut the chipped out area with a ramp like scarf joint and then inlay a piece of spruce from a cutoff that matched the grain. The chip out is right in the waste so the cut off came from about 7 inches away but the grain was still pretty close. I used HHG and let it set over night and sanded flush. The grain lines were off and the HHG left a brown glue line. This is tough because the cut out section goes across the grain.

I don't know that it's possible to ever get this right.

I didn't even take pics of my first attempt but here is my second. I once again cut out a section with a brand new razor blade and then chiseled out the waist. Since the filler piece slipped the last time I decided to first bind the guitar and let the binding act as a border to hold in place. This time I was going to avoid the scarf joint and I chose to use Titebond. I think in this case the scarf is a bad idea because when you push the filler piece in it slides along the scarf and becomes maladjusted - the grain lines don't match.

Measuring the cutout with the scrap spruce in place:
Image

Cut out area:
Image

Image

Filler ready to go, you can see the very edge chipped away so that will be yet another fill.
Image

Last little bit
Image

And here you can see the lines match well on the left side of the fill, then not so much in the middle, then they match again on the right. I really don't know how to get it any better then this but that cross grain glue line will jsut shine under a finsih won't it? IS there anything else I can do to hide that better?
Image


Last edited by jfmckenna on Fri Jan 19, 2018 9:39 am, edited 1 time in total.

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PostPosted: Fri Jan 19, 2018 9:12 am 
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What a shame. If its a commission then new top. If that was one of mine a favorite niece or nephew would be getting a nice guitar. Good luck


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PostPosted: Fri Jan 19, 2018 9:29 am 
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Brazilian Rosewood
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Can't see the photos (P-bucket?), but you can't fix a top except to spray a sunburst or black. Re-top if for sale or an order. Hard lessons...

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PostPosted: Fri Jan 19, 2018 9:32 am 
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Brazilian Rosewood
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Clinchriver wrote:
What a shame. If its a commission then new top. If that was one of mine a favorite niece or nephew would be getting a nice guitar. Good luck

It's amazing isn't it. 40 hours of work and one second to ruin it :(

I can rout off the top and use it on a smaller body guitar. It's just that I spent so much time tuning this top and the sound box sounds awesome... Oh well. [headinwall]


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PostPosted: Fri Jan 19, 2018 9:40 am 
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Brazilian Rosewood
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Haans wrote:
Can't see the photos (P-bucket?), but you can't fix a top except to spray a sunburst or black. Re-top if for sale or an order. Hard lessons...

Google Photo's I think maybe you can see now. Yeah hard lesson. I'll have to have that talk today. Maybe we can work something out like this too.

Image


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PostPosted: Fri Jan 19, 2018 10:33 am 
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Brazilian Rosewood
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I can see them now...
Nasty! I'd re-top...you will never be happy. You just can't fix that stuff.
I assume you did all the usual, climb cut routing, sharp bit, not very much hanging over the ribs. Is is Engelmann or Lutz? Softer woods are harder to rout.

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PostPosted: Fri Jan 19, 2018 10:44 am 
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I have been there, as Haans wrote you can not make it an invisible repair. For evolutionary reasons we have an extraordinary ability to pick up high frequency visual details so that no matter how close and good fitting of a joint the eye will catch the line going across the grain.

Making it more visible with an inlay can be a solution is you end up with a coherent design. Ultimately I think it would be less work to retop.

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PostPosted: Fri Jan 19, 2018 11:12 am 
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Brazilian Rosewood
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Haans wrote:
I can see them now...
Nasty! I'd re-top...you will never be happy. You just can't fix that stuff.
I assume you did all the usual, climb cut routing, sharp bit, not very much hanging over the ribs. Is is Engelmann or Lutz? Softer woods are harder to rout.


Yeah and in fact it was a brand new bit too! It's actually a master grade Carp top. I spent a good deal of time with the client selecting this one too. It's gonna be a huge disappointment. But as they say these things happen. I'll still be able to use the top on another smaller guitar though so it's not a total loss.

I think this is what happened, the top is glued down with HHG on reverse kerfed linings. I set the depth of cut too low, it was right at the glue line of the top and lining. I think if I left a paper thin layer of spruce along the bottom of the cut it would not have chipped out. Thoughts? I'm trying to iron this out so it never happens again.


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PostPosted: Fri Jan 19, 2018 11:58 am 
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Brazilian Rosewood
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The last one I chipped out wound up with a black top. It was a nice (but not expensive) top and I couldn't see retopping for the small amount to chip out it had. It came out O.K. but black tops are a PITA to do.


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PostPosted: Fri Jan 19, 2018 12:20 pm 
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Cocobolo
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I had a VERY similar thing happen the other day. Know what the problem was? A chipped uneven router bit.
May want to check yours


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PostPosted: Fri Jan 19, 2018 12:46 pm 
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Brazilian Rosewood
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Are you following the climb cut pattern as shown by Stew Mac?

As mentioned, either retop, or some funky inlay as cover up. It's all the rage these days...


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PostPosted: Fri Jan 19, 2018 8:30 pm 
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A full top thickness purfling cut seems pretty extreme. How wide was the cut?


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PostPosted: Fri Jan 19, 2018 9:39 pm 
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Clay S. wrote:
The last one I chipped out wound up with a black top. It was a nice (but not expensive) top and I couldn't see retopping for the small amount to chip out it had. It came out O.K. but black tops are a PITA to do.


I was going to suggest a tasteful edge burst


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PostPosted: Fri Jan 19, 2018 10:57 pm 
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Brazilian Rosewood
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I had an upper bout scallop when the bearing fell off the bit while routing purfling. Matched the grain with a patch from an off cut and Tony Ferguson did a nice burst with dark edges. It was invisible and a good Top was saved.

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These users thanked the author Terence Kennedy for the post: jfmckenna (Fri Jan 19, 2018 11:07 pm)
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PostPosted: Fri Jan 19, 2018 11:01 pm 
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Brazilian Rosewood
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pat macaluso wrote:
A full top thickness purfling cut seems pretty extreme. How wide was the cut?

It was a mistake for sure. There was still plenty of lining to make a good gluing surface for the top but still. The bindings we're same thickness of sides .1 inch and the purfs were .8 .

Reason why I did it was because the purfs thickness was flush to top.

Do you think, as I mentioned before, that cutting purfs on the glue line is a bad idea?


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PostPosted: Sat Jan 20, 2018 8:36 am 
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Retop or figure out some sort of inlay to hide it. I always fear these things so I keep a second LMI binding cutter that only cuts top purfling. My cutter that I use for the binding and back purfling is starting to get a bit dull so will buy a new cutter for tops and move my top one to purfling duty.

Fred

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These users thanked the author Fred Tellier for the post (total 2): mhammond (Mon Jan 29, 2018 12:56 am) • jfmckenna (Sat Jan 20, 2018 9:58 am)
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PostPosted: Sat Jan 20, 2018 10:05 am 
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Brazilian Rosewood
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Fred Tellier wrote:
Retop or figure out some sort of inlay to hide it. I always fear these things so I keep a second LMI binding cutter that only cuts top purfling. My cutter that I use for the binding and back purfling is starting to get a bit dull so will buy a new cutter for tops and move my top one to purfling duty.

Fred


I agree. Seeing that reminds me its time to order a new bit. I might be crazy, but I'm figuring 10 guitars worth of work and its time. Cheap insurance.


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PostPosted: Sat Jan 20, 2018 10:23 am 
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Brazilian Rosewood
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jfmckenna wrote:
Clinchriver wrote:
What a shame. If its a commission then new top. If that was one of mine a favorite niece or nephew would be getting a nice guitar. Good luck

It's amazing isn't it. 40 hours of work and one second to ruin it :(

I can rout off the top and use it on a smaller body guitar. It's just that I spent so much time tuning this top and the sound box sounds awesome... Oh well. [headinwall]


If you do rout off the top, consider the technique carefully. I do not know how others do it, and I have only done one. I had to buy smaller bearings to get cut past kerfed lining. And top gets flexible (of course) as you get close which can become another disaster. Seems to me now that some kind of internal support is in order. What do others do?


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PostPosted: Sat Jan 20, 2018 10:52 am 
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Brazilian Rosewood
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I always routed down past the thickness of the top. I don't know if you quite understood what I was saying, but I never left much excess top material hanging over the rib. Usually, less than 3/16" to rout off.
Not familiar with Carp, I always used red or German, but a couple of things that come to mind are those sometimes invisible cracks that don't seem to show up before you rout, and the reverse kerfing. That kind of kerfing puts the best part of the glue joint on the inside and might allow for a loose part on the outside (next to rib). Just a bit of a lousy glue joint and you're done...
Of course it chipped out at the spot where it is most questionable which way to rout. That is always a problem and if I were still building, I would consider putting several good coats of finish all around the edges.
That area is where I would have routed toward the waist. I always marked the top with pencilled arrows before I routed.

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PostPosted: Sat Jan 20, 2018 11:12 am 
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Brazilian Rosewood
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I can tell ya exactly how it happened, you know how sometimes you think you didn't quite get so you reverse back just a bit? Boom done. So don't be tempted to touch up the rout in reverse.

I've retopped a few guitars before and saved the bindings. I rout right to the level of the linings and then drop fit the new top in then rout the purfs. Since I want to save this top I'll use a hot knife for the blocks.

If I screw that up then I'll just have to re_bind,.


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PostPosted: Sat Jan 20, 2018 12:45 pm 
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Brazilian Rosewood
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Haans wrote:
I always routed down past the thickness of the top. I don't know if you quite understood what I was saying, but I never left much excess top material hanging over the rib. Usually, less than 3/16" to rout off.
Not familiar with Carp, I always used red or German, but a couple of things that come to mind are those sometimes invisible cracks that don't seem to show up before you rout, and the reverse kerfing. That kind of kerfing puts the best part of the glue joint on the inside and might allow for a loose part on the outside (next to rib). Just a bit of a lousy glue joint and you're done...
Of course it chipped out at the spot where it is most questionable which way to rout. That is always a problem and if I were still building, I would consider putting several good coats of finish all around the edges.
That area is where I would have routed toward the waist. I always marked the top with pencilled arrows before I routed.


Well, the one time I did it, I used my binding jig to do it. That puts weight on the top. Is there another way?


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PostPosted: Sat Jan 20, 2018 1:06 pm 
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I have never stopped to think about this, but would it reduce the possibility of chipout if one cut the channels in multiple passes? (start with a bigger bearing, then switch)? Anybody do that?


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PostPosted: Sat Jan 20, 2018 1:24 pm 
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Brazilian Rosewood
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Wait a minute...are we talking about routing off the excess top material or routing for binding and purfling?
Oops, answered my own question by looking at the title...

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PostPosted: Sat Jan 20, 2018 2:45 pm 
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Mike OMelia wrote:
I have never stopped to think about this, but would it reduce the possibility of chipout if one cut the channels in multiple passes? (start with a bigger bearing, then switch)? Anybody do that?

I always cut a shallow channel with a hand held router then use the tower. I don't think it helps with chipout on the top but it does help avoid chipping the sides at the bottom of the channel.


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PostPosted: Sat Jan 20, 2018 5:21 pm 
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Shoot a tea burst. Problem solved.

Andy


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