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I cut the neck block , #%^*!
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43384		 Page 1 of 1
Author:  Michiyuki Kubo [ Tue May 06, 2014 11:11 am ]
Post subject:  I cut the neck block , #%^*!
As the title says, I screwed up. While I was cutting the extra wood for the heel off (shaping the sides of the heel so it looks kinda like a V) I went straight through the neck block. After I looked at how smooth the cut was done by my saw, I immediately started going through the many vocabulary words one seems to go through during times of frustration. My question;

Does it matter later during the build if the bottom of the neck block is tapered like that?

If it has to be a perfect square, can I glue it up and resquare it?

Any input here is appreciated. Thanks.
Author:  Chris Pile [ Tue May 06, 2014 11:23 am ]
Post subject:  Re: I cut the neck block , #%^*!
Pix would help....
Author:  meddlingfool [ Tue May 06, 2014 11:34 am ]
Post subject:  Re: I cut the neck block , #%^*!
Yeah, pics would help. Did you cut through the sides as well? I would be uncomfortable with a tapered neck block. Or one that had been glued back together.
Author:  RusRob [ Tue May 06, 2014 11:52 am ]
Post subject:  Re: I cut the neck block , #%^*!
I agree, Pictures are necessary to figure out the best way to go about repairing the damage.

It sounds like you were cutting it while on the guitar? I know some prefer to do it that way. The LMI Instruction video shows Robbie O'Brian doing all of his neck carving after he installs the neck but I would never think of doing it that way. He even mentions on the video that it can be done off the guitar but that is how he learned. To me it is just asking for a situation to practice your repair skills.

Bob
Author:  Michiyuki Kubo [ Tue May 06, 2014 12:05 pm ]
Post subject:  I cut the neck block , #%^*!
Image

Here is a picture, bare with me it's hand cut. I put it in this way to make the cut, I wasn't focused enough to not cut it all the way through. I was supposed to stop in the side slot cut.

I cut this outside the box, just as it stands.


The part I am worried about is the block that sits inside the guitar. Sorry I wasn't clear on that.
Author:  theguitarwhisperer [ Tue May 06, 2014 12:25 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Put a super thick heel cap on it.....
:)
Author:  Michiyuki Kubo [ Tue May 06, 2014 12:28 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Is it possible to cut the inside piece off and glue another block on? I don't know if that joint would be strong enough. This is a classical.
Author:  Colin North [ Tue May 06, 2014 12:28 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Ooops!
Classical, Spanish neck construction. I'll leave the fix to others.
But, can I make a suggestion that may help in future.
I use it all the time, simple, or more complicated stuff. I believe it's commonly used on woodworking.
When cutting out a piece of wood. mark it, and cross-hatch the piece to be removed with a pencil.
It just makes me think about what I'm doing.
Author:  theguitarwhisperer [ Tue May 06, 2014 12:34 pm ]
Post subject:  Re: I cut the neck block , #%^*!
If a stacked heel is acceptable as a construction method I see no problem why you couldn't glue a block to the bottom and reshape it. I think it'll be plenty strong.
Author:  flounder [ Tue May 06, 2014 12:40 pm ]
Post subject:  Re: I cut the neck block , #%^*!
If you cut off the whole of the inside block then the new block will be glued purely end grain to end grain!
Author:  DennisK [ Tue May 06, 2014 1:10 pm ]
Post subject:  Re: I cut the neck block , #%^*!
I do it that way all the time idunno Always seemed more elegant to me, having the inside portion shaped the same as the outside. Nothing bad has happened... yet beehive The oldest is over 2 years now.
Author:  cphanna [ Tue May 06, 2014 1:26 pm ]
Post subject:  Re: I cut the neck block , #%^*!
I think having a tapered block inside the body would probably be okay, although not traditional. Also, a stacked heel block which replaces your current heel. I also think a bolt on mortise and tenon joint would be fine, although not traditional. As has been mentioned, avoid glueing a new block to the end of this neck, because you would have at least one end-grain gluing surface (perhaps two) and that would not be a strong joint.
Author:  Hesh [ Tue May 06, 2014 1:42 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Michiyuki what many do in situations such as this is call it a "feature..." :D Your guitars are optimized for uber responsiveness hence you remove all excess material to reduce mass..... :) This may be how the air gutiar was invented too...

My primary concern is the coupling that the neck block does with the back which is related to how the instrument keeps it's shape over time and under string tension. There is a reason why traditionally neck blocks are as massive as they are.... I just can't make that reason up at the moment...

As such personally I would not use it as is. Instead I would either add material bringing back the neck block to the intended shape and gluing surface. If it's going to be for a client or for sale I would do it all over and make it right.

By the way this happens to all of us so please don't be hard on yourself. One morning back in the my original bathroom shop while getting ready for the morning drive to my office I looked at a guitar under construction and thought heck, I have time. So I started to carve out the truss rod access from the top. I was nearly finished when I noticed that I had the tail end by the butt wedge that I was removing top material from.... [headinwall] [headinwall] [headinwall]

Although truss rod access from the tail block is likely not going to go over well as a "feature..." :D it did provide me with an unwanted opportunity to do the first retop that I ever did.... Since it was not nearly as difficult as I thought since there was no finish on the instrument yet I had no fear when I wanted to make a mule guitar and try 10 different tops on it.
Author:  theguitarwhisperer [ Tue May 06, 2014 1:52 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Oh I see, I was thinking the bottom of the heel was the problem LOL!
Author:  Michiyuki Kubo [ Tue May 06, 2014 2:06 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Thanks for the responses.

This is my first guitar so it's not going to anyone, really this guitar is a tester. It will be imperfect so I am not really worried about being exact replica. I was just worried about the structural aspect of the normal way of doin things is with a bigger inside block. If it is not a problem with the rest of the build and later on, maybe i will just glue it back up and tell myself nothing happened. Or maybe I will do a mortise.

Can one do a mortise without a router properly? I do not own a router or dremmel. So it would be done with chisel and my saw. Will have to start a search for tutorials on that if I attempt it.


Another question can the female part of that type of joint be on the neck side and not the inside block side ?
Author:  DennisK [ Tue May 06, 2014 2:46 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Hesh wrote:
My primary concern is the coupling that the neck block does with the back which is related to how the instrument keeps it's shape over time and under string tension. There is a reason why traditionally neck blocks are as massive as they are.... I just can't make that reason up at the moment...

Let me know if you ever think of it :P I never could come up with a reason that a wide heel-to-back glue area was necessary.

The long glue area of the traditional Spanish slipper foot makes sense if you're building a wimpy soundboard upper bout structure that will compress over time, in which case the foot acts as a lever arm to make the neck harder to rotate. But if the soundboard upper bout is beefed up so it can't compress, then in order for the neck to rotate, the back has to elongate... so the lever arm isn't really necessary. Although I still like to have something between the back's upper transverse brace and the heel (usually A-frame style braces).
Author:  Tim Mullin [ Tue May 06, 2014 2:50 pm ]
Post subject:  Re: I cut the neck block , #%^*!
You're fine -- carry on.

The shape of the piece in your pic looks rather wide at the base for a heel, but probably quite sufficient for a "foot" -- how wide is it (i.e., the surface that will glue to the back?). I use a Spanish foot on all my guitars, including SS 12-strings. The inside portion is tapered with a saw, as you've done -- more elegant that way than square. I remove all material from the heel with a chisel and marking knife.

I can't see on my iPad if you've cut the side slots yet -- I do that (by hand or table saw) while everything is still massive and square -- much easier to do accurately.

Have fun with it!
Author:  Tim Mullin [ Tue May 06, 2014 2:54 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Perhaps also measure the length of the foot. The pic makes it look rather short. What plan/book are you following?
Author:  Michiyuki Kubo [ Tue May 06, 2014 3:03 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Thanks Dennis and Tim. I have cut the side slots already. The top side is around 64mm maybe a hair more. Bottom part where the heel is , probably around 30 right now since I left room to carve. It is 90mm tall as the sides will be a mm under that.



Dennis can you send me a pic of the bracing on the upper bout that you are talking about? I can't visualize it right now.

Again thanks all for the help. Kinda freaked out there. My first real mistake I made so far.
Author:  DennisK [ Tue May 06, 2014 4:29 pm ]
Post subject:  Re: I cut the neck block , #%^*!
soundvide wrote:
Dennis can you send me a pic of the bracing on the upper bout that you are talking about? I can't visualize it right now.

On the soundboard or back?

For the soundboard, my current opinion is that this (my first one) is bad:
Attachment:
SidesGlued.jpg

Just a flat graft between the headblock and upper transverse brace, which does little to resist compression/rotation. Worse with a 12 fret neck like classicals, where the span is longer.

My favorite style right now is to continue the neck shaft right on through to the upper transverse brace, butted firmly and glued. It is an endgrain joint, but large enough area that it's quite difficult to separate. This is an ukulele, but same thing on guitars:
Attachment:
BracingFinal.jpg

And the other style I like is A-frame notched into the heel and UTB. This is lighter weight, especially with the long span on 12 fret guitars. This is the 2 year old one, which is holding up just fine, although I may beef it up next time I do this style (taller braces, larger headblock-to-soundboard glue area so there's more overlap between it and the notched brace ends). I also glued that flat cross grain piece in there, which is something I saw somewhere to help resist the compression force/soundboard shear, but may be overkill.
Attachment:
GluingLinings.jpg

And for the back, the A-frames are notched into the UTB, and end slightly short of the ribs to allow for future heel slip neck resets. Could add "feet" anchoring them to the ribs to make sure the ends don't come unglued from the back, but it doesn't seem to really be necessary since they're mostly in line with the grain. Feet/notched linings are definitely necessary for the cross braces though, which are under a lot of strain when the humidity drops.
Attachment:
BackBracing.jpg

Slipper foot would work as well, if your neck stock is long enough for it. Combined with the extension on the soundboard side, it makes a full C-shaped headblock, which is super strong, but also heavy.
Author:  Michiyuki Kubo [ Tue May 06, 2014 4:49 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Perfect explanation thanks. I see what you mean now.
Author:  Hesh [ Tue May 06, 2014 5:55 pm ]
Post subject:  Re: I cut the neck block , #%^*!
DennisK wrote:
soundvide wrote:
Just a flat graft between the headblock and upper transverse brace, which does little to resist compression/rotation. Worse with a 12 fret neck like classicals, where the span is longer.



Dennis I see some beautiful work in your pics! [:Y:]

You are speaking of what some call the popsicle brace which is a traditional method of bracing with countless instruments built this way.

The intent of the popsicle, although not always successful, is to attempt to counter the stress riser created by the glued on fret board extension. Countless instruments crack next to the fret board for this reason and the popsicle brace was one method... of attempting to prevent these cracks next to the extension. It was never intended to do anything else is my understanding.

On my own stuff my popsicle brace is only about 4" long spanning the underside of the extension and then some but without approaching the kerfed linings of the sides.

There are folks who offer a service to remove the popsicle brace from older and newer Martins as one aspect to "hot rodding" instruments. Does it work, I don't know but I sure respect some of the folks who provide this service so it would not surprise me if it does contribute to a more open sounding instrument.
Author:  Clay S. [ Tue May 06, 2014 7:36 pm ]
Post subject:  Re: I cut the neck block , #%^*!
Hi Michiyuki,
It doesn't look too narrow to me. I think many makers taper the slipper foot to that degree. I would glue a foot piece on the bottom as is traditionally done, making it the same width as the block at that point. Assuming the heel is the full depth of the body you can cut a "shelf" in the end block which the foot would glue to, allowing "side grain" gluing rather than end grain gluing.
I don't think M. Velasquez slipper feet are much wider than what you have.
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