getting the body geometry right and mating the neck

[tippie53]

this can help. This is all about geometry. I am now on 173 and I learned a few things that I share in the video. You need to get the geometry right to make the neck set perfect. Thing ACE Angle Centerline and Elevation. No matter what the neck joint you still have to maintain the proper neck angle , and center line of the neck to the body. If you don't think about this when the sides are in the mold , you can make getting that neck angle right difficult.

Here is how to prep the sides. No some use an arched traverse brace some don't. I use the flat but I also use the older style Martin brace, it has the same amount of wood but is stiffer.



I don't over radius the top and pay attention to how I verify the created angle. When the body is done you can then true this area with a sanding block that rides the neck so the created neck plane is dead true.

[ruby@magpage.com]

John
I have always had trouble getting the neck angle correct from the start and always end up having to work on it after the box is closed.

I have watched the video (second one in your note) several times going back a couple of years now and am a little unclear - after you radius the top, you then flatten the area above the sound hole - around 11:00 on the video. You mention that the flat side of the dish is 1/4" up from the the rim at the heel, but don;t mention how far you eventually want it to be up. I think this is what I am missing.

With the flat disk on the neck part of the rim, how far in the air is the other end over the heel when you are finished?

Ed Minch

[tippie53]

that is the gap you want. Please feel free to call me.
Once you get the chalk removed from the top of the sound hole to the neck you want to check that angle you created with the flat side of the disk , so once I have the initial radius established I check it with the flat side of the disk. I have attached a piece of sandpaper to that and now I can true the angle created with the flat side. I want to see a 1/4 in on 000 and 3/8 on the dreds.
Then once the top is glued on I can then dry fit the neck and establish the fretboard plane . With the angle created there is just a touch here. I use a flat piece of wood and attach about a 4 inch strip of sandpaper. I mark the top where the fretboard is coming on the top.
When I set the neck I am looking for more than a 1/16 and less than 1/8 at the point of the saddle. Now when you lay a straight edge on the neck you want the plane of the fretboard to match. You may need to adjust the top with the sanding block. I don't mind a .020 fall away from the neck block to the sound hole but I sure don't want a rise.

[songman101]

Hello John,
I got to tell you that I really love the method you use for the dovetail neck jointing. I cannot now imagine not using the sanding scribing process you explained in the video. I can appreciate the only way to pull the sandpaper up toward the soundboard so as not to damage (round the end of the bottom of the neck joint you talk about. I like the hammering technique you showed for setting the neck base while trueing it. I'm a newbie and I will need to watch the videos many times to completely gain the full sense of trueing the neck in like you do in 15 or so minutes amazing John, I truly believe your a master at this craft. The center line that's from the tip of the neck to the end of the soundboard at the base of the guitar should be dialed in to 1/16 ' you said is good. Is the 1/4" to about 1/8" at the edge of the sound-hole ok before the fret board id glued on? I wanted to mention the tilting of the neck, so the base open enough for the sandpaper to enter then pull paper toward the soundboard when scribing remembering that the same contour will take place on the body to the neck .You mentioned to take a little off at a time only. because you cannot add it back on .John thanks for the lesson and I will take it to my memory bank. thanks Stephen - songman101

[tippie53]

not totally sure I understood your question.
Here is one thing you need to think about , and that is you are working 2 center lines, the one from the body ( top ) and the one from the neck. The neck center should be within 1/16 at the tail of the body . I like to get the neck in the block as close as possible.
The neck angle needs to 1/16 to 1/8 more than the neck . So without the fret board , as the point of the saddle on the top you want to see .0625 to .125 and with the fret board, if you have a 1/4 in fret board you want to see about 3/8 or .375.
Once that is established you place the bridge to the center line of the neck NOT THE TOP.
Please ask all the questions you need to. We are here to help.
thanks for your kind words , I can't believe that I would have ever been this successful. I am one very lucky man.

[Tom West]

A lot of first time builders get in trouble in this area. The dash to get the body done without the understanding that the right neck angle is very dependent on body geometry. John has preached this for quite a while and has done a good job to put the correct info out there. Good job John.
Tom

[tippie53]

thanks Tom
We shot a new video to show the neck alignment process. I am sure Glenn will update us when it hits YouTube

[Zen]

thanks Tom
We shot a new video to show the neck alignment process. I am sure Glenn will update us when it hits YouTube

Did that video ever go online John ? I know this is an older posting but I'm having that very problem right now
I think I may have my neck angle slightly out on a kit build acoustic dreadnought and would appreciate any advise.Its a bolt on neck and I have not yet glued down the tongue just in case I need to make any changes.
A straight edge along the top of my fretted fingerboard is between 1/16 to 1/8th above the bridge.
I have compensated with a higher saddle which is 3/16th higher than the bridge.
First question is would that high saddle be an average height or should it be lowered.
Second question is would you recommend that I shave the heel to tip the neck forward so that a straight edge practically rests on the bridge ?
I should know this by now but keep getting confused--old age creeping in I guess
Any help or advise would be much appreciated.

[tippie53]

This is the new dovetail set video I think it is the best one I have done

[Ironsides]

Well I have just made a mistake and now need to know if there is anything I can do to correct it, I glued the top to my Martin OOO kit and the clamps pulled the top and sides causing the top to bow up. can i compensate for this so the bridge will not be to high. Also I went on and glued the bottom on too.
Any help please?

Ok, It's not as bad as I thought it was going to be for some reason the top has settled down to where it is almost level across the top. But I am still having a hard time getting the right neck height in relation to the body, it's flat.