Official Luthiers Forum!

Hi all,

I'm building my first guitar from an LMI dreadnought kit. The kit came with a pre-mortised and drilled neck block. Since the height of the neck relative to the position of the block is already fixed due to the drilled block with thread inserts, how do I determine exactly where to place the block when gluing it to the sides?

All the pictures and tutorials I'm seeing show the block being glued flush to the workboard, but once I radius the top edges, won't this push my neck above the surface of the top plate? How would I adjust the neck position since this block already has thread inserts installed?

Thanks, I've been doing a lot of reading here in this group as I've started on this project and have learned lots of great information.

/mark

If you bolt up the neck into the block you will notice there be about 1/8" or just a tad less neck proud of the block. So this tells you that the block is to be set flush to the rim on the top edge so that the top edge of the neck will end up flush with the outside of the top once the top is installed. Now the block will likely be too long to match your rim height at the back edge when the block is set set flush with the top edge of the rim. The reason for this is so that the pre-manufactured block will work on many sized guitars. That will need trimmed to match the back edge of the rim + enough extra height to sand to the dome profile.

Also There should be enough clearance in the bolt holes in the block so that you have about 1/16" of adjustment in the neck position either way to make fine adjustments to the neck/top fit

I do see that slight difference in height between the block and the neck when the holes are lined up.

My question remains though in that when I profile the sides down to the 30' radius and sand off some of the block, that moves the neck surface up??? Should I be getting this profiling and the side dimensions closer to final size before gluing in the neck block? Again, most of the pictures I'm seeing, show the block being glued in first and then the profiling taking place. Is it simply that the top profile is so slight that not much material is removed? or do I need to be cautious to remove mostly from the heel of the guitar rather than at the neck?

Sorry, but I'm still confused since I see the parts fitting exactly as they should right now, but it seems that profiling will change the position of things and I can't seem to identify how to compensate.

If you sand the top in to your dome profile all the way around you are right. the neck will drop slightly you should have enough adjustment in the bold hold size of the neck block to account for this if you keep the sanding to no more than needed to achieve the dome.

Now lets say you over sanded. You can always slot the holds in the block slightly with a small round rasp enough to allow re positioning the neck relative to the top. If I remember right LMI uses ¼” blots and the holes in the block are 3/8” That means there is 1/16 per side as it sets. If you slot the holes in the block in the direction you need 1/16” that then gives you 1/8” of adjustment. More than you should ever need. Don’t out think yourself here. And if really worried you don’t have to sand the top side of the rim to the dome. The dome braced top will pull down enough to glue just fine to flat linings/rim and still give the dome to the top. Besides you don’t have to have the upper transverse brace domed. Most of us leave the braces on the top in the upper bout flat and if we do sand the dome into the top linings we do so just to the upper x brace and leave it flat form there.

Me thinks you may be over thinking.

Thanks! I think I understand it now.

/mark