Official Luthiers Forum! :: View topic - When to rout the mortise in the neck block

I clamp my well squared neck block to my bench top and glue on the rims - (no, I do not glue the blocks in in the mold) this ensures that everything remains perpendicular to the bench surface.

Michaeldc wrote:

I clamp my well squared neck block to my bench top and glue on the rims - (no, I do not glue the blocks in in the mold) this ensures that everything remains perpendicular to the bench surface.

I need to move in this direction vs screwing through the mold into the block. There is still opportunity for things to squirm a bit, even with the screw, if you don’t have full height mold / cauls. Clamping the block to a flat surface just makes sense.

James—

I use screws, too. This is a John Hall idea. During body construction, instead of using a head to tail spreader to keep the head block and tail block flush to the mold, you drive screws through the mold from the outside and into the blocks. I use two screws per block (spread vertically), and that works well for me. Since that’s how you keep the blocks where they should be, it is a natural step to want to glue the blocks to the sides using the screws. But, as you have heard, that can be hard to do well and get a good glue joint. Some folks get better results by gluing the blocks to the sides away from the mold.

Author:	J De Rocher [ Tue Jan 16, 2024 12:41 am ]
Post subject:	When to rout the mortise in the neck block
I have a question but didn't want to hijack Brad's thread about binding blow outs when routing the mortise in the neck block. I guess this may be a general question about different work flows. The builder I learned from routed the mortise in the neck block before gluing it to the sides. That's how I've done it ever since. I use bolt-on necks with a tenon. When it comes time to open the mortise, I use a pull saw to cut a small opening in the sides covering the mortise at the top of the mortise. The opening is big enough to fit a flush trim bit into the mortise and then I free hand rout the opening. This approach has always worked for me with no mishaps (so far). So, is there an advantage to routing the mortise in the fully assembled body either functionally or as part of a work flow? I like to learn about approaches other people use so I'm wondering. Thanks.

Author:	meddlingfool [ Tue Jan 16, 2024 1:22 am ]
Post subject:	Re: When to rout the mortise in the neck block
To me, it has always made sense to base your angles from actual reality rather than predicted idealization. It’s so easy to miss by a smidge but also so easy to account for it… Any advantage/disadvantage will stem out from workflow. Either/or works if you accommodate in process.

Author:	Michaeldc [ Tue Jan 16, 2024 7:55 am ]
Post subject:	Re: When to rout the mortise in the neck block
Hi Jay, You’ve seen my approach before. I make neck blocks 10 at a time on my CNC. The same block fits everything from my “0” to my 28” multi-scale baritone, exact same block. After radiusing to match the body profile I clamp my well squared neck block to my bench top and glue on the rims - (no, I do not glue the blocks in in the mold) this ensures that everything remains perpendicular to the bench surface. Once the neck and tail block are glued in, I return the assembly to the mold/form and cut a 40’ radius on the top side using my powered dish sander. Then the top linings go in - back to the dish sander. Popsicle stick brace and upper transverse - back to the dish sander. The assembly gets checked for proper alignment throughout the process using a clear acrylic template and is finally placed on a 40’ radius assembly board where the braced top gets glued to the rims. I know it’s different, but it’s what I’ve come up with over the years. Cheers, M

Author:	doncaparker [ Tue Jan 16, 2024 8:09 am ]
Post subject:	Re: When to rout the mortise in the neck block
I’ve cut the mortise in the block before assembly, and I’ve cut it after the whole body is glued together, including binding and purfling. I currently do the latter. Both work fine, but I prefer cutting the mortise later and creating good alignment in the completed box, rather than cutting the mortise earlier and trying to maintain good alignment as the box is constructed. Just my personal preference.

Author:	SteveSmith [ Tue Jan 16, 2024 8:49 am ]
Post subject:	Re: When to rout the mortise in the neck block
I've done dovetails and bolt-on mortices in block before assembly and they worked out but like Don, I cut them after the box is built now. Of course I am also bending my sides by hand so each box is a bit different and my tolerances are not as tight as some others, especially those using CNCs.

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Author:	bcombs510 [ Tue Jan 16, 2024 8:56 am ]
Post subject:	Re: When to rout the mortise in the neck block
Michaeldc wrote: I clamp my well squared neck block to my bench top and glue on the rims - (no, I do not glue the blocks in in the mold) this ensures that everything remains perpendicular to the bench surface. I need to move in this direction vs screwing through the mold into the block. There is still opportunity for things to squirm a bit, even with the screw, if you don’t have full height mold / cauls. Clamping the block to a flat surface just makes sense. Sent from my iPhone using Tapatalk Pro

Author:	SteveSmith [ Tue Jan 16, 2024 9:04 am ]
Post subject:	Re: When to rout the mortise in the neck block
bcombs510 wrote: Michaeldc wrote: I clamp my well squared neck block to my bench top and glue on the rims - (no, I do not glue the blocks in in the mold) this ensures that everything remains perpendicular to the bench surface. I need to move in this direction vs screwing through the mold into the block. There is still opportunity for things to squirm a bit, even with the screw, if you don’t have full height mold / cauls. Clamping the block to a flat surface just makes sense. I like that idea. I've been screwing the blocks into the mold but that is a bit of a PITA. Maybe I can rig up a method to clamp the blocks down and use the mold too when I glue the blocks to the sides. Hmm....

Author:	James Orr [ Tue Jan 16, 2024 11:33 pm ]
Post subject:	Re: When to rout the mortise in the neck block
I used pre-carved necks on my first few guitars. They came as a neck/end block combo. I always worried about getting them glued in just right so that the mortis was in line with the centerline of the guitar. I personally find it easier to rout the mortis once the block is glued in. Brad and Steve, I’m not quite sure I understand what you mean about screwing the blocks into the mold? Sent from my iPhone using Tapatalk

Author:	doncaparker [ Wed Jan 17, 2024 12:00 am ]
Post subject:	Re: When to rout the mortise in the neck block
James— I use screws, too. This is a John Hall idea. During body construction, instead of using a head to tail spreader to keep the head block and tail block flush to the mold, you drive screws through the mold from the outside and into the blocks. I use two screws per block (spread vertically), and that works well for me. Since that’s how you keep the blocks where they should be, it is a natural step to want to glue the blocks to the sides using the screws. But, as you have heard, that can be hard to do well and get a good glue joint. Some folks get better results by gluing the blocks to the sides away from the mold.

Author:	Terence Kennedy [ Wed Jan 17, 2024 6:03 pm ]
Post subject:	Re: When to rout the mortise in the neck block
I started out cutting the mortise first but later went to doing it after the box was assembled. Both ways worked. I think I changed thinking the centering would be more accurate but quite honestly I don’t remember any big issues doing it first. Well except one where I opened the mortise before cutting the binding. Whoops, nice scallop right on the centerline of the back.

Author:	James Orr [ Wed Jan 17, 2024 7:29 pm ]
Post subject:	When to rout the mortise in the neck block
doncaparker wrote: James— I use screws, too. This is a John Hall idea. During body construction, instead of using a head to tail spreader to keep the head block and tail block flush to the mold, you drive screws through the mold from the outside and into the blocks. I use two screws per block (spread vertically), and that works well for me. Since that’s how you keep the blocks where they should be, it is a natural step to want to glue the blocks to the sides using the screws. But, as you have heard, that can be hard to do well and get a good glue joint. Some folks get better results by gluing the blocks to the sides away from the mold. Very interesting. I’ve always used F-clamps to clamp them from outside of the mold, into (or against) the mold. Where the sides are proud of the mold, I use a caul to protect the sides from clamp marks. Sent from my iPhone using Tapatalk

Author:	rbuddy [ Thu Jan 18, 2024 12:16 pm ]
Post subject:	Re: When to rout the mortise in the neck block
I guess the reality in my shop is that every step in building is a compromise, in this case between the perfection I want to happen and what happens in real life. Sometimes individually they don't show to the eye but cumulatively they might be enough to wish for a little correction. Making the neck mortise happen when the box is closed and bound gives me one last chance to adjust position to make slight corrections and have everything line up. Neck, top seam, sound hole, butt wedge -- all that stuff.

Author:	SteveSmith [ Thu Jan 18, 2024 3:42 pm ]
Post subject:	Re: When to rout the mortise in the neck block
For me the screws in the blocks are to maintain block alignment in the jig and to eliminate the need for a neck block-to-tail block spreader when gluing the back and top. I still also use clamps when gluing the sides to the blocks.

Author:	bcombs510 [ Thu Jan 18, 2024 4:45 pm ]
Post subject:	Re: When to rout the mortise in the neck block
Yeah, I was going to mention this too.. the possible rotation of the neck block when gluing the plates is the real way to hose up the neck geometry real quick. I like the idea Don had of two screws vertically oriented. I’ve been toying with the idea of pulling a square of vacuum through the mold as well, could be an interesting way to do it from the outside without having any holes. Some context: I don’t always want to put an end wedge in so the holes there are problematic in some cases. Ex: Spreaders are the logical answer but what’s the fun in that? Sent from my iPhone using Tapatalk Pro

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Author:	SteveSmith [ Thu Jan 18, 2024 6:28 pm ]
Post subject:	Re: When to rout the mortise in the neck block
The longwise spreader I had wasn’t very good, I’ve thought about making a better one. Then I could just use a couple of 1/8” dowel pins to index the neck block in place. I don’t see a need to index the tail block in position if I have a decent spreader to hold it in place while I glue the top and back on.

Author:	Darrel Friesen [ Fri Jan 19, 2024 5:35 pm ]
Post subject:	Re: When to rout the mortise in the neck block
I drill the holes for the bolt on neck (I use hanger bolts) and truss rod after the block is glued to the sides but before glueing the back and sides on. Easy for me on the drillpress. I have a Simpson Jig I bought at a swapapalooza way back when so still use it for setting the neck angle and routing the mortise and tenon. Transfer punches make it easy for me to mark the hanger bolt locations on the neck tenon. Nowhere near as elegant as some of the methods on this thread but works well for this luddite.