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When using a pre-machined heal block from LMI, StewMac or Watkins; do you cut off material the thickness of the sides so that the neck tenon sits (almost) flush at the bottom of the mortise, or do you leave that gap in there and just shape the block to the side curvature?

 

Also do you finish your top before you glue the pre-machined heal block on.  Without knowing the final thickness of the top, you can’t accurately compensate for it when gluing on the heal block.  Or am just I thinking in too tight of tolerances?  Hesh wrote how he used to be 1/8 -1/4” off due to bowl sanding before he started shimming and I’m thinking in terms of 0.010” off if I thin the top.  I leave the top of my sides flat and compensate while gluing the kerfing/lining on, a la John Mayes DVD (thanks for the tip), so I shouldn’t be off too much.

 

Any tricks for gluing on a pre-machined block?  The mortise makes a bit hard to glue to a centerline.  I was thinking of putting some tape over the top to mark the center on.  I just keep thinking of the abbe error at the end of the neck if I don’t align the block perfectly.

 

"Heel", not "heal"...

Make my own...

I'm an engineer, so my spelling sucks, especially when typing fast.  I deal primarily with numbers.

I would think you would be better with a heal block. When used properly the heal block would attatch itself to all wood that it had contact with in just a few days. No antiseptic needed.   

Philip

_________________
aka konacat

If you think my playing is bad you should hear me sing!
Practice breeds confidence and confidence breeds competence. Unfortunately, I'm stuck in practice.

Zach, I install it full size, then plane it close, then use my sanding dish to get it perfect for gluing.

I've seen folks chop 'em off flush only to realize they need more wood toward the inside of the body. Then they have to glue on a scrap piece and trim it to match.

We all knew what you meant when you said heal. There is a saying that says: "Time heals all wounds and wounds all heels".

Also, gluing blind to a center line, shucks a real engineer would just divide the width in half, draw an auxillary line over at that distance and clamp it up. I should have been an engineer.

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http://www.dickeyguitars.com

Good questions really, most of us initial kit builders probably looked at those blocks and said the same thing. I know where you're coming from.

The answer is, it won't matter. Here's why: you make everything flush at the top when you glue your block to the rim. Then sand your radius into the rim edge to accomodate the top. Once you glue the top on, everything is tidy. When it comes time to fit the neck, the bottom of the tenon is going to hit the bottom of the mortise before the fretboard gets to the top of the guitar...no big deal, just take a dremel and lower the bottom of the mortise to accomodate the neck. When this happens, uh oh, now the bolt holes in the block don't line up with the neck inserts. So you have to accomodate the holes in the block accordingly. On my first two, I simply took a dowell, and filled those holes, and redrilled them. That's only one way to do it, but it worked for me.

All of which leads to this: it would probably be just as easy to make your own block, and rout the mortise in the body/block when it comes time to fit the neck. That way, you get a perfect fit and get to avoid elongating the holes, etc.

If that's clear as mud, somebody will be along shortly to correct me.

Bill

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Eagles may soar, but weasels don't get sucked into jet engines.

[QUOTE=Bruce Dickey] I've seen folks chop 'em off flush only to realize they need more wood toward the inside of the body. Then they have to glue on a scrap piece and trim it to match.[/QUOTE]

Oh, Bruce makes a great point. This is exactly the mistake I made on my first. Didn't leave enough proud to accomodate sanding and had to add a shim!

Bill

_________________
Eagles may soar, but weasels don't get sucked into jet engines.

[QUOTE=zehley]

When using a pre-machined heal block from LMI, StewMac or Watkins; do you cut off material the thickness of the sides so that the neck tenon sits (almost) flush at the bottom of the mortise, or do you leave that gap in there and just shape the block to the side curvature?

 

Also do you finish your top before you glue the pre-machined heal block on.  Without knowing the final thickness of the top, you can’t accurately compensate for it when gluing on the heal block.  Or am just I thinking in too tight of tolerances?  Hesh wrote how he used to be 1/8 -1/4” off due to bowl sanding before he started shimming and I’m thinking in terms of 0.010” off if I thin the top.  I leave the top of my sides flat and compensate while gluing the kerfing/lining on, a la John Mayes DVD (thanks for the tip), so I shouldn’t be off too much.

 

Any tricks for gluing on a pre-machined block?  The mortise makes a bit hard to glue to a centerline.  I was thinking of putting some tape over the top to mark the center on.  I just keep thinking of the abbe error at the end of the neck if I don’t align the block perfectly.

 

[/QUOTE]

Zach:  I think that you mean the neck block and I'll see if I can tell you what I do with mine.

The first question - I don't understand what you are asking but I'll offer this:  On the mortise side/face of the neck block I do sand in a gentle radius that is first marked with radius templates from Stew-Mac.  It's a visual appeal thing for me and I prefer the area where the neck meets the body to have some curve to it.  Depending on the body style I may use 16" - 22" radius.  This does make the neck body joint perhaps harder to perfect since you are no longer working with flat surfaces.  But the same procedures work well, just true the area to be consistently radiused, and floss to match.  It you mean do I cut off material to reduce the height of the block for the respective sides - yes and of course it depends on the height of the sides.  As you mentioned, depending on body style, I shim the top of the commercial neck block(s) ( this works with any and all of them ) 1/8" - 1/4" but this is for when the top edge of the sides are radiused either with a plane, the dish, or both.  The shimming is only if you leave the front edge of your sides straight for bender alignment or don't intend to radius the front of the guitar.  I have not seen the Mayes DVD that you speak of so I am guessing that he uses the kerfed linings to form the radius?

On Watkins neck blocks where the holes for the bolts are on the inside of the guitar side there are counter sunk holes.  I slice this part of the neck blocks off in the band saw down to the bottom of the counter syncs to reduce weight and make the block smaller.  Again, a personal preference and it matches my bracing style better.

As for top thickness I only worry about the top of the neck block, the kerfed linings, and the sides all being properly radiused in the dish.  The height of the neck can be adjusted by taking material off the bottom end of the tenon, or, by lengthening the mortise.  The reason for why I shim the neck block and don't radius the sides prior to bending helps here greatly.  There is also the issue of the neck block bolt holes aligning.  Any time you mess with the length of the mortise or tenon your bolt holes will be off.  Again the shims help with this too.

As for the centerline that is not there since the mortise is cut I glue my sides to the block with the guitar face down which takes the mortise out of play because you can see he bottom, now up, of the neck block.  Again the sides are flat on the front face.  Do measure in advance, twice in fact, to be sure that the mortise is in fact in the center of the block and that the block is square on three sides.  Mark the center of the face of the neck block on the back of the guitar side, upright surface of the neck block, and glue the sides to the block face.

Here is a pic of one a did several weeks ago.



I hope something here helps Zach.

Bruce, I'm not questioning the faces that contacts the top and back that need to match that curve, but the face that contacts the sides and the location of the predrilled motise and holes along the axis perpendicular to the strings.  The block fits the neck perfectly before installation.  Then when you install it with the sides in between and there a gap in between the mortise and tenon the size of the side thickness.  Does it matter if that gap is there or should all surfaces be in contact.  My intuition tells me the gap is fine and will allow the neck to sit tight on the sides, but what do I know.  Then if you dont know your final top thickness at this point, the block may be too close to the top or too far away requiring adjustment to the bolt holes, countersinks and mortise (or tenon).  I like getting it right the first time so I dont have to fix it later.

If I understood your question right, you are concerned about the side thickness shortening the amount of tenon in the mortise. I look at it this way .095" is not going to shorten it enough to matter. But in truth if your tenon is 3/4" wide and 7/8" long and your sides are .095" thick the the effective shoulder of the tenon is still 7/8". All the side thickness did was deepen the mortice, not shorten the load bearing tenon length.

Michael, that is the question I was asking on the mortise depth.  I didnt think it mattered, but wasnt sure I was missing something.

Bill, Hesh, I can see how you doing it.  I just think that these parts are made on a CNC, so it seems a waste not to used the accuracy of how they were made, instead of filling and drilling to make it fit.  It just seemed logical how John planes the top edge of the sides and cuts the baks profile before bending and glues the kerfing on to make the top profile.  This solved a lot of issues when thinking about the top profile and the building process.

The hole alignment issue is because the LMI block I have, which i assume the other are the same, comes with the block and neck fingerboard surface flush.  There are instructions stickered to the part to remove material the thickness of the top.  I plan on gluing the block on untrimmed, but with the amount equal to the top thickness sticking over the sides.  This amount is my dilemma.  Not thicknessing my top yet, i dont know how far to have it stick up over the top of the side.  If all is planned right, no modifications to the block should be required to install the neck.

Terrific dude...glad you got it figured out. Don't forget photos of your progress. We're a visual bunch.

Bill

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Eagles may soar, but weasels don't get sucked into jet engines.

[QUOTE=zehley]

The hole alignment issue is because the LMI block I have, which i assume the other are the same, comes with the block and neck fingerboard surface flush.  There are instructions stickered to the part to remove material the thickness of the top.  I plan on gluing the block on untrimmed, but with the amount equal to the top thickness sticking over the sides.  This amount is my dilemma.  Not thicknessing my top yet, i dont know how far to have it stick up over the top of the side.  If all is planned right, no modifications to the block should be required to install the neck.

[/QUOTE]

Yep Zach I understand that part and thought that is what you meant.

What's missing for me here is the Mayes method of using the kerfed linings to build the radius on the front of the guitar.  If it is what I think that it is I can see how you could start from what ever height that you have at the neck block.  Maybe fill us in on this method so we can get the picture?

I have yet to build with a commercial neck block where adjustment is not needed.  So don't be surprised if you have to make some adjustments too.

Having used LMI necks until I found John Watkins I know them pretty well.  I always thought that the included note about removing material was not very clear but I understood it.  This is so your top and the fretboard surface of the neck are flush and you understood it too from what you wrote.  If this is your biggest concern why not just pick an arbitrary number, say .125 for the top thickness and remove that much material from the top of the tenon?  And of course keep your top .128ish thick in that area so allow for finish sanding and leveling of the upper bout.

But radiusing the top of the guitar changes many things.

I probably had it figured out before, but would rather learn from someone elses mistake than make one my own.  I'm always looking for tricks to make it easier, but sometimes there are none.  I've been taking lots of pics because I'm visual as well(thats why I cant spell very well), just never had time to get them out of my camera.  I'm either at home trying or planning the next step, or at work trying to work and not think about making geeters.  Its definatly an addiction.