Attach routing template to spruce top

[Peter Wilcox]

I need to route a neck pocket in an acoustic guitar with a spruce top. I can't think of a reasonable way to do it without the template moving with clamps, or wood tear out with tape. I did one by attaching sandpaper to the bottom of the template to give it some purchase against the top, but of course I couldn't clamp very hard because the sides are thin and I didn't want to damage them (back not on yet). Well, it moved so I had a repair to do also.

My next thought is to use painter's masking tape glued back to back to make double sided tape, then heating the whole template when done so it releases off the top without tear out. I'd probably clamp it too as I don't have much confidence in the tape.

Any other suggestions?

[Bryan Bear]

I would say you should have good results with masking tape and heat to remove but practice on scrap to see if you can get it warm enough to release easily through the template.

[Barry Daniels]

Painters tape is not very strong. I use thin, fabric reinforced double sided tape. A couple of square inches of coverage with this tape will not let go until you soak in a little bit of mineral spirits for release.

[Bob Gramann]

How about making a template with a central tongue that you can screw into the middle of the area to be removed. Once the perimeter of the pocket is cleanly cut, you can remove the template and carefully free hand the cutting out of the center. Or, then make a template that fits the pocket with the center excluded so you can then cut out the center. In other words, two templates, two steps.

[Peter Wilcox]

Thanks for your replies. Bob, I think I'll try your idea as the simplest and most secure. I'll try to modify the existing template I just made to put a tongue in it to screw down to the central pocket area. I'll let you all know how it works out (or if I'll be rebuilding the guitar. )

[Bob Gramann]

You can attach the existing template to a new board and cut just the perimeter with the existing template leaving the tongue on the new piece, now, the new template.

[Peter Wilcox]

Too late, I already modified the existing one with scraps, and I'm too cheap to waste another piece of MDF. Maybe a little overbuilt, but I don't want it to move.

Now I just need to ramp up my intestinal fortitude to use it on the guitar, but scrap first as usual.

[Clay Schaeffer]

You could cut out the "sound hole" area in your template and clamp it through the soundhole of the guitar.

[Peter Wilcox]

I thought of that, but then realized the clamps would likely be in the way of the router base. The sound hole starts less than an inch below the end of the neck.

[Clay Schaeffer]

Most soundholes are close to 4 inches wide. If you clamp at the far end and use a trim router ( take several shallow cuts) you may be able to get by and not mis-align the jig in the process. A PC 690 has a 6 inch sub base, and you would only need a little less than 1/2 that distance for clearance, but there may be something I'm not considering that would make it impracticable.

[Marshall Dixon]

Any other suggestions?

Something to think about next time, maybe:

I build a composite heel-block which leaves a 3/4” wide by 3/4” deep pocket that runs about 3/4 the depth of at the top. If it were music it would be a waltz.

Anyway, I cut a notch in the top/sides where the neck goes, big enough to get a 1/2” bearing-on-bottom router bit in there and use the pocket as a guide. I just rest the router on the curved top keeping it perpendicular by hand control. As this doesn’t cut through the top (because I stops the bearing at the bottom), I save the tear out part for when I pretty it up by hand. I've taken to scoring the face of the mortice by hand. A foot operated on/off switch helps here.

I've read of some luthiers who cut the dovetail mortise on a table saw before glue-up and I‘ve done that with a Stauffer type neck.

When gluing the rim with heel block to the back (or the top if you do that first) you need to make sure the block is true to the centerline in all cases.

[Peter Wilcox]

Hi Marshall - I don't quite understand your process from the description - a picture would help if you have one.

Yesterday most of the snow finally melted and it was 50 degrees outside, so I finally did the neck pocket.(I like to route outside so the wind blows the dust away. ) It went well except for chipping out part of the side. I put tape on the right side of the pocket where I knew there would be a problem, but didn't realize the bottom would be too (and it looks like it wasn't glued very well either.) I guess pre-scoring these areas as you suggest would be the way to go. Live and learn. I found the chip and glued it back in, so it should be fine.

Here's a few pics of the results.

[Bob Gramann]

Congratulations. Nice rosette.

[Steve Sawyer]

Congratulations. Nice rosette.

I'll second that! VERY nice!!

[Marshall Dixon]

Hi Marshall - I don't quite understand your process from the description - a picture would help if you have one.

Hey Peter,


That looks like the back side of Lassen on the other side of the neck pocket.

Here is a picture of the heel block of my most recent build. This guitar is an experiment, in case you're wondering what the inner plate is about. The wood was narrow and long. Thinking about my speaker building days I'm aiming for some lengthening of the box as found in transmission line or folded horn speakers. Just a slight boost in the lower range would help the smaller box. We'll see:

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There is a 3/4" spacer at the bottom of the joint as pictured here on a cut-away; the V-cut to get the bit inside, and the result with extra space in the top for the truss rod. Clamp the guitar upright hand holding the router. The router stops at the V in the top when the bearing hits. Finish by hand:

[Peter Wilcox]

Sorry Marshall, I'm still having trouble visualizing it. What does the neck heel look like that fits into it, and how does it attach - glue?

That's an interesting idea folding the acoustic space inside the guitar. Let us know how it sounds. I occasionally make speaker cabinets, and years ago wanted to make a folded horn for bass. I found one at a yard sale, and it's size and weight made it impractical for an old guy to transport to gigs.

That is Thompson Peak in the picture looking southwest, with US395 and Janesville in the valley. Here's a pic of the rising moon I took yesterday morning over Honey Lake looking southeast from my deck. Nice up here on the side of a hill.

[Marshall Dixon]

...Here's a pic of the rising moon I took yesterday morning over Honey Lake looking southeast from my deck. Nice up here on the side of a hill.

Fresh air. I'm in the canyon of the Rogue with 1800 foot ridge to the north and a 4200 ft mountain to the northwest. Miss the wide open spaces. I bet the stars are something to see from your place.

Ok, so now I get to air my dirty laundry.

I hadn't done this joint for 5 years and had several guides to put in my tenoning jig and used one too short. So I had to move the threaded inserts closer together. That required filling of the original hole in the headblock and drilling a new one after the body was together. Also that nasty little bit of tearout on the top just below the mortice. Let's keep this to ourselves.

You could glue the this but I want to be able to take it apart in future. A dovetail would be easier to take apart.

This joint is fairly easy to make a nice fit and take apart again. That's important when you have to do it 3 times because you're still not happy with it.

Here are a couple of pics that I think will explaine it. I use epoxy on the threaded inserts. I used to worry about the strength of these, probably because of some implied inferiority by some. I read an article in American Lutherie magazine, by a physics oriented builder, that the pull on the heel 2 1/2 inches from the top, with 165 lbs tension (med steel strings) was 35 lbs. Or so - thats from recollection. And if they come out... well, just put them back in.

Got the fretboard slotted today. next steps: peg head, fingerboard (I fret it first) heel cap, shape neck, finish. I have a feeling I forgot something.

[Marshall Dixon]

.. seems like I have more trouble with this software than I do building guitars.The 4200 foot mountain is to the SOUTHWEST dammit.

[Marshall Dixon]

.duplicate

[Peter Wilcox]

Thanks Marshall, I get it now.

Here's the design of my neck attachment. It's held on by string tension (and a nice tight pocket), and it's so great to be able to adjust the action with just the turn of a small screw through the fretboard. Here's the thread if you haven't seen it, and a pic from that thread.

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