CNC Laminated Neck

I'm currently building a couple laminated CNC necks using flame maple for the base, hard northern maple for the cap, and contoured Indian rosewood fretboard like this:

http://saguaroguitars.com/imgs/Lam Neck 01.jpg

I'll strart by making the trussrod anchors. After an old strat I have had the trussrod break loose in the anchor, I've wanted something that would not lock itself to the anchor by peening the threads. I came up with using a 5/8" aluminum rod, drilled and milled to fit the bent section of a 3/16" trussrod.

http://saguaroguitars.com/imgs/Anchor 01.jpg

This was built using a 5/8" aluminum rod I got from McMaster Carr cut to 0.475" lengths.


http://saguaroguitars.com/imgs/Anchor 02.jpg

I then place five of these in a jig I made and use my CNC to drill pilot holes in the center of the anchors.

http://saguaroguitars.com/imgs/Anchor 04.jpg

I drill these pilot holes through on my drill press and tap them with a 6/32 tap so I can use 6/32 screws to secure the anchors to the bottom side of the jig. I then screw them into the jig and route the area for the bend in the trussrod.

http://saguaroguitars.com/imgs/Anchor 05.jpg

I then drill through them with a 3/16 drill on my drill press. Here is a finished one with a bent trussrod installed.

http://saguaroguitars.com/imgs/Anchor 06.jpg

Next I'll drill the pilot holes for the tuner screws and the threaded inserts for the neck bolts on the backside of the flame maple base.

http://saguaroguitars.com/imgs/Base 02.jpg

http://saguaroguitars.com/imgs/Base 03.jpg

http://saguaroguitars.com/imgs/Base 04.jpg

Cool. Is that a spindle or a milling machine?

It's a Hitachi router

What kind of cnc machine, DIY or commercially made?

It is a DIY with 1" aluminum plates for the gantry. It has 29" X, 22" Y, and 4.5" Z travel.

Pics of the CNC please. ;-)

The neck base is flipped over and the trussrod channel is cut. This is roughed with a 0.125 End mill and then the bottom of the channel is rounded to a 0.093" radius with a 0.125 ball mill

http://saguaroguitars.com/imgs/base 05.jpg

http://saguaroguitars.com/imgs/base 06.jpg

http://saguaroguitars.com/imgs/base 07.jpg

Then the anchor route.

http://saguaroguitars.com/imgs/base 08.jpg

An area around the trussrod route is then routed. A section of the cap will fit into this route.

http://saguaroguitars.com/imgs/base 09.jpg

The area near the end is for the bullet trussrod adjuster. The bullet is longer then this of course, but the CNC will not leave a nice round hole milling it like this, so the bullet hole will be drilled with a jig.

http://saguaroguitars.com/imgs/base 10.jpg

http://saguaroguitars.com/imgs/base 11.jpg

Here it is with the anchor installed.

http://saguaroguitars.com/imgs/base 12.jpg

http://saguaroguitars.com/imgs/base 13.jpg

Now I'll mill the cap. An area in the center is surfaced -0.01"

http://saguaroguitars.com/imgs/base 14.jpg

The trussrod anchor route.

http://saguaroguitars.com/imgs/base 15.jpg

And then the trussrod channel. Again it is roughed with a 0.125 end mill and then the bottom is rounded with a 0.125 ball mill.

http://saguaroguitars.com/imgs/base 16.jpg

Then a large area is roughed with a 0.500 end mill.

http://saguaroguitars.com/imgs/base 18.jpg

And then the fine cut is done with a 0.250 end mill.

http://saguaroguitars.com/imgs/base 19.jpg

http://saguaroguitars.com/imgs/Base 20.jpg

http://saguaroguitars.com/imgs/Base 21.jpg

Here it is with the trussrod installed

http://saguaroguitars.com/imgs/Base 22.jpg

http://saguaroguitars.com/imgs/Base 23.jpg

Here is the cap with the trussrod and the base where it will fit into:

http://saguaroguitars.com/imgs/Base 24.jpg

Gluing the two together.

http://saguaroguitars.com/imgs/Base 25.jpg

Here is the neck with the cap and base glued together.

http://saguaroguitars.com/imgs/Base 26.jpg

http://saguaroguitars.com/imgs/Base 27.jpg

Then I mill the headstock area to a specific thickness for my trussrod bullet jig. The three holes are 0.250 holes drilled in the tuner hole locations for the pins on the jig

http://saguaroguitars.com/imgs/Base 28.jpg

Here is the trussrod bullet jig.

http://saguaroguitars.com/imgs/Base 29.jpg

http://saguaroguitars.com/imgs/Base 30.jpg

If I miss the trussrod, the neck is firewood. Luckily I didn't miss.

http://saguaroguitars.com/imgs/Base 31.jpg

http://saguaroguitars.com/imgs/Base 32.jpg

What kind of accuracy are you getting out of the CNC? In other words, your plug and the cavity...did you have to adjust the numbers besides the offset, to get it to fit?

I'm within a few thousands. The biggest thing I learned was getting the tool offset in my CAM software correct. A 0.250" end mill is not always 0.250". When I get a new mill I start cutting a 1" hole and change the offset until it is 1". Once I have this correct I can draw a cavity 0.005" larger then the part that fits it and the part will fit in snug, like it should. The above base and cap was drawn with 0.005" clearance and it fit snugly with no sanding.

That's a good point. I've never added offset from the CAM to my programming. I should try that myself. Thanks.

Whats your reason for using two pieces of maple? I know it will theoretically be stronger and less prone for warping, but wont it look weird aesthetically with that flame maple? Or am I missing the boat on this one?

Whats your reason for using two pieces of maple? I know it will theoretically be stronger and less prone for warping, but wont it look weird aesthetically with that flame maple? Or am I missing the boat on this one?

In theory, it will hopefully be less prone to warping and should be a more stable neck. Guess I'll have to wait until it is finished, but I think it will look OK with having a thin stripe (~0.100") of regular maple between the flame maple of the base of the neck and the contoured rosewood fretboard. I'll have the position dots centered height wise in the "cap" section.

it is kind of an experiment, if it does look horrible, I guess I have a new neck for my personal guitar.

Now I'll cut the back neck contour. The CAD drawing of the neck contour is below:

http://saguaroguitars.com/imgs/Base 34.jpg

It will be a thick, soft V, about 0.97" at the 1st fret and 1.00 at the 12th fret. So the board is mounted back on the CNC with the back side up.

http://saguaroguitars.com/imgs/Base 33.jpg

The contour is first rough cut using a 0.500 end mill.

http://saguaroguitars.com/imgs/Base 35.jpg

http://saguaroguitars.com/imgs/Base 37.jpg

http://saguaroguitars.com/imgs/Base 38.jpg

Note how the cutting depth went through the 0.830" thick base board, which is OK, this is outside the cut line of the neck.

Now it's time for the fine cut. This is done with a 0.500 ball mill. I use a 0.05" step over which seems to be a good compromise between keeping the CNC time reasonable without having too much time sanding.

Here it is doing the fine cut.

http://saguaroguitars.com/imgs/Base 39.jpg

Not much to see as the dust shoe blocks all the action. Without it, I'd have clouds of maple everywhere.

http://saguaroguitars.com/imgs/Base 40.jpg

http://saguaroguitars.com/imgs/Base 41.jpg

http://saguaroguitars.com/imgs/Base 42.jpg

That is pretty much what I did on my pine Les Paul neck in my earlier thread, " les pine more paul", I used a round nose for all the cuts with a .o4 stepover if I recall correctly.

Now I need to cut a negative 9.5" fretboard radius in the bottom side of the rosewood fretboard and a positive 9.5" radius in the cap. First, I'll need some new radius blocks. Here is the negative block cut on the CNC.

http://saguaroguitars.com/imgs/Base 43.jpg

And the positive radius block:

http://saguaroguitars.com/imgs/Base 44.jpg

This is the two blocks after cutting them out on my table saw:

http://saguaroguitars.com/imgs/Base 45.jpg

Here is a jig I built to hold the rosewood fretboard while cutting the negative radius. I built this jig to be held by my neck jig.

http://saguaroguitars.com/imgs/Base 46.jpg

Here is the fretboard after cutting the negative radius.

http://saguaroguitars.com/imgs/Base 47.jpg

http://saguaroguitars.com/imgs/Base 48.jpg

I used a 0.02 stepover with a 0.500 Ball. At this stepover, the ball mill leaves tiny tool marks in the rosewood. I suppose I could decrease the stepover to get rid of this, but the # of passes and CNC time gets pretty long, so it is easier to clean up the board with a few passes with the sanding block.

http://saguaroguitars.com/imgs/Base 49.jpg

I found out the hard way on a previous neck that it is difficult to hold a radius block square to the neck by hand and if you don't, the edges of the fretboard get rounded off. You can see the fence I pin down to the jig to keep the radius block square.

Here is the fretboard after sanding:

http://saguaroguitars.com/imgs/Base 50.jpg

Here is the neck after cutting the positive 9.5" radius in the cap.

http://saguaroguitars.com/imgs/Base 51.jpg

And here it is with the fretboard sitting on top before it is glued.

http://saguaroguitars.com/imgs/Base 52.jpg

Looks good!

The fretboard was glued on last night so I mounted the neck back on the CNC.

http://saguaroguitars.com/imgs/Base 53.jpg

I cut the headstock transition with a 0.500 bakk and used a 0.02 stepover.

http://saguaroguitars.com/imgs/Base 54.jpg

I mill the headstock to 0.680 thickness for my trussrod jig. Now I need to mill an area to 0.590 thickness for the headstock. This is done with a 0.500 end mill.

http://saguaroguitars.com/imgs/Base 55.jpg

That's not the shape of the headstock, it is an area the headstock will be cut out of.

I do the outline cut in two sections. The main outline cut from the headstock to the heel is done with a 0.500 End mill and looks like this.

http://saguaroguitars.com/imgs/Base 60.jpg

Note the tabs near the heel to hold the neck to the neck blank. The tuner holes are then drilled and then the headstock is cut out with a 0.250 mill.

http://saguaroguitars.com/imgs/Base 61.jpg

There are two tabs on the headstock end as well.

So everything is going along great with the main cutout and then dumbass me forgets to raise the dust shoe during the cut so it clears the neck on such a deep cut. The dust shoe ran into the neck and the CNC lost steps in the Y direction. The machine makes a sickening sound as it is cutting alot deeper and I hit the E stop.

http://saguaroguitars.com/imgs/Base 57.jpg

It basically took about 3/16" off the high E side all the way down the neck. Great, more expensive firewood. After calming down a little I got to see what the side of the neck will look like with the thin (~0.13") strip of normal maple from the cap with the flame maple in the base.

http://saguaroguitars.com/imgs/Base 62.jpg

Some may not like it, but once the fretboard radius is cut, the rosewood would be the same thickness and I think it will look pretty good.

Guess I get to start over with another one. At least this one shouldn't take as long sice I now have all the drawings and jigs this one needed.

I hate when that happens. Can you bind the fingerboard and add some more maple to make it usable?

I hate when that happens. Can you bind the fingerboard and add some more maple to make it usable?

I don't think I can repair it and make it look like much. I usually keep messed up parts for my personal guitars, but I think I could just about build another one to the point this one is by the time I repair it.

Just have to move on and build another one. Oh well, it's probably not the last time I add to the firewood stack.

That is just too cool.

Could be a starting point for a guitar built for smaller hands/children, would likely take some reconfig of your cam file to round out the back and fret board to the new width though.

Could be a starting point for a guitar built for smaller hands/children, would likely take some reconfig of your cam file to round out the back and fret board to the new width though.

That I hadn't thought of. I'll have to take some measurements and see if that is possible.

So I started over with another neck. Here it is after cutting the heasstock transition and tuner holes.

http://saguaroguitars.com/imgs/Base 66.jpg

http://saguaroguitars.com/imgs/Base 67.jpg

http://saguaroguitars.com/imgs/Base 68.jpg

Now I'll do the main cutout with the 0.500 end mill. This time I remembered to raise the dust shoe so I don't screw up another neck. I guess some lessons like this need to be learned the hard way.

http://saguaroguitars.com/imgs/Base 70.jpg

http://saguaroguitars.com/imgs/Base 71.jpg

http://saguaroguitars.com/imgs/Base 72.jpg

Then the headstock cutout with a 0.250 end mill.

http://saguaroguitars.com/imgs/Base 77.jpg

Here are photos of the base to cap transition.

http://saguaroguitars.com/imgs/Base 75.jpg

http://saguaroguitars.com/imgs/Base 76.jpg

http://saguaroguitars.com/imgs/Base 80.jpg

I'll let it sit for a few days still attached by the tabs to whats left of the neck blank to let any stresses in the neck relieve themselves before cutting the fretboard radius and fret slots.

What are you using for the slot cutting operation?

Man .......... for a caveman like myself with my primitive tools this is a little hard to follow.

What are you using for the slot cutting operation?

I've got an 0.023" end mill to cut the fret slots. It has an 0.090 maximum depth of cut, so the fret slots are radiused with the fretboard.

Man .......... for a caveman like myself with my primitive tools this is a little hard to follow.

UGH, UGH :wink:

Been making bodies, and updating my website, etc, but finally got around to working on this neck and updating the thread.

So here it was after gluing the rosewood fretboard on and doing the outline cuts.

http://saguaroguitars.com/imgs/base 83.jpg

Now it needs the fretboard radius cut. I do this with a 0.500 ball mill and have been experimenting with the stepover. I'm finding that getting the stepover down to 0.02" or less leaves a much smoother surface even though it is slow. I didn't time it, but at 75 inches per minute, I think it was somewhee around half an hour to cut the radius. Since a one way trussrod can only take relief out of the neck, I put the trussrod bullet in and tighten it a tiny bit so I'll actually cut a small relief into the fretboard. Here is an after shot without any sanding.

http://saguaroguitars.com/imgs/base 84.jpg

Now I'll cut the nut slot. The bottom of it is radiused to match the 9.5" fretboard radius. Since the slot is 0.125" wide, I cut it with a 0.093" end mill.

http://saguaroguitars.com/imgs/base 85.jpg

Now I'll cut the 0.254" diameter holes for the MOP marker dots with a 0.125" end mill.

http://saguaroguitars.com/imgs/base 86.jpg

Then glue in the dots.


http://saguaroguitars.com/imgs/base 87.jpg

Then sand them flush with a 9.5" radius block.

http://saguaroguitars.com/imgs/base 88.jpg

Here's what the dots look like after sanding

http://saguaroguitars.com/imgs/base 89.jpg

The fret slots are cut with a 0.022" end mill. The fret slots are also matching the 9.5" radius.

http://saguaroguitars.com/imgs/base 90.jpg

http://saguaroguitars.com/imgs/base 91.jpg

The tabs holding the neck to what is left of the neck blank are then cut with a dremel. The neck is then rough sanded. I haven't built a jig to hold the neck sideways on the CNC, so the side marker dots are done on a drill press.

http://saguaroguitars.com/imgs/base 92.jpg

It still needs fretting and finishing. It will be stained, tru oiled on the back, and laquered over the headstock decal.

http://saguaroguitars.com/imgs/base 93.jpg


http://saguaroguitars.com/imgs/base 94.jpg


http://saguaroguitars.com/imgs/base 95.jpg


http://saguaroguitars.com/imgs/base 96.jpg


http://saguaroguitars.com/imgs/base 97.jpg

That looks nice!