Official Luthiers Forum!

Hi everyone,

I'm about to enter the cnc market as a programmer (btw I offer my services) for musical instruments.

My first challenge is to program a les paul style neck.

I'm up to 4 setups, and I can't machine the headstock contours, since I'm doing 3 Axis only.

Anyone wants to share their machining method, fixtures, etc.. for a neck of this type?

I've seen many videos from factory tours, but none seems to show what I'm looking for.

Any help is greatly appreciated.

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CNC is a tool, not cheating

I'm not sure this will be of any value to you but I've been doing a few LP necks. I machine the tenon on a router table as my cnc has some loose linear guides in its design. These need to be replaced asap. I use the Cnc router to cut the neck shaft, heel, and transition up to the peghead. With a 17degree pitch and 8 inch long peghead, I stop there because of the time aspect. It is faster to cut out the peghead and thickness it then watch the router go for another half hour and cut air. I've been using double sided tape to hold the fretboard surface down to the table. I have also tried a fixture holding the neck in place with the truss rod slot. Either one works about the same.
That little light spot on the heel is from not leaving enough waste when bandsawing out the rough shape before milling.

Not being able to do headstocks isn't a limitation of 3 axis machinery; most companies and luthiers with CNC machines are using 3 axis machines to do theirs.



Are you sure you should be offering to charge money for your services in the same message that you're asking how to execute them?

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I didn't say it wasn't doable, I said that I (myself) wasn't able to do it. If you know how to do it i'd like to know as well. That's why I was asking for help.

Maybe I expressed myself in a wrong way, but this is for a friend. No money involved. I was offering my services in a web forum (here), which usually means free, or trade...If I want to promote my services i'd use a more professional way, eh?

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CNC is a tool, not cheating

Fair enough.

The standard style headstock machining fixtures are shown in the Collings visit Frank Ford did:
http://www.frets.com/FRETSPages/Feature ... ngs01.html

Olson has a bunch of pictures of his headstock vacuum fixtures here:
http://www.olsonguitars.com/shop_fadal.html


Lots of videos here, can give ideas on different fixtures and toolpaths being used:
http://www.youtube.com/results?search_q ... uitar+neck

Taylor was using more or less a long flowline toolpath when I was there, though that was on an acoustic. Those generally work well for electric necks as well, though. If you're in software that doesn't allow them, then it can make sense to make a few parallel toolpaths and stitching the 'right' parts from each together so that you have a low stepover at the edges and a higher stepover in the middle (less steep) part of the neck.

Look up posts by myself or Parser using the forum search for some CAD stuff. I've written some long posts about good tools to use for modeling necks in Rhino, and Parser did a tutorial on neck modeling as well as having posted a lot of helpful stuff in other threads.

A lot of people use a 'trick' of having the back of the headstock surface come down into a triangular type point against the back of the neck to get the blend to look good. I don't use that one, but it works well. You'll see it if you look at a lot of peoples' neck models with edges showing.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I mostly do the backsides of my necks in one operation…..because I have no neck/body angle although I’ve done it both ways.

I use a roughing operation from a crude, squared blank. With a little tweaking, the speed of removal on a roughing operation ought to remove any thoughts of taking risks with band saws and such. I leave .1” on all surfaces for roughing operations. This is usually done with a ¾” ball nosed endmill. When roughing, I always cut the outside contour line first and then work in….which eliminates edge tear out.

For the finishing op on the main length on the neck a 1/2" bull nose endmill is used with a corner .03" radius and a surface operation with a step of about .1". Using a bull nose cutter cuts back on the sanding as compared to using a ball nosed cutter. The cut is oriented 90 degree to the neck. I’ve seen some factories going 0-180 for these cuts but I seem to get better, more predictable results going 90 degrees across the neck.

For the volute the same cutter is used with a finer surfacing step over of .025". This cut is broken down into two operations, one for each side, cutting on a 45 and a 135 degree angle respectively.

For the tenon I use matched, left and right rotating end mills and attack the wood from each direction such that the cut cannot pull out on the surface edges on cross grain cuts. On my main design, the neck is not angled to the body. On a Les Paul there is a 6 degree angle to the body so this operation must be done with a second operation. I can't describe the fixture except to say that I ALWAYS use an aluminum tooling fixture to be able to locate precise origins on my tooling.

The back of the headstock is cut with a surfacing operation using a ½” ball nose cutter. This time the orientation is 0 - 180 up and down the headstock using a .05" stepover. Before that, however, a 3D contour path is run right down the middle of the outside contour line of the headstock using a ½ ball nosed cutter. This removes material that could potentially rip out during this surfacing operation.

There is, perhaps, an interesting trick I use to establish tuning peg hole position. When cutting the back surface of the headstock, the surface is 15 degrees relative to the cnc table. (D)imples are programmed into the model on back of the headstock in the proper position for the tuning pegs and then are cut with a 3D contour operation. This allows registration of the headstock into a fixture with corresponding (p)imples so that cuts can be made on the face of the headstock that register perfectly to the rest of the neck.

Lastly, on the backside set of operations, the rough outside edge of the headstock is cut using a flowline operation, leaving .1" on the edge. This extra material is removed later in a final operation that occurs after the headstock facing is glued into place. The dimple/pimple part and holding fixture relationship facilitates that final cut and maintains the relationship of the headstock profile to the tuning pegs and the inlays.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic