Mon bon ami, Alain Moisan, was kind enough to put together a tutorial on his neck carving jig. He also invited me to post it up on the forum which I think is a good idea as it's exceedingly clever. I especially like how he does the volute. So here it is (I'm cutting and pasting from what Alain sent me):
My neck carving jig
This is a small document explaining my neck carving jig. It is used to carve part of the neck heel, the neck itself and the small volute at the back of the headstock.
Once the neck is out of the jig, the area where the heel meets the neck will still need to be manually carved (I haven’t been able to figure out a way to jig that part out…). Also, about 1,5mm to 2mm of extra wood around the neck is left to be manually carved.
The purpose of this jig was not to gain speed as much as it is to obtain similar results from one neck to another one.
This jig uses a small router similar to a laminate trimmer, used with a 1/4’’ spiral bit.
First , here is what the neck blank looks like before being handled by the jig.
You will notice a small birch plywood block has been glued with two face tape on the heel. This will be needed to prevent tearouts when carving the heel.
Here is the base of the jig, with the router attached.
Here is a close-up of the one of the two stoppers.
And a close-up of the router holding device.
You will notice a shaft holding on with wing-nuts. This shaft can be removed to allow the router to rotate. This is used for carving the volute at the back of the headstock. Will will see this later in more details.
Here is the extension that is used to carve the heel. It’s essentially a holding divice that pivots around an axis. It is moved up gradually allowing the router to do multiple passes until the heel is carved.
A guiding hole is made in the neck. A guiding pin placed on the jig is inserted in that hole . It will be used as a center of rotation to allow the neck to rotate while carving. (You will notice there is also a hole with a dowel in it, that is for the bold-on inserts.)
In line with the guiding pin is a press-screw that holds the heel in place while still allowing it to rotate.
Here we can see the neck pivoting around the guiding pin/press-screw axis.
Now here is the jig fully mounted with the heel carving extensionon, ready to start carving.
Here is one half of the heel being carved (itself about half way through…)
I drew a line on the extension to show me where to stop rising the heel. We can see I’m not quite there yet.
Once one half of the heel is done, the entire heel carving extension is fliped and reajusted to do the second half.
And here is a finished heel. (You can clearly see why there is a need for a plywood cap!)
Now that the heel is done, we introduce the main neck carving extension. This will hold the neck in place while carving it.
At each extremity of that extension are cams. These cams will be used a shaping guides.
Here is the neck blank fixed to the extension.
At the heel, some screws are used to hold the neck in place.
This is a close-up of the rectangular block on which the cams will lay. There is one block like this at each end of the jig. The top of these blocks is perfectly in line with the top of the router bit.
In order to do multiple passes, I use small shims placed in between the blocks and the cams. After every pass, I remove on shim at each end, with the last pass done without any shims on.
Here we can see the entire setup ready to start carving.
At each end of the jig, elastic bands are placed to insure the cams are always in contacts with either the shims or the blocks.
Here we see the neck half way done.
And here it is finished.
At this point, I remove the screw with the wingnuts at the base of the router holding device. This allows it to pivot around an axis.
Repeating the process with the shims again, I just rotate the router around its axis and that carves the volute at the back of the headstock.
Here is the neck out of the carving jig, ready to be finished by hand.
One nice thing about my jig is that it doesn’t take much space once stored,
So that’s it. I hope all this was clear enough to understand the process.
Have a nice day!
Alain Moisan
Les Guitares Moisan
www.guitaresmoisan.com