I made a little more progress the past couple of days. I got my first order of stuff from StewMac the other day - fretwire, control cavity templates, and neck ferrules. I started work on the control cavities and actually took pictures of several stages of the process, and figured I'd show them here. This is the same basic procedure that's used for routing neck pockets and pickup routes as well.
First, I trace the outline of the cavity on the body and remove the majority of the material with a Forsner bit (the largest I have is a 7/8" which works pretty well). I drill to within about 1/8" of the line, and down to about 1/4" above the final depth.
Although the StewMac templates are durable, I feel safer making a "slave" template out of scrap plywood A) so I don't ruin the master and B) so I have a thicker template.
The template gets attached to the body with double sided carpet tape. I use the Duck brand, which you can get at Menards, Home Depot, etc. It's actually the cheaper indoor/outdoor stuff - it's very thin, and seems to stick pretty well. You need to make sure you use an adequate amount of tape, make sure both surfaces (body and template) are extremely clean, level and smooth, and that you apply good pressure when sticking the two together. Then it's just a matter of slowly routing away the remainder of the material using a router and a template bit. You can't really see the bit in this picture, but it's a 1/2" diameter bit with a 1" long cutting length. There are two types of "flush trim" router bits, and both can come in handy, but for this operation, the bearing is attached at the shank end of the bit, which allows you to use it with a template.
Here's what it looks like after the first pass. Because my router bit is only 1" long, I have to make the cut in two stages for the control cavity. The first pass is about an inch deep. For the second pass, the template isn't required, as the bearing just rides on the portion of the cavity that has already been routed to the desired shape.
Here's the final result after the second pass. The depth of the cavity is 1/4" less than the body thickness. 1/4" seems thick enough to me for the front side of the control cavity (where the controls will be mounted). Most pots don't have threads longer than 1/4", so in most cases additional material will need to be removed for each of the controls, but I like to leave as much material in place as practical for durability sake.
Routing for the cavity requires two separate templates - one to do the inside of the cavity, and then a shallow route to accept the cover plate. When I was making my "slave" template for the control plate recess, the collar holding the bearing on the router bit came loose, and the bearing slid out of position... which let the bit dig right into the template. So I'll have to route the outter recess later, after my new template arrives from StewMac.
Up next will be drilling all of the recessed sockets to accept the ferrules for the neck bolts. I also need to see if I can find any place locally that sells something other than brass or zinc threaded inserts (I'd like to use steel if I can find them). Then I'll be able to mount the necks. Lots more work to do before I can actually start finishing any of these - fretboard radiusing, installing the frets, carving the necks and bodies, etc. Some day one of these will actually be usable!
.
