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Holes in the neck pocket
- Thread starter Brando_Beast
- Start date
I'm not certain, but my guess would be it was used for a temporary holder to support the body during painting and finishing.
If you see two extra smaller holes that look like screws were in them, those are usually from attaching the body to a holder during painting, like Evan said.
A single larger hole in the middle is usually for an index pin, used to locate the body blank accurately in a holding fixture, in a Pin Router or CNC Router. The routing is done in several steps, front and back. The pin in the hole makes sure it is indexed correctly when the body is flipped over.
A single larger hole in the middle is usually for an index pin, used to locate the body blank accurately in a holding fixture, in a Pin Router or CNC Router. The routing is done in several steps, front and back. The pin in the hole makes sure it is indexed correctly when the body is flipped over.
That makes so much sense now, plus it should have been obvious because I have watched so many guitar videos on YouTube.
I think Bruce gets the points on this one. Those photos look like they show a single larger hole for an index pin.
I think Bruce gets the points on this one. Those photos look like they show a single larger hole for an index pin.
Of course one hole isn't normally enough for indexing/registration - to prevent rotation there will be another somewhere on the body - normally under the bridge or some other place that will be covered by another bit of hardware such as a pickguard.
I think Bruce gets the points on this one. Those photos look like they show a single larger hole for an index pin.
Well, I actually do this professionally. I design processes, tooling and fixtures for....routing bass bodies. For CNC machines and old-school non-CNC Pin Routers. Holes and index pins are the common method of aligning parts in machines.
If you are curious about this stuff, check out my long thread about Pin Routers. In there, I show how I use steel dowel pins to index blank parts onto fixtures.
https://www.talkbass.com/threads/pin-routers-the-old-school-production-workhorses.1405214/
Like SteveCS points out, we usually use two index pins to accurately line up the part. There's commonly a second mysterious hole back under the bridge. Those two holes are a clear sign of a CNC-cut body. They are usually about 1/2" diameter x 1/4" deep.
The reason for that is that they are cut with the same router bit (usually 3/8" dia) that cuts the neck pocket and pickup cavities. After the bit has finished routing out the neck pocket, the computer code tells it to move to the center of the neck pocket, plunge down 1/4", and spin a little 1/16" radius circle. The result is a 1/2" dia x 1/4" deep shallow hole, accurately placed in relation to the other features of the body.
In the next operation, the body blank is flipped over and placed into another fixture. That fixture has two 1/2" dia x 1/4" high steel pins sticking up. The body blank pops onto those two pins to line it up accurately. Some other clamps are secured. And the operator presses the Go button to start the next sequence of routing operations.
That's probably way more technical info than you wanted, but that's what those holes are for.
I absolutely love this stuff, I am fascinated and wish I had all this info when I was a teenager (I am 36)
Thanks for the lecture. Please don't ever think "sorry for lecturing you" Lecture me! That's what I signed up for sir!
Thanks for the great explanation!
How does Fender keep everything lined up when they cut their American Vintage Series bodies? Those bodies don't seem to have any of those indexing holes.
I don't know specifically, but there are many ways to index a part (a wood blank) without leaving those telltale holes. Most likely, they placed two index pin holes in the waste wood area outside the perimeter of the body. Then they make of all the operations, drilling and routing, happen while that waste wood is still there. Every holding fixture has pins that go into those same two holes, so that everything lines up. The final operation is a skim trim around the perimeter which breaks through a thin web of wood, and the body breaks free from the waste wood scraps. The index holes go in the dumpster with the scraps. But the body doesn't need them any more because all the machining operations that require accurate alignment are done.
Over in my Pin Routers thread, you'll see that I do a similar thing when I'm routing all the internal chambers inside the top or back of one of my Scroll Bass bodies. Two big index pins in the opposite corners of the waste wood, outside the perimeter. After I do all the routing of the chambers, I rout the perimeter down to a thin sliver, then trim off the waste wood on the bandsaw.
You can see the index holes out in the waste wood. The four larger holes are for bolts that clamp the board down into another machine, while I'm doing the surface planing. The two smaller holes on opposite corners are the indexing holes. They fit on 3/16" pins on the big fixture in the pin router.
Here's the back with the waste wood trimmed away.