Hey frets4ever;
I still stand by my statement that a pin router with a fixture and a human operator can be more efficient in a high production factory. It has to do with dividing production down into operations which can be all be run continuously, at the same time. That's how you get the highest flow of parts per hour.
A single complex CNC machine that does a sequence of operations on the part can end up becoming a bottleneck in the production flow, because while it is doing one operation, all its other operations are shut down, waiting. It can't do them all at the same time continuously.
On the other hand, if you divide the production down into a sequence of individual operations, each being done by its own simpler machine, then all the machines can be kept running all the time, without having to pause and wait for each other. This multiplies the flow of parts per hour.
For example:
A basic slab-style bass body. You can set up a CNC machine with a tool changer to do a sequence of operations covering almost everything on the top face of the body. The blank pops into a single holding fixture. Maybe it's four routing operations, each with a different router bit, and three drilling operations, with different size drill bits. It'll do the whole sequence in, say, 7 minutes.
If you directly compare a CNC machine with a non-CNC pin router, the cutting time for a simple 2-D routing operation is about the same. The pin router, with a good fixture and trained human, can feed almost as fast. The feed rate and depth of cut in both machines will be limited by how far you can push it without breaking the part or burning the wood.
One big advantage of the CNC machine is the rapid tool change. In 2-3 seconds, it can change to a different router bit. Different size or shape. That's something a pin router cannot do quickly.
The other big advantage of a CNC machine is that it can change the depth (Z axis) on the fly, continuously. This speeds up 2-D cutting, and allows 3-D cutting. A pin router can change fairly quickly between a sequence of pre-set depth settings, but not continuously variable. A pin router is basically a 2-D machine, although it can do some limited 3-D cutting with more complex moving-part fixtures.
For drilling holes, a CNC machine is slower. It has the advantage of a tool changer, which can change from a router bit to a drill bit, or to a different drill bit, in a few seconds. But it can only drill one hole at a time, because it only has one spindle. In comparison, a human-operated multi-spindle (gang) drill press can be set up with different drill sizes and a good fixture. It can drill all the holes at the same time, in a few seconds total.
Back to the example: On the other side of the room, you set up four pin routers and one gang drill press. Each with a single, special fixture. Each pin router does its operation with one size cutter. Now, if you take one wood blank and go through the sequence of the machines, four pin routers and one drill press, it'll take maybe 10 minutes total. A little longer than the CNC, mostly because of the time to move the blank from one machine to the next, vs the automatic tool changer. So, the time to make one body is a little longer.
But here's the important thing: Put a human in front of each of those work stations, and keep them running continuously, passing the blanks down the line. Then every 10 minutes, they'll be completing 5 bodies not 1. That's the multiplier.
That's how you make a high production factory. The old Henry Ford idea. Break the job down into individual simpler defined tasks, in a tight sequence, where the workers can all do their operations continuously, without having to wait for others. The key is making an efficient handoff of the product from one work station to the next.
