Asymmetrical - this refers to the situation where the dovetails aren't a mirror image from one end of the joint line to the other.
Example:
Code:
Symmetrical:[FONT=Courier New]
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[U]V V V V V[/U][/FONT]
Asymmetrical:[FONT=Courier New]
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[U]V V V V V[/U][/FONT]
In that example, try to image the tail panel in the same plane as your screen, with the pin panel perpendicular to the screen (coming up at ya). This is exaggerated, of course. Each joint has the same width, and the pins are pretty nearly arranged the same way. But in the second example, that pin next to the right end is not exactly "symmetrical" compared to its mirror image pin on the left side. Although this example is a little exaggerated, this is actually EXACTLY the situation you get with one of these Leigh jigs. Since you layout the pins by eye, there will certainly be some minute asymmetry like this. You can do it intentionally for effect, or you can try to line things up as exactly as you can. Either way, it doesn't matter, there will still be some degree of asymmetry with this jig.
Now, here is why this is important: you can see how this creates a unique situation where the side panels are not interchangeable... you couldn't flip the tails board over and expect it to still fit over the pins in the pins board. This is probably a little hard to visualize, but believe me - when you make a sample joint you will see immediately why this is true. This is why you have to figure out ahead of time which face is the OUTSIDE/INSIDE face for each panel and MARK each face accordingly - BEFORE you start cutting!
It's hard to see, but I did this on my D4 storage box. Look at the bottom joint - you can see it more clearly. The pin on the left end (front of the box) is wider than it's mirror image pin on the right end (back of the box).
I did this intentionally so I could make room for the groove for the sliding door. But you can see how I couldn't take that end panel and flip it over (inside for outside) and still expect it to fit. Hopefully this all makes sense... I know I need more coffee. 8-O