Originally Posted by
Charles Lent
I've made a lot of dovetails using my Leigh D4R jig.
I learned early on that router weight was important when cutting dovetails all day, because I remove the router from the jig each time when changing the work pieces. Lifting the router on and off of the jig can really be hard on the muscles if you do this all day. I built a small platform with a hole in the middle that is the same height as the dovetail jig, to put the router on when I'm changing the work pieces, so I can minimize the lifting and movement of the routers. I did this after the first full day, because I couldn't fully raise my arms to lift the routers again on the next day and had another 2 days of dovetail work to go.
I went with two Dewalt DW618 routers with the D handle bases, because they are one of the lighter routers available that have 1/2" bit capability (too much flex in 1/4" bit shanks). Using 2 routers eliminates the problem of getting the bit heights exactly right when changing the bits in a single router. Set the height on both bits once, and they will be right for as long as you need that setup. The bit height is very critical when doing 1/2 blind dovetails. I like the trigger control that's available when using the D handle bases. I have two 3 base DW618 router kits and a third 2 base DW618 kit in my shop router stable and I prefer them over others that I've tried using for dovetail work. I bought the second router bushing from Leigh, because I found that my router bushing kit did not contain the size bushing that was needed that was close enough in diameter to the original Leigh bushing. The one in the bushing kit was 0.018" smaller in diameter than the Leigh bushing. Use what you want, but this combination of routers and bushings is what has worked the best for me.
When using two identical routers, it's wise to put tape on the top of the router motors with a marking pen profile of the router bit drawn on it to show which bit is installed in the router. DAMHIKT !!
I also learned that drawing a marking pen arrow on the top of the router base and always pointing this arrow toward the D4R when doing the routing, pretty much eliminates the need to get the router bushing and bit perfectly concentric with each other. I go through the centering cone procedure, but if I'm a little bit off with this (can happen if bit height is changed later), keeping the router orientation the same using the arrow will result in a perfect fitting joint pattern, if I do everything else correctly. Doing this will remove any concentricity errors from the joint, because it will shift the whole joint slightly and not change the spacings of the cuts within the joint.
I learned to make two passes for each cut, to make certain that I have stayed against the jig guides, as it's easy to miss a spot and not stay tightly against the guides while making the first pass. Making a shallow climb cut from right to left when first cutting into each cut, then plunging in on the left and working to clear out the rest of the cut will reduce chip out.
I also learned to make use of the bridges between the ends of adjacent guides, so I don't make a cut between them where I shouldn't. I now use pieces of pine to make these bridges, since it's easy to cut the stock for them on the table saw from scrap. I usually then hand cut them to length with a hand held razor saw.
Charley