On Sunday, July 31, 2016 at 8:29:41 AM UTC-7, Leon wrote:
On 7/30/2016 11:47 PM, whit3rd wrote:
On Saturday, July 30, 2016 at 9:11:39 PM UTC-7, Leon wrote:
On 7/30/2016 4:09 PM, whit3rd wrote:

For making sliding-dovetail slots, one requires a guide jig.

Actually I made sliding DT joints with my router table and fence. No jig.

I'm making dovetail slots across a 7' board, for tall bookshelves. Can't
get it accurate enough on the router table,

Well there you only need a straight edge guide, I don't see the need for
a guide bushing. The guide can be a hunk of plywood.

The slot isn't the size of one pass with the dovetail bit, though. It's nearly the
full thickness of the thinnest of the shelf boards There's only about
..003" tolerance, for the shelves to be a press-fit in the uprights. I'm actually
using half-dovetails, one router with straight bit against the left edge, one with a
dovetail bit against the right edge; that simplifies the shelf-end cuts.

The guide is plywood, but the guiding edge has a hard face applied; I tried steel,
and quartersawn oak. Both work, but straight steel L-section is expensive
(and if it's not-so-straight, you're back to seeking hardwood scraps for the
next edge).