Mark & Juanita wrote:

Every time I use it, I spend a great deal
of time getting it set up and in the past have finally "settled" for as
good as I can get. I decided not to settle this time and have spent a
great deal of time trying to get the jig to provide me with gap-free 1/2
blind joints.

I get the part about adjustment up and down loosening or
tightening the joint.

The problems I am having are getting gaps on the
*side* of some of the joints, and the bottom gaps when adjusting tightness
not being even across the width of the board (only 3 1/4") despite the fact
that
- the fingers are flat on the pin board and
- the spacer board and the tail board is uniform across the width of the
spacer board.
- I've tried recentering the router bit
(one of the reasons I bought template bases for my Bosch laminate trim
router was so I could easily center the bushing),
- I've tried swapping jig fingers (now I've got a bit of springiness
when
tightening the finger jig because of having to remove the ends).
- I've tried rotating the router 180 degrees to rout the pins after
routing the pins.

Nothing seems to be helping much.

Next thought is lapping the router baseplate dead flat.

I've been trying to hold it flat to the center, but am getting rocking.

Would a 5 mil rock cause significant problems?

Any help would be appreciated. As a pre-emptive, the answer, "just chop
them by hand" is not an answer I'm seeking -- I'm really trying to figure
out why this machine is not working as advertised.

Mark:

As you've discovered - while having variable spacing fingers - there are
several inherent problems with the Leigh DT Jig design - starting with
those moveable fingers. To move them you have to have SOME slop
in the hole in the finger - and some way of locking the fingers in
postion
where you want them. That's the first design flaw. ANY slop introduced
error is DOUBLED because of the Flip The Fingers Over design of the
jig.

The second design flaw is support for the router. You didn't mention
if you have the accessory Front Support Bar. If you don't, you're
supporting the weight of the router plus any downward force you're
exerting on those adjustable then locked down fingers. And the longer
the support bar is - the more it must resist flexing, bowing downwards
under the weight of the router and the downward force you provide.
You didn't mention if this is the 12" model, the 16 or 18" model or
the 24" model.

Now to what YOU may be doing to cause the problem.

The Tails board appears in the photo to be cupped a little - which
could explain some of the problem

The most common problem with using dovetail bits is that they want
to pull themselves out of their holding collet. Since ALL of the DT
Jigs that use Fingers require that the bit's shank diameter be small
- 1/4" or 8mm diamter, the router's collet holding the bit doesn't
have that much gripping surface area - even with the four slots
collets. And if you've got gunk in the slots the collet can't close all
the way.

The other common problem is setting the bit ALL the way down in
the router. THAT can lead to a jack hammering affect as the bit
cuts - sometimes pushing the bit up out of the collet - and even
just a little height change can screw up the fit.

Then there's the router itself. I may be mistaken but I think you said
you were using a Bosch - and I think it was the COLT - a small, fairly
light weight trim type routers - with a relatively small base - and not
a whole lot of weight - and thus not much inertia. While the lighter
weight may be of benefit in terms of less weight on the ends of the
jig's fingers, there's not much mass to resist "bouncing" as the bit
begins cutting harder then softer grain. A full sized router may
be part of a solution to your problem.

Have you checked to see if the GAP is on both sides of the joint
and not just at the Show Face side? Rub a pencil lead on the faces
of either the pins or the tales, put the joint together, take it apart
and see where marks have been transfered to the sides of the tails.
This might give you a clue as to what's happening.

Also, are you sneaking INTO each cut or going all the way in and
then to the side and then back out? A "fronter board" can reduce
or eliminate grain tear out.

Hope this gives you some more things to check out.

BTW - The AKEDA, by design, eliminates the Fingers Slop Problem
AND
the router support tilting problem.