Re: Leigh Dovetails and Dewalt 618 Router

Ok, you mention Joint, singular. If you are trying to correct an ill
fitting joint, forget it. You cannot recut a joint.
With each adjustment that you make you have to start with new wood.
Why? Because the depth adjustments have the opposite effect on mating
pieces of wood. One piece may get wider tails which requires narrower pins
or visa versa depending on whether you make a deeper or shallower cut.
Either way you cannot make previously made tail or pin cuts, narrower.

Because of this blind dovetails are unforgiving on any jig of this style
regardless of what router you are using.
Every DT bit has its "sweet spot" as to which depth it is going to cut
correctly at. You should have scrap pieces of the same type of that you are
going to use. Thickness is not really a factor assuming your finger
template is resting flat on top of the wood although same thickness is
easier to test with. Correct bit depth will be the same for any thickness
wood. Make practice cuts until you get the right fit and then record that
depth setting for that bit for future DT's. Simply cut the pins and tail
off if the fit is not right. DO NOT attempt to "fix" a cut. Start over
after making depth adjustments.
As you mentioned, if the fit is too tight make a shallower cut. Too loose
make a deeper cut.

A few other things to consider. Do not rotate the router when cutting the
DT's in case the guide bushings are not perfectly centered to your bit. Be
certain that you clean out all the area between the jig fingers when
routing. If you unintentionally leave a little extra in there the fit will
be too tight.


"Bubba Wood" <bubbawoodnospam@xxxxxxxxxxxx> wrote in message
news:1unq729tqsre3v16nebb4jql2v9g9f3j2f@xxxxxxxxxx
Anyone have experience with this combo. I have a D4R Leigh dovetail
jig and a Dewalt 618 router. Using good PC brass bushings I can not
get a workable halfblind joint in 3/4 sides and 1/2 fronts and backs.

After 8 attempts following every instruction I gave up. The joint
never really changed in fit. It started out tight. Per instructions I
raised the bit "Slightly" about 1/128 and cut new. Same result. I
eventually moved the bit up 1/16, no change.

I reset the fingers. They started out all set tight against each
other. I eventually put a 1/32 between each. Still no change in fit,
it was tight. Tight means the joint will not slide together. Tight
means trying to pound the joint together with a mallet results in the
wood splitting out. (OK that was frustration on # 6)

Finally I started looking at the router. The thing is so loose when
you release the adjustment lock I can adjust height by pulling or
pushing the base and get a 1/64 of an inch slop. Also and more
importent is the side to side concentricty of the bushing to the bit.
It can vary so much that the bit shaft contacts the bush. That can't
be good.

To allow for this I double routed the last two tests, as in hold
router one way, rout... turn router around 180 and rout again. This
method did produce the closest thing to a workable joint but still too
tight.

Anyone else experience anything like this?
OH 7/16 bush and a 128-8 bit starting depth of cut 3/8

Thanks
Larry


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