Hi,

I'm just starting to use an incra jig and I have a question on making
doube dovetail joints.

I have cut the first dovetails and slid the second set into the first.
But when I try to make the net set of dovetails I keep having the wood
split on me. I know these are delicate pieces ( the wood is 1/2 inch
thick) and I am trying to make small cuts where possible. I have made
three attempts and all have had the same results, the pieces of the
second dovetail are broken off.

Is the a trick to makeing these joints? I'm thinking that the first set
of dovetails is too tight and I'm starving the joint of glue. Does any
one have any experience with this?

Unsure how close your spacing is (which template?), or what type of wood it
is. Will assume you have the grain oriented correctly, else that's your
problem.

In general, you need to calibrate your bits with scrap, adjusting for enough
play to slide the dovetails together with only light pressure. Any tighter
than that, and they'll jam when you add the glue.

Have made many dovetails with the Incra, and haven't had that problem even
with thinner stock, IOW you will get past this issue.

GerryG

On 1 Jan 2005 19:34:47 -0800, "Joe" wrote:

Hi,

I'm just starting to use an incra jig and I have a question on making
doube dovetail joints.

I have cut the first dovetails and slid the second set into the first.
But when I try to make the net set of dovetails I keep having the wood
split on me. I know these are delicate pieces ( the wood is 1/2 inch
thick) and I am trying to make small cuts where possible. I have made
three attempts and all have had the same results, the pieces of the
second dovetail are broken off.

Is the a trick to makeing these joints? I'm thinking that the first set
of dovetails is too tight and I'm starving the joint of glue. Does any
one have any experience with this?

Thanks for the response. Here is what I've done so far.

I've used scrap pieces to set the bit height and the joint can put
together by hand even after adding glue but you do need some force to
slide the pieces and when the pieces slide together a good amount of
glue seems to be pushed out of the joint. Is this normal?

The joint I am making is IDDD using a 1/2 inch bit at 14 degrees. The
wood type that keeps breaking is maple.

The grain direction is an interesting question as I was going to play
with this anyway. From the drawings in the book it appears that I make
the openings in the wood by running the board through in the direction
of the grain. That is to say, the grain and the fence are parallel with
each other and when the joint is made you would see end grain showing.
In the picture below, when the mating piece is installed, you would see
end grain when looking at it.

__ __
\ / \ /
----------------
| |
| |


I was thinking of changing the direction of the cut so that the grain
of the mating piece would run along the length of the board. i.e. in
the picture above the grain would run
in the direction indicated by the arrow below.
----

I would do this by running the piece through with the grain
perpendicular to the fence. (the end grain would be butted against the
fence)


Am I on the right track??