Eric Scantlebury wrote:

snip

In that plan the carcass is assembled by butting the end of a board into a
rabbit and held with glue and screws. Seems simple enough. However, I
just finished reading an article about locking Miter Joints in the February
issue of Popular Woodworking and now I'm leaning towards using that method
to assemble the cabinet carcass (top, bottom, sides and back). With that in
mind I have a few questions.

1. Is there a strength difference between the two types of joint? And if
so which is the stronger joint? It would seem to me that the miter joint
would be stronger than the butt end joint.


You're doing this in ply rather than solid wood?

If ply (or MDF) my gues is 3/4" right?

Assuming ply or MDF, the answer is the lock mitered joint will be
stronger than the rabbet, glued and screwed. Screws don't hold real
well into the sides of plywood.

The lock mitered joint is, if cut properly, self aligning and as noted
in the article, somewhat self supporting. It also almost doubles the
glueing (sp?) surface area - thus more strength.

2. If it is feasible to substitute the Miter joint - is it possible to
miter the back in the same manner? In other words creating a "square"
cabinet seems simple enough but what about attaching the back using the same
method. Is this possible? If so is their any special considerations when
routing the panels at the intersection of the "corners" of the carcass
where, say, a top meets a side and the back? If that description makes any
sense at all.


The lock miter joint will accomodate your idea -but the parts have to
be
cut very accurately and the lock miter joint must be cut accurately on
all
four edges of all six pieces. The sides and the top and bottom are
easy.
As long as the sides are the same length and width and the top and
bottom
are the same length and width you'll get an open ended box without too
much trouble. It's cutting the front and back to exactly match the
opening they must fit into that's the critical part of the process.

But, if you do all the cuts on all the parts that use each fence set
up
or cross cut stops, you're half way there. When you cut the lock
miter
joints on the router table you've got to use feather boards for
holding
the stock firmly against the fence for the vertical cuts and feather
board to hold the stock down flat on the table for the horizontal
cuts. Any wandering of the stock while routing will definitely show
in the resulting edges of your box.


3. If all is well with this method - is it possible to run that type of
bit effectively in a PC690 using the PC router stand and still get good
results? Or does a bit like that need a heftier router?


And there's the rub. The Baby Lock Miter bit is 2 inches in diameter.
The Lock Miter bit is about 2 1/2 inches in diameter. That's a chunk
of
metal to spin at 22-28K rpms and remember, on half inch stock it's
eating a half inch on a side triangle in one pass. Works fine with
a 2.25 HP Dewalt 621 plunge router in my router table. The 690 might
work.


Thanks for any input and answers.


Now you've got me curious. Have more baltic birch ply. Will think
through the cutting set ups and cutting sequence and give it a try.
Will post the hows, whys and a piciture or two to a.b.p.w. when
I've either got it or have given up.

charlie b