On Sun, 14 Nov 2004 17:50:11 -0800, Pete Martin
wrote:



On my Ryobi 10" contractor style table saw (my wife bought it!), I've
got a (cheap) dado to make it 1/4" wide. As I take the 3 1/2" wide
poplar board over it to create a (?? tenon for a rabbet?), I see the
width change even thou I holding down very hard. See below.


/
/ 3 1/2" wide
/
--------------
| 1/4" top ^ to bottom \/
---
|
| 1/2 "
|
------------
^
^
^ -- 1/4" dado

The blade is set to 1/2" at the edge of the 3/4" board. The 1/4" left
over has not been consistent. And it doesn't matter that it's a the head
or tail of the cut. I'm holding it down hard, but it's still the same. I
have to file down the pieces in order to make them fit better if not
properly. I haven't been able to figure out why that is. Suggestion??
Pete,
from your description I think you are trying to cut a rabbet which is
1/4 x 1/2". I am not sure which 1/4 inch dimension is the one you are
having trouble with (the 1/4 inch deep rabbet or the 1/4 that is left
over after you cut 1/2 deep). Since you seem to think holding down
the board harder should help I am thinking that your problem is with
the 1/4 inch left over from your 1/2 deep cut. Let me know if this
assumption is not correct.

One possibility, especially with an inexpensive saw, is that there is
backlash in the height adjustment mechanism and the depth of cut is
varying as the blade changes height slightly. Are you sure you have
locked the height adjustment? For your rabbet I would cut it with a
regular rip cut blade rather than a dado. Set your fence so that
there is 1/4 inch to the opposite side of the blade. Make sure you
measure to the tooth, not the kerf of the blade. Set your blade
height to slightly less than 1/2 inch (7/16 would be good). Lay the
board face down and cut the slot. Do all your pieces.

Next set your fence so that the fence is exactly 1/2 inch from the
opposite side of the blade and set your depth slightly less than 1/4
inch (3/16). It is best if you use a feather board to hold the work
piece against the fence, This cut will be on the edge of the board
and will cut away the waste piece. Do not stand directly behind the
board as you push it through as the waste piece might catch on the saw
and fly backward. In setting up the cuts this way you are using the
fence as the reference point for your critical dimensions rather than
relying on the blade width or height. I suggest that you get a
beginners Table Saw guide book as this will give you tips on cutting
rabbets, dados, and safety.

Let us know how this works out.

TWS