I need to rout a dado for some shelves I am building. I use a straight
edge to guide the router. The upright is about 24 inches wide and I
need to rout a 3/4 inch dado.
Problem in the past is I always get one or two spots where the bit
kicks away from the straight edge a litte.
Any ideas/techniques on how to prevent this?
I assume you know to rout in the direction such that the rotation of the
bit is forcing the router against the straight edge.
You can use an undersized bit and rout twice, once on each edge of the
dado. Of course, if precision width is important, then fence alignment
is critical (but can be accomplished more easily with a spacer to align
the fence the second time).
Use two guides, one on each side. Use a 1/2" bit. Make one pass and then
come back to do the other side and clean up any imperfections on the first
side. Be sure to make the passes in the proper direction, but you already
It isn't intuitive, to me anyway. I cut in the wrong direction
watching the base move away from the guide wondering why I had to hold
it so hard against the guide. A post had words that shouted, to me,
USE BIT ROTATION TO FORCE THE BASE AGAINST THE GUIDE STUPID!! Now I
"already know that". I used the "right-hand"rule" as a mnemonic when
hand routing to determine proper direction.
With a 3/4" bit you are plowing through the cut in one or two passes
depending on the depth. With the smaller bit, you plow through the first
time but on the second and any subsequent passes there is more room for the
chips and I find a cleaner cut.
Works well for me, but it is not the only way.
Advantage of using a 1/2 bit to route a 3/4 dado is that you make 2
passes, and if the router jumps a bit, the 1/4in lets it move without
gouging the far side, you just go back and make another pass to
correct the spot where it jumped
On 19 Jul 2004 12:25:25 -0700, email@example.com (George)
Your bit pretty well centered in the guide? If so, make a plywood jig with
some 1/4" ply, nailing two parallel strips of wood to it, as far apart as
the diameter of guide you will be using. That way you can attach a fence to
butt it against the pieces you're routing, make stopped dados by nailing a
couple pieces of your spacer at either end of the parallel strips, etc. As
the router is contained between the strips, no problems with jump. You
might even get a little wacky and try routing a sliding dovetail - same jig.
Those guides are great items, though some tend to think of them as pattern
routing aids only.
It is mainly a matter of practice, but...
If one side is less critical than the other, besure to put your straight
edge on the critical side!
That sounds obvious, but it took me a major screw up to learn it.
What works for me is consider the right thumb the saft of the router
bit and fingers the direction the bit is rotating. If the thumb point
up rotation is counterclockwise and if down rotation clockwise. If
down router is held against the nearside of the fence or board to be
contoured and moved left to right, rotation PULLING the router tighter
against the fence. Right hand rule from school days in EE.
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