Keep in mind that this is just a guideline. You need to exercise
good judgment depending on the type and condition of the material
you're cutting.
A common mistake that many new woodworkers make is the speed of
feeding the stock through the cutter. If you feed through to slow,
you get a lot of wood burn. If you feed through to fast, you get a
rough splintery and uneven cut.
Another common mistake is in trying to remove to much material
from your stock in a single pass. Better to take a number of cuts
then try to do to much at once. Too much at one time, takes it's
toll on the tool, the bit, usually results in a poor result and
jeopardizes your safety.
Always try to cut with the grain. This is easier said than done.
It will avoid a lot of tearout and chips being taken out of the
wood. I use a lot of oak and can tell you from experience it can be
pretty ornery. A steady feed and lighter passes will very often keep
the tearout under control.
Anti-Kickback Bits
The picture on the right illustrates what a conventional bit
would look like in your router. The design of the bit is a pair of
cutter wings
milled
out of the single piece of steel that the shaft is milled from. In
the case of carbide, they braze on carbide, clean up the braze
points and grind to a fine cutting edge. What I'm trying to
illustrate here is how the entire cutter face is completely exposed,
the only horizontal depth limiting factor is the bearing. While this
is not a bad thing, the opportunity for kickback is greater because
it's up to the woodworker to control the entire cutting process with
the help of only the bearing or ideally a fence. The next photo
attempts to illustrate the components of an anti-kickback bit.
If
you look closely, you will notice that the piece of wood doesn't go
against the bearing at this point. If you look at the front of the
bit you will also see extra steel in the profile instead of two
wings sticking out of the shaft. Like the conventional bit, the
entire bit is milled out out of a single piece of steel. Quality of
steel is very important here. Since there's more mass which drives
more torque etc., fatigue proof steel is an important factor. What
I'm attempting to demonstrate in the picture is how on the
anti-kickback bit, the cutting points are actually spaces ground out
of a round profile. The carbide is again brazed on and
sharpened. The milling process here as well as the brazing
process is more intricate. The accuracy is more critical as well
since there is more mass at the end of the shank, vibration could be
a problem if you don't have balance. The design is an attempt to
control how much the bit will take off at a single point in the cut.
While only the woodworker can insure his own safety, these bits help
somewhat in that they reduce the amount of exposed cutting surface
area. Again the bits won't guarantee the safety of the user, only
the user can do that.
Using a Fence/starting a cut?
Why use a fence? Who needs a fence when I've got a bearing on the
bit to control the horizontal
depth? Safety, Safety, and Safety. Starting a cut is probably one of
the riskiest points in routing. As I've tried to illustrate in the
photo on the right, if you're not really careful the bit will catch
the end grain and actually throw the piece either off to the side or
directly back at you. In addition, aside from the safety hazard, you
may wind up putting a partial profile on the end corner where you
may not want it.
What
I've tried to illustrate in the second photo is the use of a fence.
The fence doesn't necessarily manage the depth of cut on a bearing
bit, but helps to insure control of the work piece. The fence should
sit just slightly behind the bearing, and split just enough to clear
the bit. If you don't have the dollars to spend on a fence, they're
easy enough to make and attach to the table with clamps.
On
an irregularly shaped piece where a fence isn't practical, use a
starting pin. It will help maintain control of the work piece when
starting the cut. Most companies that sell table inserts provide
these pins. Here's an example from Rockler.
As I continually repeat. The woodworker is the only one who can
guarantee their safety. These tips will hopefully make it easier. If
you would like to check out, tables, lifts and the like, there's an
excellent selection
here to choose from.
Depths of Cut
Depths of cut discussions can be confusing. There are two
depths
associated with a router bit. With the illustration to the right,
I've used the rabbet bit. The vertical depth of cut is controlled by
moving the router. Doesn't matter whether it's in a table or router
base. Moving the router up and down controls the vertical depth of
cut. The horizontal depth of cut is controlled by either a bearing
as you can see in the illustration or by the router fence in a table
set up. A router edge guide will do the same job when working
freehand with the router. A valuable bit is the rabetting bit.
Getting a bit with multiple bearings is indespensable.
 |
Rabbeting
Bit Set
Includes
bit and bearing soft 5/16'', 3/8'', 7/16'' and 1/2'' rabbets.
Allen wrench included. Vary cutting depth by changing
bearing...
Rabbeting
Bit Set |
If you have anything that you would like to see added here, that
would help out our fellow woodworkers drop me a line. andrew@andrewsworkshop.com
Page 1,
2
