TUBE NOTCHING MADE EASY USING A HOLESAW NOTCHER
*Note: The following procedures are designed to work with the
standard type holesaw notcher. There are a few other notchers
capable of a greater degree of adjustment that gives them the
ability to cut from a complete opposite angle. This would change the
approach to which side of the tube would get marked and is not
considered in these procedures.
Many a notcher manufacturer will demonstrate how a notch is made
using their machine but that is the easy part of notching. It's the
right placement that's critical and makes the difference between a
good joint and one that requires either a lot of gap welding or in
worse case, starting over again.
Making a wrong notch is costly in both time and money. Using a
common holesaw type notcher such as the
SYNC180 Notcher, we'll outline the following procedures to
help simplify and hopefully make for a better and closer fitting
notch for many a fabricator. These procedures work - regardless of
the angle and regardless whether the joining tubes are parallel,
divergent or skewed.
A basic notch starts with laying up the tube where you want the
joint. Temporarily secure it so the tube can be easily marked so it
can be correctly placed into the notcher. Position yourself to view
both tubes at the intersection from a right angle perspective so you
can accurately mark both the centerline of the tube (to be notched)
and the intersecting point(s). The more accurate the marks - the
better the resulting notch will fit. Always mark the point of
intersection on the obtuse (or greater) angle side as shown in the
A Centerline Finder may be helpful in locating centerline. Read more
about the Finder below.
Record the acute angle(s). Know that most notchers consider
a right angle notch as 0degrees so convert your measurement
to a notching angle by subtracting them from 90degrees. For
example: if the angle measures 70degrees then the notcher
should be set at 20degrees.
handy gadget that is helpful in marking the intersection is
a snap-collar locator. It can be slid into position for
accurate marking with a nice straight line and if the tube
has to be rotated, when positioning the tube into the
notcher, a snap-collar makes for an easy reference -
especially if the tube has to be flipped over to notch from
the opposite side. Snap collars can be purchased here:
Another important point is to make the
tube the right length before you begin a notch. You don't
want to leave the tube long and just 'plow' through the
notch because doing so takes longer to notch and will put
more wear on the holesaw - besides leaving a feathered edge
that will need to be ground back. So before you place the
tube into the notcher, cut it to proper length.
So at what point do you cut for a 'proper length'? A good
rule of thumb is that if the notcher angle is less than
45degrees then cut the tube a bit longer by about a 1/4 of
the diameter of the tube.
If the notcher angle is greater than 45degrees then cut the
tube at the 'intersected' mark.
Set your notcher to the necessary angle. Position the tube
into your notcher with the centerline mark showing at the
very top. (In some cases the mark may end up on the bottom.)
Regardless, this places the tube at 90degrees in relation to
the center of the holesaw. The edge of the holesaw should be
positioned in line with the intersection mark. If you're
using a snap-collar be sure to slide or remove it out of
harm's way. Make the notch.
In these two pictures you see that the edge of the holesaw
is targeted to the intersecting mark. Note again the amount
of tube that extends beyond the intersecting mark. For any
angle 45degrees or greater there is no tube beyond the mark.
For angles less than 45degree there should be some extra as
Quite often it becomes necessary to rotate the tube
180degree when notching at the opposite end. Using a
snap-collar makes it easy for accurate referencing. Or just
eyeball the end of the tube and mark it as close as you can.
Remember, the more accurate the mark the better the fitting
notch will be.
As was mention at the beginning, the basic procedures
outlined above will work for all joints regardless if the
joining tubes are parallel, divergent or skewed. Spanning
between two tubes that are skewed (not in the same plane) is
really no more of a challenge than working with any other
span. What is important to know is that as long as the
centerline of the tube to be notched is correctly marked in
relation to the joining tubes - your notch will come out
Just remember to position yourself so that the view is from
a right angle perspective. Skewed angles can play with your
eyes so it's important that each joint intersection be
viewed separately. In other words don't try to mark both
intersections while standing in one spot. Take the time to
view each joint individually.
If you still struggle with marking centerline correctly try
using a 'Centerline Finder'. You'll find that this handy
tool will take the guesswork out of joining tube.
Now that the basic guidelines have been established, here is
a short cut that can save you even more time.
Here's how: Simply lay up the tube as you would normally and
record the angles as before. Don't bother to mark the
centerline and intersecting points yet. Use a tape and
measure the distance between the two spanning tubes and cut
the tube somewhat longer.
Notch one of the ends at the measured angle without any
regard to a centerline because at this point there is no
Take that tube and puzzle the notched end up against the
tube to where that joint will be.
Secure the tube in place and follow the procedures for
marking the other end as outlined previously, which, in
*Mark the intersection
*Cut the tube to the proper length
*Reset the notcher to the remaining angle
*Set the tube into the notcher jaws with regards to
*Complete the notch and your ready to weld
JOINING TO A CURVE
For a tighter fitting joint when tying into a curve or bend,
start the notch at the usual point of intersection but
set the notcher angle at about a negative 2degree or
3degree. Doing so will result in a better fitting notch.
The value depends on the radius - the tighter the curve the
greater the angle.
You can get a good idea of what the angle should be by
laying a square-cut end of a tube up against the point of
attachment and visualize the gap as an angle.
The next picture shows a good fitting notch when a negative
angle is used. Compare it to the following picture where the
notcher was set at 0degree.
You can see where there is a bit of a gap where the tubes
fail to meet.
One last notch we'll consider is where an additional member
is to be joined at a 90degree junction. Typically the
90degree joint will already be welded together so the new
notch may have to be relieved on the inside for a snug fit -
the snugness will depend on the quality of the weld itself.
Lay up the tube and mark the intersections and centerline.
Cut the tube to length with that length being about the
diameter of the tube past the intersection (indicated by the
Cut the tube to length at the dashed line.
Set your notcher to 45degree and position
the tube into the jaws so that the holesaw will begin the
cut on the dashed line.
Rotate the tube 180degree without moving the tube from side
to side. This is easily done by using a snap collar and
indexing the tube against the notcher on the opposite end.
This assures the proper position for the second notch.
Cut the second notch.
This particular notch, as shown, fits rather well without
having to relieve the inside of the notched tube.