Last month, I showed you how I
created the G-code for the top and
bottom of the domino box. With a
domino loaded face down and
tightened into the vice, it is time to
load the G-code for the bottom. The
bottom G-code file was saved as
“Bottom Pocket.txt.” That’s the file we
will load into Mach 3 now.
Once the file is loaded, you will
notice two major changes to the
Mach 3 interface. The first (Figure 17)
is a list of the G-code commands that
the program is going to run. The
second (Figure 18) is a rendering of
the tool path.
In order to start the process, we
need to do the following:
• Make sure the bit is raised off
the stock and near the center.
• Make sure the center of the
cross hairs on the tool path rendering
is pointing to the same point on the
stock where the bit is positioned over
• Set the speed on the MF70 to
18 (Figure 19).
• Turn on the spindle motor
The final step is to start the job.
This is done by hitting the “Cycle
Start” button shown in Figure 20. It is
important to note here that some
machines will start the spindle
automatically. Some will even set the
speed of the spindle for you. Once the
job has started, the bit will start
cutting the stock as shown in Figure
21. As the job progresses, you will see
Mach 3 cycle through the commands
in the G-code screen. When the job is
complete, the bit will move up away
from the stock.
When this happens, turn off the
spindle. On some machines, the
spindle will stop automatically.
The domino top is done exactly
like the bottom. Since your machine is
already referenced, all you have to do
is load a fresh piece of domino stock
and load the G-code file for the top.
Repeat the same processes and hit the
Cycle Start button to begin the job.
Once complete, stop the spindle
and remove the stock.
The top and bottom shown in
Figure 22 fit together so well that I
have to use a screwdriver to pry them
apart. At this point, I would go back
to the drafting stage and increase the
pocket size to remove just a little from
the outside of the lip to loosen the fit.
This can also be done directly in the
The machine referencing may
seem a little tedious but, in reality, it
goes very fast. In addition, once
referenced, you can cut several parts
without making any more
Referencing the Z axis can also be
automated by adding a depth probe
to the CNC. I am currently working on
a upgrade book for the KRmf70 CNC
where I add spindle control and a
I hope this series has given you a
better understanding of part design
and creation on a CNC. Keep in mind
that this process is different from full
3D design and milling. 3D milling is
done with a V-bit (or bull nose bit)
and in a series of overlapping passes
on the stock. SV
SERVO 08.2015 57
toD i nC
Front s &
; Cost effective prototypes
and production runs with
no setup charges
; Powder-coated and
anodized finishes in
; Select from aluminum,
acrylic or provide your
; Standard lead time
in 5 days or express
manufacturing in 3 or
ts u gis e
W tsiesa T
If you want more information on my KRMx02, KRmc01, or KRmf70 CNC books, you can
find them at www.kronosrobotics.com. You also can download an early version of the
KRMx01 CNC router book for free at www.kronosrobotics.com/krmx01/index.shtml.
If you have any MF70 questions on this or previous articles, please use the forum at