A “How To” CNC Mill Project Example

Milling a Red Oak holder for my CNC spindle collets.  Please click on an image for a larger view.

I finally bought a set of ER11 metric collets for my CNC milling machine.  The new collet set runs from

1mm to 7mm in 1/2mm steps.  I recently had a project that required using a very small drill, and the

1/16” collet, previously my smallest, simply couldn’t hold the drill that I needed to use.  Here is an

example project where I used some scrap 3/4” red oak I had from a previous project.  To mill a holder for

my collets, and two spare ER11 collet nuts.  You can click on any of the images for a larger view.

Step 1:  As a first step the collet block was created using Xara

Designer Pro X9.  The drawing included the ER11 collet and nut

recesses, the text, and outside border of the block.  The drawing was

exported as an Adobe Illustrator (.AI) file which VCarve-Pro could

import.  VCarve-Pro generates the gCode files to drive the mill.

Step 2:  After the .AI file is imported into VCarve-Pro, the milling

parameters are set.  These include the mill bit to use, the depth of each

area to mill, and the size of the tabs to be included when the border is

milled.  The VCarve-Pro simulation can be seen at right, with two of the

four tabs shown at the top and bottom.  The text was milled with a 1/8”

30

o

 V-Bit, and everything else was milled with a 1/8” end mill.

Step 3:  In order to fill the text with black paint, and not have the paint soak into the

wood where it’s not wanted, the wood was prepared before milling.  Zinsser Bulls Eye

Seal Coat, a Wax Free Shellac purchased from Home Depot, was used to prepare the

wood.  The shellac works great as you only have to wait 30 to 45 minutes between

coats.  Three coats were used to fill in the open grain of the red oak lumber.

Step 4:  After the last coat of shellac has dried, the panel can be milled.  The oak panel

is clamped to the mill table and the Mach3 CNC control application is launched on the CNC mill PC.  The

gCode file to mill the text is loaded and a 1/8” V-Bit is installed in the ER11 spindle

collet.  The ER11 spindle is set to run at 16,000 RPM, and the text is milled into the

wood.  The 1/8” V-Bit is then removed and the 1/8” end mill is installed.  The spindle is

run back up to 16,000 RPM and the collet and ER11 nut recesses and the border are

milled.  The photo shows the milled block.

Step 5:  In order to make the text stand out, a heavy body acrylic paint, purchased at Michael’s Arts and

Crafts Supplies, is used.  The stray small wood fibers left over after milling are removed

from the milled areas.  Then, as shown in the picture, a small rubber spatula is used to

press the heavy paint into the text.  The shellac prevents the ink from soaking into the

adjacent areas of the wood.

Step 6:  A small router is used to round off the top and bottom edges of the block, and

then the block is sanded and varnished.  Sanding removes the excess paint around the

text left over from applying the black paint.  Or the top of the

block can be shaved off in the mill, instead of simply sanding off

the excess paint.  After the block is sanded, two coats of water

based polyurethane semi-gloss varnish, are applied to finish the

block.

Key Holder:  This project was an oval key holder for the kitchen.  For

this project, a 3/4” router bit was used with the CNC mill to

flatten the red oak surface before the shellac was applied. 

Three coats of shellac were added, and the images and

boarder were milled.  Two coats of black paint were applied

and allowed to dry without removing the oval from the mill

bed.  The same 3/4” router bit was then used to remove a

thin (0.025”) top layer of the red oak oval to remove the

excess black paint.  This worked much better than sanding off

the excess paint, as the paint tends to clog the sand paper

which needs to be cleaned often.  The oval was then routed,

sanded, and varnished to finish.