Light Duty CNC Router
The following describes the construction of a homemade CNC router
based on drawer slides
NOTE: the following is for information purposes only.
Remember,
you get what you pay for. And, unlike many web sites on home CNC,
I'm asking for no money for the "knowledge" contained here. I
will
bear no responsibility for any loss or injury resulting from the
somewhat
crazy ideas below. Use at your own risk.
Light duty mini-cnc router
The following describes a light duty mini-cnc router that I have
recently constructed. Although I do have a smaller mill CNC mini-mill,
the need to machine larger sheet parts drove me to design this
machine. The machine is based around cheap drawer slides mounted
on malimine covered particle boards. As can be seen by it's light
weight construction, this cnc machine is only intended for light duty
machining, such as PCB milling & drilling, cutting modelling parts
from balsa wood and plastics. The machining volume of the machine
is x=24", y=8" and z=5". Most of the parts can be purchased from
local hardware stores. Lead screws, gear racks and stepper motors
can be purchased from surplus dealers and gear & belt suppliers.
Above is a close up of the spindle head. A light duty Makita
laminate trimer is used as the spindle. To the right is a 12V
blower motor picked up at a local surplus store. The blower is
used to remove dust and to keep the tool cool when machining
plastics. A white LED light was added to help "see" when you are
finding the zero.
Here is a close-up of the y-axis lead screw. The zero-backlash
nut can be seen at the back of the picture. The drawer slides
have very little slack in the "side-ways" direction. However, in
the "verticle" direction, there is almost 1/16" movement. This
can be compensated by pre-loading the slides by using a pair of clamp
spreaders before the assembly is fixed to the table.
Here is a close-up view of the y-axis stepper motor and coupling
mounts. The teflon zero-backlash nut can be clearly seen in the
centre of the picture.
Above is the rear view of the Z-axis. Springs are used to lighten
the load on the z-axis stepper motor as the lead screws are not self
locking. Again, the two drawer slides were pre-loaded with clamps
before the assembly was fixed to the front panel. The X-axis
drawer slide can also be seen. They are mounted 90 deg. from each
other, again to prevent any slack. These inner portion of these
slides had to be cut to allow for a full 24" of motion on the X-axis.
Viewing from the bottom side, the x-axis rack & pinion is
shown. The 24" rack is 32-pitch. Luckly, the stepper motors
came with the pinion gear.
The three stepper motors are driven in unipolar fashion with Allegro
UNC5804b driver chips. Also visible are switches for both the
laminate trimer and the blower motor. An amp meter connected to
the spindle motor allows for monitoring of the current draw. 5V
and 12V for the whole machine is supplied from a surplus computer power
supply.
created April 17th, 2004 by V.Chan.