Monthly Archives: January 2012

CNC Build

I have come to the conclusion that while I am moderately handy, I still frequently fall short of the goal line when it comes to execution.  I like to envision, plan, and design things and then get frustrated when I can’t make them physically turn out as I like.  I have been eyeing CNC machines for quite some time but have been put off by the price of entry, and the space they require.  I have recnetly moved my workshop from the basement to the 3rd stall of our garage to accomodate an office build out I recently completed – so that took care of one of the barriers.  The other was conveienty (somewhat) overcome as I came across a co-worker whom had a cnc machine.. so he could manufacture my wood parts for me.  I think the concept of self-replicating tools pretty fantastic!

I got a ‘kit’ of goodies from buildyourcnc which got me going.  The kit included the electronics, and the code required to cut out the wooden parts (called gcode).  It also came with all the nuts/bolts/chain/sprockets etc needed to assemble.  It took about 5 hours of milling to get the parts cut out of 3/4 plywood, but it was entrancing to watch!  Below is a pic of all the parts drying after having poly applied.  Probably wasn’t necessary, but as it will live in the garage I didn’t want the humidity cycles to affect it.

From the bottom up here is how those parts come together:

  • 2×4 frame on locking roller wheels from Lowes.  This was pretty basic, but I did do lap joints in all the corners for stability.
  • On top of that is a 2′ x 6′ torsion box made out of MDF.  There are lots of good guides on building torsion boxes, and it was suprisingly easy with just my portable tablesaw.  The advantage of the torsion box is it should stay dead flat over time.  I also put 2 coats of poly on this as MDF loves to suck up water!
  • On top of the torsion goes the actual bits that make up the CNC.  The X-axis rails go on the torsion, which the gantry rides on.  Y and Z axis are rails on the gantry.  Its a pretty amazing design, v-groove bearings ride on basic aluminum L rails.

 In the gantry are three stepper motors that are controlled by the electronics below.  Pretty basic wiring for the most part.  PC parallel port goes to the breakout board bottom-right.  This controls the 3 axis via the black boxes top right.  Power supply for the 36v needed on the top left.  Bottom left are two electrical boxes for outlets.  The left most one will have a circuit to turn the router on/off.. but that is a post for later, as I intend to mill the circuit board with the cnc.

There are a lot of steps not documented here, but you can see very detailed build videos on if interested.  I just wanted to share my beginnings on this project, and will post more detail as I go off the beaten path and start to create my own parts.  Below you will see the first milling operations I completed – the manufacture of the sacrificial top for the machine.  This top is intended to be replaceable as it will get chewed up over time.  The T-Slots allow mounting of wood for milling out of parts.