Pretty Picture

I have been playing around with the rendering program Kerkythea, which has a great sketchup plugin.

From RJH's CNC Build

Design Z-Axis

The design for the Z axis is relatively straight forward. The plan is to build the rest of the machine then just use relative dimensions to build the Z axis, it will undoubtedly change from the design here.

From RJH's CNC Build

Design Y-Axis

The Y-Axis supports are double thickness, and shaped in order to have a center of gravity closer to the middle when a router is added. For reinforcement of the Y gantry I used long strips of MDF that I intend gluing to the main support, this was to saved on weight over simply doubling the thickness of the MDF.

From RJH's CNC Build

From RJH's CNC Build

Design X-Axis

I used sketchup to outline a design based on the CNC zone posts from Grunblau.  The x-axis area is approx 3'x5', to allow the cutting of 2'x4' ply with room to spare.  The x-axis is reinforced, I did not go for a full torsion box, but have used multiple long beams with a few cross braces (not shown in the pictures).

From RJH's CNC Build

From RJH's CNC Build

From RJH's CNC Build

Bench

Rather than build the CNC with its own stand, as in some previous designs, I decided to make a workbench / cabinet. I designed a low workbench with multiple drawers, cupboards and open cabinets, to provide some much needed storage space. I used sketchup for the designing, it's free, and easy to use. I intend putting in the time to learn a real CAD program soon. The bench is made out of 3/4" MDF, sitting on a frame made from 2x4's. The 2x4 frame has 5" heavy duty casters attached so it can be moved around.

From RJH's CNC Build

From RJH's CNC Build

Design brief

Primarily my interest is in building a machine for woodworking, for both cutting large parts and doing basic relief carving. I am limited in size by my available workshop space, but want to be able to cut parts from a quarter sheet of ply, i.e a cutting area of at least 2x4 feet. Lots of machines have been built using MDF (Medium Density Fiberboard), it is structurally very stable and relatively inexpensive, the other option is 80/20 aluminium extrusion, which is extremely structurally stable but relatively expensive. Due to budget limitations, and my existing woodworking abilities, MDF was the obvious choice.
After a lot of research on cnczone forums I chose two builds on which to base my design, the original being by Grunblau, the second based on this build was by Turbo1zz. From the forum posts I was able to gather a lot of information and set about making my own detailed designs.

Introduction

This all started after reading Make magazines issue on desktop manufacturing. In particular the article entitled "Your Own CNC For Under $800" by James Floyd Kelly. After reading the article I immediately ordered Jame's book from amazon, "Build Your Own CNC Machine", which would be the beginning of my interest in designing and building my own CNC machine. I have never been one to simply follow instruction, so while the book was a good introduction to home built CNC I never really considered simply following the detailed instructions in the book.
I don't want this blog to be an introductory course on CNC, there are lots of resources already out there. I would recommend that anyone interested in CNC simply spend some time browsing the web. This blog is intended, primarily, to be a diary of my CNC build. I will undoubted make mistakes, and I don't pretend that this will result in a perfect CNC machine, but I do hope that I will learn a lot along the way.