Home built CNC Machine Part 1 - Supported Linear Rails

This instructable is part of an on-going project to build a home CNC machine.  In this part of the project, I will show you how to build a supported linear rail which can be adapted for the desired length (X-Axis) of your own CNC project.  

Most people are put off from building a useful sized CNC machine because of the cost of parts.  Others use angle iron and skate board bearings for their linear rails.  The instructable may look compllicated but it really is not.  With a little care, it is possible to make an accurate CNC machine and will enable you to build a decent sized machine.

When I first designed my machine, I started to look at much cheaper alternatives to aluminium box sections, proprietary lead screws and proprietary linear rails.  I finally decided to build my machine to this design which includes some junk yard parts and home made linear rails which can be made to any practical length required.  The parts shown in yellow are steel parts which are fabricated by a local laser or plasma cutting shop and will form part of a later instructable.

The two end sections of the base were cut from industrial shelving brackets obtained from my local junk yard to which I have welded cleats for connection of the linear rails.  The two (red) intermediate rails are steel channel with steel cleats welded on the end.  The overall size of my machine bed is 800mm x 1800mm but of course you may build your machine to whatever (practical) size that you wish.