Step 11: Gantry Bottom Support
After watching this video, you will see that the CNC router is coming together and starting to make sense. The bottom support of the gantry, if cut to the correct length, will provide enough holding strength to hug the surface rail support (x-axis rail support/surface cutting area). To built the bottom gantry support, all we will do is make more right angle connections. Now you're starting to understand why I made that technique the second step... It's important.
The CNC router's bottom gantry support consists of two 4" x 2' 3" boards, cut down to the proper length. Yep, it's time to use those longer boards that I specified in the cut schedule. The extra 3" over the 2' was intentionally specified to give adequate clearance around the x-axis rail support. The method to derive the length to cut the boards is at the end of the video Step 10: Gantry Sides. The measurement should be shortened by about 1/32" or 1/16" to provide for some space for tightening.
The gantry will be fully tightened and supported by the y-axis rail support. We will get to that later. Half of the functioning components such as rails are also serving the dual purpose of structural support. The video also shows the use of small linear slide bearings. I used these for illustrative purposes. Longer bearings will need to be built to provide for much stronger support along the rail to prevent the gantry from possible rocking. Stay tuned for that build.