Step 8: X-Axis Front and Back
We are going to cheat and skip to the x-axis for a minute, well... actually 8 minutes since that's about how long the video is. The CNC router has a table, right? The flat piece that you put the stuff on to cut, right? Well, that piece has this thing called the gantry riding over it. How does that gantry move? It needs to hug this surface and requires a piece underneath. In other words, the gantry cannot move unless this surface is lifted above the ground to accommodate the gantry support and the motor underneath.
In this video, we are making the stands for this surface. You will use two 4" x 2' pieces. Nope, we still haven't gotten to the 4" x 2' 3" pieces yet. One for the front and one for the back. You really could use pieces wider than 4". In fact, these two pieces could be your standing height stands (if you do, you will have to support them somehow, maybe I'll get into that later after this series.). Guess how you're going to connect them??? Right, step two!
I use three holes and connections on each end. You can put as many connections as you feel, but three should be enough. The x-axis motor will be mounted on one of these ends. In addition, each end of the lead screw will be affixed to these stands.
Revision on the Build: "Pimp My CNC Machine"
If the large table size of 24" x 48" was a concern to you, well... that's a well founded concern. I have noticed a deflection of about 1/32" towards the center. The day after, a miracle happened... the nanny stepped on the machine and totally broke the cutting surface. No! It can't hold the weight of a person. I have subsequently reinforced the machine and totally tricked it out as you will see in these photos. I will add this section to the stands portion of the steps process.
So... what did I do to reinforce the x-cutting surface? I slapped two 24" x 48" pieces together and chamfered only one side of each piece. The good news: The gantry measurements did not have to change since only 3/8" was added to the top and bottom of the cutting surface. With the measurements I used, there is still enough space for this to occur.
The only major changes to the machine is a new size for the aluminum angle at 1-1/4" x 1/8". It's pretty inexpensive. You can see that I also dramatically changed the stands and made the whole unit into a cabinet (with wheels, or casters as they call it at the local hardware store). This thing is so heavy it's even difficult to more with the casters, and I go the pricier ones.
Other changes were to the gantry y-axis rail support, but this machine is so flexible, I just used a few spacers and it's all back to snuff. No play, or flex at all and this puppy is solid! Some detail... notice the double bolts near the motor and the single screw on the cutting surface. The single screw is to hold the two boards together. I also wanted the two board to act against each other so there would be no flex. There are four total on the cutting surface. The double bolts are just the standard connections I always make. This is stronger as well since the board on top is a load acting on the board below, but with the wonderful laws of physics, there is a great amount of pressure keeping these boards intact.
Can you see a glimpse of some electronic components in the cabinet? I will explain that a bit later after the driver and power supply is complete. My computer is down there. It works for me since I'll be using it in my bathroom, remember? The only negative aspect of this design is that Nicco, my son, climbs into that space and makes me very nervous. The caster contribute in the transfer of a large portion of the loads associated with the computer monitor and other stuff, including Nicco.
If you are building a smaller table, you may not need this reinforcement. Optionally, if your x-axis table slides on its own, that will be very little load to create any sag, so you will be safe. There are other ways to reinforce without going through this trouble (not much trouble, it took me about 4 hours to complete the cabinet and new motor mounts) such as when pieces to be cut are clamed down, a lot of the deflection will be eliminated, depending on how you clamp the work, that is. We will play more with this idea later. Give me your thoughts.