CNC Machine

Gary and I have built a CNC machine. CNC stands for Computer Numerical Control, and refers to the computer control of machine tools to make complex parts in wood as well as other materials. In other words, we use a computer controlled router to make exact cuts.

This whole thing started because Gary’s dad owns a machine shop which fabricates pin caps (a part used in construction that helps when laying concrete). They make thousands of these pin caps and wanted to automate the process, so Gary helped make a machine that moved on 2 axis’ and would help weld the pin caps.

I’m not 100% sure on this, but I’m pretty sure Gary’s machine was the second one built (not sure who built the first machine). And in theory, it was great, but in practice ended up being slower than the first machine or something. Long story short, I think they went back to using the first machine. But, while creating that machine, Gary realized that if he added one more axis to his machine, it would basically be a CNC machine.

After he explained (and re-explained) what a CNC machine was to me, we started collecting parts to make our own. We first bought the stepper motors, driver board, and power supply from a company called Hobby CNC. As you can probably tell from their name, they deal with smaller hobby sized CNC machine. We bougt their largest package that came with 3 200oz motors (at the time of ordering it was their largest, they may offer larger sizes now).

Once we hooked up all of the components to see how they worked together, we made a small table and frame out of wood and some linear motion parts Gary had from some previous projects. A normal CNC machine has a router attached to cut through the material, but we just wanted to see how our kit worked, so we just attached a spring loaded pen and used it to draw. Even though it wasn’t pretty to look at, it was great to have that first machine working.

Shortly after that, Gary headed up to his Dad’s machine shop and threw a larger table together out of metal (the larger table is approximately 5′ X 5′). He did this without any real plans, just an general idea in his head how he wanted it to work, and we’ve only made a few modifications to his orginal idea (he’s very clever and mechanically minded).

Our original plan was to put the machine in Gary’s basement, but there is a tight bend on his stairway to his basement, and even after removing his stairs, the table would not fit (we have since rebuilt some stair for his basement, sorry Heidi).

With no idea where to put it, Pappy was kind enough to offer the basement of his clinic. He had a tight bend on his stairway too, but not quite as aggressive as Gary’s, so with a little manuevering, we got the table into the clinic basement and started putting the rest of the machine together.

It didn’t take too long to realize that the 200oz Hobby CNC motors were not going to cut it for our X and Y axis (the Z axis doesn’t need a huge motor since all it does it move the router up and down). We finally found and purchased some new 1200oz motors to replace them with.

While the new motors did help quite a bit, we still had problem with our Y axis binding because the way the table was layed out. We originally used one motor to drive both sides of the axis (which were connected underneath with a metal bar). If either side got off even a little though, the axis would bind and the motor would stall.

We fixed this by purchasing a new 1200oz motor, removing the bar underneath that tied the axis together, and driving each side of the access with it’s own motor. This has worked much better, and aside from a heat issue that we fixed recently, has been great.

We also replaced the 200oz motor on Z axis so that we could have the Hobby CNC kit complete to make a smaller table in the future (to do small jobs). We will use our current machine to cut the future machine (I’m pretty sure this was part of the plot to Terminator 2).