Hi, my name is Edward and I like to build CNC machines. I also like open hardware and open source software projects. I like all of them so much I put them all together and came up with Project ShapeOko. You can read the history of the machine below the break.
email: edward at this domain
For a more professional version on the story, read the makezine interview here: http://blog.makezine.com/2012/04/06/shapeoko-the-affordable-cnc-mill-kit/
CNC Mill v0.1 (2004)
This was the first solid attempt at building the machine. I chose MDF for the basic frame material as it was relatively inexpensive and easy to get my hands on. To make the cuts I used a standard hand saw, cordless 5-1/4″ circular saw, and a square. Dad has a bench top drill press so we used that to make all of the holes. This first one was fully assembled at my parents house, because Dad has better tools and more space than me.
The biggest obstacle to overcome with something like this is keeping everything square. Of course we were only spanning about 34″ max at any given point, so it seemed like squareness shouldn’t be an issue….. I was wrong, even across 34″ it’s terribly difficult to stay truly square.
Since I hadn’t ordered the stepper motors yet, we ran the X, Y, and Z using drills! However once the axis’ reached their ends you could see and feel the strain on the brass “bearings” as it would almost always tear apart one of the seams.
CNC Mill v0.1a (2006)
After the first attempt was cleary not going to work, I set about designing a new mill. For a guy who isn’t an engineer and had never really “designed” anything mechanical before, this was both challenging and rewarding, as the cliche` goes.
The most noticible difference between v1 and v2 is the material. Instead of using MDF, v2 was made entirely out of steal. I had the luxury of having a contact who had access to a laser table and cheap steel, this was a huge breakthrough for me. Now I didn’t have to worry about making mistakes cutting the pieces, I just had to worry about making mistakes drawing them! In retrospect, it’s almost as easy to mess up a drawing as it is a physical cut.
My first order of business was to buy a set of stepper motors, a controller, and a power supply. There are ample resources on the web to salvage steppers from printers and make powersupplies from scrap PC parts and etch your own controllers, but for me this was just out of the question. Although I wanted to claim this as “my own” design I also wanted to eliminate as many variables as possible, and still stay within my budget. The last thing I wanted was to troubleshoot a circuit board when something didnt’ work, when to be honest, I didn’t know squat about circuit boards.
I ended up buying the whole kit from xylotex.com. At the time of purchase he was selling 410oz/in motors for the same price as the 270oz/in, so like most, I thought to myself “bigger must be better”. I was disappointed after seeing the motors run, their speed was a lot slower than I wanted. They do have more torque and would obviously be better for cutting thicker material at slower speeds, I was not planning to cut anything other than plastic or MDF, so the added torque didn’t do much for me. An expensive mistake though….
With the steppers in hand I started drawing. Wait, first I had to learn how to use 3D modeling, then I started drawing!
This machine actually ran for about a month! I cut a few pieces on it and drew several shapes with a pen mounted to the Zaxis in a makeshift sort of way. The biggest problem was the accuracy and repeatability. I had a few BIG problems with this design.
Acme nuts: The nuts I used were home made from a piece of 1″ x 2″ x 2″ UHMW tapped horizontally. The design lent itself to backlash, and tons of it. Also, UHMW may not have been the best choice, it seems really soft compared to the delron nuts I had seen elsewhere.
X Axis Rail Design: The whole thing there was a mess. I still can’t figure out why I didn’t flip the rails so they were on their sides instead of mounting them flat to the base plate of the machine. Mounting them flat made spacing really difficult to adjust for because I was dependent on the thickness of certain materials, which I now know varies
Details: There were a bunch of little things that I just couldnt’ get right, like the bearing mounts, the motor mounts, and the couplers.
All of these things made this machine basically worthless in function. However, the flaws taught me what I did wrong and what I would need to improve in order to get a functional machine.
CNC Mill v0.1b (2007)
I started a minor revision of the version 0.1a CNC machine. The biggest improvement is the z-axis slide plate was redesigned out of metal and I rided myself of the MDF contraption I purchased for the original design.
Things were going along grand until I realized that the entire design was flawed because of the orientation of the X axis linear rails. I was “stacking” on top of these rails instead of mounting them 90° to how you see them. This caused some serious mis-alignment of the X axis acme nut an basically the height of the entire machine. I was forced to “shim” certain parts in order to align everything, this made for a goofy center of gravity and ended up being the straw that broke the camels back.
With all the design flaws, and a growing amount of frustration, I shelved the project in Late 2007. It wasn’t until mid 2008 when I decided to gather up all my parts and sell them on ebay, and start fresh. I didn’t keep anything except 1 set of linear rails.
With the knowledge I had gained from the previous 3 failed builds, I set out to design a simple to assemble, low cost, reliable, CNC machine that anyone could make. I call it shapeOko, named after shapeways (the original 3D print company I used for the z axis) and Ponoko, *the* online laser cutting source. The jury is still out on if I was successful or not. You can judge for yourself. Here is a gallery with shots from my previous (learning) attempts.
One kickstarter project and 9 months of design and aquire time, and that leads us to where we are today.