Our CNC machine was a tufting machine. I was in charge of the mechanical design and the design of the machine. I also documented all of the advances in every area of the machine.
This was one rough sketch of our idea. It suffered some modifications.
Mainly, my contribution to the project was to adequate the structure and build the mechanisms that will move the machine and the tool. Below I explain more of both jobs, I also documented the whole process.
As a team the difficuty was to work at a distance. We are 4 members, two from Puebla and to from Mexico City, though we worked together one day in the machine and will advanced a lot, the rest of the work was done by distance and then integrated. The communication played a huge role in the success of our project.
The future of this machine is a much portable solution, we were thinking in a structure that could be mounted in any canvas and do the job.
For making improvements and advances in this machine, it's imperative to work together in the same place. It's true that the new technologies makes easy this kind of collaborations but I still prefer working in person.
That was the design plan. But then we found some old structure abandonned in our Fablab. The structure was made of aluminum T profiles. Which is a sturdy way to support a machine. We understand that these profiles are not good for prototyping because they are expensive but we found them without an use and we thought that was a good idea to recycle them, we reuse something and at the same time we create a much more sturdier machine.
Some of the modifications we made to the structure were the heigh in which the tool was ubicated. In the original structure was too low.. We needed at least 23 cm iso we can put the needle in the correct angle. In order to correct that detail we scavenged another larger T profile and replace the middle vertical bars. The we posioned the tool with x axis on top of the new T profiles. The scavenged T profile was cut with a metal blade.
One of the changes made to the original idea of the tufting machine, was to change the power band to move the X axis to another worm gear. We know that the worm gear provides an slower movement, but we anticipated that our tool may be too heavy and the power band wouldn't be able to move it, so we changed it to a worm gear, slower but supports more weight.
Other modification to the original structure was, obviously, the work zone. The work zone was a simple mdf square measuring 25 cm per side. We designed a frame to tense the fabric. The frame was composed by some L shape pieces that gives us the height. We stacked two pieces with a 5mm thickness to have a 10mm thicknes per side. then we put the main face of the frame which had some holes to put screws in them. We know that this is not the best way to tense and frame the fabric. The screws gives us good tension but the mounting and removal of the fabric is slow and complex. We are working in a second porotype for the frame with out screws and with a put and remove design.
The fabric must be really tense and it must have a large grid. This means that the space between every thread must be big. If the space is too small, the tufting needle will rip the fabric apart.
The unions for the aluminum T profules were 3D printed. The machine uses 3 different unions. One type of union to work as vertexes for the aluminum T profiles, as displayed in the picture. Other type to balance the tool and join it to the middle profile, this union holds together the x acis and the side bars of the structure. And the 3 type of union holds the y axis and the guide pipes of the y axis. All of these unions are 3D printed.
In the picture above we have the stepper motor and the worm that works as our y axis. In the original structure that we decided to recycle this axis was a little bit bended up. This bend cause that theis axis didn't work correctly and the movement got stucked. We traced back the problem and we found out that the union thaat holds the other extreme of the worm wasnt secure with screws, instead the original designer fixated it with double side mountage tape. This cause that the union got a little bit hhigher than the motor. We secure the union with screws to solve that problem.
We can see the union now with the screws holding it down.
In the picture above we can see me working on the machine. Securing the tool and x axis to the main structure.
I also helped in the tool design and adjustmen of the latter to be mounted in our structure.
One of the real challenge of this machine was the tool. Every CNC machine works the same, it is the tool that defines this machine. In our case it was the tufting tool. This tool must move up and down at a certain speed in order to penetrate the fabric just as fast enough to put the thread and not shred the fabric. This speed also must be coordinated with the X axis movement.
First we design a model in the software Solid Works. We used this software because it's really professional for creating ensembles, and it also has a lot of simulation modules so we can make it work to test the up and down movement before we manufacture it. It is also easier to use than other professional softwares like Catia.
The trick for the up and down movement is a cam and gears. This was design in order to solve some of the issues of the tool.
The Cam serves the purpose of transforming the rotational movement generated by the DC motor into a linear movement. The function is explained in the picture. The axis rotates, rotating the cam, every turn of the dc motor the cam will push down the follower which in this case is the needle for the tufting.
The gears were added to the design so we can slow down the spin speed of the DC motor. Our motors spins so fast that the needle and the fabric may break. We calculated our gears to slow down the motor and gives us the necessary speed to tuft the fabric.
Once our design was ready we decided to prototype it using our laser cutter. This was the fastest option and the more precise for the gears, the cam and other elements. The needle was manufactured in a diferent way using our lathe.
The elements were cut in the laser cutter. Someof the elements needed more thickness than the one provided by our material. 3mm MDF, so we cut multiple times that element and glued them together to gain the thickness that we were looking for. For the metal profiles we used some aluminum pipes that we have in our waste basket and we used the lathe to gave them the 1/8 rope.
This is how it looks assembled.
After those assignments and all the documentation work, I helped in the tests of the machine.
After realizing that the gestalt nodes that we design weren't working, and after we solder the new modules, we needed to try them out. One of our earlier tests was the single movement of a single motor.
Obviously the next step in our tests was to move simultaneously two stepper motors, controlled manually by the computer.
When the tool was completed we need to try the movement. The tool uses a DC motor to move up and down.
After the tool worked we wanted to integrate it in the machine right away. We adjusted the tool with some locks to stop some of the gears to fall out.
In the end, our FABuluous machine worked like this:
Then we programmed a small routine so the machine draw a figure