Making a Computer-Controlled 4 Axis Hot Wire Cutter
This was a group assignment. Please see the fab lab’s webpage for a full documentation. This site just shows my contribution.
This was a group assignment. Please see the fab lab’s webpage for a full documentation. This site just shows my contribution.
We decided to fabricate a computer-controlled 4 axis hot wire cutter. After discussing how the machine should work and which additional materials we would need, my first job was to fetch
The microswitches would be connected to the Gestalt nodes and used to calibrate each axis. I bought all materials at Rotor Amsterdam. The microswitches were quite costly.
Back at the Waag, I set up an environment to test if the wire properly cuts. I looked for some appropriate connectors for the power supply and found some prefabricated cables w/ crocodile clips and appropriate connectors for the power supply. So, I didn’t need to make the cables. I sawed two wooden sticks of approx. 20 to 30 cm lengths and wrapped the wire’s end around the sticks’ ends. I fixed the sticks using the workbench’s holes and connected the wire to the power supply with the cables. The product sheet stated that the wire would be hot 100 °C at 4 Ampere. Together with Alex and Henk, I tested the hot wire cutting. We smoothly cut some foam with about 2 A and 5 to 6 V.
After testing hot wire cutting, I sat together with Natalia and Casper. We worked on hooking up the Gestalt nodes. First we read and followed these two tutorials:
Natalia and I made an appropriate cable to connect the Fabnet USB and the first Gestalt nodes. This had to be carefully done. After figuring out how to connect a FabTiny*ISP to a Gestalt nodes, I ran a Terminal test command in order to make a basic check and initialize the Gestalt nodes: avrdude -c usbtiny -p m328p. It worked well.
We all downloaded the Gestalt Single Stepper Node. To install the firmware on each node, I located the right folder in the Terminal and ran the Makefile. I tripped on an error message and had to edit the Makefile in order to indicate my FabTiny*ISP. I replaced avrisp2 w/ usbtiny and saved it. I ran the make command followed by make program-usbtiny-fuses. I successfully installed the firmware on the first node. Natalia and Casper repeated these steps and installed the firmware on the other 3 Gestalt nodes. Thanks to Zaerc for giving some advice!
Please download the saved Terminal output here.
Next, we downloaded and installed the Gestalt framework and followed the tutorial Getting Started With Gestalt Nodes to set up and test the environment.
Again, we tripped on some error messages. We double-checked the connections using a multimeter and reviewing schematics. The photo below shows our setup. It differed from the tutorial by James.
We tried to connect 2 nodes and ran some of the sample code, but we got another error message in the Terminal. The serial communication seemed to not properly work. We had to edit the script and determine the FDTI serial interface. We stopped here. It was already evening and we decided to go on with it the next day.
Meanwhile, I assisted Joe a little bit assembling the cardboard machine parts. I fixed some screws and worked up some cut cardboard elements.
We decided to make a first cut with the machine before the global lecture would start. We had to quickly finish the machine. Casper, Henk and I worked on a guide system for the stages. Casper got a concept, so, Henk and I helped him building an improvised construction from scratch.
We got a big piece of foam differing from the foam which we previously used for a test cut. So, I made another cutting test. We needed a second power supply which I borrowed from the fab lab’s electronics workshop. I carefully set up a test environment. The wire wasn’t tightly clamped and I had to fix the 3D-printed wire mounting with some hot glue. Due to its age, the power supply got some idiosyncrasies. So, I tested it with a multimeter to be sure it would display the right value. Henk and I determined that we need 2A and 7V to heat up the wire and cut the foam.
Later, when we computer-controlled cut our first piece, I increased the power to more than 3A. The whole machine was unsteady but successfully cut a nice coded shape.
On Friday, I met Koen and we spoke about some final tasks which had to be done. We still needed a stable bed, a stage guide as well as a properly clamped wire. I decided to build a bed based on a simple cardboard construction. I would design and cut the construction, Keon would design and fabricate a guide system as well as a system to tense the wire. We took some measurements of the machine. Then I started to design.
The laser cutter was able to maximally machine a size of 46 × 96 cm. To keep it cheap and simple, I designed a bed based on small box elements made of laser-cut cardboard. Four sticks would support the stage guide. I found a long wooden stick in the workshop. It wasn’t long enough to make four pieces, so, I looked for a substitute and found a copper pipe. The wire’s tension would keep everything together. To laser-cut cardboard, I drew on Joe’s settings.
Unfortunately, I wrote down a wrong value. Koen told me a number of 57 but I noted 75. I already cut the first cardboard sheets which we just bought. I didn't want to waste material. I decided to go on and use the boxes already fabricated. Finally, I adjusted my design.
Design files
Color keys
Production photos
The boxes were glued upon a cardboard sheet (36 × 57 cm) and covered with a surface cardboard sheet of the same size. Four 65 cm high sticks were plugged into the boxes and got a stable footing. The sticks supported two guides and a ceiling.