Waldo's blog

The Fab@Home now has the hardware capability to print eight or four materials in a single print without changing syringes. Thanks to the use of servos instead of snap motors, I was able to make an eight valve tool that measures only about 13.5 cm by 10 cm. Compared to the old four valve tool, the new eight valve tool has much more build space.

For those who only want four materials, I made a similar four valve tool.

We are starting to make designs for servo based electronics for the Fab@Home which will allow the use of these tools.

Well, I found some servos that will work for the valve tool, and I made a 4 valve tool using them. Unfortunately, it is too wide.

It can go forward and backward about as much as the single displacement tool, but it has an effective build space of about two or three centimeters across. The reason for this is that it takes up double it's width in horizontal build space (except for the width of the mounting bracket, which is already accounted for). The build space is effectively the overlap between where the leftmost syringe can go and where the rightmost syringe can go. In future tools, this fact should be remembered.

I do not plan to post this tool to the wiki, since it is so wide and I plan to make a better 4 valve tool. If anyone wants me to build this tool, however, I will happily post it and instructions on how to build it on the wiki.

I am currently working on another 4 valve tool that will not be as wide. The motors will stick out sideways instead of forward, and they will be staggered so that the motors that point in opposite directions can interlock. It should be done by the end of the year.

Since I finished the old valve tool, I have been exploring different motor options which should make the valve tool cheaper and smaller. I found some servos which are considerably smaller than the snap motors, and I am working on a four valve tool that uses them.

The nose piece on my glasses broke the other day, and then I lost the pieces. I tried just wearing my glasses without it, but that made my glasses sit crooked. Then I came up with an excellent solution: I printed myself a new nose piece.

It was originally meant to be a temporary solution, since I did not have time to try to get a new nose piece right then. I have been wearing it for several weeks now, and I still haven't gotten around to getting a new nose piece. I am not sure if I will, because the printed one is more comfortable than the original nose pad. The silicone is actually soft, as opposed to the fairly rigid original nose pad. Plus, it is so convenient to print another one when I get tired of this one I can just print another one, perhaps a clear one.

The valve tool is complete. It is an improvement over the regular syringe tool in many respects.

The valve tool uses a valve to control the deposition of material that is under steady pressure instead of using a worm gear to press down a plunger like the regular syringe tool does. This makes changing materials easier, since there is only one configuration that needs to be changed. Moreover, printing with compressible materials is much easier, since the material does not seep out of the syringe when it is not supposed to.
By simply changing the syringe stabilizer plate, the valve tool can be modified to hold 55 mL syringes, thereby allowing prints that are five and a half times as large as the regular syringe tool.

The main disadvantage is that the valve tool has to have an external air supply. Also, printing with materials that react with air is difficult, since the material is extruded by air pressure.