I had my brother over for Christmas and as he is a scientist and I have done some work for him earlier, he asked me if I could build him an XY table to navigate over a microwell plate http://en.wikipedia.org/wiki/Microtiter_plate
Everything seems easy late at night after some beer, and after all, he gave me this great 3D printer. So after a quick specification I started designing it in Google Sketchup. As most of the parts are from eBay and shipped out of China the project had a slow progress in the start but was quit fun once I got all my parts.
The parts I got from eBay were;
- 6MM STAINLESS STEEL ROD BAR
- LM6UU 6mm Linear Ball Bearing
- Step Motor DC 28BYJ-48 with ULN2003 Driver Board
- T5 Timing Belt for RepRap Prusa Mendel
I’m not sure what the XY table will be used for but I have built in a bracket system so different devices can be mounted. For testing I had this Micropump mp6 and controller and it is hooked up to the Arduino. I’ll probably also add a bracket for a 9g servo so one can have some probes going in to the wells.
One requirement was to have it mounted on a clear acrylic plate so that one could add light from below (the protected film hasn’t been removed yet).
As driving two steppers from an Arduino would use lots of IO pins I added a shift register on a proto board so that the steppers only uses two pins (clock and data). One added bonus of using the shift register is that one can run both steppers at the same time.
Also on the proto board I added a trim pot and a extra tack switch. These are used to run the pump both for priming and to measure the volume it pumps out. The volume is controlled by the trim pot.
Note. The trim pot is not hooked up to the pump. It only gives an analog value on A0 that is translated to the time the pump is on. So the pot can be used for something else on another probe. The same goes for the switches, they can be used for different things in the Arduino sketch.
All none essential switches are connected with jumpers so he can mix it up and change what he plugs in to the Arduino. I also avoided hardwiring the SPI as he might need an SD card later on.
All in all a great project and I had great fun building it.
Here are some more pictures
The Sketchup model
From the build
And some detail from the complete XY table
Here you can see the Micropump mp6 in the front and the controller on a small PCB
The bracket system
It uses about 2,4 sec. to address each well to the run for 96 wells takes less than 4 min.
XY-table Mark II
This summer I had another request for an XY-table. First I was a bit reluctant as building the same thing twice sounded a bit boring. But as I wasn’t completely satisfied with the first version this gave me an opportunity to build a better one and correct some of my first mistakes.
The first thing was to find some different stepper motors as the one I used is absolutely crap. So I went for these small NEMA-14 motors from Phidgets.com http://www.phidgets.com/products.php?category=23&product_id=3301_0
As these are different motors than the one I originally used I had to redesign some parts of the XY-table to fit these motors.
I also wanted to make my own driver shield for the Arduino so that I could build more if there should come along another request. That was really the fun part of this build and the first time that I used SMD components on my board.
All in all a fun build and probably the first time that I’m actually making some money from my hobby.
Some pictures from the new version.
This is the stepper driver board I made. So if anyone is interested I still have a couple left. The board runs two stepper motors via 3 Arduino lines leaving lots of the IO pins available for other stuff.