Chalk up another win for PVC Pipe Storage solutions! I spotted this garbage can corral during one of my recent journeys around western Queens. This intersection is especially windy, so my suspicion is that whoever built this corral did so to keep the containers from blowing around whenever they’re empty. Such a simple solution to an otherwise aggravating problem!
Recently, we’ve been messing around with motors and gears at Pemtech. Students in one of my classes are building an underwater ROV, and we don’t have any decent propellers. Rather than shop for them, we’re fabbing our own with the laser cutter and MakerBot. Earlier this week, Jett worked out the proper dimensions to fit a plate to a motor shaft. He did this by measuring out a range of holes and then cutting them in quarter inch acrylic. Once they came out of the laser, he tried pushing the motor into each of the holes until he found the “Goldilocks fit.” Now that we had a plate, he used the same process to cut a series of holes into the plate that could be threaded with M3 screws. This setup allows us to attach anything to a motor.
Last week, we were printing motor holders. These were designed in Sketchup, and printed out on the MakerBot. After fine-tuning the design to fit the motor, shaft, and provide bolting holes, we added a bit of height. Ollie and Kyle then set about waterproofing them with a combination of petroleum jelly and candle wax. They used the hot pot and made a double boiler to make the wax. Brad set the motors up with soldered leads that can be connected to the snake. This motor holder allows us to attach a motor to anything.
Among the ways that these breakthroughs will come in handy are by combining motors to gears. The other day, I had a bit of class preparation time, and decided to return to my desire to design my own gears. Recalling a passage on making gears in Dustyn Roberts’ excellent book Making Things Move, I opted to give Inkscape’s gear generating tool a try. There is a very informative version of the tutorial for designing gears on Make: Projects. After cycling through it a few times making cardboard gears for my self and through a few students, I slimmed the instructions down to just a few lines for getting started. It now only takes five minutes or so to design a pair of gears that will work together, fit on an axle and onto a motor.
Chris, one of the students in the Fashioning Tech class, saw the need for a propeller, and suggested modifying a computer fan. We removed the hub motor and found a 1 inch cavity in the center of the propeller. By cutting disks to the right exterior dimension with a hole in the center sized for the motor, it could hold with a compression fit. To make sure it can be secured to the propeller, we cut a set of holes in the disks to accept the M3 screws and nuts. A bit of quick work with the drill and the fan blade can now be attached to the motor, which can in turn be attached to the vehicle.
One of the things that we will be needing next is assemblies to hold gears that can be adjusted to various ratios. Those can be designed out of flat stock with a variety of holes cut at intervals. We’ll work it out in cardboard, then upgrade to acrylic. Another will be a rack and pinion or other system allowing us to convert the rotary motion of the motor to the linear motion needed for manipulators and water testing tools. There are some excellent visualizations of mechanisms over on Robives.
Jaroslaw Lupinski designed the Senpai (Shield for Extra Nimble Programming of Arduino) shield, to make it easy to program AVR microcontrollers using an Arduino:
If you want to take your device to the next level, you’ll need to program a bare AVR chip to run the code you’ve developed. If you want to build around the ATMega328 chip (the same chip that’s inside the Arduino), you can even program the bare chip with the same code as the Arduino sketch. A great sketch has been written by an Arduino user that lets you turn your Arduino into an AVR programmer. It’s great if you just need to program one chip and be done with it, but sometimes you want to develop code while a chip is socketed on a board, to program surface mount components, or to program lots of chips in a short amount of time. Using the shield I developed, you can use the ZIF socket to quickly swap out chips to be programmed (it supports 3 device families), or use the Atmel standard ICSP protocol to program chips that are already in-circuit with the ICSP header.
Last night I was out on an adventure. In the morning, the shower curtain fell down because the pole was a bit too short. After I pulled the paper towel tube shim out, I tried to twist the rod to lengthen it. Since it was maxed out, it needed a little something special to help make ends meet.
When I went downstairs, I took a few extra steps out to the car, got the MakerBot, and returned to fire up the computer with Sketchup. It took two iterations to get the dimensions right. The new part came out sized to fit over the end of the curtain rod and take up a bit of the gap.
When everybody else woke up, conversation turned to MakerBots, 3D printing, shower curtains, and how someday everybody will have their own plastic manufactory. Just think, twenty years go, not too many people had a home color printer. What might we see twenty years from now?