redg8r and myself have been in discussion about creating a drying wheel that its controlled by a Micro Controller. With my background in discrete electronics and my hobby in robotics it shouldn't be that hard to accomplish. I have some basic design plans laid out below and would greatly appreciate input from the community on every step in this process.
- Adjustable RPM (1-10?)
- Adjustable cycle time (1 hour -12 hours?)
- LCD Screen to display time left and RPM
- Enough Torque to turn large drying wheels (whats large?)
- Easy to retrofit drive system to existing wheels.
- Arduino Dev Board or AVR prototyping board.
- Low Voltage DC Motor (12v Max) (Stepper, Geared DC, or Continuous Rotation Servo?)
- 20x2 Character LCD. Parallel input.
- 2 button input system.
I have 2 ideas for the drive system at this point and really would like some input on them.
Quieter and Cheaper Drive System
This drive system would use a Geared DC 15 RPM motor that would be driven by a transistor and controlled by an Arduino. The motor would have a 2-3" rubber covered wheel on it and this would mate up to a second wheel on the drive end of your drying wheel. The wheel size would have to be calculated to give us a max RPM of 10 or what ever the community decides is fastest useable RPM. Estimated cost to complete the electronics and drive system $50 +-$10
More Powerful, Louder, and Slightly more Expensive System.
This drive system utilizes a NEMA 17 sized stepper motor that would direct drive a length of 1/4" all thread that would serve as the axle that holds the drying wheels. By design stepper motors are a little noisy, and require a stepper motor driver chip in addition to the Arduino. This would be the easiest to design and would by far be the easiest to fine tune and maintain. I estimate this one at $50 +-$15.
Those prices are would it would cost for one to build this themselves using a pre built Arduino and Stepper Driver Shield. I could get the cost down some by building a custom PCB and eliminating the unused electronics.
Open Source Hardware Compliant
I am a huge supporter of the Open Source Hardware movement and was part of the initial OSHW Definition acceptance. This whole process will be thoroughly documented and the final code and design files will be released under the GNU Free Documentation License (still reading up on this so it may change.) so that anyone can make, modify or do as they please with the end product. So please feel free to speak up and comment on anything here that you think should be changed, amended to, or completely redesigned.