I second the use of arduino as an easy to use microcontroller. With a few lines of code you can have this thing turn the motor one way and then another. I'm sure you could probably find a PID routine to control a heater for the water as well.
I'm working on setting one up as a processing timer.
what about adapting something like the hot-dog rollers that are in gas-station food courts?
simple stainless steel rollers all geared together, you could just set it into a tray of water say 1" deep.
-Dan
MMMmmmmmm - hot dogs while you develop film!!!!
Kirk - www.keyesphoto.com
Nice idea but I've never seen those things turn very fast. Also might have electrical bits that would end up in the water if you submersed it..Originally Posted by DanielStone
Well, since you are a photographer, you do realise we are expecting pictures of the finished article?
I'll be happy to but after looking for parts today it will take some time to get things together.
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"I fabricated one years ago using a small Hurst high-torque motor (reversible)..."
Thanks Joel I'll look into the Hurst motors and 1/4" SS shaft is plenty strong. I will probably go with two motors now for 8 rollers. Thanks!
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"You can use an H-Bridge like this......."
Thanks Domaz! I'll need some time to look into those controllers further.
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"I second the use of arduino as an easy to use microcontroller. With a few lines of code you can have this thing turn the motor one way and then another. I'm sure you could probably find a PID routine to control a heater for the water as well.
I'm working on setting one up as a processing timer."
Sounds like this is what I will end up using.
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"what about adapting something like the hot-dog rollers that are in gas-station food courts?"
My initial idea was to turn the tubes with sets of rollers similar to that but now the design is exactly like the hot dog cart rollers turn, only each roller (BTZS tube) will easily be removable.
Think of one side of the hot dog cart having individual supports for each roller (for each tube). Each of these supports have spring pressure normally holding them at a perfectly verticle position. The BTZS tube rotates in the bearing that is mounted on the tube, and that bearing sits in a round hole in the spring tensioned support. The supports can be pulled back against the spring pressure about an inch and a half giving the other end of the tube enough clearance to slide out of a slightly larger tube at the other end.
On the other end of the tube, the cap end, there will be a little over and inch of extra tubing. This will have two - 1/4 inch slots cut on exact opposite sides of the tube from the end of the tube back about 1" so when the tube slides into the slightly larger pipe a 1/4 inch pin slides into the slots. This pin that is slid into the slots will turn the BTZS tube. Haing long slots in the tube will allow for various tube lengths to all work. There will be no spring pressure pushing against the end of the tube once it is in place.
The slightly larger tube with the pin that the BTZS tube slides into will be mounted on a 1/4" Stainless steel shaft that runs through the support on the other side. This side will be like the hot dog stand design with a solid long support with all the shafts going through it mounted in bearings or bushings. The other side of the 1/4" shaft will have small ribbed belt pulleys mounted on it. A long belt will run across the all the pulleys to a motor. The belts will move a little water around and protecting the eletrical parts is important.
I will probably use two motors to turn 4 tubes each though as there will be less stress on the small belts when all the rollers start turning and it may make the timing easier as well.
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"I do like the idea of something like this waterwheel in the attachment. The tubes could fit in the slots on the wheel and bungees could hold the tubes in place."
Jerold -For a system for 8x10 tubes you would just have to beef up the sizes of the shafts and motors etc., and I hope my description above helps you visualize the design a little better.
Thanks all!!!
Domaz or Jack,
Is this the board and the code that I need?
http://www.arduino.cc/playground/Main/DCMotorControl
This motor controller was recommended in a post at the Robot Shop Community Forums and it works with the Arduino.
http://www.robotshop.ca/pololu-high-...or-driver.html
That is exactly the sort of thing you need. I'd skip that circuit that you posted in favor of something like this which has terminals to connect to etc. etc. unless you want to solder a bunch of things together.
Then just write a bit of code for the arduino to control it.
Thanks so much Jack! You and Domaz have made the controller curcuit very easy to find and put together.
There were a lot of kits to make the controller board but with all the robotics around they are getting very common and ready made for different applications. There are the light duty ones for toy size robots as well as the more robust ones for large robots.
I still have not decided exactly which motors to run but once I do someone at the Robot Shop site can probably point me to the code for the Arduino. The code to reverse the motor(s) at a certian time interval is very basic compared to the all the various coding used for the robots.
Lots of H-bridge controller videos are on YouTube as well.
Thanks again!
It should not be too difficult to write something that will reverse the motor gently to minimize strain on the system. This is where having a micro-controller is preferable to a simple reversing switch.
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