I really enjoy building mechanical movements, and I am terrible at it. It is really difficult to build things that move without relying on expensive pre-built mechanisms. Thus I am always looking for cheap ways to design and build cogs, gears, and sprockets.
For gears it is tough to beat the online wooden gear generator at woodgears.ca. It lets you specify size and number of gears, and also lets you see how they mesh and tweak a bunch of variables. I usually print these to pdf and then import them as vector to illustrator. With this site you can build any number of compatible gears. They have rather large teeth because they are meant to be cut out of wood with a bandsaw, but they will work very well for low-precision work. There is also an inkscape plugin that generates gears as described here by MAKE.
One note on importing all of these files into illustrator. Illustrator has strange import prefs, and if you import a dxf that is in mm, and your preferences are in inches, centimeters, or anything else, then it will scale your drawing on import. Be careful. This is an easy way to mess up at the very first step.
Timing belt cogs are another deal entirely. There isn’t an online generator. There are a few python scripts that purport to build cogs, but they never seem to work right. One other way to do it is with blender and a plugin, but then you end up doing more 3d modeling than cutting.
To build one in illustrator you will need to know the belt you plan on using and the number of teeth you want the cog to have. You will also want to go to sdp-si and download an example any cog that uses your belt pitch. Set your units to mm in illustrator>preferences>units. Grab the dxf of that cog and open it up in illustrator.
More than likely you will see something similar to the image below. It has two example teeth showing the tooth spacing, but the entire cog isn’t drawn out as a time saving measure.
I just got back from the Sparkfun AVC. It was a blast! I shot a lot of video, but that will take a while to get processed edited and uploaded. In the meantime here are the things I thought were cool on the ‘factory tour’ with a few AVC shots thrown in.
This pond instill fear in a lot of AVC owner/operators. Strangely enough the airborne division didn’t seem to mind the water as much as the trees.
This lil guy broke down the day before the big race. Sigh. It’s not easy being autonomous.
Known for it’s blazing speed, Bluebot held it’s own. It eventually claimed first place in the DNF division!
My newest project involves reincarnating a very old (1998) cd duplicating robot. It is a DTP-1000 that was originally SCSI only. Due to the fates smiling down upon me I was able to pick it up on ebay for $11. I bought it intending to put an arduino in the place of the control board and probably have to do a lot of reverse engineering. The next day I happened upon this site where, amazingly someone has already opened one of these up and has instructions on how to enable serial control! I still am in awe of how lucky I got and really happy that DarkBane dropped all of that knowledge on the world.
There are a lot of pics below, since that was the one thing I could do to add to the fine directions DarkBane has already provided. Another thing is that in his command set he has two typos. I will quote his post after the pix and note the command set in bold.
Check out my new(er) cd robot project here. I grabbed an old scsi changer machine from ebay and have been working on adding serial connectivity to it. If it works, it will be a much simpler route!
One of my “always in my head” projects is a CD changing machine. I have seen the myriad of otherprojects out there, and this always captivates me, in that it is just out of reach, but it seems to be a fairly simple concept. I have been thinking and sketching on this one for SUCH a long time that I have decided to post it before it is fully polished up.
The basic premise is I have an arm that swings up and down mounted on a platform that rotates 180 degrees. Both of those are positioned by hobby servos. On the tip of the arm there is two vacuum aided suction cups and some hdpe tubing.