Starting a Mini Sumo Robot Project

For a while now I have been intending to put together all the modules I have lying around to make a Mini Sumo Robot. I have a tank tread platform, a dual motor controller, an old battery pack from an RC car, and the board from my tachometer project. With those parts plus IR emitters and sensors, I have the beginnings of a sumo bot. Below is the approximate layout (not yet hooked up).

Pieced Together Mini Sumo Bot

My first attempt at creating the IR emitter and sensor circuit failed miserably... mostly because I was trying to do too much at once.  The other problem I think I am getting is the vast differences in the IR detectors I purchased from RadioShack.  I have one of the Sharp distance measuring units I bought from Sparkfun (GP2Y0A21YK) a while ago... I should probably purchase another and leave the building my own module for the future.

Completed Simplex Air Engine Drawing

Now that the engine is up and running, I have updated the drawing so that all of the bugs are out (or should be).  

Completed Simplex Engine Drawing

Working Simplex Air Engine

After a long time of starting and stopping work on the simplex air engine, I have finally got all the main parts made and assembled.  After a little tinkering, I got it working!

I'll updated the drawing and re-post it shortly along with a longer and nicer shot video.

Hole Tapping Guide with Spring

The best way to manually tap a hole, when the part is still on the mill, is to use a shaft which has a tapered end.  The tapered end interfaces with the hole on the end of the tapping handle.  This ensures your threads are "perfectly" normal to the part.

While tapping a hole during the Simplex Engine Project, I realized I did not have this helping taping guide.  The simple way to go would be to use the shaft with the tapered end as I described above.  Using that way would force you to move the quill as the tap moves downward, but who wants to do that?  So I came up with a three-part (plus one screw) design that uses a spring to save me from that 'extra' labor.

Assembled Tapping Guide with Spring

To use it, simply put the non tapered end into your chuck, put the tap and tapping handle in place, and move the quill down until you have compressed the spring a reasonable amount.  Now you can rotate the tap with the tapping handle while maintaining some axial force.

Although the drawing uses 1/4 rod, I ended up using a slightly larger diameter since that's what I had laying around.  Whatever you choose, make sure it's small enough to fit in your chuck.

Tapping Guide Parts

Tapping Guide Drawing