Friday, December 14, 2012

The Robot Dragster Project-Chapter Three

This is the week that the big stuff gets hauled over.  Tools, materials.  We by now have an actual shop cart to pile stuff on and more importantly a dedicated place to park it away from inquisitive or acquisitive fingers.
Some of the stuff I hauled in

Goals for the day were:

1. Range test the two competing radio systems outdoors.
2. Wire up a solenoid, explaining how it actually works.  Connect it to an RC switch and fire it remotely.  Using the best range radio option, see what happens when signal is lost.
3. Consider wheel options for the "heavy" dragster.  I had a strong suggestion for the "light" unit.
4. Cut 1/2 inch plywood for bases for each dragster.

It may seem a bit early to do this.  After all, real engineers would map out the gear ratio, use CAD to create a virtual prototype and so forth.

But the point of this class is to take kids who don't know a lot about engineering and help them figure out what does and does not work.  We probably have enough class sessions to have each dragster fail once and be revised with whatever is needful.  Different pulley sizes, more powerful motor, lighter battery options and so forth.

The class session went very quickly.  Outdoor range testing showed, as I suspected, much better results.  Both the Futaba and JR systems held control out to 500 feet.  Beyond that I am pretty sure the kids will not be able to see the dragster well enough to make delicate steering adjustments anyway.  We did not have time to do fail safe testing.

I went over the basics of how radio control switches and solenoids work, then turned some kids loose with the schematics.

It helps that I have a couple of kids who did the advanced class last year, so it only took them about a half hour to have the system all set up.  The threw the switch on the radio transmitter and sure enough, the starter motor fired up.

I asked them: "Does anyone here know how to build a remote starting system, like what you would use to start your car out in the parking lot?"

They said no.

"Well guess what.  You just made one"

In other parts of the work area:

Brainstorming ideas for steering mechanisms.

A mounting bracket for the Magmotor.  When plotting out how long various things should take you really do have to make allowances for these being middle schoolers.  They just do not have the arm strength yet and, for instance, drilling holes in metal is time consuming.

Also, these being middle schoolers, there is always one kid who just has to monkey around with stuff.  Flipping switches on and off, waving tools around.  Tonight we had one who was way too fond of a big rubber mallet we use for tapping components down snug.  After about the fourth warning about monkey behaviour I decided to take a different tack.

"C'mere.  I'm gonna teach you how to use an angle grinder."

After a few minutes of supervised use of this scary tool he saw things differently.  He said his hands were getting numb from the vibrations and that the shower of sparks was landing all over the place.

He also said that when he told people he was using an angle grinder he figured half of them would not believe it and the other half wouldn't know what it was.

We will see if a greater respect for tools is forthcoming.

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