Having had success with my Pink Foam armature, I looked for something that would be a lot more rugged to work with. My local Alro surplus outlet has quite a few different types of "drops" of various plastic type materials. I first tried some nice black nylon. What a disaster that was! That stuff is just to soft and sticky to work with. Even my circular saw did not like to work with it. Ended up cleaning up my blade, tooth by tooth after trying to cut a block of it.
I next tried some other kind of Acrylic, much harder and very slippery feeling. it is a bit lighter than Nylon, and really machines great. Cuts with my saw, and my mill really goes to town on it as well.
So, I made a few armatures to see just how easy it would be to machine.
Here is a pictures of my results.
The pink foam one is done, the white ones are trimmed to size, and have the corners cut to hold the windings. I did all that on my circular saw by setting the blade at 45 degrees and simply rotating the piece and passing it over the bairly exposed blade.
Next I setup the mill to make the side cutouts to fit the solar cells, and a deeper area to remove some of the weight and make a place to do the internal wiring.
Here are a couple of pictures of that process.
I wanted to have the 1 X 3 inch solar cell just fall into the mounting area. I will be using rubber cement to hold them in place in the finished armature, after all the wiring and final balance is done.
Here is how the solar cell looks, just laying in it's new home.
Rather than pass a .125 brass shaft through the block, I decided I wanted to thread some brass rod and screw it into the armature core. Here is how I used my lathe to thread the brass rod. I really like the way my little HF Lathe chuck can turn so slowly. Makes a great threading device!
Here are enough of them to build all the armatures I am making.
To drill the hole in the armature core, I put my 4 jaw chuck on the lathe, and very carefully centered the block by turning the chuck round and round, using a cutting tool in the holder to indicate at the corners of the block. It was really quite easy to get them running very evenly.
Being that the material is much softer than metal, I first center drilled the block, and then dirilled an undersize hole into the block. I figured that the threaded brass rod would thread itself into the acrylic material very easily.
Not wanting to scar up the brass rods, I used a small Jacobs chuck, I have for my mill, to hold the rod making it easy to screw in by hand. Length sticking out of the core is critical, so I marked each with a stop point, before screwing them into the armature core.
Here is how the looks having the shaft screwed in carefully by hand.
Here they are ready to spin and check for initial balance.
And finally, here is one of them on the magnetic frame piece. I am pleased that they all hand spin very nicely. Not a wobble in the group! Guess my holes must be very close to center, the holes drilled very straight into the armature cores.
It is really something, you spin it between your fingers and it will rotate for a full minute or more. Barely any friction at all on the support end.
Next I am going to d rill through the center pieces, making a wire-way to run the winding connections between sides and the ends of the armature core. This will be done very carefully and as symmetrical as possible to keep balance problems down the road to a minimum.
My Magnetic Clock build has been keeping me away from this project, but it looks like I now have some time to make some more progress.
As always, your comments and questions are always welcome,
George
