Friday, October 30, 2015

GENERATING STATION

A model generating station has just been completed. It is not a scale model, but a simple representation of a very early 1900s vintage generator, shown below.
These were low voltage high current machines. I'm not sure of all the things they were used for, but some powered arc furnaces to refine metals.
The pole pieces for the model were made from 1/2" steel plate machined to shape. Above you see some of the forming taking place on a rotary table mounted on the milling machine.
The commutator was built by turning a copper sleeve and epoxy gluing it on a turned Micarta insulator sleeve , and then sawing a slit between the segments.
Several castings were needed, but I only had to make a pattern for the base. The other patterns were pulled out of my pattern pool.
   If you note the brushes are set up like the original, so they can be rotated around to find the place of greatest efficiency.  The field magnetism is provided by a stack of ceramic magnets clamped between the pole pieces. The armature is wound with regular magnet wire.
   The generator was under construction during most of the month of October, and was finally completed yesterday. Below is a short video of it doing it's thing.
video






Monday, October 5, 2015

OLDHAM'S COUPLING

Another project has just been completed called Oldham's coupling named after the inventor John Oldham, (1779-1840) an Irish engineer. It is simple and compact, and unlike a universal joint it is constant velocity. Although it was invented about 200 years ago it is still used in many of today's machines in various forms.
My project was constructed by looking at the picture the Z5 thing shown above. Which was probably a classroom demonstrator.
Below is a short video of it in operation. In the video the shafts are offset slightly over 1/2". As you can see it works very free and easy. It is just so much fun to turn cranks.
video



Thursday, October 1, 2015

RECTILINEAR


While searching the web looking for things of interest and ran onto this gadget, which is a demonstrator of James Booth's 1843 invention of a "rectilinear" linkage or mechanical motion that was intended to be used on  a compact steam engine. Apparently there are no records that such an engine was ever built. However more recently English model builder Anthony Mount ran onto the patent drawings and designed a scale model. It is the model shown to the right on the cover of his book shown below.
This project started by making a wood pattern and pouring castings. While I was at it, I also poured castings for the next intended project.
This was a simple project with few parts, but still took several days. Yesterday it became operational, and this morning it received a little paint and a wood base. Although it is interesting to watch the movement, I do not know how practical it would be in a steam engine. I'm sure my model will end up being another desk toy.
video