Recap of February 4, 2009 meeting


The evening began with Nick recounting the earlier colloquium by Andrew Ng of Stanford about Intelligent Robots. As members arrived we discussed various aspects of AI and robotics.


Recounting last meeting’s coverage of the Kreg pocket hole jig, Jon showed us a Kreg jig in a carrying case that he purchased recently and a shelving project that he did for his wife. He talked about the challenges and successes of putting together melamine shelves.


Also recounting last meeting’s coverage of mold making and casting, Ken showed an acrylic project. Using a small plastic film canister and easily available casting acrylic (fiberglass casting resin, readily available at home centers is tinted grey and will not work for this, so Ken recommended Clearlite casting acrylic available from TAP plastics, Ken has preserved wedding cake for his two son’s weddings as a memento. (Pictures to be posted



Ken also spoke about the use of polymer clays (Fimo or Sculpey) as a modeling tool for making parts. Polymer clay works well for non- functional, decorative items, such as moldings or frills, but for practical parts such as knobs or handles it is too fragile. Instead, sculpt the item you wish to create in polymer clay, fire it at 250 degrees for 20-25 minutes per ¼”, and use the resulting object to cast a negative mold. Then recast the object in acrylic (clear or dyed, or paint it afterwards) and you can create multiple, sturdy items.

Alternatively we also talked about using polymer clay as a one-shot negative mold for casting acrylic or plaster items. Once the medium has set up the polymer clay can be ablated away, leaving the cast object.


Nick showed us the results of his tube-casting, which utilizes the tube mitering template software that he designed.  After creating a complex design of mitered tubes, printing out the templates, taping them together using card stock, and then bracing the tube-template-mold in sand, he filled the tubes with plaster.  There were some voids, and as it turns out the mold was somewhat tilted, but he ended up with a post-modern sculpture which could be a desk ornament or a hat rack. One thing he has learned from this casting experiment is that due to the fine nature of plaster, all of the seams, tape and even some minutely raised lettering on the cardstock were imprinted in the plaster.


New member Walter brought us news of a DIY group in Philadelphia called The Hacktory They have a shared space for working on projects, meet once a month, offer a variety of classes, and … have just received a 3D printer from a fellow inventor.

Walter told us tales of putting this thing together and making it work, and then filled us in on his own Arduino/LED matrix projects.

His goal, to make an Arduino driven 90×90 LED matrix that displays monochromatic grey scale full motion video. As part of his project he is exploring the design and manufacture of sub-components that can be daisy-chained together.


Many of us have expressed interest in a “field trip” to Philly to visit The Hacktory.


Rob has suggested that he will bring in a discarded (but working) B&W television next meeting for us to experiment with, and if Ken can find it, he will dig up his Timex/Sinclair to produce RF output for the TV.


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