OpenHouseAtNextFabStudio: Difference between revisions

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* The "forcing cone" with a taper matching the piston
* The "forcing cone" with a taper matching the piston
* Various parts such as the trigger mechanism (use a simple design like on old siege engines), linear rail, etc
* Various parts such as the trigger mechanism (use a simple design like on old siege engines), linear rail, etc
== Proposal 4: Ramjet, Dave S ==
There are many hobbyist websites that discuss DIY ramjets, show fun videos of benchtop versions, etc, but to my knowledge none have actually demonstrated positive net thrust. I believe one major reason for this is that they don't use the sort of speeds that are required, and that the best approach is to either fire it out of a suitable cannon or (more likely) use rocket motors to get the vehicle up to speed. As a high-power rocketry enthusiast I can help provide the "oomph" needed to get the vehicle sustaining.
Most small DIY ramjets are made out of something like 0.010-0.015"-thick stainless steel sheet metal, TIG welded together. We would probably want a design that was intended to be mounted to a rocket, perhaps in a pair (one on either side of the body tube).
I do have a very crude and unfinished ramjet simulator I put together that has several elements that would be of some use in our design.

Revision as of 19:00, 4 December 2011

We are excited to announce a very hacking winter-time Hive76 open-house hosted by NextFabStudio: Hive76 Open House December 20th, 2011, 7pm - Midnight @ NextFab Studio @ 3711 Market Street This Hack-tacular event will be at NextFabStudio and will get us free access for the night to some of their most awesome tools, such as: CNC plasma, CNC embroidery, e-textiles, electronics, 3D printers, shop bots... There will be food too. So Awesome. I'm proposing the first project below (we can have many of them!!)... Add your proposal below. Be as descriptive as possible so NextFabbers will be able to assess feasibility and logistics given the time constraints. Let's get hacking! -Jordan

Proposal 1: 2 Complete Hive76 Chess Sets, proposed by Jordan

A double-set of Hive76 chess pieces and boards. I want 2 complete sets in 4 colors so we can play Bughouse Chess which is just begging for 4 3D printed chess set pieces. If we get really creative maybe some magnetics and electronics could be enabled as well. Here's complete details, and an attached inspirational rendering. =] The most awesomest chess set on Thingiverse is the gangsta chess set:

Thingiverse Gangsta Chess
The original gangsta chess set on Thingiverse

I've compiled all the pieces onto one build plate and printed on reprap -- it is a 4 hour print. I'll make a set in Red, Orange, Yellow, Blue. The chess pieces have a 1" or 0.8" diameter circle on the bottom. Maybe we'd want to print the pieces larger, too, given the access to NextFab Studio's higher-end 3D printers. The complete STL files are here. Here's a rendering and the completed set:

Gangsta Chess
Gangsta Chess on one build plate
Complete Gangsta Chess Set
Complete 3D Printed Gangsta Chess Set (Red) on SloateBot
Complete Gangsta Chess Set
Complete 3D Printed Gangsta Chess Set (Yellow) on SloateBot

At NextFab we could lasercut an entire chess board made of interlocking pieces in these 4 colors, then glue them together. It will take some testing to get the kerf just right and figure out what size to make the tile so the pieces fit comfortably well inside. It would also be nice to laser engrave the chess boards. Maybe make the chess boards all Black acrylic with surface etched white squares. Not sure yet. At NextFab I'd also like it if we could embroider some felt with the Hive Logo and then cut out and glue the embroidered felt onto each individual piece. This will also take some testing. To comment or make suggestions please join our maling list!

Proposal 2: Assorted Hive76 Labels, compiled by Dave S

  • Laser-cut name tags for all members
    • Cut/etched plastic or etched anodized aluminum
    • Perhaps suitable for labeling members' storage bins?
  • Laser-cut rubber stamps with Hive logos
  • Hive76 "maker's mark" CNC-machined steel punches, perhaps in a couple of sizes
    • Good for permanently labeling soft metals, plastics, leather, etc, with a quick hammer strike

Proposal 3: Two-Stage Light Gas Gun, Dave S

A 2-stage light gas gun uses light gas (usually hydrogen or helium) compressed rapidly to create tremendous pressures and temperatures, firing projectiles at incredible speeds. Because the light gases have higher speed of sound than ambient air, and the intense heat from compression raises the speed of sound substantially more, it is possible to fire projectiles at faster than the ambient speed of sound (something that is basically impossible with a traditional gas gun). Ultimately it would rock to make a device that was cocked by hand like a crossbow and which fired a projectile (ideally a standard Airsoft pellet or BB) at multiple times the speed of sound. I have a crude and somewhat unfinished simulator I put together for this purpose that should be able to at least help direct the design. The general design is as follows:

  • Surgical tubing resistance bands are used to store the energy
  • A heavy mass is propelled down a linear rail by the resistance bands
  • The heavy mass strikes a piston, compressing the working fluid (hydrogen, helium, or air)
  • A thin metal scored burst disk ruptures under the pressure, expelling the projectile at very high speeds

Some parts that could benefit from the use of a machine shop:

  • Burst disks of varying thicknesses, with carefully scored "X" to control the rupture
  • The piston (possibly UHMW turned into a conical shape)
  • The "forcing cone" with a taper matching the piston
  • Various parts such as the trigger mechanism (use a simple design like on old siege engines), linear rail, etc