Archive for December, 2009

Thorium Power – Possibly the Next Best Thing to the Flying Car

Tuesday, December 29th, 2009

A while back a friend from college sent me a link to this video discussing the possibility of using Thorium as a fuel in nuclear reactors.   Wired also has an article covering Thorium as a potential reactor fuel as well.   I don't think this is a magic bullet by any means, it seems to me that outside of the original formal research many of the numbers seem off the cuff, a lot of research still needs to be done, and the long term costs of maintenance are unknown at this point.  It's an interesting idea with some potential and I hope it gets off the ground some time soon.

Seeing the passion many of the Thorium advocates have does make me wish more people had that kind of optimism when it comes to nuclear power, or just science in general.  I had grandparents that seriously believed that one day they would be able to have things like personal nuclear reactors the size of an air conditioning unit that they could just plug into their house for power.   It's kinda disappointing that our pie-in-the-sky aspirations for technology we'll see in our life time are limited to electric cars and better cell phones with more advanced social networking applications and maybe a stem cell breakthrough that will give us the ability to thwart death when our severely abused stock organ systems begin to fail.  I can't help but wonder if our aspirations of limitless clean nuclear energy, moon bases, flying cars and personal jet packs have faded with time because no one delivered on a practical solution (or wanted to foot the bill for development).  Well, maybe the jet pack thing is still a common aspiration.

PS:  If someone knows how they made that kid fly in the last segment, let me know.

CNC Project Update – Stepper Motors, Controllers, and Miscellaneous Electronic Bits Acquired

Sunday, December 27th, 2009

Progress on my CNC router platform has been progressing slowly but I've hit a few milestones.  I got 4 RepRap 2nd generation motor controllers assembled and tested and have acquired 4 new NEMA23 steppers and one used high torque Xylotex NEMA23 from  the local swap meet to use in the prototype.  I got the X axis up and running and was quite pleased with the torque even the smaller steppers put out.  I also picked up some nice 4-pin sockets, terminal strips, and limit switches for the prototype build as well as a few other electronic goodies at the SSARC Hamfest about 2 months back.

As far as design goes, I've decided against the 1" square tubing and skate bearings design pictured above.  It's just too bulky for anything other than the X axis so I'm going to switch over the the more traditional precision ground shafts and bearings for linear guides on all axes at this point.  Other than being bulky, I like the design and will probably try to utilize it at some point in the future.  I've already acquired some shafts and bearings for testing this new setup but have yet to cut new bearing brackets to install on the boot-strap platform.   The overall design is on its second revision on paper with details for the X and Y axes specified and sketched up.  I'm looking at alternative linear motion setups that I could possibly fit within the specified budget so it may undergo another revision before I start cutting parts for the boot-strapped version.

This project will likely progress slowly for a bit longer as I seem to have outgrown my current work area.   I'm hoping to be able to move to a more suitable location in a few months time and set up a proper workshop, or at least that's the plan.

MakerBot Extruder Postmortem

Sunday, December 6th, 2009

Construction of CCCKC's CaveBot and my PE00001 MakerBot was pretty straight forward for the most part.  The only major snags we hit were versioning issues and a finicky extruder.   New laser cut parts are easy to get our hands on and relatively cheap, but extruder parts have to be ordered from MakerBot Industries costing us time and money.  Also, if you want to re-use your nozzle and heater barrel, you have to soak your parts in an acetone bath for a few days to clean it out, which is a real pain because you also have to agitate the bath as well if you want to be reusing those parts any time soon.  I've been told you can also use a lighter to melt out the plastic, but I have yet to experiment with this.

Anyway, here are a few things we picked up while debugging the extruder to consider in addition to the instructions on the MakerBot site:

  1. Don't cross thread the PTFE!  This is relatively easy to do since PTFE is a pretty soft plastic.  If you're worried about it, use the 3mm hex wrench as a guide when screwing the heater barrel in:
    PTFE Threading Help
  2. Remove the PTFE as a load bearing structural component.  This amounts to adding an M6 nut and washer in between the PTFE insulator and the fender washer.  This translates force on the heater barrel back up to the main plastruder body through the bolts connected to the fender washer.  While this won't stop damns of plastic from forming and slowing down extrusion, it should keep the heater barrel from getting pushed out of the PTFE, stripping the threads out as it does so.
    Extruder Nut
  3. Add a hose clamp where the heater barrel and PTFE meet.  While not required, it probably couldn't hurt and it may stop damns from forming.  I'm hoping this will extend the life of my extruder a bit.  Remember to periodically tighten this clamp up as the PTFE "flows" away from the clamped area over time.
    Hose Clamp

Check out this entry on the MakerBot Blog for some additional info and some more awesome mods to the basic plastruder setup.