OpenSCAD Model of Hot Cathode

8 05 2012

Here’s a rendering of the hot cathode and the cylinder mentioned in the last post. The important dimensions here are diameter of the holes in the cylinder, and their distance between them, because they were made according to the measurements of the actual cathode. The rest of the dimensions are approximate. We will take more measurements and tweak the model to fit them.

Here’s a link to the OpenSCAD code.




New Parts: Cathode Ray Tube, 3D Ceramic Test

18 08 2011

I bought an old oscilloscope CRT at Leeds Radio. RCA-3BP1

I will eventually break this tube (implosions! I know!) and use the electron gun and phosphor inside the vacuum chamber.

The idea is to run the sydney experiment with a pure electron beam. We are currently using an air or deuterium plasma.

Before I break the CRT I will operate it in tact. Here is the pinout for 3BP1.

This sweet CRT hack is a good start for the power supply needs.

Already got the hot cathode running:


On the 3D printing front I received the 3D printed ceramic coffee cup I ordered last month:

It looks really promising. Soon we’ll have a 3D printed ceramic magrid.

Check Out This Image

9 08 2011

I’m working on an all ceramic 3D printed version of the coil formers.

Made this image by mistake:

UPDATE: Progress towards a coil former with integrated electron gun:


More progress on this design… can you see it evolve?



BRL-CAD / STL Progress

30 05 2009

Shout out to Michael Davis. He read about my BRL-CAD STL problems and suggested I use combinations instead of regions. This largely fixed my STL export issues, and the export is generally much faster. I still have to check that a service bureau can use the STL files produced. Here is a render of the STL output:


You can see the faceting produced by the chosen resolution. Looks like we are back in business with designing and producing Polywell cores.


16 04 2009

I’ve been having some problems getting BRL-CAD to export to STL.

Going to try and hack my way around the problem today, so we can order the first core prototype.

Hercules Extruder 3D

29 12 2008

Still cutting my teeth with sketchup. Here is the hercules extruder in 3D:




The sketchup-svg-outline-plugin is great for producing laser cuts for Ponoko. I recommend this sketch-svg tutorial.

Added the trapped nut cutouts:

trapped_nutThis intersect model tutorial was essential for making the trapped nut cutouts.

I just ordered v1 of the extruder from ponoko:



20 12 2008

Seeing as I’ll be doing a lot of prototyping, I figured it would be good to have my own rapid prototyper. So I’ve built a reprap, it’s almost finished. This is the ponoko model. Progress so far:  ponoko


16 11 2008



This iteration of the design is nearly ready for rapid prototyping. The chassis walls are thicker, and there is more room for the coils. Also the joints are hollow now, so the coils can be wired together. Specs:

  • outside_radius: 242.487113059643 mm
  • torus_midplane_radius: 192.693468865964 mm
  • donut_exterier_radius: 107.8 mm
  • torus_radius: 77.0 mm
  • donut_hole_radius: 46.2 mm
  • torus_tube_radius: 30.8 mm
  • torus_tube_hollow_radius: 25.564 mm
  • joint_radius: 21.56 mm
  • joint_negative_radius: 7.546 mm
  • torus_tube_wall_thickness: 5.236 mm


Here is the corresponding array of 12 lids:



9 11 2008

Now we have the completed polywell shape, with connectors:


Now we can export to an STL file, and produce our first physical object (in plastic to begin with).


23 10 2008

Further progress towards a working chassis:

this is what it would look like before inserting the coils.

here is a closeup:

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