Machinist Training Almost Finished and Modified Cavity Simulations


  • The Faraday cage at the University is being replaced by a modern RF anechoic chamber.
  • I signed an NDA with Roger Shawyer and I am now simulating a cavity with the modifications suggested.

Since the last update, I am now two classes away from completing the “CNC Certificate”program at NAIT which means I will start applying for jobs as a “CNC Operator”.  With my strong programming background and 3D CAD experience, I plan to quickly transition into CNC programming.  In the last class, we cut an inside bore and then an external tapered NPT thread.

Tapered external NPT 3/4 thread in steel

I have been looking at local machine shops and have found a bunch I have short listed, both for working at and for building the parts I am currently simulating.  Here are few that stand out:

The great news is that all of them are within a twenty minute drive.

As for the cavity, as per the agreement with Shawyer, I can’t say much about the alterations necessary to get a high Q, but now that I have seen them, they all make a lot of sense.

On the simulation front, I tried using a modification of my previous model, but the results haven’t been satisfactory and I am rebuilding it from scratch.  The problem is that my previous model used a vacuum as the background material to which was added a thin skinned copper cavity.  However, the AKS Eignemode solver then treats the external air as a valid location for modes which are useless.  The new model will use a metal background into which an appropriately shaped vacuum will be inserted which means a a simpler model with fewer tetrahedral mesh cells.  The mesh cells only need to make up the vacuum and the probes.  For example here is one of my test structures from a month ago:

As an aside – I have decided not to build the test structures because, as confirmed by Shawyer, the Q will be too low (as is expected with small cavities at 6Ghz, the tolerances required a very tight and wall heating is high).  With the necessary alterations for the 2.4Ghz cavity, the test structures are redundant.  The test structures were really plan B if Shawyer decided not to respond.  NAIT has also not responded to my request to use their CNC machines, which is where I had planned to build the test structures.