Machining Western Electric 13a throat

No shortcuts : cast iron throat exact replica

Heavy machinery needed to thread the end in which the brass insert is screwed, US thread obviously!

All fun…


  1. Wow. Interesting method of clamping. As a mechanical engineer and perfectionist, I would never use such a set up. Al those parts under the vice result in stack errors. I would strongly advise the machinist who is responsible for this very imperfect clamping method to read the following books:

    1: Foundations of mechanical accuracy by Wayne R. Moore 1970.

    2: Holes, contours and surfaces by Richard F. Moore 1955.

    These a 2 standard books that are mandatory for every machinist.

  2. For those who are not able to see what is going on here at first glance (like me) the milling head is being used to hold a center. It is probably a spring loaded center used to keep the tap centered and aligned. If you look closely you can see the squared end of the tap at the end of the center. This is quite the elaborate setup for just one or two pieces (mono or stereo) but it shows the care needed to avoid a disasterous mistake. If the tap was not accurately aligned mounting the transducer would be a mess and many hours would most likely be spent trying to make it work or just to re-do it. Also, I would guess that each horn has enough variance that each one takes some time to get right. At least the horns are not that awkward and are easy to clamp. Kidding of course.
    My point being that although the setup takes a lot of time, it is necessary. Photos like this I think help interested parties including clients see just how much work goes into a project like this especially when there is no production line. As a builder myself (speaker and amps) I wish I could give people a better sense of what it takes to make custom builds.
    Anyway, kudos to you with this and all of your builds.

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