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Can anyone provide *definitive* specs on mandrel taper angles? I'm building an electronic cylinder phonograph and am designing the mandrels in CAD and need the taper angles for "normal" cylinders as well as Concert, Salon and whichever other ones people can send me info for.

The spec is supposedly ⅜" taper, per foot, which equals a taper angle of 0.895*. Even a protractor with a vernier scale has difficulty confirming if this is exactly correct. I also tried a micrometer and measuring a few mandrels, but the results are anywhere from 0.812* to 1.336*.

Any info on correct taper angles, as well as if different types of cylinders have different angles, would be much appreciated.

Thank you.

Just meanwhile you get your measurements ... I've seen some other phono makers don't use a complete mandrel. They only put two cones to be inserted at both ends of the cylinder (one in the root, another in the end gate). The cones are much steeper than the original mandrel, and this serves for fine adjustment of the cylinder concentric position to avoid wow.
Look in yt for homemade electric cylinder phonographs and you'll see some good ideas...

Don - I've made mandrels from the specs on the poppy records page for phonographs in the past.

The poppycrods page (and site) should answer most questions.

https://www.poppyrecords.co.uk/tec001/tec01.htm

Link below to one of the very simple players I made many years ago using the dims from PoppyRecords. My own measurements of mandrels were similar.

http://www.christerhamp.se/phono/lomasmadi.html


-Rob

Edisonia Records & Reproducers.
www.edisonia.com

Inigo wrote: Wed Feb 23, 2022 8:48 am They only put two cones to be inserted at both ends of the cylinder (one in the root, another in the end gate).

That's what I did
https://youtu.be/QP42Cqz14RI

I thought it was a simpler and more flexible solution than a single mandrel

I understand the original Edison spec was ⅛" in a four inch cylinder, or 1 in 32. I make mandrels on my 3D printer at that taper and they work a treat. Obviously some unlined indestructibles have shrunk, and often at different amounts ar each end, but 1:32 is a good starting point.

Hope this helps

Keith