Ferrule Installation
Click on the thumbnails for more details. The ferrule installed here is Mason's Micarta Tube with a 3/8-24 thread. This is only one method of installing a ferrule but it incorporates some of the best ideas. A register diameter is nice for accurately locating the ferrule concentric to the tenon while the threads provide a solid mechanical bond. The cross section view shows how nicely everything fits. The fine threads fill the tapped hole almost perfectly for a solid connection. I recommend the use of a 1/4" shank cutting tool to reduce cutter deflection. It definitely won't look like this if you use a compression die.
See HERE for one method of threading a tenon. Note that the video shows 3/8-16 threads being cut while the above pictures show 3/8-24 threads. I've experimented with 5/16 tenons in 18 and 24 pitch and also 3/8 tenons with 10, 16 & 24 pitch. All things considered, I prefer 24 pitch.** The tenon remaining is about as strong as you can get while still using a ferrule. It is significantly stronger than a 5/16 diameter tenon with the added benefit that it is not excessively undercut by a coarse thread.
**UPDATE ON THE PARAGRAPH ABOVE: After experimenting with 3/8 threads for quite some time, I'm revising my statement about preferring 24 pitch. That pitch seems to be a better solution with MM or LBM - mainly because it's easier to cut the smaller threads in the ferrules. However, when using Juma, Elforyn or Ivorine 3, I find that I like 3/8-16 instead. When using ivory, I go "old school" and use a 5/16-18 capped ferrule with a .250" long shoulder.
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Another sequence showing the installation of a short ferrule on a 3/8-24 tenon. This tenon also has an 1/8" locating register at the shoulder.
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This customer wanted 3 shafts with 3/4" long capped black linen ferrules.
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Ivory Ferrule Construction & Installation in 2 Pictures
Progression of an ivory square as it becomes a ferrule.
Progression of the ferrule installation on a 5/16-18 tenon.
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Ferrule installation video using all live tooling.