DIY tenon making

by Paul Combs, CPG There are plenty of great postings and comments on the PPN Blog about Peterson Tenon Extensions – how they work, the difference they make in the smoking qualities of Peterson pipes, whether the cross-drilled vents matter, what material they are made of, and occasionally getting them to fit properly (see Posts #208,  154, 290, 322 ). Tenon extensions are a feature of the higher-grade Peterson system pipes including the Deluxe, Supreme, Premier, and System Star lines. Going back to the Patent days, 1898 being the oldest example I personally have seen and until around 1960 the most recent, the tenon extensions were made of bone. Since then, they have been made of aluminum. Working with Peterson pipes of varying ages I have seen tenon extensions in these configurations: • 8.3 mm diameter thread, 0.75 mm pitch, 5 mm bore (made of bone, both with and without cross-vents) • 8.0 mm diameter thread, 0.75 mm pitch, 5 mm bore (bone) • 7.0 mm diameter thread, 1.0 mm pitch, 3.5 mm bore (both bone and aluminum) • 6.3 mm diameter thread, 1.0 mm pitch, 3.5 mm bore (aluminum, with and without cross vents) • 6.0 mm diameter thread, 1.0 mm pitch, 3.5 mm bore (aluminum). In recent production, 6.0 mm x 1.0 mm appears to be the Peterson standard. When I requested a replacement tenon extension from Peterson three years ago this is what they sent; unfortunately, it won’t grip in a tenon that is tapped at 7.0 mm or 6.3 mm diameter even though the 1.0 mm thread pitch is the same. Over the years I have made several tenon extensions myself out of aluminum, a couple out of Delrin, and have long wanted to try my hand at making one out of beef bone. This was in part because I wondered how bone behaved as a material in the shop and secondly because I hoped, if it worked, to be able to make period-authentic tenon extensions for some of my older pipes. I assumed that the bone Peterson used was bovine (beef) because they are hard, a decent size, and readily available. I asked my wife to set aside some bones for me the next time she made soup, which brings us to the next step in the adventure… These bones have been thoroughly cooked, so I trust are also sterile. Choose a bone slice with straight grain and a thick wall.   I used a scrap of 3/8” round stock to mark a ‘target’ zone and then marked cutting lines. Plain old hacksaw for this step… Chuck it up in the 4-jaw nice and snug, adjusting so that the block is relatively straight horizontally and the target circle is close to centered. Making it round. This step is a bit noisy at first and smells like soup! Part way through… One end is now round. Flip it around and turn the other end. I switched to the self-centering 3-jaw chuck in this step for convenience.…