Here’s my method of replacing a broken tenon. Sorry I forgot to include more photos but maybe these will illustrate my work.
First remove the broken tenon from the shank with a screw and pliers.
Now the work begins. I drill out the tenon remnant in the stem by hand using progressively larger drill bits until it’s 1/4″ opening. When I use the 1/4″ bit, I put it in the drill press and use a vise clamp that I made with guidance from Tim West. I cut a 90° groove various depths on 2 pieces of wood to hold rods or even premolded stems square. This would also be the time to use a Forstner bit to make the face of the stem square and flush.
Now I need to drill out the delrin rod. I put a 3/32″ drill bit loosely in the drill press upside down. Then I lower it into the vise, tighten the vise and release the drill press, keeping the bit perfectly centered. Then I put a piece of delrin up to 1/2″ dia. into the drill press and lower it onto the bit in stages. This prepares the delrin for turning with the tenon turning tool.
Then I mount the turning tool in the drill press and set it to take off just a bit at a time. After lubing the tool’s guide pin, I turn down the delrin until it fits the hole in the stem. I forgot to mention I tap threads into the stem. This helps when I put the tenon in, giving more area for the epoxy to adhere to. I scar up the part of the tenon going into the stem, also increasing bonding surface. This isn’t the safest way but I hold the delrin with some pliers and feed it onto the tool, until i have it turned down to fit. Here’s some examples of when I either turned the small part too small or turned the main tenon too loose into the shank.
After gluing the tenon in the stem, I can turn it down to fit the shank. I always bevel both sides of the tenon for smooth airflow.
Here are 3 I finished this week. Minor tweaks were needed for a perfect fit. Some sanding and touch up staining and here they are.
Thanks for reading about my methods, comments welcome!