Using Delrin Tenons: Difference between revisions

First, decide on your tenon diameter. Most folks will use 5/16", but 3/8" and 1/4" are not uncommon.

Next, find a drill bit that's going to give you the right size hole for your delrin. As any machinist will tell you, 5/16" is not 5/16" from one drill bit or piece of stock to the next. In this case, you can count on the delrin being the same size, as these are manufactured to rather close tolerances. Like it or not, you're going to need to experiment on briar. other woods will not react the same as briar to drilling, and will not give you an accurate gauge of hole size. Scraps of briar are fine, as long as you can drill them using the same methods you intend to use when you make a pipe.

Once you have a drill bit that you know will provide a consistent hole size, you're ready to start using it. Be aware, that the bit that provides the right hole size for briar, may be to small for drilling a hole in vulcanite or acrylic. You'll need to be sure of your drill bits before you start.

* face the shank with a 1-1/4" precision Forstner bit. I take care not to use to heavy or aggressive a hand in this step. You want to avoid grain tearout.

* drill the mortis, about 3/4 of a turn of the tailstock at a time. This works out to about 1/12 or so of an inch for each advancement. After each advancement, I remove the bit completely from the hole, and clear all the dust and chips. The depth is roughly 1/2" inch when the mortis is completely drilled (at this point I continue on with the airway and tobacco chamber, that's not covered here.)

* I chuck the rod stock and face with a 1-1/4" precision Forstner bit

* total hole depth in the stem material is about 1/4" to 1/2" depending on stem shape.

* Slice off a length of delrin approximately the length I need. I usually go about an 1/8" longer just to be sure I can bottom out the tenon in the mortis in the stummel.

* first, I take a triangle file and slightly deepen the grooves on at three points around the circumference. Do not depen the grooves all the way around. The goal is to get a slight triangle shape in the grooves so that the delrin will not rotate in the stem once the epoxy has cured. Just a couple swipes of the file in each groove at 120-degree intervals should be quite sufficient to hold it.

* use the toothpick to put a dollop of epoxy in the stem mortis

* insert the delrin tenon into the mortis. Epoxy will go everywhere, this is normal.

===Preping the Delrin===

Now that our epoxy is fully curred we can fit the Delrin tenon to the mortise. First bevel the tenon so it will not damage the mortise in the stummel, then check the stummel and measure how much to trim off the tenon:

Next we measure for the depth of the first drilling. Shown is a 5/32" tapered drill, which does an excellent job of drilling. 5/32" tapered also provides an open draw while tapering down to a smaller hole. Stop about 1/2" to 3/4" short of the end and then follow with a 1/16" drill on through the stem. This last section will eventually flatten out and be funneled wider at the bit end of the stem to provide for a continuous airflow, and yet facilitate a thin comfortable bit:

Next we change to the 1/16" drill, and drill completely through the stem. Again, this must be done very slowly and the drill removed to clear chips:

The draft hole can be sanded up though most of it's length by wrapping sandpaper around the 1/16" drill bit. The final 3/4" or so cannot be reached, but it will be carefully opened, filed, sanded, and buffed later. Steel wool does a nice job cleaning up the tenon end after the sanding.