Making a Pipe (Part 2): the Stem

Introduction: Making a Pipe (Part 2): the Stem

Edited to add: Per the request of scoochmaroo, Part 1 can be found here:

If you're inclined to make your own pipe stem and have access to a lathe, you're at the right place! Now, if you're coming from my first guide (Part 1: The Stummel), there is something I need to mention here before I edit that tutorial to include something that I should have mentioned before: It's easiest not to finish your stummel until you have fit a stem to it... In all likelihood, you will want to sand around the mortise opening of your stummel to get the stem fitting just the way you want it. On top of that, you will probably also want to sand the stummel shank and the stem together to achieve an aesthetically pleasing transition from shank to stem. Of course, you can always go back and sand away from the tung oil if you've already finished your stummel, then re-finish when you're ready; but it's a lot harder if there's a layer of carnauba wax between your sandpaper and the wood.

You might be pleased to know that this isn't nearly as time-consuming or labor-intensive as carving out the stummel, although some shaping will be required.

Some history: I made my first pipe out of crabapple (in July 2011 if you can believe that) and had no idea what I was doing. It just happened to work out that the chamber, airway, and mortise I drilled were actually fine. However, I wasn't quite sure how to do a stem since I didn't have access to a lathe at the time. With no other options, I used a little section of a Crape Myrtle stick -- drilled through it and slowly carved it down by hand... Yes, I hand carved both the mouth region (relatively flat, with a lip at the tip) and the tenon from a stick. It was slow, tedious, and ugly with a capital U... But it worked! I somehow tapered the tenon correctly so there wasn't any air leak through the mortise! Still though, what was otherwise a relatively (it was too big) pretty stummel became something of a monstrosity in light of the crude stem I made.

The takeaway lesson here is this: The stummel is only half the pipe. And if you are going to make your own stem, take your time to do it well. The stem will either add to the beauty of a stummel or detract from it, as I learned firsthand.

Step 1: Ingredients: What You Will Need

Like I did in Part 1, I'll briefly talk about some of the materials to choose from. Most modern pipe stems are made from vulcanized rubber, with the trade name "ebonite." As you might guess, the name "ebonite" is a nod to the material's original use as an alternative to ebony. I believe these stems are made directly in a mold (i.e. the reactants added and the vulcanized rubber formed in the shape of a stem, rather than "cooking up" the material and then shaping the stem). Another popular modern material is "lucite," which, after a quick google search, I was surprised to learn is actually just poly methyl-methacrylate (PMMA)! The same thing they use in orthopedic bone cement. Anyway, lucite can be cast solid and then worked down on a lathe -- and I believe this is how lucite stems are done... After all, pen turners use lucite rods, which until now I didn't know were widely available:

Way back in the day, pipe stems were made from amber... Yes, amber. Fossilized tree sap. How anyone was patient and skilled enough to shape amber into a pipe stem with archaic technology is beyond me.

Having not known I could get lucite rods until literally just now, I've been using two other materials: African Blackwood and "RhinoPlastic"... RhinoPlastic is the brand name of a particular kind of acrylic acetate that I presume is patented, either in composition, manufacture, or both: In my honest opinion, there is a night and day difference between the quality of RhinoPlastic blanks and foreign-manufactured generic acrylic acetate... It feels stronger, better resists burning, and smells a lot less bad when turning. If you're familiar with pen turning, then you might already be familiar with RhinoPlastic (not to mention, this tutorial will be a breeze for you).

Now, did I research the idea of using acrylic acetate as a stem before taking a whack at it? Sort of... I found two things.
1) At least one person has done it before:
2) It clears California Prop. 65! That's right. In a world where even a dietary alternative to sugar is a carcinogen, the synthetic RhinoPlastic contains no chemicals known in the state of California to cause cancer.

The very first few stems I turned were African Blackwood, and they came out alright. They had to be straight, of course. And they'll take a few bite marks, although these stay pretty shallow (which is why I went with the hardest thing I could find). You might ask: If I discouraged using Dalbergia species for the stummel, why am I now advocating African Blackwood as a decent wood for stems? Well, it's a two-part answer. First, nothing is being burned in the stem, so there won't be any smoke or combustion byproducts coming from the wood itself. Second, it's rock hard and as such will resist unsightly bite indentations. African Blackwood has found an application in the manufacture of woodwind instruments (clarinets, oboes, bagpipes, etc.) due in large part to its ability to tolerate moisture and saliva -- it's in fact more often favored over ebony, which is less moisture-repelling and can be brittle.

Alright. Sorry about the essay up to now. Here's a list of what you'll need:
- Stock material (lucite, RhinoPlastic, or African Blackwood -- in order of my preference)
- A mortise drilled into your stummel (can be uncarved or almost finished)... see Part 1
- Lathe with a chuck that can be tapped into the tailstock
- Drill bits
- Caliper
- 80 through 400 grit sandpaper... although up to 600-1000 is probably better for synthetics, as I've learned
- At least one knife suitable for carving
- Spindle/Drum sander, or sanding drum that you can stick in the lathe (optional)
- Bench vise (optional)
- Heat gun or torch (optional, if you want a curved stem and are using a synthetic material like RhinoPlastic or lucite)

In the second picture attached to this step, you'll see the Argentine Osage stummel I shared in some of my other pictures before I finished it. Below that is a RhinoPlastic blank -- "coal mine" is just the brand's name for solid black -- and an African Blackwood blank.

Step 2: Planning

As you can see in my rather crude drawings on this step (the second picture was included in Part 1), the more-or-less "critical" lathe-necessitating part of the stem is the tenon -- the part that snugly fits into the shank and allows overall easy access for cleaning. It's generally best to turn one stem to one stummel, for two reasons: For any given mortise you drill 1) Regardless of how carefully you drilled the mortise, or how exact the depth of that mortise is, it's virtually guaranteed to be slightly wider, narrower, deeper, or shallower than any other mortise you drilled; and 2) There is no better gage for your tenon than the mortise itself!

Regardless of how carefully straight you try to turn your tenon, it is close to inevitable that it will have a very slight taper. That's a byproduct of the method I use to stop and check for fit: When I shut off the lathe and try to jam the tenon into the mortise and it doesn't quite fit, I fire it up and remove a little width from the end -- then I shut it off and try again. This time, it might get stuck halfway in, so I'll rinse and repeat. The end result is a slightly tapered tenon, which is OK! Trying to keep the tenon straight can lead you to accidentally turn the tenon down too narrow (at which point you can either settle for using thread-sealing tape or just turn a new stem).  Despite the taper, it's still possible to get adequate contact area with the mortise to prevent slipping and wobbling -- and in fact, the taper itself is what will yield the tight fit you want). This is shown in the main picture (cross-section) attached to this step -- although I had to actually exaggerate the taper just to make it visible (shaded in areas are open spaces, including the airway; and the red line highlights the edges of the tenon).

Step 3: Roughing Down the Stock Material

If you're already familiar with any kind of turning, then you're familiar with turning cubes and prisms into cylinders. However you mount your blank is up to you -- and if you're a pen turner (which I am not), you probably have a much better way to do the entire turning process than what I share in the steps that follow... And if you do, please share it in the comments!

I like to simply use the small inner jaws in my chuck to grab the flat surfaces of the blank at one end (starting with a square blank cross-section, see the second picture) and lining up the other end of the blank to a live center in the tailstock. If you're not familiar with turning synthetics and you have a synthetic blank to turn, check out for some turning tips. I don't really worry about getting the blank down to a perfect cylinder at this point because it's easy to accidentally remove too much material in the process. In general, I just like to round the edges consistently about the turning axis.

Step 4: Notching the Rod for Centering

Another appropriate title for this section would have been "Cut-marking the tenon" because both things are being accomplished. It'll make sense as I explain. I use a caliper to gage the depth of the mortise (second picture) and hold it up to the tail end of the rod, then mark that point (third picture). From that mark to the tail end of the rod will be the tenon. Now, most pen blanks are about 6" long, and your finished stem -- including the tenon -- will likely be from 3" - 4" long... I wish I could get longer pen blanks so I could get two stems per blank, but alas! I cannot. Getting back on topic: You'll want to also mark where to cut off the excess material. I do this subjectively, just holding the stummel up to the rod and deciding how long I want the stem. You can see this in the third picture... I believe that for that pipe, I cut the rod at the dark, shiny band seen on the left.

Advice: For a 6" blank, don't simply cut it in half for two stems... Both will be stubby and awkward-looking on the finished pipes. As a rule of thumb, I like at least 2" of length to the visible (i.e. not including the tenon) part of the stem. Of course, you might want something shorter, and there's nothing wrong with that.

Don't turn your lathe on yet! It took me a couple tries to realize that if I simply grab a cylinder with the chuck jaws and leave the other end free, it is NOT centered. That's because the chuck jaws are rather thin, meaning there isn't a whole lot of surface contact area to  force the rod straight. As a result, the rod will wobble if it isn't centered on the other end (and in order to drill through the rod, one end will have to be free since the tailstock will be occupied with a drill bit). The way around this problem is to cut notches/grooves for the chuck jaws to sit in, increasing surface contact area and giving it one more dimension. Of course, this needs to be done while the rod is centered, which is why I said not to touch or remove anything yet (since right now, it is centered). You will cut two grooves: One where the tenon starts (which you marked); and one about 1/2" in from the stem's other end (which you marked). Use a parting tool that's about as wide as your small chuck jaws, and don't groove in too far -- just barely enough to make a sharp notch in which your chuck jaws can rest securely. Of course, a groove that is too deep will render the tenon useless, so err on the side of caution.The main picture for this step shows the grooves I just did a horrible job of describing.

Once satisfied with your grooves, cut off the excess about 1/2" or more from the groove on the left.

Step 5: Drilling the Rod

In the main picture for this step, you'll see what I was talking about with the grooves: The groove that was on the left in the last step is now clamped within the small jaws of the chuck, and the tail (tenon) end of the rod is free. Being able to clamp the chuck in on that groove keeps the rod from wobbling so it can be drilled exactly through the center. As you can see, I have a smaller chuck tapped into the tailstock, holding a 3/32" drill bit. For drilling, I simply fix the tailstock in place, turn on the lathe, and use the wheel on the tailstock to push the stationary chuck and drill bit into the rotating rod.

Now, you'll notice that most 3/32" drill bits (mine included) are rather short... In fact, too short to make it through the whole rod. This is why I cut two centering grooves: After I bottom out the drill bit on this side of the stem rod, I remove the stem rod from the chuck and turn it around, clamping the small jaws into the tenon groove so I can complete the hole from the other side (seen in the second picture on this step). Again, this is why it's so important to keep it centered (so the two holes intersect). You might also notice that I slide the drill bit up in the chuck to give myself more length to work with. You can check for a complete hole by blowing into the rod... this can also clear debris left from drilling.

Step 6: Cutting Down the Tenon

After you drill the airway through the stem rod, you need to cut down the tenon to fit in your mortise. So remove the rod from the chuck and turn it around, exposing the tenon end (and of course, clamp down on the groove). If you're working with a synthetic material, I'd recommend using a live center on the tail end... A couple days ago, I wasn't being very careful and my skew chisel forced the tail end off center, which caused enough shear at the chuck to snap the rod off at the groove.

I like to do this in a stepwise manner, first gaging the diameter of the mortise with a caliper and removing material along the whole tenon length until it's left slightly too large to fit through the caliper (second picture). After this, I slowly and carefully shave off some material from the last centimeter or so of the tenon, stopping the lathe frequently to see if the tenon fits into mortise (third picture). Once the end of the tenon fits easily and snugly into the mortise, I work on the rest of the tenon -- again, stopping frequently to check the fit. Now, it eventually gets to a point where I can force the tenon most of the way into the mortise. That's when I put away the skew chisel and use 80 grit sandpaper to remove less material so I don't accidentally leave the tenon too narrow (third picture). I check, then use 120, check, then 220, etc. until I'm happy with how well it fits -- not too tight so it has to be forced, but snug enough to keep it from sliding out without twisting it first (fourth picture).

You'll notice that I have a hose clamp tightened around the shank. That's to keep the tenon from splitting the shank while I'm checking the fit and the tenon still has to be forced. As you might guess, I did split a shank before I started doing this -- and if you split your shank accidentally, it's not the end of the world. Just super glue the split and use a hose clamp for pressure.

Step 7: Shaping the Stem

There are two ways I shape stems, depending on the material I'm using. For wood, I simply carve them down flat by hand with a knife. For synthetics (like RhinoPlastic), it's probably better to use a spindle sander with 80 grit paper. If you're hand carving, you can just check the second picture here for some ideas on the shape you want. And of course, sand it down very finely (at least 320). For wooden stems, this is the last step.

For RhinoPlastic, I just grind the stem down flat on a spindle sander and do the rest of the shaping by hand with sandpaper or a file. Just be patient, since this takes more time to sand and shape than wood. Also, synthetics need to be sanded down finer for the smooth finish you'd expect -- I've had good results going to 600 grit.

Now, here's the cool thing about synthetics: You can do a curved stem. The next step is optional, if you're inclined to curve your stem (although I wouldn't sand it down too fine before curving).

Step 8: Optional: Curving the Stem

RhinoPlastic can be permanently deformed with heat. If you haven't already ground your stem down flat, go ahead and do this before heating it -- having it flat will help it bend easily in one direction. You'll want a heat gun or a small torch for this, as well as a bench vise if you have one. I wet down a rag with cold water and wrap it around the tenon, and clamp the tenon in the jaws of the vise -- the rag will keep the jaws from putting indentations in the tenon, and the cold water will protect the tenon from the heat so it won't bend. I start heating slowly, alternating on both sides of the stem to keep the heat even on the tension and compression sides. After about 2 minutes, I   hold the tip with pliers and begin pulling gently while I keep the heat applied. Depending on the length of the stem, you may also want to move the pliers to about halfway down the length of the stem (i.e. away from the tip) to achieve a longer curve. Throughout the whole process, keep the heat applied evenly.

You'll notice that when heated appropriately, RhinoPlastic exhibits elastic behavior -- it's rubbery. You want to keep it in this rubbery state by keeping it hot, but not overheated to the point that it bends on its own weight or (worse) melts. Once it's cooled down, it returns to a hard and rigid state. So once you're happy with how it's curved, simply hold the tip as steadily as you can where it is and remove the heat. It's important not to apply any more force than what's necessary to hold its curve -- otherwise, it can fracture while it cools. I've found that holding the curve for about 3 minutes after removing heat is sufficient to prevent it from recoiling back straight.

The next time I grind and curve a stem, I'll try to remember to take some pictures to add!

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    3 years ago

    Good work. Thanks for sharing.
    I've just bought a dozen 80yo stummels for a bargain price.
    Most have a diamond shank.

    What files will I need to shape stems?


    Very nice. When you're bending the stem, you may find it helpful to first insert a pipe cleaner through it--this will help keep the draw hole from closing.