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  • jwh784

Hot Air

Updated: Jan 19, 2021

This post will be about pipes, honest. It has been observed that, for a pipemaker, I don’t actually write about pipes very much. That’s a fair cop. Part of the reason is caution. Unless you’re just starting as a pipe smoker/collector, it is quite likely that you have experience with a greater range of pipe brands and artisans than I do.

That said, I am a pipe maker, at least as far as this website is concerned, and if I want my blog readership to break out of the dozens perhaps I had better write about pipes. With apologies to those who read my blog for the recipes, this week I'll examine a make-or-break part of the pipe — the airway — and how I approach it. Not to imply that I have knowledge or skill that other makers don’t, but because there might be more interest in a blog post about minute details of pipe construction than in a post about, say, opera.

One can only hope.

As topics go, the airway has been thoroughly worked over on internet fora, and for good reason. A poor airway can relegate the most beautiful pipe to the rack; perhaps the converse is also true. Functionally, there isn’t much to a pipe — it’s a bowl and a hose. Cosmetically and ergonomically, that’s another story, but nobody claims any longer that straight grain pipes smoke better than cross grains, or vice versa. So if we’re going to discuss what makes a pipe smoke well — or poorly — we’re down to the bowl and the hose.

Well, almost. The wood itself used to get a lot of attention, and pipes that smoked poorly and tasted awful were — probably correctly — blamed on briar that had been boiled in stagnant pond water. This may still be a consideration for basket pipes, but when I buy briar today I know who cut and cured it and I have his email address. If pay $40 for a block and hit a flaw, that’s life, but if it’s poorly cured or smells weird I want my money back. Bowl design is another discussion, although I do have some thoughts about it. How the tobacco is packed is another round table topic, but I’m trying to stay on track here. I’m also going to avoid prefacing every statement with “in my opinion.” Blanket disclaimer: EVERYTHING here is my opinion, and you’re free to disagree and, even better, tell me why in the comments. I also do not suggest that the way I do things is the only way, the fastest way, or even the correct way.

So, about the hose. Leaving the previous paragraph aside, when we praise or blame a pipe for its smoking qualities we are primarily talking about the airway, about how it draws, about the air column linking the smoldering ember and the tongue. Ideally, there is a sensation of connection between one and the other, and this sensation is ruined by a draw that is either too tight or too open.

Certainly tastes vary, and we can get accustomed to (or adjust other factors for) anything, but once you get used to a smooth draw it’s hard to enjoy smoking through a cocktail straw. I’m going to settle on “smooth” as the adjective for the sort of draw that I think is ideal, rather than “open.” That may seem hair-splitting, but perfection lies somewhere between too little and too much, and there is such a thing as too much. Most of us would agree on what happens if the airway is too small: when puffing, we feel the constriction of the airway rather than the response of the ember, and, unless the pipe is perfectly packed, we soon lose control of it. We puff too hard, the pipe gets hot and the tongue roasts, we back off and the pipe goes out. And gurgles like Trevi Fountain.

Maybe we’re stuck with that double thick milkshake of a pipe for some reason so we learn to pack expertly and smoke slowly enough that we never exceed the limits imposed by the miserly draw, so that's our normal. Certainly many tons of tobacco have been run through restrictive pipes. Falcons, for instance. The machine that cuts the aluminum air tube to length rolls the cut edge inward so the already smallish bore is reduced by some amount and a razor-sharp edge is created where the tube enters the bowl. While I think the pipe is improved by using a small round Dremel burr or the tip of a knife to remove that edge, I’ve never seen a Falcon other than mine that was so modified. But I digress, let‘s proceed on the assumption that a pipe that draws more smoothly is easier to smoke and that there’s no harm in that.

It might seem like the remedy (for a briar pipe anyway) is simple: drill the holes bigger. To an extent, it is indeed that simple, and many a tongue-incinerating, gurgly pipe — perhaps drilled too small, perhaps choked by cake — has been rescued by running a 5/32” or 4mm drill down the shank. This treatment is thoroughly argued in Rick Newcombe’s book, In Search of Pipe Dreams. However, it doesn’t follow that if a little does a little good, a lot’ll do a lotta good. A draw with zero resistance degrades the connection between tongue and ember too. The pipe may stay lit all by itself, but the smoke is apt to be hot and flavorless. You can more easily compensate with packing for a too-open draw than for a too-tight one, so it’s the lesser of two evils, and if you insist on a 5mm drill in your pipes I see your point. If removing all the resistance in the airway were the answer, though, all pipes would have 1/4” airways and little brass screens in the bottom of the bowl.

So, how do we find that point between too little and too much?


The end.

Joking, I’m joking. I’m going to tell you everything. Of course, that’s everything according to me, and for what it’s worth. Let’s start with drill diameter. I don’t vary the airway drill from pipe to pipe, I always use a 5/32” drill and adjust from there. Why that size? Because 1/8” is too small (although not uncommon, especially in older pipes) and 11/64” is too big. Not just too big in terms of keeping the tobacco in the bowl, but in terms of not leaving any margin for tuning — tuning in the sense that you tune a carburetor. If the jet is too big, you're screwed.

With every pipe, after I drill the stummel, drill and slot the stem and put the two together, the draw will be tight, which is exactly what I want. I want to remove resistance from the airway in a specific order, and just enough so that the easy draw feels effortless, the hard draw meets some resistance, and in between it feels smooth and linear. The perfect draw should have a slightly elastic, cushy feel to it.

I almost got through a blog post without a reference to music, but what I’m talking about is a little like how I want a clarinet mouthpiece to feel. I want it to respond easily, but also want to meet resistance as I put more energy into it so the tone holds together. What I don’t want is unproductive resistance, an instrument that holds me back and doesn’t respond, or one that has no resistance and gives me no support at fortissimo. Getting a great mouthpiece can be difficult. You have to try lots of nominally identical ones. The old joke goes,

Q: How many clarinetists does it take to change a light bulb?

A: Just one, but he has to try every bulb in the box.

We clarinetists spend a lot of money on mouthpieces, and a lot of time with craftsmen working to adjust them, and it’s one of the most frustrating exercises you can imagine, to sit working on a mouthpiece that’s just a little tight, sanding a tiny bit out somewhere on the inside or slightly changing the curve against which the reed vibrates (the “facing,” if you’re interested). You take out a little; it’s better but not enough, so you do it again. Better, but still not right. So you scrape just a smidge more and ARRRRRGH too much, it’s ruined.

Pipes aren’t quite that bad. I think the same sort of feel in adjusting the airway is useful, though. As I said, we start with a 5/32” drill. There is no need to go larger. The points of restriction are the transition from round to flattened at the button, the transition from shank to stem at the mortise, the opening of the airway inside the bowl, and the surface finish inside the airway.

The degree of restriction at each of these points will vary from pipe to pipe. Let's start at the button, which is the most obvious place, where the round hole in the stem has to be tapered and flattened so the bit can be thin. There aren't really any secrets about that. The stem is drilled from the mortise end with a tapered drill to meet a smaller hole from the button end, and the smaller hole is slotted and widened (or "funneled") to create sufficient flow through the bit and make a smooth transition. Most makers do more or less the same thing, starting the slot with a tiny circular cutter, nibbling out the corners with a small drill (I use carbide dental drills), then widening and smoothing the funnel with tools of choice. I use ground-down jigsaw blades and needle files. If you’ve seen the How It’s Made episode on pipes that was shot at Dunhill you’ll remember the swiveling jig with the skinny rotary file that did this operation in about five seconds (2:30 in this YouTube video; not the narration I remember). Like I said, my way isn’t the only/fastest/best way.

The bit transition is where I start in tuning the airway. If you look at the photos of the amber stems, you can see how the bright line of the flat “V” from the corners of the slot meets the darker line of the round hole so the outside line basically goes straight down the stem. A 1-inch Canadian stem will take a different treatment than a 3-inch Billiard stem, but I want practically no resistance at the bit transition. That said, I don't want to remove material from the bit area needlessly, and it’s really a tiny adjustment between when it’s not quite right and when the stem flows. Once the bit transition yields adequate velocity I'll feel for turbulence or whistles, and work the interior and the mortise flare until those go away. The finished stem airway may feel open by itself, but it's still 5/32", and drawing harder creates a gradual increase in resistance. At some point the smooth flow will break down, of course, but at that point we're well beyond any velocity the stem will see with tobacco lit. Now we see what the stummel needs to match up.

With bent pipes, obviously the mortise junction jumps out as a spot that will need attention. And I’m not talking about the flush fit of tenon to mortise floor, everybody knows about that, and no artisan nowadays will be so reckless as to connect misaligned holes with a quarter-inch gap and call it good. Past that rudiment, restriction in the shank is mostly a matter of dealing with any edges at the transition. As I said in The Bends, I don’t consider it a sin to ramp the airway in the mortise of a bent pipe to bring it into alignment with the stem; past a certain point if you want more bend in a pipe something has to give. But it does take some attention to make sure that this angle doesn’t introduce edges or protrusions. As I also said, this isn't an issue with a straight pipe. Just make sure your drilling is centered in the stem and the shank and Bob's your uncle. Every pipe is different, though, and I've found it interesting in making club pipes, where there have been between eight and forty pipes of exactly the same configuration, how differently each pipe behaves.

James Gleick’s book, Chaos, has some interesting stuff about laminar flow. Also about sensitive dependence on initial conditions. Sometimes something really small can have a disproportionate effect on a larger system. For instance, where the airway enters the bowl, the greater the angle, the sharper the edge between the top of the airhole and the wall of the bowl. When you have a fair bit of forward bowl cant like in a Zulu, it’s usually not an issue, but with a bent pipe the top edge sometimes — not always — creates turbulence. And occasionally there will be a tiny chip or burr left from drilling, that's always something to watch. Anyway, rounding that edge just the tiniest bit, nobody would ever know just looking at it, can make a surprising difference.

We've covered the entry and exit points and the joint in between. All that’s left is the finish of the airway in general, and I’m not going to say that it has to be sanded to 600 grit or anything, sometimes I don’t touch it. Every block behaves differently; some cut like wax and every tool leaves a glassy finish, others want to chip and chatter and fight you down to the wire. I’ve had Canadian shanks flow great right off the lathe, and I’ve had Billiards take a lot of work. Sanding the airway is not a virtue in itself, but if the pipe needs it, it needs it.

One final observation: earlier in my career, I left airway tuning for last because it was fiddly and I didn’t want to waste all that time on a pipe that might wind up in the trash because I sanded into a crevasse at 400 grit. Experience has taught me to do it first, while the pipe is still rough and handling does no harm, because once a pipe is finished nothing good can come of me handling it. The best I can do is NOT drop it, or scratch it with a callus, or put a nick in the edge of the shank. Adding scratches and nicks is YOUR job.

If you’re looking for some objective reason to prefer artisan pipes over factory pipes I suppose this amount of attention spent on a pipe — and I’m certainly not the only carver spending it — might be useful, but it could go the other way, too. Not all molded stems flow poorly, and in fact there is less of a barrier to putting a good airway in a molded stem than a handcut one because once you’ve made the mold a good airway is no more work than a bad one. And some stummels will just drill smoothly and cleanly, so you put a good molded stem with a good stummel and you have one of those Comoys or Butz-Choquins that smoke so well that you question the sanity of anyone who pays more than fifty bucks for a pipe.

Then again, maybe you get the short end of the stick and you reach the opposite conclusion, that your odds of getting a great pipe are better if you know you’re getting some individual attention for your money.

Which is exactly why people keep arguing about it.

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Feb 24, 2021

As a pipe maker, I really appreciate the thought you put into your decision to go for a smooth or not. On several occasions I have reached the end of the process and on examination and consideration, decided that my finish was not up to snuff-the grain pattern didn’t justify the finish, or on several occasions, the ring pattern took the understain too strongly and wound up looking like tool marks, or it just didn’t look right.

Your thoughts are extremely well expressed. Great thinking and great writing.


Jan 13, 2021

It's probably just as well that this post wasn't about opera, one of my two least favorite subjects (the other being politics, the bane of human civilization). The subject of airways is far more interesting to me. Nevertheless, if a post about opera were to appear here, Jack, I would read it. If there's anyone who could make it entertaining, 'twould be you.

I appreciate the reference to Gleick's Chaos. Chaos is the seed bed from which complexity arises. It's on the border between completely random chaos and perfect order, both of which are boring. Complexity is where everything interesting resides.

And it's the reason why pipemaking is not strictly an engineering task.


Jan 13, 2021

LOL: "I am a pipe maker, at least as far as this website is concerned"


Jan 13, 2021

Jack, I’m glad to see you writing about this aspect of pipe-making! It might feel like beating a dead horse to you, but to those of us who have smoked your pipes, we KNOW that this post represents the difference that makes a difference in a pipe. Having exceeded the two dozen Howells benchmark, and having personally experienced the similarity in smoking performance in your pipes, I also appreciate the predictability and the reliability that your process enables. I like that you worry whether I’ll like a pipe I bought from you. I’ve known you long enough to know that you do. Obviously, you’re not the only pipemaker that pays attention to producing a well-engineered pipe. However when it comes to…

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