The germ for this article came from thinking about an innovative pipe maker’s design for a one piece pipe. Random pioneered the one piece pipe which was designed to have absolutely no gap between mortise and tenon. The impetus behind this design was, as I understand it, to eliminate any turbulence and condensation created from such a gap. Turbulence is created when a flow encounters a significant change in the diameter of the tube it is flowing within. When the flow of tobacco smoke is thrown into such turbulence, the tiny droplets of water residing in the smoke collide and form larger droplets, eventually falling out of the stream of smoke and collect in the low point of the pipe. This low point may be within the tenon or at the entrance to the draft hole from the bowl. The result is an undesirable gurgle.
I should note here that not all pipes with gaps in their mortise tenon junction have this gurgle. The reason behind this is a mystery, although it is generally attributed to a particular person having a style and rhythm of smoking that mitigates the fallout of moisture.
While the idea for the one piece pipe is fascinating and innovative, the design had a fatal flaw. On order to crate a pipe such as this, the stem and stummel had to be glued together before the drilling. Hence, the draft hole was necessarily of a single diameter throughout the pipe. And in order to accommodate a sufficient draw, this draft hole had to be rather large, i.e. 5/64″. This in turn led to a bit thickness that was often found undesirable. The pipes never truly caught on. Although a small number of pipe smokers did, and probably still do, enjoy the pipes.
My thought was to use this one-piece design premise in such a way as to allow for both a consistently easy draw and a thin bit. In pondering the possibilities, I began to see that a modification of the draft hole shape might not only make the one-piece design feasible, but may have application in traditional two piece pipes.
Current draft hole design in a pipe involves either a stepped or tapered diameter from the bowl to the button within a pipe. The reason for this change in diameter is to allow for an easy draw while also allowing for a thin bit. The idea that I will put forward here, for your consideration, is that a single ovoid channel, made by drilling three 1/16″ draft holes next to one another and smoothed out via manipulation of the drill bit will provide a better flow and draw than either a stepped or tapered draft hole. An illustration is seen below:
This design of the draft hole has two benefits. First, the volume of the draft hole is actually greater than that of the traditional designs while also allowing for a bit as thin as any today. This greater volume means that the draw possible through the draft hole is as easy or better. Second, the design, even in a two piece pipe, allows for a smoother, less turbulent flow.
While it might seem counter intuitive to think that an ovoid draft hole with a height of only 1/16th of an inch would have a greater volume that a traditional draft hole, the math bears it out.
Stepped draft hole
Overall length: 4 inches
Step 1 length: 2.25 inches
Step 1 diameter: 5/32 inch
Step 2 length: 1 inch
Step 2 diameter: 1/8 inch
Step 3 length: 1/4 inch
Step 3 diameter: 1/16 inch
Slot width: 5/16 inch
Slot depth: ½ inch
Sloth height; 1/16 inch
Volume = Vstep1+Vstep2+Vstep3+Vslot
V step1 = (Pi*R step12)H
(3.14159*5/642)2.25
(3.14159*0.078122)2.25
(3.14159*.00610)2.25
.01916*2.25
.04314 inch3
Vstep2 = .01226 inch3
Vstep3 = .00076 inch3
Vslot = .00488 inch3
Total Volume = .06103 inch3
The tapered draft hole is as follows:
Overall length: 4 inches
Step 1 length: 2.25 inches
Step 1 diameter: 5/32 inch
Step 2 length: 3/4 inch
Step 2 diameter: 5/32 inch tapering down to 1/16 inch
Step 3 length: ½ inch
Step 3 diameter: 1/16 inch
Slot width: 5/16 inch
Slot depth: ½ inch
Sloth height; 1/16 inch
V step1 = .04314 inch3
Vstep2 = .00511 inch3
Vstep3 = .00153 inch3
Vslot = .00488 inch3
Total Volume = .05466 inch3
Lastly, the ovoid draft hole
Step 1 length: 3.5 inches
Diameter: Ovid – 1/16 inch high and 3/16 inch wide
Slot width: 5/16 inch
Slot depth: ½ inch
Sloth height; 1/16 inch
V step1 = .06104 inch3
Vslot = .00488 inch3
Total Volume = .06592 inch3
Contrary to what one would think, the ovoid draft hole actually has more volume than its traditional counter parts. This should lead to a draw that is open and easy as the more traditional counterparts.
As a hobby, I make pipes. Doing so in the spare 15 minutes I have each week. I think my next pipe will incorporate this design, and I undoubtedly will let you all know of its progress and results. In the mean time, I would love to hear your thoughts and opinions of the idea.
Tags: draft hole, engineering, one piece design, pipes, tobacco
April 24, 2009 at 4:04 pm |
I thought this read was great and I can’t wait to hear how it works for you. I really like tech discourse about my hobbies.
I’m interested to hear what other makers thoughts are as well.
Nice blog that you’ve got going. I look forward to it every day. Hope that it dosen’t become to much like work for you.
April 24, 2009 at 11:53 pm |
Hey Nick,
I think it’s a great idea in theory, but would be very difficult to accomplish in practice. It’s hard enough to get the slot nice and even while manipulating the 1/16 bit, and it’s only around an inch or so deep.
Doing this for the entire length of a stem would be very difficult. Not to mention drilling three 1/16 holes close enough together and straight enough side by side to accomplish the desired outcome. Then you have to get the enire length of the ovoid smoothed out.
I look forward to hearing how it comes out for you. Good luck!
Rad
April 25, 2009 at 4:57 pm |
Yea, those are the same troubles I foresee Rad. God knows a bit that thin will wander. We’ll see I suppose.
April 25, 2009 at 8:39 pm |
Would it be possible to use a thin, long, side-cutting bit to make the ovoid hole in one pass? I’ve usesd these to open up the mortise and draft hole in the bowl and, while they don’t cut really well on the side of the bit, they do cut.
The tapered design of this type of bit makes it fairly stiff and very thin at the tip. and the nominal diameter only starts right after the shank.
Just a thought, ’cause all that math made my head hurt!!
Bob
April 27, 2009 at 1:49 pm |
One thought I’d had was to drill the two outside holes, and then use the bit to cut sideways, as you suggest, between the two. It might work. Or it might just be silly. Still, I’m all about silly!
April 27, 2009 at 2:29 pm |
Interesting stuff. I hope that you actually do the experiment and see how well it works.
Construction is certainly a challenge. While you draw it with a smooth oval surface I’m not sure that it’ll really turn out that way. I’m wondering if you’ll have a lot more channel surface area (potentially ragged) where the 1/16″ holes adjoin and whether that will disturb the stream flow in implementation. Of course even a smooth oval channel has a larger surface area than a circular channel. Engineers have toyed with oval channels in cooling and condenser applications because of this. But is a larger channel surface area, for a given cross sectional are better for a pipe?
I wonder about the origin of stepped channels. They’re a bad design.
The ideal airway channel moves the smoke stream at a constant velocity from the inlet at the bowl to the end of the stem without restrictions and minimizing turbulence. For that to be the case the channel must have a uniform cross-sectional area. That cannot occur with a stepped channel. And as your design shows, the steps are not necessary. This is probably the most important design difference between older classical shaped pipes and today’s well crafted pipe. Channel uniformity is far more important than delivering max volume. We haven’t yet corralled the size of the smoke channel but it’s pretty clear that it can vary quite a bit and still yield a very fine smoking pipe.
If the channel size varies then the velocity of the smoke stream varies. It is slower in a wide channel faster in a narrow channel. And the pressure changes too when the speed changes. These changes have consequences for the smoke stream. And this is the cause of moisture precipitating out the stream. This is physics and not something a smoker can change by puff style. Here’s a demo of the smoke channel that you can play with:
http://home.earthlink.net/~mmc1919/venturi.html
How well the pipes channel deals with moisture determines whether we notice it or not. One can certainly see evidence of this in any used pipe with a gap or channel problem – they’re black with gunk in the mortise.
Still, I’m looking forward to hearing about the results of the experiment. How will you know whether it’s good?
April 27, 2009 at 2:54 pm |
“How will you know whether it’s good?”
Good question? I have no clue. I suspect it will be similar to the old pornography definition. Not sure what it is, but I’ll know it when I see it. or rather smoke it. I may have to send it around to get other opinions.
April 28, 2009 at 12:31 pm |
I’ve enjoyed your new blog, Nick. Thanks, and keep up the good work! As for this radical new design, my initial thoughts were two-fold: It makes great sense in eliminating the stepped-chamber weaknesses, but secondly, as Rad stated, how would this be accomplished, practically? On first blush, it would seem nearly impossible; but then again, the pipemakers I know have all had to nearly manufacture or remanufacture their own tools; so maybe they could come up with some innovation for this. I’ll be extremely interested in seeing how your experiment turns out. I’m sitting on my back porch, taking a break from yard work, and enjoying some older Escudo in a Jeff Gracik Tomato, reading a new pipe blog. It doesn’t get a whole lot better than this!