Does pipe design contribute to tongue bite?

[ShiniKoroshi]

What I am specifically referring to is chamber (bowl) design; taper vs. straight. All of my pipes have a tapered chamber and can give bite if smoked too hard. The pipe that I made has a straight walled chamber with a similar diameter and depth as the other pipes. However, I smoked that pipe hard, straight to the bottom, without the slightest hint of bite. Bottom of the chamber was completely dry in spite of 80-90% humidity. Repeated several times with blends I have that do bite and nothing. Then the bowl cracked on the inside which is pretty much the end of this experiment until I make another pipe (from briar this time). I did grab another pipe and verified the existence of bite with those particular blends under the current environmental conditions.

BTW, I usually smoke in high humidity and am used to keeping my powder (tobacco) dry and packing light.

My theory is that the taper causes moisture and heat to concentrate on the small bit of tobacco near the bottom making the associated issues greater. But, I have very limited pipe smoking experience and would appreciate the thoughts of those who do on the matter.

Thanks!

 

[deluxestogie]

If the flow volume of the draw is constant over time, then the flow rate through the combusting cross-section of tobacco increases as the diameter of the cross-section decreases. The higher the flow rate, the hotter the combustion temperature.

Bob

 

[ShiniKoroshi]

Exactly what I was thinking Bob, thanks. So it only makes sense that if you want the smoothest smoke from a pipe then a straight-walled chamber is the better design.

 

[deluxestogie]

a straight-walled chamber

I think so. To confuse the issue, the ideal diameter of the bore seems to vary with the specific tobacco being smoked.

Bob

 

[ShiniKoroshi]

That also makes sense based on my limited experience. Obvious question though; why do pipe makers use a "V" shaped or tapered chamber design? And, is a rounded bottom that important? (I think not).

 

[deluxestogie]

I have never read this book, but perhaps it might clarify the drill bit design.

https://vermontfreehand.com/product/pimos-guide-to-pipe-crafting-at-home/

You might also have a look at their tool offering.

Bob

 

[ShiniKoroshi]

Its certainly worth a read to find out, thanks!

 

[Havok]

The answer you’ll find in that book is that it is better for airflow to all of the tobacco chamber as compared to a hole that is drilled with a flat bottom -as the corner of the chamber farthest from your draft hole will not burn… and is demonstrated by an illustration showing what they expect the difference in air flow to be. Having just lectured a group of engineers this last week on even distribution of flow through multiple branches on headers, and my experience in fluid dynamics, I’m hesitant to say (without having done any calculations or simulations on tobacco chambers) that their illustrations are correct -my closing words in the lecture were “Just because you wish for flow to behave a certain way, doesn’t make it so.”.

Pipe makers may use a tapered or cylindrical based on the shape and design of the stummel or bowl, because they believed one profile was better than the other, or because it’s the tool they have or are comfortable with. Boring the chamber, before a lot of these tool designs or tricks started being shared over the internet, was possibly based on the designs and aesthetics of that region, or based on what tools were available or made for that purpose in that region.

The acceleration in a tapered bowl based on the changing cross sectional area throughout the length of the tobacco chamber Vs. A cylindrical bowl is thought provoking but I think overridden by the velocity through the diameter and length of the draft hole and mouthpiece -but I may be wrong. I have often thought of, and then became bored with, the idea of analyzing the draw on a tobacco chamber, but never in a comparison between two different chamber designs (I always drill cylindrical chambers)… I hate doing work outside of work (more than doing work inside of work), but I’m a bit tempted now.

 

[ShiniKoroshi]

Ah, I do miss my drag-car building days.

A pipe with an off-center draft hole will burn down the center if packed properly. One of my better smoking pipes, an antique, is one such case. Point being that the tobacco is part of the system and a variable one at that. Slip a restrictor plate under the tobacco and now you have much more control over flow characteristics and no issues with complete burn. But regardless, burning all the tobacco is secondary to a pleasant smoke.

You know as well as I do that many, if not most, design aspects are driven by production efficacy rather than performance. A taper-shaped reamer will cut a smooth hole as where a straight drill bit will leave a little roughness that will need to be sanded out. Secondary to production efficiency is marketing and this is where in the last century we have seen a steady decline in quality with ever increasing promises of performance. Ill take antique anything over new. In fact Im typing this right now on my Commodore 64.

Ok, so there is a lot of junk science woven in and around pipe smoking. I came across this and his basis is findings by Finnish scientists (good read) and the rest is "hypothesis" where he goes off in all directions.
How and why chamber geometry impacts tobacco flavor

Our Finnish scientists Pentti Ermala and Lars Holsti explain the thermodynamic process that places those aromatic particulates in the smokestream:

“When a pipe is smoked, the temperature does not rise very high; the heat, on the other hand, spreads rapidly outside the area which is actually glowing and burning in the closed bowl. Temperature of the combustion zone was about 500°C. (variability, 380°-620°C.). The distillation zone was very large. Experiments show that, of the tobacco below that still unburnt, about 25 per cent reached a temperature exceeding 300°C during the suction, and at least 60 per cent a temperature exceeding 100°C. The corresponding fractions of the substances in the tobacco leaf were thus distilled into the smoke without being burned and without attaining the higher temperatures at all."

 

[KroBar]

And, is a rounded bottom that important? (I think not).

I don't know about the smoothness of a round bottom ( ), but it seems to help burnig up the tobacco at the bottom of the bowl, from my limited and unquantifiable experience...
Although, THink of a cob, they burn up just fine. Maybe more important to have the draught hole under the bowl (rather than coming in the side), for a better "bottom burn".
I know that's not really what you're asking after though

 

[ShiniKoroshi]

I tend to dump a bowl once the flavor heads south and usually will pick through the remaining tobacco to see what happened. I compare this to the few times Ive dumped a bowl when the smoke was perfect. IMHO, once tobacco is charred (under the cherry) all its goodness has already traveled down the pipe. I have yet to acquire a taste for coal and tar. lol

 

[ShiniKoroshi]

Im on the last chapter of the PIMO book and finally get why a tapered reamer. Now, I do understand his reasoning though I still don't find value in that last little bit of tobacco at the bottom of the bowl. It wasn't until I took his advice to make a drawing that I saw the #1 reason for a tapered pipe chamber, aesthetics. A full-diameter straight chamber, rounded at the bottom or not, limits the external shape of the pipe. I was trying to draw out a simple Dublin and was having the hardest time getting all the external and internal lines to work and still keep the proper proportions of the overall shape. And I thought to myself, "it sure would be nice to have a tapered chamber reamer." Anyhow, Im not yet ready to invest that much into pipe making and will use a 118° split-point bit for the current Billiard build and the Dublin can wait till next time.

 

[johnny108]

Would a ball grinder/rotary burr work, and be cheaper, maybe?

 

[Havok]

Just modify a spade bit. It’s simple, cheap, and drills a smooth chamber.

 

[Havok]

If you don’t have a bench grinder and don’t mind paying the extra $10, buy one from Steve:

https://vermontfreehand.com/product/chamber-spade-bits/

 

[ShiniKoroshi]

The only concern I have about a "flat bottom" hasn't come up nor is it mentioned elsewhere. Looking through a "cracked pipes" search I didn't find any either. My concern was cracks forming from the 118° angle and propagating radial cracks outward but this more of a metalwork concern. The few smokes I got out of the first pipe were great so Im trying this "cylinder" chamber shape again.

When I do upgrade, likely to the VF special ground spiral bits, it will also include the rest of the tools used to make a pipe. Pipe #2 is going to be Hard Maple and #3 Goncalo Alves, made using what I currently have in hand. Pipe #4 will be Briar and a total tooling upgrade. By pipe #5 I should have mastered the art.

I looked at the burrs and my concern with them is the small shallow flutes. Minimal cutting will fill the flutes with sawdust and begin to burn the wood. A ball-end endmill is an option though a more expensive one. At that price-point I have toolmakers who will produce anything I want. Three flutes is very stable and smooth cutting for materials that form large chips. I believe there is a company that already makes these in various shapes for pipe chambers and the price is in the 50 dollar range.

 

[adamziegler]

cracked pipes

Did a double take on first read