Chamfering

[saltedplug]

So, the tenon inserts into the mortise and then into the airway in the shank. The tenon tip is chamfered, that is cut away most at its center and gradually less to its tip, so that the smoke traveling from the shank to the stem through the tenon is gently rather than abruptly transferred.
The shank is also chamfered so that any smoke that escapes entering the tenon but instead travels down its side is transferred back to the tenon tip and into the stem and not lost to the joint of the shank and stem. I can't explain how this happens, really, but the suction of the draft at this point is at the tenon tip, so the chamfer of the shank must somehow transfer the escaped smoke into the stem.
You may think that no smoke escapes entering the tenon, but no shank's draft hole and no tenon are perfect circles, and with the normal expansion and contraction of the mortise due to the moisture in the smoke as well as the wear on the tenon, a small amount I think, would escape; thus the need for the chamfered shank.
Not a critical topic, something that's been at the back of my mind for months. If you can fill any of the blanks, please do.

 

[Chasing Embers]

I wouldn't over think it . Cobs for the most part have no camfering, and smoke very well.

 

[zack24]

Most tenons are friction fit into the mortise. There’s not a chamfer in the sides of the mortise- some Pipemakers drill mortises with a drill bit which produces a conical bottom- I use a chucking reamer which actually leaves a flat bottom in the mortise and allows the mortise to be adjusted by .0005”- (picked that up from Lee von Erck). There is always a space between the tip of the tenon and the bottom of the mortise- I use .05”, I’ve seen estate pipes with as much as .25” gap/ if there were no gap, any swelling or gunk would force the tenon out and create a gap at the stem/shank junction.
The exception to this is a military mount which use maybe a 2 degree taper on both the tenon and mortise

 

[pipestud]

Dadgum, being a pipe maker sounds like work... So, I think I'll just smoke 'em and not worry about what parts of my pipes have or have not been chamfered. :wink:

 

[Chasing Embers]

Dadgum, being a pipe maker sounds like work... So, I think I'll just smoke 'em and not worry about what parts of my pipes have or have not been chamfered.

:clap:

 

[mso489]

I'd never noticed particular beveling while cleaning my pipes, on the stem or shank. Next time I'll look more closely.

 

[jpmcwjr]

Chamfering or not, gap or not, smoke doesn't escape anywhere.

 

[saltedplug]

I wish I had such absolute knowledge about many things, pipe smoking not the least of them.

 

[saltedplug]

I was disappointed that this thread had such short air-time, and that most of the responses were to state disinterest or that I was over-thinking the issue. I think some know the rationale for chamfering but didn't feel that they wanted to reply.
The practice that is supposedly a marker for a well-made pipe is still done. Is it merely a custom that has been handed down from one generation of pipe makers to the next that has no utility, like bowl-coating, or does it in fact somehow enhance the draft and manage moisture? Did it come along with stingers, and like them been abandoned in the absence of measurable gain?

 

[aldecaker]

Chamfering the tenon gives one less spot for condensate to form. Whenever I get a new pipe, if the tenon is not adequately chamfered, I use a countersink tool and chamfer it myself.

 

[sasquatch]

Salted, your original post asked no questions, really, I wasn't really even sure what you were shooting for.
If you don't chamfer the tenon end, pipes whistle. Toot toot like. What is whistling? Physics tells us a whistle means cavitation - this is why your car will "thump" if you open only one window on the highway too. Low frequency whistle. Cavitation = turbulence, turbulence = condensation.
The square corner is not nice and smooth for the smoke to flow around. Yes - smoke fills any little void or plenum space inside a pipe, and yes, there are always such spaces, by necessity - only a VERY few pipes are made with a "don't ever take this apart" philosophy, and I suppose they could be made virtually perfectly smooth inside. But your ordinary pipe with a stem that comes out for service, they need a little space for junk to collect, for the wood to move etc. And just for... ordinary tolerances to be used such that every pipe doesn't cost 500 bucks in meticulous labor. As soon as you have that little bit of space, the funnel on the tenon tip is basically mandatory to keep the airflow laminar at the tenon tip.
So the short answer is that by and large, pipes with a funnel or chamfer smoke a hell of a lot more pleasantly than pipes without. Are there good smoking pipes without? Yes. Would they be improved with a chamfer? I'd argue yes.

 

[pianopuffer]

Ah so that’s why my pipes whistle...well, not all of them but a couple come to mind.

I bought a few different countersink bits awhile back when I was opening up some of my draft holes but never got around to using them.
Maybe I’ll give these a go tonight when I get home. Any tips or advice for using these on a tenon?

Thanks.

 

[aldecaker]

Two pieces of advice: turn them by hand, and piloted are easier to use than non-piloted. I use 100-degree piloted c'sinks designed for aircraft sheet metal work. A good alternative are the type that are for woodworking and have a drill bit for a pilot. Take the drill bit out, turn it around, and use the shank end as the pilot. And turn them by hand. Vulcanite and acrylic are soft.

 

[sasquatch]

Yeah just go slow.
Pipe can whistle in any number of places - the transition from bowl to airway, airway to stem, stem through button... any of them can cause problems, and the easiest place to start is with the tenon end chamfer.

 

[aldecaker]

And if you put a dried pea in the bowl, they whistle a lot better. :wink:

 

[Chasing Embers]

Went through several of my pipes, and the only ones with chamferring came from Bruce Weaver, and none of mine whistle. Even the tenon from a Dunhill Zulu has no chamfer.

 

[aldecaker]

The wall thickness on that one is so thin, I wouldn't think it would need a chamfer, nor would one make a difference. The ones I chamfer, they look like a brick wall before chamfering.

 

[Chasing Embers]

Here's a narrower example. Preben Holm, no whistle, no gurgle.

 

[aldecaker]

That's another one I would leave alone. A lot of mine that needed chamfering have been on bulldogs or Rhodesians that have a chunky stummel, and a chunky tenon diameter to go with it. My Bing's Favorite, on the other hand, was more similar to the examples you show. It's all about the wall thickness.

 

[Chasing Embers]

Come to think of it, the only pipe I've ever had make any noise, or gurgle was a Dr. Grabow Omega, and that was decades ago.