Differences in Interior Stem Design

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aztecbull

Might Stick Around
Aug 31, 2023
68
747
Title edited. Original: "Stem interior design difference why and which type you prefer?"

Hey pipers,

This seems to be a topic which does not get discussed often. With the pipes I acquired, I notice different makers have different practice making the interior of the stem. Some like to have a straight channel from the tenon all the way through the bore. While some makers like to make an enlarged V shaped slot inside the stem ( Please see my attached illustration if you do not get what I mean from my poor english).

I always wonder why the difference practice in making the channel? Probably the V shaped channel for a bigger smoke output and more open draw?

To me, I actually prefer the straight channel rather than the V shaped channel. Just wondering what you guys think and prefer?

Keep puffing bros!

IMG_5854.jpeg
 
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Sigmund

Lifer
Sep 17, 2023
2,092
19,117
France
I’m interested and also wondering about the differences. Ive wondered to but I dont know enough to say why one method is chosen over the other.
 
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aztecbull

Might Stick Around
Aug 31, 2023
68
747
I’m interested and also wondering about the differences. Ive wondered to but I dont know enough to say why one method is chosen over the other.

I once asked a maker about this and I quote what he says " Inside the stem, from the button to the bore, there is a wide “V”-shaped slot. This design ensures very easy and comfortable smoking of the pipe. You don't need to make any effort to get another dose of tobacco smoke."

I am not sure if this is the only reason. To be honest, I am not very comfortable with the big smoke output form the V shaped channel stem, espically when smoking VA or Vapers blends, I am not sure why.
 
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Sigmund

Lifer
Sep 17, 2023
2,092
19,117
France
It seems to me one of those difficult things to compare. I have pipes with both but of course they are different pipes and designs. So it is difficult to accurately gauge the cause of one smoking different than another. Variance is a SOB in many fields.
 

aztecbull

Might Stick Around
Aug 31, 2023
68
747
It seems to me one of those difficult things to compare. I have pipes with both but of course they are different pipes and designs. So it is difficult to accurately gauge the cause of one smoking different than another. Variance is a SOB in many fields.

True, that's why want to see what you guys think and trying to find out more why the diffrence.
 

hoipolloiglasgow

Can't Leave
Oct 14, 2023
462
2,181
United States
I've been told the v shape is best. Yet, I love my English pipes with just the straight, well its more of a deeper straight cut. I have a custom cob that has a deep v shape stem, it's good. Prefer the regular, but deeper cut straight that I have on everything.
 
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OzPiper

Lifer
Nov 30, 2020
6,209
33,776
71
Sydney, Australia
Calling @georged and @sasquatch

I’ve often wondered.
But this is a tad too technical for me.

I have pipes of all ages. With orific, slotted and semi-orific buttons.
And I use softy bits on all my stems.
So beyond the curiosity, I accept each pipe just as they are.
Variety is fine.
 
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Chasing Embers

Captain of the Black Frigate
Nov 12, 2014
44,056
112,292
Though not a piper, I'll cast my two cents. I've never seen one with drilling as exaggerated as the second illustration but funneling of the mouthpiece has never affected the smoking of a pipe for me. I get more of a difference between pipes with the diameter of the draft hole. Even orific stems smoke fine with a clean open airway.
 
Jun 9, 2015
3,970
24,765
42
Mission, Ks
I always wonder why the difference practice in making the channel? Probably the V shaped channel for a bigger smoke output and more open draw?
It really more a matter of what tools were used to make to slot. The shallow radiused slot is made with a slitting saw type bur and the V shaped slot os made with a side-cutting drill.

V slots are generally only seen on hand cut stems and normally require a shallow slot to be made first and used as a guide to make the V slot. It's labor intensive and takes a lot more time. There are a hand full of companies that have a machine that can cut V slots but not many. I have one...

The shallow radiused slot can be made repeatedly and fast.
 

sasquatch

Lifer
Jul 16, 2012
1,702
2,959
So, here's the theory on stem interiors. If we are making the perfect smoking machine, it should be designed with the idea of minimizing condensation (minimizing "gurgle"). How is this acheived? It's simple, you make the airway as smooth as possible, you avoid jagged transitions and plenum spaces, places where the smokestream would swirl. Swirling causes cavitation and condensation. This is just straight fluid dynamics. ( It's also exactly what the Peterson System pipes don't do, and quite on purpose. They knock out condensate by forcing the smoke through a circuitous route, offering "dry" smoke, in theory. )

Back to our design: We want to have the smoothest trip possible for the smoke, no sharp corners, nothing weird going on, and the best way is probably to try to acheive a "constant volume" through the airway. We need the stem not to be an inch thick at the bite (and those old orofic stems are!), so rather than just cutting a tube and leaving it, we make a flat area, the slot, and this allows us to make stems quite thin and comfortable. In theory you would design the slot such that it is intersecting with the (probably tapering) airway just exactly in a way that kept the cross-sectional area of the "tube" the same at all points, a constant volume but a changing shape of the tube as it were.

In practice it's enough to just cut a fairly smooth, deep slot, and keep everything kind of polished up nice in there. That's what most makers of hand-made pipes do, and it's part of why these pipes smoke nicely.

The only other debateable factor in this is whether it makes sense to build the entire pipe as a venturi, which is to say a tube that is getting smaller and smaller as it goes. The theory would be that as the smoke is made to travel faster, it exerts less pressure (interacts less, physically) on the side walls of the tube. This might be beneficial in an environment where the tube was colder on one end than the other (probably the case with a pipe). And the old Peterson pipes very much show this idea, the P-Lip originally was very much a venturi stem.

There's lots of ways to skin this cat, and any reasonable amount of care generates a very adequate smoker indeed. What's more surprising is how many pipe manufacturers refuse to exert a reasonable amount of care or thought as regards this stuff. We still see tiny airways, misaligned drillings, stems with all kinds of poor physical setups.
 

Scottmi

Lifer
Oct 15, 2022
3,488
48,641
Orcas, WA
Following same logic as @sasquatch , this is the design I made for my custom stem:

At the bit where it looks like it narrows in one pic, it actually ovals out to maintain the volumetric space, then flares to finish
 
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sasquatch

Lifer
Jul 16, 2012
1,702
2,959
thanks for the detailed info Sir!

But I find it quite hard to see hows the stem is making inside though
Drill from the tenon end with a tapered bit, stop about 1" from the end. Drill in from the other end with maybe 1/16" and connect two holes. Then you widen the slot with tiny saws and files, smooth out the transitions. Takes some doing, which is why pipe companies, by and large, don't bother.

20240125_133349.jpg
 

kcghost

Lifer
May 6, 2011
14,301
23,782
77
Olathe, Kansas
You know to be honest I have no idea this was "thing" with some people. I guess I am going to have more diligent on this issue. I usually smoker artisan pipes or those quality factories pipes, I have never a pipe that didn't smoke but few a little "tight" on the draw and I had to open then just little (this operation was handled by someone else).
 
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