Saw this on the NASPC site. Cool read.
http://www.naspc.org/airflow.htm
What are all your thoughts on airflow? Does a wider draught hole make a better smoke?
Neat article I found
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KurtHuhn
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Proper airflow is *critical* for smoking pleasure. That air passage has to wide enough so that the smoker isn't actually "sucking" per se, but simply puffing.
I notice one mistake in the first part of the article, the conversion of 4mm to 5/16" is all wrong. The actual diameter in inches is 5/32" - which is what I use, and I believe what most other makers I've spoken to use. Some use bigger, but, as the article mentions, there are pitfalls associated with that as well.
Think of it in terms of fluid dynamics. The larger the pipe, the more fluid can pass through, and with less effort - either pressure or vacuum effort. That's why forced-induction engines have huge exhaust pipes, to expell the hot gasses in as efficient and speedy a fashion as possible.
When I first started carving pipes I did a comparison between a bunch of different bit diameters. What I found was that 5/32" was the best balance of airflow and restriction - you need *some* restriction after all. Some restriction helps to keep the smoker in check and reduce chances of him getting the pipe too hot and having a burnout. At least in my opinion. Also, some restriction is important for people to feel as if they're smoking something. The feel/taste of smoke on the palet is important for a lot of smokers, and that's greatly reduced if the draught hole is too big - this is why the smoker may actually puff harder with a big draught hole and get the pipe too hot.
At least these are my findings after much experimentation.
I notice one mistake in the first part of the article, the conversion of 4mm to 5/16" is all wrong. The actual diameter in inches is 5/32" - which is what I use, and I believe what most other makers I've spoken to use. Some use bigger, but, as the article mentions, there are pitfalls associated with that as well.
Think of it in terms of fluid dynamics. The larger the pipe, the more fluid can pass through, and with less effort - either pressure or vacuum effort. That's why forced-induction engines have huge exhaust pipes, to expell the hot gasses in as efficient and speedy a fashion as possible.
When I first started carving pipes I did a comparison between a bunch of different bit diameters. What I found was that 5/32" was the best balance of airflow and restriction - you need *some* restriction after all. Some restriction helps to keep the smoker in check and reduce chances of him getting the pipe too hot and having a burnout. At least in my opinion. Also, some restriction is important for people to feel as if they're smoking something. The feel/taste of smoke on the palet is important for a lot of smokers, and that's greatly reduced if the draught hole is too big - this is why the smoker may actually puff harder with a big draught hole and get the pipe too hot.
At least these are my findings after much experimentation.
Neat observations Kurt. Currently I use a 1/8ths bit for the draught hole. Although thats more because that the store I bought the bit at only had a bit sufficiently long enough in that size. I would have preferred a bit of 3/16ths of 5/32nds.
If I remember right 1/8th is about 3.2 mm and 3/16ths is around 3.6 mm. In all honestly, I think I have a lot of development before the difference between 3 mm and 4 mm will make a significant impact on the smoking qualities of my pipes. Like getting the fricking draught hole centered. LOL. Its a learning process right?
What do you other guys use for a draught hole size?
One of the neat things I heard recently was the idea of flattening out the draught hole in the stem. Keeping the same approximate volume while allowing for a thinner bit. The idea seems sound, but I wonder if the change in shape would create turbulence.
Random, I have a kernel of a memory that you have comment on this before on ASP.
If I remember right 1/8th is about 3.2 mm and 3/16ths is around 3.6 mm. In all honestly, I think I have a lot of development before the difference between 3 mm and 4 mm will make a significant impact on the smoking qualities of my pipes. Like getting the fricking draught hole centered. LOL. Its a learning process right?
What do you other guys use for a draught hole size?
One of the neat things I heard recently was the idea of flattening out the draught hole in the stem. Keeping the same approximate volume while allowing for a thinner bit. The idea seems sound, but I wonder if the change in shape would create turbulence.
Random, I have a kernel of a memory that you have comment on this before on ASP.
I use 5/32 or 11/64. The 5/32 seems to be just a little better in combination with the stems I have been using.
John
www.crosbypipes.com
www.crosbypipes.com
I use 5/32 most of the time and 11/64 on occasion. Both seem to give a nice open draw and I like it that way. There are many different opinions on this though. I think it just comes down to what one is used to. I believe that you have to tailor your smoking technique depending on the size of the draw. My favorite Castellos seem to have an open draw so I'm just used to smoking that way. When I get a pipe that is more closed, it does not smoke right for me so I will either open it up or will sell it. Others are used to a more closed draw and so they don't get the resistance they are used to when the draw is more open. I guess as a maker, we each have to do what works best for us and then understand that some will like it more than others. Maybe this is one of the factors that leads to brand loyality. Once you become accustomed to the draw from a particular brand, then other pipes of the same brand just seem to smoke right because they feel familiar.
Stephen
Carving Pipes in the Oldest Town in Texas.
Carving Pipes in the Oldest Town in Texas.