Dead Center Airways

ckr · Post by **ckr** » Sat Mar 03, 2007 9:34 am

Thanks Hienz,

That's is truely another great rustification on your part and excellent finish
and not wanting to clutter your page with a newbie treatise. I thought about putting it in stummels but I can't seem to have any of this make sense without the subject pipe, but I did it anyway

viewtopic.php?t=2253
third pic down

My understanding is that the airway is suppose to be dead center at the bottom of the bowl (at the tip of the conical shaped chamber). I have had problems accomplishing this many times. My problems have been a poorly shaped bit, over drilling the chamber or my drilling just being plain off.

http://www.aspipes.org/parts/parts2.html

The above link, while not going into great detail, indicates dead center
bottom is correct and the angle of the shank is going to somewhat effect it. Trever had a blog on this issue about a month ago.

http://www.talbertpipes.com/archives2/2 ... hive2.html
See: Relax, I got an angle!

http://members.cox.net/ckreynolds/17a.jpg

From the picture the appearance seems to be that the airway enters at the back of the bowl. I have been surfing the web and been checking out a lot of overhead views of drillings by several pipe makers. Of the clear shots that I thought were pretty much straight down the chamber very few seemed to be dead center bottom. Some even looked to off to the left or right.

I also have several pipes of several brands that I have been checking. Some are dead center and others are entering at the rear. A couple of the ones that enter the rear are also high off the bottom of the bowl. Another thing I noticed is that a slight pitch of the bowl can move a perfectly centered airway back or forward and even to the side. So much for a picture being worth a thousand words.

Upon rechecking some of the web pics I could also determine that several were indeed off center from the circular markings left by some of the drillings. I guess the issues are an even draw down the chamber and smoking the tobacco to the bottom of the bowl. But these pipes were of some noted makers that have been sold to happy pipers. Also, remembering my last visit to the local B&M few I had noted that most of the one I looked at were more to the rear than centered. I have never tossed a pipe for this reason and do not necessarily measure a great difference in smoking qualities (if all things between all pipes could ever be equal).

Is this a hobbiest level of perfection?
Is there an accepatable range of tolerance?
Is is a sale killer or pricing factor?
Any opinions out there?

Nick · Post by **Nick** » Mon Mar 05, 2007 9:34 am

To me, this is one of the attributes of a well made pipe. Centered and at the bottom.

Having said that, I have a few pipes with draft holes that aren't centered or aren't at the bottom, one or two are neither. But they smoke great anyway. I really don't think it makes a huge difference in the smoking. A little high or a little low is fine. Its the same with left or right. Neither are show stoppers. When you see the ones that are way off, well that might be an issue.

One thing I have always wanted to do was make a pipe with two draft holes that hit the bowl around 4 and 8 o'clock. I think that would be really neat, and wonder what effect it would have on smoking.

souljer · Post by **souljer** » Mon Mar 05, 2007 6:50 pm

Hello,

I agree that this is desirable, at least in my eyes, and I've been trying to do this with some success. Then I got some surprising feedback.

First, I've managed to learn how to drill the draft hole center-center; right at the bottom of the bowl. It took a lot of practice but I can now do it fairly consistently. Feeling good after having done this a few times I showed a few fellow pipers to gauge their reaction.

Almost everyone said to move the draft hole back towards the shank side wall.

I think that people are so used to seeing it that way that they actually think it's the right way to do it, and a hole in the bottom of the bowl just looks weird to them.

I did adjust things but it's still pretty much in the center. One thing to consider is that center-center set up also makes it easier for bits of tobacco and moisture to get in the draft hole since it's the lowest part of the chamber and there is no real flat places for tobacco crumbs and such to settle out of the way. Just something I've noticed on my pipes. So that was another reason to make some minor adjustments to the floor of the bowl.

RadDavis · Post by **RadDavis** » Mon Mar 05, 2007 7:58 pm

Guys,

I believe by "dead center on the bottom" most people are talking about the hole being centered relative to the sides of the bowl and not relative to the front and back. Getting it the way Souljer is talking about, creates a sump for moisture to collect in. This is not good.

The narrower the bowl is at the bottom, the closer to center (front to back) the smoke whole will appear, but it always should be at the back of the bowl on the bottom.

Rad

souljer · Post by **souljer** » Mon Mar 05, 2007 10:04 pm

I C.

And this is sort of what I was getting at/experiencing with that design. That's why I was still refining.

Thanks Rad.

ckr · Post by **ckr** » Tue Mar 06, 2007 5:26 am

Man, am I glad I ask the dumb ones, what a misconception I have been under the spell of. I have even stopped drilling due to the hole moving off the center-center. Rad, I had actually reasoned that this was a factor in why many of your pipes are (bent) forward.

Thanks all, guess my stem stays in the chamber a while longer.

pierredekat · Post by **pierredekat** » Tue Mar 06, 2007 5:48 am

I, myself, am thinking there's some wiggle-room there. It depends a lot on your overall design.

Sure, if you're building nothing but production runs of straight pipes, sooner or later you should be able to consistently hit the bottom-center of the tobacco chamber.

But with bents, and particularly when you're talking about a custom design, it gets a whole lot harder to hit that bottom-center mark.

And I, myself, don't think most end-users are going to get their panties in a wad about the exact location of the hole.

Just so long as you're not more than, say, 1/16 inch up the sidewall on a semi-custom bent, you should be okay.

Of course, you could improve your odds of hitting that bottom-center mark if the bottom of your tobacco chamber is more conical/rounded.

Fact is, I think it'd be pretty much impossible to hit that mark if your tobacco chamber is more flat on bottom and your pipe is bent.

Unless, of course, you can start your draft hole through the shank, get the bit right below bottom-center, and then finish it up by drilling down the center of the main-bore.

It's certainly do-able, I guess. But you might wanna have a lot of scrap briar figured into your price.

RadDavis · Post by **RadDavis** » Tue Mar 06, 2007 11:23 am

Rad, I had actually reasoned that this was a factor in why many of your pipes are (bent) forward.

Actually the further a bowl is canted forward, the closer the smoke hole will get to center/center. But this isn't the reason I make a lot of pipes that way. I just like the shapes!

Rad

LexKY_Pipe · Post by **LexKY_Pipe** » Tue Mar 06, 2007 5:01 pm

Rad is dead on center with his first post. The centering has to do with side to side, not with front to back.

Side to side centering is a must!

Ray Cover · Post by **Ray Cover** » Sun Mar 25, 2007 11:45 am

CKR,

I appreciate you asking. I learned a lot from it. I have been ponering the same questions. And thanks for your links above. The diagrams were a great help.

Ray