Me & Al down by the schoolyard - Dunhill pipes

Posted: Fri Sep 19, 2008 4:41 pm

A week ago a fellow pipe smoker sent me a generous gift. I've been puzzling over its workings and I think I understand it now. I've learned things that surprised and impressed me. They are things that I've never seen explained before so I'll take the liberty of doing so here. Maybe it's not news to some of you but I've never seen it written down.

I've been critical of Dunhill and their pipes mostly because of the brand mystique and the prices. There just hasn't been enough nuts and bolts tech talk to win me over. The talk always stops at the mystique, the stamped symbolism, and dating yada yada yada. But there is a good engineering story here. Having a really good look at the 'innards' is an educational experience for any critic or engineer. There's a lot more than mystique to the Dunhill pipe than I knew.

Yes, the gift is a Dunhill pipe. It's a pretty Dunhill group 3 Bruyere Dublin pipe 42F/T from the early 70's complete with box, paperwork, a packet of paper filters, a roughly 3" aluminum tube that looks like a giant medical needle, and, a marvelous original Dunhill tobacco brochure. The tobacco lineup outlined in the brochure all by itself confirmed for me the pipes approx date. All, but the box, looks new. The box itself has that ratty aged look but it did its job.

After opening the package I picked up the pipe and took it apart to look inside. I wasn't critical. I was curious. Though I've smoked a Dunhill before I never bothered with why it is the way it is and I've always ignored the little bits that accompanied the pipe. I suspect that most people do likewise.

Looking down the stem air channel I saw something that intrigued me. There is an abrupt step-down midway up the stem channel. It changes diameter abruptly. Next I looked in the stummel and there was a bigger mystery inside that. The floor of the mortise is not flat as with most pipes. Instead it slopes away from the tenon into a cone that joins the air channel into the bowl. It looks like the inside of a funnel. Mystified, I put the pipe away for a day or so. Steps in stem channels and gaps between tenon and mortise are not usually good news. But I had a feeling that there was more to the story but it's a story that I didn't know. With a little help the pipe told me the story.

A day later I wandered in on my son watching the movie Apollo 13. It was at the CSM-LEM docking scene. As they showed the CSM's docking probe being captured in the LEM's docking cone I suddenly realized why the Dunhill's mortise floor looked the way it did. If reliable registration of a probe is necessary then a cone to guide the probe into place, without damage, is a solution. I must also admit that I seriously wondered whether the Apollo engineers, who design the Apollo, smoked Dunhill pipes because the solution is identical for both the pipe and the Apollo docking registration mechanism. The pipe's probe is the inner-tube. That little hollow aluminum tube that I had ignored, again, is central to everything that drives the internal design & drilling of the Dunhill.

Of course I knew the standard story about the purpose of the inner-tube but it's obsolete. We have pipe cleaners now and we clean rather than toss our briars. I put the pipe together just the way Alfred intended, repeatedly. Wow. The step in the channel holds the inner-tube precisely where it needs to be and the 'Apollo docking mechanism' that is the mortise floor guided the inner-tube, reliably and repeatedly, into position without any effort or care. OK, so the pipe now had my undivided attention and increasing admiration. I recognized the way it worked as good engineering. Not in the vague way that we usually mean but really! This is a well engineered design. A lot of thought went into this. And the design has a lot of implications.

First, the design ensures that a Dunhill pipe, any numbered shape, will always take a pipe cleaner, with or without the inner-tube in place. It simply must be well drilled or it can't take the inner-tube. That is a by-product of the design. There is a level of manufacturing precision here that doesn't occur with any other manufactured pipe of which I'm aware. It's probably requires precision beyond that of hand-made pipes. Second the dimensions of the inner-tube must influence the way a Dunhill pipe looks in its proportions. The numbered shapes have inner-tubes. And inner-tubes have fixed sizes. Is there more than one size? I don't know this is new to me. I ignored it all before.

So I measured the tube. Three inches to the middle of the opening at the needle end. 3" seems rather arbitrary doesn't it? One and a half inches sit inside the stem. That leaves the other 1 & 1/2 inches for the stummel. I now had the uncanny feeling of following Alfred's path or at least one of his engineer's because a good engineer designed this thing. I'm hooked now. I measured the i.d. & o.d. of the inner tube and then the id of the draft hole in the stummel and the same in the stem.

Have you ever measured the diameter of the air channel in your pipes? The hole in the stummel is big and the hole in the stem is small. Why are they different? Who knows? I've never gotten answer. The odd difference is not a satisfying discovery.

The i.d. of the inner tube is 7/64" precisiely. And this is the same as the upper half of the stem airway. The Dunhill, as designed, has the same 7/64" airway from end-to-end. OK, it's an old standard but you've got to admire the consistency. There is no good reason to have the stem airway smaller than the stummels. The o.d. of the inner-tube is exactly 5/32". And of course the airway in the stummel matches as does the lower channel in the stem. It has to. Is there a hint here? Did everybody else measure the Dunhill airways sans inner-tube and just blindly adopt it? It's speculative but I'm beginning to think so. It certainly explains what I measure in Ardor's, Savinelli's, and most other manufacturers. Some had amazingly asthmatic 3/32" stem airways matched to massive stummel holes. Amazing huh? The only pipe that I found among mine that was clearly well thought out was a Talbert Ligne Bretagne. Both stummel and stem are drilled to 9/64" and it works.

The Dunhill is a little more open feeling without the inner tube. And it still smokes well. You're not just buying mystique or reputation with Dunhill. There is also a very well engineered pipe and they employ precision manufacturing to deliver on that good design. Impressive.

....R

Posted: Fri Sep 19, 2008 5:12 pm

Where can I find a friend like that?

Posted: Fri Sep 19, 2008 6:01 pm

It appears its a different guy who engineer these Dunhills as compared to the one you have.

Posted: Fri Sep 19, 2008 6:32 pm

Quote:

It appears its a different guy who engineer these Dunhills as compared to the one you have.

I must be missing something. When I open your link I see a Strand magazine but I don't see anything specifically about Dunhill. Could you help me by providing more detail?

I'm out of character as a Dunhill defender but the pipe has an undeniable charm as well as being well engineered - literally. Dunhill pipes should really write a little bit more about their internals I think there's a story in these pipes that is interesting.

Posted: Fri Sep 19, 2008 6:35 pm

You description got me curious to see if I could pull a patent on the design to see if I can get a diagram which could illustrated what you were describing. There were two patents I found which deal with the the tube insert but not necessarily with the unusual stummel and stem drilling (then again a modifcation of an exisitng patented device occasionally is deemed covered under existing patents and is not awarded a separate patent)

Interesting to not that these patents are from the 10's and 20's
Patent 1130806 March 9, 1915
Patent 1343253 June 15, 1920

Posted: Fri Sep 19, 2008 7:15 pm

Quote:

You description got me curious to see if I could pull a patent on the design to see if I can get a diagram which could illustrated what you were describing. There were two patents I found which deal with the the tube insert but not necessarily with the unusual stummel and stem drilling (then again a modifcation of an exisitng patented device occasionally is deemed covered under existing patents and is not awarded a separate patent)

Yes, after I thought that I understood the design I also did a patent search. While the patents describe the inner tube, Dunhill's implementation is an improvement over both. There are two difficulties with the 1915 picture. The inner-tube is not constrained to remain in place adequately and it cannot be reliably installed without eventually bending the inner- tube on the flat mortise floor shown as 'd' in the later patent. The second patent actually shows the inner-tube modified to be fixed in place at or near the mortise 'd'. However getting the pointed tube into the hole is still problematic and not reliable.

What Dunhill did instead is:
1) left the inner-tube as a standard tube as in the first patent,
2) drilled the lower stem channel 5/32" and the upper stem channel is 7/64" - there is implicitly a step in the stem wall and this stops the inner-tube from creeping up the stem and constrains it in place.
3) changed the mortise floor (shown as 'd' in the second patent) to be a mild 'V' with the narrow end pointed toward the bowl - this ensures that the mortise itself guides the inner-tube into the bowls airway channel.

They didn't publish these modifications.

Posted: Fri Sep 19, 2008 11:17 pm

Makes me want a Dunhill.

Posted: Sat Sep 20, 2008 6:16 am

Hey Rusty, want to be my friend? Wink

Sounds like you have a very nice pipe, makes me want one as well.