322. Tenon Work on an 1890-1990 Patent System Commemorative with Gary Hamilton

Athbhliain Faoi Mhaise Daoibh!

This morning I welcome back Gary Hamilton, CPG. He and I met up at Ascension Coffee in the Design District of Dallas not long before Christmas and one of the topics that came up was my recent acquisition of an estate Patent System Commemorative oom paul, part of the 1990 set for which we share a mutual enthusiasm.My pipe had some turbulence and he wanted to take a look at it and see if he might do anything about it. He could, as a matter of fact, as you’ll read in just a moment. First, some geeky historical information about the set I hope you’ll enjoy, as it was the swan song of the Late Republic era (1969-1991), when the company was under the direction of the very capable Jimmy Nicholson and Tony “Jolly D” Dempsey.

Alongside and before the Patent Commemorative set, K&P during the Late Republic era had produced the Sherlock Holmes Systems in 1990, the Original SH set in 1988-91, the Dublin Millennium set in 1988, the SH Original in 1987 and the Mark Twain in 1981. An amazing achievement for this tumultuous period when the company was set loose from the direction of the Kapp family for the first time in its history.

Window and Strutcard

In an interview for Smokeshop magazine, Tony Dempsey said this set wasn’t a limited edition, although it was created to specially mark the occasion. The brilliance of the design aesthetic perfectly captures the zeitgeist of 1990, offering something quite original yet firmly rooted in K&P’s historic design language. Interestingly, the company decided to place “Patent No. 12393”–the first patent number–on one side of the ferrule. This would be a source of confusion to later collectors, some of whom even thought these were Patent-era pipes!*

The original pipe box was a dark blue-gray, as seen above, with a white rayon lining which typified the high-end boxes at this era of the company’s history. Inside was a folded pipe box brochure, the kind of treasure Pete Geeks want to find in every K&P box:

If you own the big Pete book, you can go to one of its early chapters and identify the exhibition medals seen in the photo. The decorative device on the pipe box front was taken from the 1906 catalog. Even the pipe socks are great: they were a kind of chamois. Note also the heavier font used on “Peterson,” which to me seems to reflect the house style better than the later Dublin era’s slimmed-down version.

My original smooth set is illustrated on pp. 180-81 of the Pete book, where you can also see why Gary wanted to create a new tenon extension for the straight System of his set: notice the tenon only extends to the end of the shank. This short tenon creates a problem in the chamber’s straight System engineering, inasmuch as the air hole is drilled in the bottom of the chamber and the tenon should extend to meet it underneath.

The oom paul of the set also has an interesting bit of engineering: no aluminum tenon extension at all. A curious omission on a sterling mount commemorative, all the more so since a special tenon had to be created for the Straight System. In smoking my smooth version of this pipe, I always thought there was some turbulence. Having long since traded off the set, I’d forgotten about this problem when I received this Pebble Grain. Yet there it was: the rough air flow. Gary Hamilton to the rescue!The following is my brief photo essay of some recent stem work performed on Mark 1890-1990 System Commemorative oom paul. The original pipe was fitted with a vulcanite stem having the molded tenon extension, as typically used on the Standard grade of System pipes. Today’s work plan is to transform the stem’s molded tenon extension into an aluminum tenon extension, as used on the Premier, Deluxe and Star grade stems.

As received, a wonderful 1890-1990 Patent System Commemorative

This is just too nice of a pipe to be fitted with a “Standard” type stem configuration, changes are needed!

The molded stem’s airway measured just ever so slightly under 6mm diameter at the end of the tenon opening.

For the end result, I want to have the airway through the aluminum extension to be as near to this same diameter as possible, and preserve the airflow characteristics.

During the initial evaluation of the stem, a discrepancy in the taper of the tenon was noticed. Shown in these two photos, you can see a distinct difference in the taper, it is not a smooth surface. At first, I thought this to be nothing more than the often seen “scarring” from tenon insertion into the mortise. But upon closer examination it became apparent that the diameter of the taper was different in the area where a distinct “line” is seen, about 10mm from the small end of the tenon. Hmmm…

The taper of the tenon is not smooth, or continuous. The bright “gleam line” from the reflected shop lighting is interrupted. There is a distinct “bump” in the tenon’s taper. An oversight in manufacturing from the factory? Some prior owner’s attempt at “pipesmithing”? We will never know. What I do know is that it would be best if corrected.

Using a strip of 600 grit paper, supported by a hard “backer board” I slowly started working the taper lengthwise, starting from the large end toward the small end while simultaneously rotating the stem.

Continued iterations of working the 600 grit paper while rotating the stem showed good progress at removing the “bump” while preserving the overall taper. Getting closer…

Looks about right, a light buff with some 4/0 steel wool and the “gleam line” from the reflected shop lighting is continuous, nice and straight, not wavy or interrupted as seen before. The initial test fit seems pretty good, maybe a wee bit more “tweaking” needed, but it certainly is looking more up to our expected “Peterson Quality” for a pipe of this significance!

In getting on with the operation, the molded vulcanite tenon extension needed to “disappear”. A few seconds at the vertical belt sander made quick work of the removal. Following the belt sander, I finish dressed the end with some 400 ad 600 grit paper on the surface plate, much the same as one would do to “top” a damaged bowl rim.

Taking a new measurement, it seems that the diameter of the airway is now at about 5mm. So, our “target” airway diameter for the yet to be machined aluminum tenon extension is going to be set at 5mm.

Now we have to drill a larger diameter hole into the existing 5mm hole so that the new aluminum tenon extension will have a place to reside. This is where it gets tricky sometimes. We know we need a 5mm hole in the extension, but we need a bigger diameter than 5mm, or you can’t drill the 5mm hole through it. And always being mindful of enlarging the airway hole in the stem, not to lose too much wall thickness in the vulcanite tenon!

The most difficult part about drilling a hole is how to hold the work (the stem in this case) while turning the drill bit and keeping things all lined up as you drill the hole deeper…this is not a hand held operation if you want satisfactory results. It’s all about the “work holding”! If you can securely hold it, you can work it.

A while back I made a work holding jig to use with the lathe for operations such as this. The jig takes the place of the cutting tool holder on the lathe’s compound rest. I wrap the tenon end with a few layers of good ‘ol USA made 3M vinyl tape (not the Chinese stuff!). This layer of tape will protect the tenon when the jig is clamped tight onto the tenon. Using a 5mm pin gage, held in the lathe’s spindle with a collet, I adjust and tweak the alignment of the stem so that the pin gage is in perfect alignment with the airway hole. Once satisfied, the jig clamp screws are snugged up tight so there is no chance of the stem moving during the drilling process.

When I was satisfied with the set-up, and double checking it…again and again…I changed out the 5mm gage pin and installed a center drill into the spindle of the lathe. Setting the lathe at about 800 RPM, I slowly engaged the work. I like to start like this for a couple of reasons. First you can get a feel for how secure the stem is being held, and secondly it will provide a nice countersink to help guide the drill bit.

Success! As can be seen, a nicely formed countersink (chamfer) that will help guide the drill bit.

Swapping out the center drill for a 7mm drill bit, and double checking the set-up once again, it’s time to drill the hole! The 7mm drill size was selected to allow for a 1 mm wall thickness of the aluminum extension with the 5mm airway hole.

Drilling proceeded quite well, keeping the lathe’s speed at 800 RPM.

Drilling to the predetermined depth of approximately 6mm, the hole turned out very nice.

Lately for the aluminum tenon extensions, I’ve been trying something different. Instead of using a threaded connection, I’ve had great success with using a slight “friction / slip” fit. Quite a few of the earlier era pipe manufacturers used a similar “fit” when attaching various “stingers” to the stem’s tenon. My previous versions of this “slip fit” are working well, and the outward appearance looks “factory”. This also saves a few steps and headaches in the threading process!

MARK: Gary and I talked over coffee about the efficacy of this friction-fit extension, and I want to share his observations here, along with the illustration he drew as we talked.

The tenon extension on Deluxe Systems has always been threaded. The problem with a threaded tenon is that the threads most always extend further up the airway than the tenon. That space, and the space between the threads, is a moisture trap and potential place for air turbulence. I know it collects moisture, because I swab it out the stem’s threads and off the extension’s threads every time I smoke a Deluxe.

Gary’s idea–one that K&P might consider, in fact–is that as the tenon “carries no stress or load” the threads are unnecessary. That is, if it is possible to manufacture a close tolerance friction-fit. This is the same principle informing all traditional mortise-tenon pipes, simply applied to the tenon extension and the stem.

Because of the tenon-mortise fit, the tenon extension slides all the way in the “mortise” of the stem’s airway. There is no bump between the two, so there is no turbulence. There is no gap so there is no moisture build up.

Time to make the aluminum tenon extension!

A 3/8” diameter piece of aluminum was selected and the 5mm airway hole was drilled first. The 7mm diameter X 6mm long part of the extension is being machined in this photo. Then the process of shaping the outer taper of the tenon extension begins.

The taper of the tenon extension was cut using the “compound rest method” with the angle set at 5 degrees. Successive passes were made until the desired taper and diameter was achieved. Although not shown in this series of photos, a 3/16” radius carbide cutter was used to make the final shaping cut at the base of the tenon extension to get that “factory look” with the radius.

The finished aluminum tenon extension!

The aluminum got a little bit of polishing, and the final “slip fit” was checked and fine-tuned. A slight twist while either inserting or removing the extension is all that is needed.

Such a classic pipe, and all the better now that it’s fitted with an appropriate tenon extension!

This was a fun project! (Mark, you can open your eyes now, it’s all over and done.)

Good grief, I think it’s time for a Guinness!


–Gary Hamilton



Can You Imagine?

Paul Combs writes: Yes, this is an XL5 bowl – my photo mockup in response to Mark’s comment to Ken Sigel on the December 26 post about wanting to see the House Pipe stems available not just on the oversize bowls but [as in Charles Peterson’s day on Standard bowls as well]. Even a single release with something like the XL5 would be fantastic. The XL5 with the House Pipe stem definitely has visual appeal. Maybe we can persuade K&P as Ken suggested – perhaps as a POY or a PPN commemorative?


Linwood Hines sends this photo of one of the original Pete Geeks, Allen Rosenfield, with a custom House Pipe stem (note the impressed aluminum P), silver cap & meerschaum bowl, from the 1980s:



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