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Five questions about mortises and tenons

Posted: Sat Jul 04, 2009 6:22 pm
by Kettletrigger
I'm pretty new to the forum and have been soaking up as much information as possible. I've done some searching and haven't found answers to these questions; please forgive me if they've been asked before and I missed them.

These questions all came up as I've been planning my first pipe. I'm worrying (perhaps unnecessarily) about the joint between mortise and tenon loosening over time and any steps I can take to prevent that from happening.

1. Why does the tenon always seem to be located in the stem with the mortise in the shank and not the other way around? I've seen this on pipes with both integral and delrin tenons. I would think that the synthetic material of the stem would be more dimensionally stable than the briar shank, and therefore a better choice for the mortise when using a delrin tenon.

2. Would there be any advantage/disadvantage to a metal or delrin "cup" as an insert in the mortise?

3. Would there be any advantage/disadvantage to an anti-rotation locating pin in the meeting faces of the mortise and tenon?

4. Would there be any advantage/disadvantage to a screw-on stem instead of just the friction fit between mortise and tenon?

5. In a pipe with a briar shank and delrin tenon, how tight should the fit be between the two?

Thanks!

Re: Five questions about mortises and tenons

Posted: Sun Jul 05, 2009 2:53 am
by Frank
Kettletrigger wrote:I'm worrying (perhaps unnecessarily) about the joint between mortise and tenon loosening over time and any steps I can take to prevent that from happening.
My best fitting tenons, with nary a sign of loosening, are the ones I made with ABS. Use Delrin or ABS for the tenon. Since they both have more "give" than vulcanite and lucite, and are somewhat "self lubricating"(slick), if you make them just a smidgen (a really tiny smidgen) oversize, you'll still get an excellent friction fit that shouldn't loosen over time.

With reference to question #1, I have come across the arrangement where the tenon was removeable from both shank and stem. Perhaps someone else knows the pros and cons to this.

With reference to question #2, if by "cup" you mean a mortise sleeve, then a Delrin sleeve would be fine. I've seen this arrangement on a number of pipes, especially meerschaums. Personally, I wouldn't go for a metal sleeve.

With reference to question #3, a locating pin won't prevent a stem from becoming loose in the mortise if that's the way it's headed.

With reference to question #4, I've seen many older pipes where the button slot is no longer parallel to the bowl top when the stem is screwed in.

I can't really answer your question #5. You just get a "feel" for the correct fit. If you have access to a number of different pipes, remove and insert the stems a few times and you'll start to get a "feel" for what a decent fit should be.

Re: Five questions about mortises and tenons

Posted: Sun Jul 05, 2009 1:55 pm
by pierredekat
First, welcome Ketteltrigger!
Kettletrigger wrote:1. Why does the tenon always seem to be located in the stem with the mortise in the shank and not the other way around? I've seen this on pipes with both integral and delrin tenons. I would think that the synthetic material of the stem would be more dimensionally stable than the briar shank, and therefore a better choice for the mortise when using a delrin tenon.
I think this mostly boils down to tradition.
2. Would there be any advantage/disadvantage to a metal or delrin "cup" as an insert in the mortise?
I think I would lean toward a delrin cup. I have a hunch that any little burr or sharp edge on a metal cup would tend to chew up a tenon in short order.
3. Would there be any advantage/disadvantage to an anti-rotation locating pin in the meeting faces of the mortise and tenon?
Most pipes I have owned required a little twisting action to separate the stem from the stummel. Putting in some kind of anti-rotation deal would force a person to do this separation with a straight pull. I think that would require more arm strength and increase the risk of yanking off a tenon.
4. Would there be any advantage/disadvantage to a screw-on stem instead of just the friction fit between mortise and tenon?
Like Frank said, these types of setups almost never line up like they probably started out.

But I think a design something like a "Jobey link" has a lot of merit.

Image

It's more or less like a normal tenon, except that when you accidentally snap it off, you can simply unscrew/pull what's left of it, screw in another one, and you're good to go.

But if I were going to do one, it would have to be more like 8 mm, I think. 6 mm seems a bit small to me.
5. In a pipe with a briar shank and delrin tenon, how tight should the fit be between the two?
Tight enough to keep them together during normal use.

Re: Five questions about mortises and tenons

Posted: Mon Jul 06, 2009 9:11 am
by ToddJohnson
Kettletrigger wrote:I'm pretty new to the forum and have been soaking up as much information as possible. I've done some searching and haven't found answers to these questions; please forgive me if they've been asked before and I missed them.

These questions all came up as I've been planning my first pipe. I'm worrying (perhaps unnecessarily) about the joint between mortise and tenon loosening over time and any steps I can take to prevent that from happening.

1. Why does the tenon always seem to be located in the stem with the mortise in the shank and not the other way around? I've seen this on pipes with both integral and delrin tenons. I would think that the synthetic material of the stem would be more dimensionally stable than the briar shank, and therefore a better choice for the mortise when using a delrin tenon.

2. Would there be any advantage/disadvantage to a metal or delrin "cup" as an insert in the mortise?

3. Would there be any advantage/disadvantage to an anti-rotation locating pin in the meeting faces of the mortise and tenon?

4. Would there be any advantage/disadvantage to a screw-on stem instead of just the friction fit between mortise and tenon?

5. In a pipe with a briar shank and delrin tenon, how tight should the fit be between the two?

Thanks!
Just make a pipe, dude. Put the mortise in the shank and the tenon on the stem. Later, once you've made a few, you may have answered a lot of your own questions.

TJ

Re: Five questions about mortises and tenons

Posted: Mon Jul 06, 2009 4:27 pm
by kbadkar
ToddJohnson wrote: Just make a pipe, dude.
Wise words!

Re: Five questions about mortises and tenons

Posted: Mon Jul 06, 2009 4:33 pm
by KurtHuhn
ToddJohnson wrote: Just make a pipe, dude.
Not only do I completely agree, but I support the statement and wish to subscribe to your newsletter.

Re: Five questions about mortises and tenons

Posted: Mon Jul 06, 2009 6:16 pm
by baweaverpipes
Just make a pipe, dude.
Brilliant! Simply Brilliant!
As one pipe maker put it (certainly a member of Mensa :lol: ): "It doesn't take a rocket surgeon to make a pipe."

Re: Five questions about mortises and tenons

Posted: Wed Jul 08, 2009 1:58 am
by souljer
Hi,

If you've never ever made a pipe before, I agree with your studying up on it before you get started. However as has been pointed out, if you really want to learn, you have to get dirty and do it. Do not fear making mistakes. Instead enjoy them as you learn what happened and figure out how to do things better the next time.

You can read all you want about swimming, but if you really want to learn you're going to have to get in the water.
Kettletrigger wrote:I'm pretty new to the forum and have been soaking up as much information as possible. I've done some searching and haven't found answers to these questions; please forgive me if they've been asked before and I missed them.

These questions all came up as I've been planning my first pipe. I'm worrying (perhaps unnecessarily) about the joint between mortise and tenon loosening over time and any steps I can take to prevent that from happening.

1. Why does the tenon always seem to be located in the stem with the mortise in the shank and not the other way around? I've seen this on pipes with both integral and delrin tenons. I would think that the synthetic material of the stem would be more dimensionally stable than the briar shank, and therefore a better choice for the mortise when using a delrin tenon.
I have often thought about this too. I agree with your analysis regarding the stem material v. the briar wood of the shank.
I think that this is traditionally the way to do it because if it's the other way around, as the pipe hangs down, moisture in the mortise and tenon connection may run out of the seam between the two parts. Moisture is channeled down the draft hole and into the tobacco chamber the way things are done now.

Test the theory and make one the other way to see if you end up liking it better.

Kettletrigger wrote:
2. Would there be any advantage/disadvantage to a metal or delrin "cup" as an insert in the mortise?
A metal or delrin sleeve reenforces the mortise and shank, adding strength and durability at one of the weakest and most often twisted and torqued parts of the pipe.

There are plenty of pipes that do not have this feature however so it's not usually required except in the thinest of shanks or specific materials. The pipes I make do have a shank/mortise reenforcement. I like the idea of making this area stronger than necessary.
Kettletrigger wrote: 3. Would there be any advantage/disadvantage to an anti-rotation locating pin in the meeting faces of the mortise and tenon?
I'm not sure what you mean.

If the fit is correct and the parts do not rotate on their own, why would you need this?
If the fit is so loose that the parts could rotate freely, what is to prevent them from sliding apart regardless of (anti)rotation?
Kettletrigger wrote: 4. Would there be any advantage/disadvantage to a screw-on stem instead of just the friction fit between mortise and tenon?
Many pipes have been made with a screw-on stem. Older Kaywoodies with their "Drinkless" stingers and threaded shank caps for example.

Besides a threaded sleeve that reenforces the shank the biggest advantage I can think of is the ability to remove the stem in mid smoke for cleaning or clearing a blockage.

Get one, smoke it for a year or so and see what you think.
Kettletrigger wrote: 5. In a pipe with a briar shank and delrin tenon, how tight should the fit be between the two?

Thanks!
The fit should be just right.
Neither too tight nor too loose. I'm not trying to be facetious, that's basically the answer.

I can't explain experience. You have to earn that on your own.

Posted: Thu Jul 09, 2009 6:05 pm
by Kettletrigger
Thank you to everyone who took the time to actually answer my questions. I'm obviously new to this and your answers have shed some light on things while I've been waiting for supplies to arrive in the mail. My briar and acrylic order arrived yesterday from PME so I can finally get started!

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 2:56 pm
by Mike Messer
Sorry about the late reply, I've been busy. I'm a bit new to tobacco pipemaking, too, but I have made several pipes. I can't say that I have this all worked out, but I use the traditional Ebonite Tip - Tenon, and drill the traditional Mortise in the Shank. Here's an example.
Turned Tenon to .3750 in. diameter, finishes to .3675, 1/128 in. smaller.
Drilled Mortise with a #U .3680 in. bit, actually drilled .3700 in., and finished .3750 in. diameter.
So, the Tenon is .0075 in. (1/133 in.) smaller than the mortise, and it fits nearly perfect, perhaps a shave too tight.
Problem is, after the pipe is smoked a bit, humidity will swell the wood in the shank, and the fit will be too tight.
Another example, without the numbers.
I have a pipe where I made the Tip Tenon too small. It was so bad that it would just fall out if you turned the pipe up vertical. So, I made another tip to fit correctly.
After a few weeks of heavy smoking (I really liked the pipe). The new tip fit way too tight, and the original, loose tip, now fits perfectly.
Edited 8:31 P.M. - The difference in diameters of the two tenons is .0039 in. (about 1/4 of 1/64 in).
I haven't worked out or chosen an alternative solution, yet.
M.M.

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 3:27 pm
by jeff
Mike Messer wrote:I'm a bit new to tobacco pipemaking, too...

What other kinds of pipes have you made??

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 4:29 pm
by ToddJohnson
Mike Messer wrote:Sorry about the late reply, I've been busy. I'm a bit new to tobacco pipemaking, too, but I have made several pipes. I can't say that I have this all worked out, but I use the traditional Ebonite Tip - Tenon, and drill the traditional Mortise in the Shank. Here's an example.
Turned Tenon to .3750 in. diameter, finishes to .3675, 1/128 in. smaller.
Drilled Mortise with a #U .3680 in. bit, actually drilled .3700 in., and finished .3750 in. diameter.
So, the Tenon is .0075 in. (1/133 in.) smaller than the mortise, and it fits nearly perfect, perhaps a shave too tight.
Problem is, after the pipe is smoked a bit, humidity will swell the wood in the shank, and the fit will be too tight.
Another example, without the numbers.
I have a pipe where I made the Tip Tenon too small. It was so bad that it would just fall out if you turned the pipe up vertical. So, I made another tip to fit correctly.
After a few weeks of heavy smoking (I really liked the pipe). The new tip fit way too tight, and the original, loose tip, now fits perfectly.
I haven't worked out or chosen an alternative solution, yet.
M.M.
I do what Mike does, but I like to take my measurements to the eleventh decimal place rather than stopping at the fourth. For those of you who do not have a computer numerical controlled lathe capable of machining internal components for the space shuttle, I would suggest getting a 5/16" drill bit and then turning the tenon down until it's tight in the mortise. Alternatively, you can also use 5/16" delrin.

TJ

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 5:10 pm
by bluesmk
I love u guys ! :lol: :notworthy: :mrgreen:

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 5:11 pm
by bluesmk
Dan
Gabrieli Pipes LOL !

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 6:06 pm
by Kettletrigger
Mike Messer wrote:Sorry about the late reply, I've been busy. I'm a bit new to tobacco pipemaking, too, but I have made several pipes. I can't say that I have this all worked out, but I use the traditional Ebonite Tip - Tenon, and drill the traditional Mortise in the Shank. Here's an example.
Turned Tenon to .3750 in. diameter, finishes to .3675, 1/128 in. smaller.
Drilled Mortise with a #U .3680 in. bit, actually drilled .3700 in., and finished .3750 in. diameter.
So, the Tenon is .0075 in. (1/133 in.) smaller than the mortise, and it fits nearly perfect, perhaps a shave too tight.
Problem is, after the pipe is smoked a bit, humidity will swell the wood in the shank, and the fit will be too tight.
Another example, without the numbers.
I have a pipe where I made the Tip Tenon too small. It was so bad that it would just fall out if you turned the pipe up vertical. So, I made another tip to fit correctly.
After a few weeks of heavy smoking (I really liked the pipe). The new tip fit way too tight, and the original, loose tip, now fits perfectly.
I haven't worked out or chosen an alternative solution, yet.
M.M.
Mike, thanks for taking the time to post such specific information. I'm pretty particular about numbers myself and I'm wondering if you're getting those dimensions based on actual measurements or just mathematically (based on listed drill bit sizes). I ask this because even a brand new drill bit will consistently drill a couple of thou over in precision equipment, and much worse in the standard home drill press. I've got a nicely-set up metal lathe and I can't get closer than +.0003" with a new reamer in a floating holder (measured with a bore gauge).

I realize I may be picking the fly shit from the pepper here, but I think that if we're gonna talk in tenth's, I'd like to be sure of your measurements.

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 8:58 pm
by Mike Messer
No problem, Kettletrigger. I did not measure the #U bit .3680 in. I measured the mortise with a simple caliper marked in 32nds of an inch, but magnified. I can estimate maybe to about 1/8 of 1/32, .0039, but usually only about 1/4 of 1/32, .0078.
I like to have a somewhat accurate target dimension when turning the tenon on a my metal lathe, which is marked in large 1000ths of an inch, so I can estimate easily to .00025 in., then I don't have to keep taking the tip off of the lathe to see if it fits the mortise, But that's just my method, for now. I do stop and measure it with calipers frequently.
I can't say for sure how accurate this is, but it seems to work okay, except when I forget I need to take another .025 in. off the diameter of the tenon and I crank .025 more on the lathe which is the radius measurement, and then I cut .050 in off the diameter, and the tenon is too small. Have to make a new one.
Edit 8-27-09: Also, my drill press is about 50 years old, military surplus, but very heavy duty, cast iron, and I'm not sure how good it is.

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 9:13 pm
by Mike Messer
jeff wrote:
Mike Messer wrote:I'm a bit new to tobacco pipemaking, too...
What other kinds of pipes have you made??
I made some pipes similar to Native American Indian pipes (which may have been used to smoke something other than tobacco).
But here is an interesting fact. "...the Mayan people of Central America were among the first pipe smokers several thousand years ago and archaeologists have found pipes dating from around 2,000 B.C..." (British America Tobacco Co.) That's 2500 years before the Europeans even knew what tobacco was. I think it is amusing that "History" teaches us that Christopher Columbus discovered America in 1492, and at that time the capitol of the Azctec empire, Tenochtitlan, an advanced cultural center of a quarter of a million, with architecture, art, religion, and government, already existed in Mexico. So, Maybe Columbus was a little late.
Anyway, Every way, keep up the good work, Jeff.
M.M.

Posted: Tue Aug 25, 2009 9:35 pm
by Mike Messer
ToddJohnson wrote: I do what Mike does, but I like to take my measurements to the eleventh decimal place rather than stopping at the fourth. For those of you who do not have a computer numerical controlled lathe capable of machining internal components for the space shuttle, I would suggest getting a 5/16" drill bit and then turning the tenon down until it's tight in the mortise. Alternatively, you can also use 5/16" delrin.
TJ
I don't especially like all that Epoxy glue used to glue in the Delrin, which is a trade name for Polyacetal or Polyoxymethylene(POM) plastic. Just messin' with you, Todd, you make some excellent pipes, so whatever you're doing, it can't be wrong. Seriously, I have been considering some Acrylic tips, and some Bakelite tips, too, since I saw J.Alan's "Modern Egg."
And, one of my uncle's, actually did "machine internal components for the space shuttle." and other government and military projects, since WW-II. But that's not me.
MM

Re: Five questions about mortises and tenons

Posted: Tue Aug 25, 2009 11:40 pm
by RadDavis
Mike Messer wrote:No problem, Kettletrigger. I did not measure the #U bit .3680 in. I measured the mortise with a simple caliper marked in 32nds of an inch, but magnified. I can estimate maybe to about 1/8 of 1/32, .0039, but usually only about 1/4 of 1/32, .0078.
I like to have a somewhat accurate target dimension when turning the tenon on a my metal lathe, which is marked in large 1000ths of an inch, so I can estimate easily to .00025 in., then I don't have to keep taking the tip off of the lathe to see if it fits the mortise, But that's just my method, for now. I do stop and measure it with calipers frequently.
I can't say for sure how accurate this is, but it seems to work okay, except when I forget I need to take another .025 in. off the diameter of the tenon and I crank .025 more on the lathe which is the radius measurement, and then I cut .050 in off the diameter, and the tenon is too small. Have to make a new one.
Mike,

It's much easier to cut the tenon to fit the mortise rather than relying on a measurement. Just leave the stem in the lathe chuck and push the stummel onto it. If it won't go, cut a couple more thousandths off and try it again until you get a nice snug fit that you like.

When using this method, there's no measuring involved at all.

Rad

Re: Five questions about mortises and tenons

Posted: Wed Aug 26, 2009 9:26 am
by Nick
This is pretty much what I do too, but I sure as hell seem to cut more than a few tenons too small. (Dammit!) If you do try this, be very careful with thin walls on your shank. use a very light hand, as even just a bit of pressure can crack your shank.