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Okay. I am working on a pipe as a gift for my best friend and smoking buddy, who is retiring from his profession at the end of the month. I had the option of using delrin for my tenon, but it was a real tight fit - so tight that it was extremely hard to get in and even harder to get back out. I am not convinced it was seating properly either.

So I was in a discussion in another thread with Wayne and Scottie, and based on some of their comments, I decided to turn a tenon by hand on my wood lathe. It came out perfect in that it is exactly the same size all the way along its length. But while the delrin (0.313") was way too tight, this hand cut integral stem ended up at 0.310", and is just a hair loose. If I were gluing it into something I would consider it perfect. But I ain't gluing it into anything.

Are stem tighteners/expanders any good? The only ones I have been able to find are from Pimo. Is there another way to fix this without tossing it and starting all over again? I can do that, but if I can fix it I would rather give that a try first.

LittleBill wrote:Okay. I am working on a pipe as a gift for my best friend and smoking buddy, who is retiring from his profession at the end of the month. I had the option of using delrin for my tenon, but it was a real tight fit - so tight that it was extremely hard to get in and even harder to get back out. I am not convinced it was seating properly either.

So I was in a discussion in another thread with Wayne and Scottie, and based on some of their comments, I decided to turn a tenon by hand on my wood lathe. It came out perfect in that it is exactly the same size all the way along its length. But while the delrin (0.313") was way too tight, this hand cut integral stem ended up at 0.310", and is just a hair loose. If I were gluing it into something I would consider it perfect. But I ain't gluing it into anything.

Are stem tighteners/expanders any good? The only ones I have been able to find are from Pimo. Is there another way to fix this without tossing it and starting all over again? I can do that, but if I can fix it I would rather give that a try first.

Properly-fitting tenons for the same mortise don't measure the same because of Delrin's lubricity. Delrin has to be larger.

Avoid the Pimo tool categorically.

Adjusting mortise/tenon fit tenons is a really fussy and surprisingly complicated business for all kinds of reasons. Too lengthy and situation-dependent a subject to address in a post, plus it's repair thing, not a pipemaker thing, so even if I wrote it all out no one would read it or care.

I'll be glad to talk with you on the phone if you decide to mess with the one you already made, and not just have another go.

Hey Bill,

First, try heating the tenon up with a heat gun and the dunking it in cold water. Sometimes this will expand the tenon enough for a good fit.

Barring that, you can use a knitting needle to insert into the warm tenon end to expand it, slowly twisting it as you go so as to keep the expansion even. Don't just jam it up in there, go slowly. If it gets too big, do it again.

Rad

RadDavis wrote: Barring that, you can use a knitting needle to insert into the warm tenon end to expand it, slowly twisting it as you go so as to keep the expansion even. Don't just jam it up in there, go slowly. If it gets too big, do it again.

Depends if he wants a quick, function-only fix, or one that matches the quality of the pipe, Beev.

There are lots of kitchen table ways to make a tenon merely stay plugged into a mortise by flaring it, trumpet-style.

Expanding it so it's both cylindrical and stays that way is another thing entirely.

Hope this helps

Mr. Dibos

LatakiaLover wrote:

RadDavis wrote: Barring that, you can use a knitting needle to insert into the warm tenon end to expand it, slowly twisting it as you go so as to keep the expansion even. Don't just jam it up in there, go slowly. If it gets too big, do it again.

Depends if he wants a quick, function-only fix, or one that matches the quality of the pipe, Beev.

There are lots of kitchen table ways to make a tenon merely stay plugged into a mortise by flaring it, trumpet-style.

Expanding it so it's both cylindrical and stays that way is another thing entirely.

Hope this helps

Mr. Dibos

George,

This is actually a valid pipe maker's topic. There is no such thing as a pipe maker who hasn't turned a tenon too small at some point...frustratingly often in lots of cases. A quality fix would be worthwhile info if you care to post.

Thank you gentlemen, for both of your answers. George, thanks for taking the time to talk with me on the phone. I learned a lot. Rad, I also appreciate the knitting needle trick. It worked. Just heating the tenon wasn't quite enough. My daughter had a selection of needles she was willing to let me use. I found one which the tip would go completely into the airway, right up to the shoulder where the needle straightened out. So I heated it up slowly, and worked the needle in slowly, as far as I dared. Then I let it cool off before removing the needle. I now have a tenon that is fitting somewhere between very snug and pretty tight. It fit well enough that I was able to put the whole mess back on the lathe and turn the shank and stem down so I have a very smooth transition between the two (so far).

I am just going to let things sit for a bit now, and then come back to it to make sure everything is still as it was before I monkey with it any more. George, I think if I had used a conical section, the tenon would have a bulge. But I was able to use the cylindrical section of the needle, and while I have not yet measured, it stands to reason that by shoving it completely through the tenon it should have expand it evenly. I will measure it as I progress on it.

LatakiaLover wrote: Depends if he wants a quick, function-only fix, or one that matches the quality of the pipe, Beev.

This might be a good time to point out that the overall quality of the pipe is going to be "beginner" anyway. It isn't that I don't care about quality, but rather that I am being realistic about it. This is for my best friend, but he is also a guy whose best pipe ever has been a $35.00 cheapie from the local smoke shop. If the one I am making for him turns out as well as my last one for function (aesthetics aside), he will really enjoy how it smokes.

I have also used the same tapered drill bit to expand a tenon, I figure it should be the perfect fit for the air way and should expand it evenly, any ways it worked on two occasions I needed it to, with no buldge

LittleBill wrote:

Wait a sec... I thought we were talking about a finished, or almost finished pipe!

If this is as far as you got before the tenon mishap, heck, at this point, I'd just grab another chunk of stock and turn a new stem. Take the one you messed up on and lop the bad tenon off, reuse it for another pipe with a shorter stem!

LittleBill wrote:George, I think if I had used a conical section, the tenon would have a bulge. But I was able to use the cylindrical section of the needle, and while I have not yet measured, it stands to reason that by shoving it completely through the tenon it should have expand it evenly.

A clean & proper mortise/tenon fit has an astonishingly narrow dimensional range. About 1.5 thousandths. That a random knitting needle happened to be exactly the right size was an amazing stroke of luck.

Since it went completely through---and provided the base of the stem was heated along with the tenon--- any trumpeting should be negligible.

Having it stay expanded for a long time depends a lot on that "step" business we talked about, but for a project pipe that's hardly a worry.

WCannoy wrote:Wait a sec... I thought we were talking about a finished, or almost finished pipe!

If this is as far as you got before the tenon mishap, heck, at this point, I'd just grab another chunk of stock and turn a new stem. Take the one you messed up on and lop the bad tenon off, reuse it for another pipe with a shorter stem!

With the amount of time I have had lately to put into pipes, this IS almost finished! Seriously, your suggestion was one of my first thoughts, but I am parsimonious in some ways, especially when it comes to materials. This is as much about learning how to fix problems for me as much as it is getting a finished product. I figured I could try, and if it didn't work, then I could start over with another chunk of ebonite.

LatakiaLover wrote:

LittleBill wrote:George, I think if I had used a conical section, the tenon would have a bulge. But I was able to use the cylindrical section of the needle, and while I have not yet measured, it stands to reason that by shoving it completely through the tenon it should have expand it evenly.

A clean & proper mortise/tenon fit has an astonishingly narrow dimensional range. About 1.5 thousandths. That a random knitting needle happened to be exactly the right size was an amazing stroke of luck.

Since it went completely through---and provided the base of the stem was heated along with the tenon--- any trumpeting should be negligible.

Having it stay expanded for a long time depends a lot on that "step" business we talked about, but for a project pipe that's hardly a worry.

I think it is more likely that the random needle was able to be shoved through to make the tenon a hair bigger than it needed to be, and it can be sanded down again, very carefully! I did heat as much of the blank as I could without burning my fingers, so I am pretty sure the base of the stem was hot as well.

Worst comes to worst, I will have to make a new stem for him down the line. Then again, he is pretty old.

Tyler wrote:
This is actually a valid pipe maker's topic. There is no such thing as a pipe maker who hasn't turned a tenon too small at some point...frustratingly often in lots of cases. A quality fix would be worthwhile info if you care to post.

I didn't realize that over cutting was a common problem.

Fixing old stems and making new ones is probably half of what I do on an average day, and dealing with tenon & mortise related problems is a big piece of that, so sure, I'd be glad to put something together.

had this idea seems like a good place to throw it out there. I fixed a shop pipe with a loose tenon with CA on q tip to coat the mortise. seemed to add a thou or two. its invisible, isn't any more exposed to the draft than the epoxy used to glue a delrin tenon in or the epoxy in a shank extension, so is this a big faux pas or a magical fix? also considered sodium silicate might have worked as well, which for the boal coating crowd would be acceptable to have in contact with the airway. I'm sure making a new stem or expanding the tenon is the proper technique, but I was thinking the water glass or ca swab maybe followed by reamer would produce a clean tighter sized mortise. is there potential issues with the fit or someone gasping that their mortise is too shiny? is this ever an acceptable fix for a mid range pipe?

mcgregorpipes wrote:had this idea seems like a good place to throw it out there. I fixed a shop pipe with a loose tenon with CA on q tip to coat the mortise. seemed to add a thou or two. its invisible, isn't any more exposed to the draft than the epoxy used to glue a delrin tenon in or the epoxy in a shank extension, so is this a big faux pas or a magical fix? also considered sodium silicate might have worked as well, which for the boal coating crowd would be acceptable to have in contact with the airway. I'm sure making a new stem or expanding the tenon is the proper technique, but I was thinking the water glass or ca swab maybe followed by reamer would produce a clean tighter sized mortise. is there potential issues with the fit or someone gasping that their mortise is too shiny? is this ever an acceptable fix for a mid range pipe?

Coating and reaming a mortise must be done by hand, and an off-axis result is the too-likely outcome. Then you have a whole new can of worms to deal with. (Sometimes there is no choice but to rebuild a mortise, but when, why, and how is a whole different subject.)

Coating a tenon to enlarge it will never work on Delrin (for long), and depending on the pipe will eventually deteriorate on plastic and vulcanite. Some substances work better than others, and the solution is fine as a quick way to return a tobacco access device back to service, but a band-aid approach isn't a proper pipe repair, imo.

LittleBill wrote:Okay. I am working on a pipe as a gift for my best friend and smoking buddy, who is retiring from his profession at the end of the month. I had the option of using delrin for my tenon, but it was a real tight fit - so tight that it was extremely hard to get in and even harder to get back out. I am not convinced it was seating properly either.

So I was in a discussion in another thread with Wayne and Scottie, and based on some of their comments, I decided to turn a tenon by hand on my wood lathe. It came out perfect in that it is exactly the same size all the way along its length. But while the delrin (0.313") was way too tight, this hand cut integral stem ended up at 0.310", and is just a hair loose. If I were gluing it into something I would consider it perfect. But I ain't gluing it into anything.

Are stem tighteners/expanders any good? The only ones I have been able to find are from Pimo. Is there another way to fix this without tossing it and starting all over again? I can do that, but if I can fix it I would rather give that a try first.

Bill,

Another option is to just roll up some sandpaper and sand the inside of the mortise so the delrin will fit better. I do this on every pipe I make. It also will clean up the mortise a little from tool marks. Just be sure to get grit out of the mortise before you put the tenon back in.

LatakiaLover wrote:Coating a tenon to enlarge it will never work on Delrin (for long), and depending on the pipe will eventually deteriorate on plastic and vulcanite. Some substances work better than others, and the solution is fine as a quick way to return a tobacco access device back to service, but a band-aid approach isn't a proper pipe repair, imo.

Do you feel the same regarding using beeswax to tighten up a tenon? Just curious.

I'd recommend going to a numbered size drill bit just over the airway size - warming the tenon, then inserting the drill bit (shank first) all the way past the tenon so it is well into the meat of the stem. This will barely expand the tenon while keeping it straight at the same time

irish_lord99 wrote:

LatakiaLover wrote:Coating a tenon to enlarge it will never work on Delrin (for long), and depending on the pipe will eventually deteriorate on plastic and vulcanite. Some substances work better than others, and the solution is fine as a quick way to return a tobacco access device back to service, but a band-aid approach isn't a proper pipe repair, imo.

Do you feel the same regarding using beeswax to tighten up a tenon? Just curious.

That often works well, but only for a short time. I consider it another band-aid, but a less objectionable one than nail polish or similar, because you know it's not a true fix (if that makes sense).

kkendall wrote:I'd recommend going to a numbered size drill bit just over the airway size - warming the tenon, then inserting the drill bit (shank first) all the way past the tenon so it is well into the meat of the stem. This will barely expand the tenon while keeping it straight at the same time

Yup, that's the method. The step size of even machinist's (numbered) bits is too large to be optimal, though. Vulcanite and plastic hold an expanded size better if they are not stretched there, but only expanded with heat and "frozen" in stages. The most expansion you'll usually get without stretching is about two thousandths, so that should be the step size of the inserted rods.

HSS drill blanks are cheap from McMaster-Carr, and a set that ranges around your preferred airway size (as a maker) is easy to put together.

Repair work needs a wider spread, but it's still cheap. Here's the set I use which goes from .124" to .158" in .002" increments. It makes a somewhat hazardous, time-consuming-to-recover-from-when-you-get-it-wrong task practically foolproof.

Oh yeah... grind a shallow taper on the insert end of each rod before using. They arrive with electro-cut, razor sharp ends that will catch on and/or shave the airway if you don't..