Tenon length

[NathanA]

I was wondering if anyone would like to comment on minimum tenon length. I have been working at making some hand cut stems and I am working with limited tooling and integral tenons. With the tenon cutter I have the max tenon length is about 11/16. If I have an inlay of 3/8 to 1/2 inch, will that leave me enough tenon to grab the mortise?

(Rad, I have spent a lot of time cruising through your pipe gallery and have noticed that on certain styles the tenons are much shorter than on others. Could you enlighten me as to how you determine how long the tenon should be?)

Thanks everyone...

[RadDavis]

The tenon should be as long as the mortise is deep.

On bent pipes, the mortise depth is determined by where the mortise line intersects the smoke hole line, so that the smoke hole is as close as possible to the center of the bottom of the mortise.

I've made some pretty short tenons. The minimum should be enough to get a secure fit of the stem to the stummel, I guess.

Rad

[Sasquatch]

Another way to think about this is to figure on the "grab" area of the tenon, which is to say the circumference x the depth. A thicker tenon can be shorter and have an identical contact area as a longer, thinner one. (Occassoinally a thicker tenon will allow a better drilling angle too).

Eventually, a really short tenon is going to require tremendous pressure (tight fit) to hold still, and of course, a cracked shank will result. What's the exact length? I dunno. I'd guess somewhere around 3/8" or less, you are going to have a tough time making things hold still without a really tight fit.

Some of this probably depends on the material you are using too.... I cut integral tenons, and an acrylic tenon vs vulcanite vs ebonite... man, they feel different at the "correct" fit.

Longest tenon in my collection is a Mastro de Paja at 3/4". Shortest is an old Karl Erik second that jams in tight after about 5/16", and I have no idea if that's the original stem.

[KurtHuhn]

I have recently become a very big fan of short, fat tenons. On bent pipes these days I typically use a 7/16" mortis/tenon that's only about 3/8" or 1/2" long. But this is very dependent upon the style of pipe, and since I prefer a more robust shape, that tenon size works well. As was said, this also allows a much more extreme drilling angle if needed, without nicking the face of the shank.

For straight stems I still typically use a 5/16" or 1/4" tenon, but I extend the length to about 5/8" to ensure a secure hold.

[Sasquatch]

And all the girls say "Oh Kurt, what a big tenon!"

[wdteipen]

I try to stay around 1/2 to 5/8" in general. I like the idea of a thicker shorter stem on bent pipes though. I'll have to toy around with that sometime.

[bloodysafety]

i always figured you follow tenon rules for furniture making 1/3 diameter in and around...but then again i have no clue what im doing...

[Sasquatch]

The difference is, our tenons have a hole in them of a certain size, and that size is often a good percentage of the tenon, so there are practical limits to how small you can make em.