Why do I keep breaking shanks?

Cory · Post by **Cory** » Wed Jan 02, 2013 12:07 am

I have turned three pipes on the lathe - they never got finished because I keep breaking the shanks!

One of them was a catch - which is fine and dandy and understandable; my mistake. The other two however, were from test fitting stems...I am not jamming them in there. They were snug fits at best and the shanks just split. Happened twice on one of them.

So I have three pipes with half inch long shanks and I don't know what to do with them - the drilling is perfect and bowl shape is fine so far. The most recent one I am trying to do a shank extension out of acrylic followed by a cumberland stem. Is shank extensions the only answer as to what I can do with these failures?

Does anyone know what is going on? Shank walls just too thin - the most recent one was a 3/8 mortise in 1/2 hole. Should I have used a 1/4 mortise on that one?

Thanks,
Cory

RadDavis · Post by **RadDavis** » Wed Jan 02, 2013 12:55 am

If you're talking about a 3/8 mortise in a half inch shank, that could be a little thin and need great care in fitting a stem. You're only leaving 1/16 around the outside if I'm understanding what you're saying.

Rad

Cory · Post by **Cory** » Wed Jan 02, 2013 1:25 am

RadDavis wrote:If you're talking about a 3/8 mortise in a half inch shank, that could be a little thin and need great care in fitting a stem. You're only leaving 1/16 around the outside if I'm understanding what you're saying.

Rad

That is correct. What is a safe wall thickness on the shank?

Post by **Tyler** » Wed Jan 02, 2013 2:26 am

There is probably not a good reason to do a 3/8" tenon for the pipes you describe. That is unnecessarily large. 5/16" would be fine (and standard) for a 1/2" shank, and 1/4" would be a good choice if it was a Delrin tenon.

caskwith · Post by **caskwith** » Wed Jan 02, 2013 5:37 am

Does sound like thin walls to me. SInce I use delrin for my tenons then they are all the same size except on unusual designs. 6mm tenons let me comfortably go down to a 10-11mm shank regularly.

The Smoking Yeti · Post by **The Smoking Yeti** » Fri Jan 04, 2013 6:25 pm

Chris... please speak American, mm are foreign here.

caskwith · Post by **caskwith** » Fri Jan 04, 2013 6:50 pm

The Smoking Yeti wrote:Chris... please speak American, mm are foreign here.

Sorry unlike software I am not back compatible, I only deal in up to date measurements.

d.huber · Post by **d.huber** » Fri Jan 04, 2013 8:58 pm

caskwith wrote:
The Smoking Yeti wrote:Chris... please speak American, mm are foreign here.
Sorry unlike software I am not back compatible, I only deal in up to date measurements.

mredmond · Post by **mredmond** » Fri Jan 04, 2013 10:53 pm

Hey, wait...Chris, don't you guys still refer to weight in stones? : )

pipeguy · Post by **pipeguy** » Fri Jan 04, 2013 11:19 pm

Yes up to date measurements and yes stone is also up to date here here

Cory · Post by **Cory** » Fri Jan 04, 2013 11:56 pm

At least they use Newtons instead of slugs...what a lame unit of measurement...

I am all for the metric system.

Sasquatch · Post by **Sasquatch** » Sat Jan 05, 2013 1:44 am

If you have to push any harder than .237 Erg it's too tight.

The Smoking Yeti · Post by **The Smoking Yeti** » Sat Jan 05, 2013 1:59 am

I'll wager two shekels of silver that Sas is drunk.

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