Loose stem in bamboo shank

[kbadkar]

I made a pipe with a bamboo stem with a delrin insert and 5/32" draft hole which accepts a 5/32" O.D. SS tenon. The SS tenon got swaged somewhat on the end from the live center on the tailstock when I turned the stem down a bit. I didn't realize the end of the SS tube had flaired out when I inserted it in the delrin the first time. I forced it in since it was tight and ended up "cutting" the diameter of hole in the delrin a little larger. It held up OK for awhile, but now it's loose of course.

Is there a quick fix for this, aside from drilling out the old delrin insert and putting in a new one? I was thinking... if there were some way to "increase" the diameter of the SS tube somehow, problem solved.

[Tyler]

I'm sure there's a better way, but you can protect the tube with a rag and squeeze the tube with some pliers. Make it ever-so-slightly out-of-round, and it will firm up. Not ideal, but workable if you don't want to go to the trouble of a new delrin insert.

[KurtHuhn]

That's a tough one. It's not like a vulcanite tenon that can be expanded. I agree with Tyler. Try to tweak the tenon oval, and it should tighten up.

And then grind the flare off the end.

[ToddJohnson]

I don't ever line my bamboo with Delrin, but there is a sure trick for tightening mortise/tenon fit in an unlined bamboo. Give it a try and see if this works. Put a spot of superglue on the end of an extra fluffy pipecleaner and insert it into the mortise once or twice. This will put a very very thin coating of CA glue on the mortise walls, essentially shrinking the diameter by a few thousandths. Delrin is pretty slippery though, so I have no idea if regular superglue will adhere to it or not. Good luck.

Todd

[kbadkar]

Thanks for the advice guys.

I'll try the superglue first, but I'll see if I can get a even layer on the tenon first and sand down high spots with a fingernail file, if necessary. I am also unsure how the superglue will hold on the delrin, although the mortise is pretty scored up from the expanded tenon end. I'll test it out on a scrap piece.

If that doesn't work, I'll pinch the tenon a tad. I will use this method as a last resort, because it the fit is still unsatisfactory, I'll have to re-do both the delrin insert and the stem.

If I re-do the insert, how would you drill out the old delrin insert now that the bamboo stem is epoxied to the stummel? I was thinking I could hand drill it out using a handled jacobs chuck, increasing diameter one step at a time, using the old drilling as the pilot.

Todd,
How do you make a long lasting tenon/mortise friction fit in the bamboo if you don't use delrin? I imagined that the bamboo material itself, since rather soft and pithy, would wear quickly, causing an inevitable loose fitting stem.

[kkendall]

You could change from 5/32 OD tubing to 3/16 OD (roughly 5/32 ID) tubing in the stem. Then use a 3/16 tapered drill bit to open the delrin insert.

[KurtHuhn]

How do you make a long lasting tenon/mortise friction fit in the bamboo if you don't use delrin? I imagined that the bamboo material itself, since rather soft and pithy, would wear quickly, causing an inevitable loose fitting stem.

I have found that, in most circumstances, you just don't have to worry about that. Bamboo has a tendency to swell slightly when moist - and tobacco smoke is moist. And I like to use a very long tenon - sometimes as long as an inch. Possibly not needed, but it's what I do.

[Ryan]

I have but a very thin layer of ca glue on the tenon and it works great.

If you put to much on you can always buff it it lightly for a better fit.

[kbadkar]

And yet more great info/advice. I love this forum. Thanks.