Replacing broken inegral tenon with delrin

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Oakbear
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Replacing broken inegral tenon with delrin

Post by Oakbear »

Hi folks.

The title refers to a repair i've done a couple of times now, where a tenon has broken leaving a jagged edge.
I've been drilling it out, making a delrin tenon which i then glue into place. This has worked fairly well, but the join between the shank and stem isn't perfect, just off by a fraction of a mm, leaving a little ridge.

Without sanding the join down, as you would when shaping, and thus having the hassle of a full stummel refinish, any suggestions to get this right?

Thanks in advance!
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sethile
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Re: Replacing broken inegral tenon with delrin

Post by sethile »

Ronnie B of Night Owl Pipeworks showed me a really slick way of doing this, but I suspect it takes a bunch of practice to get the hang of it, and involves a little bit of risk if you screw it up.
  • Fit the new delrin to the old mortise for a good sung fit
  • Drill the remaining old tenon out of the the stem and fit the hole oversize enough to have a little wiggle room for your new tenon
  • Roughen and/or grove the tenon surface to be inserted into the stem, and the hole you have drilled in the old stem to receive it in order to insure good adhesion
  • Put carnuba wax or some other dependable release agent on the face of the shank and mortise to prevent accidental gluing
  • Insert the new tenon into the shank mortise
  • Epoxy the stem side of new delrin tenon into the stem using long cure epoxy, while minimizing any squeeze out (you don't need to be too afraid of squeeze out if you have a lathe as you can easily face it off once it's dried)
  • Carefully align the stem and shank with the wiggle room in the oversize hole in the stem and tape it in place using masking tape and let it cure overnight
  • Once the epoxy is thoroughly cured, remove the tape and remove the stem from the stummel (hopefully your tenon stays in the stem ;)
  • Use a tapered drill to clean any epoxy residue inside the tenon and stem, and perhaps open up the tenon side of the stem if desired
  • Face off the stem face by putting the stem on a pin gauge in your lathe.
If you do all this correctly, you'll have a near perfect repair. If not, you'll have a huge mess, and maybe a one piece pipe!
Scott E. Thile
Collector, smoker, and aspiring pipemaker.
http://sethilepipes.com
Sysop: http://pipedia.org
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Oakbear
Posts: 103
Joined: Mon Aug 06, 2012 4:47 pm
Location: Nottingham, UK
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Re: Replacing broken inegral tenon with delrin

Post by Oakbear »

Thank you so much for the reply, that makes perfect sense. I feel dumb for not realising it before!

I had been fitting the new tenon to the stem then trying to fit it to the mortise, rather than the other way round. This way is much better as one doesn't need a perfect fit into the stem if you're using a decent epoxy. There's less wiggle room in the mortice.

Thanks again! :D
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