Delrin tenon failure avoidance

For discussion of fitting and shaping stems, doing inlays, and any other stem-related topic.
LatakiaLover
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Delrin tenon failure avoidance

Post by LatakiaLover »

This guy's pipes regularly sell for over $1K US. Some well over that.

He uses made-to-spec tenons that are pre-textured in BOTH directions (vertical grooves and horizontal grooves).

The walls of the "mortise" in the stem that will be touched by glue are also textured.

You'd think all was well, right? Not so.

Not textured enough?

Wrong kind of adhesive?

I'd say both.

The ONLY way to keep this from happening is to create a "3D puzzle". Assume any adhesive other than epoxy will break down over time, that epoxy will not stick to Delrin, and proceed accordingly. Cut divots into both parts sufficiently large to mechanically hold protuberances/spikes of cured epoxy, and make sure they are all filled before joining the parts.

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Sasquatch
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Re: Delrin tenon failure avoidance

Post by Sasquatch »

Nice, yeah that's not gonna fail.

Looks like the epoxy (assuming it was epoxy) was maybe a bit old on the first one. I've had 2 fail in the ... 250 or so I have done, and both right at the same time in my career, ie, the same batch of glue that had maxed it's shelf life, it got all pebbly.
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wdteipen
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Re: Delrin tenon failure avoidance

Post by wdteipen »

Precisely why I prefer to turn integrated tenons.
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n80
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Re: Delrin tenon failure avoidance

Post by n80 »

Does epoxy, like T-88, expand as it cures?
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Re: Delrin tenon failure avoidance

Post by LatakiaLover »

T-88 was designed for homebuilt wooden aircraft. It works great on, well... wood.

For both replacement and original tenons regardless of material (Delrin, vulcanite, or acrylic), or the material they're going into (vulcanite, acrylic, Bakelite, Juma, etc) use G-Flex. It isn't rubbery, btw, just microscopically flexible so doesn't behave like glass.

As for expanding as it cures, it doesn't. (I've never seen any other kind do that either, though. Are you sure?)

EDIT: Did some research. Since epoxy generates heat while it cures trapped air either in or under it will be heated as well, so the epoxy-air MIXTURE can expand, but epoxy itself doesn't.

The solution is to always "flat stir" when mixing not "scoop-flip stir" to minimize air capture/bubble creation.
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Sasquatch
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Re: Delrin tenon failure avoidance

Post by Sasquatch »

I've had really good results with the JB Weld "Plastic Bonder" in black (comes in tan too).
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sandahlpipe
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Re: Delrin tenon failure avoidance

Post by sandahlpipe »

I know gorilla glue has a couple of formulations that do expand to cure. Not their wood glue, but the one I used to glue the toilet lid back together, and the regular gorilla glue do expand in a foam-like way. I don’t think that’s a 2-part epoxy though.

As for G-Flex, it’s basically all I use now. Works great.


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KurtHuhn
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Re: Delrin tenon failure avoidance

Post by KurtHuhn »

Sasquatch wrote: Mon Oct 21, 2019 7:05 am I've had really good results with the JB Weld "Plastic Bonder" in black (comes in tan too).
This is good stuff. It not only forms a mechanical bond, but a chemical one as well - fusing with the plastic for an enhanced hold. I use wherever plastics are involved. It also does not outgas as much as some plastic bonders can, so it won't cloud the unbonded surfaces.
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RickB
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Re: Delrin tenon failure avoidance

Post by RickB »

Looks like it wasn't in there really far either - what, like maybe 5/16"? I've been trying to bury mine about 3/8" at the barest minimum, and have been using the good ol' slot-cutting Dremel 199 to cut 1-1.5mm diagonal slots all around it.
Sasquatch wrote: Mon Oct 21, 2019 7:05 am I've had really good results with the JB Weld "Plastic Bonder" in black (comes in tan too).
I'd rather it was two bottles because for some reason I don't love the plungers, but seriously where has this been all my (stem making) life?
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n80
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Re: Delrin tenon failure avoidance

Post by n80 »

The original Gorilla glue does expand and will even push apart things that are not clamped. As per the instructions you wet one surface, apply glue and clamp.

I find Gorilla glue to be exceptionally strong with quite a few materials including wood. But if you can't clamp adequately it is a no go. It is also nasty to mess with and stains skin (for days) and clothes (forever). As mentioned, it also forms foam which has to be cleaned up. Not ideal for pipe making.

It isn't cheap either.

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Sasquatch
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Re: Delrin tenon failure avoidance

Post by Sasquatch »

Gorilla glue is a weird moisture-cured urethane, I've had it stick certain things like crazy, but as you say, that expansion pressure is just too much of a pita for daily all-purpose use.
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Re: Delrin tenon failure avoidance

Post by n80 »

I have a related question on this topic. I have purchased some sheet vulcanite to make spacer rings for a ring of different wood from briar on a briar shank. In other words it would be briar shank-to-vulcanite spacer-to-alternate wood and stem would plug into alternate wood on the end of the shank. What would be recommended for adhesion of the briar shank-to-vulcanite spacer and vulcanite-to-wood ring joints.

I have the T-88 already but as mentioned it is primarily for wood-to-wood junctions. I can order some G-Flex if that would be better, or the JB Weld, for vulcanite -to -wood but at this rate I could be buying better pipes than I'm making for less money than I'm spending to make them. :lol:
wdteipen
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Re: Delrin tenon failure avoidance

Post by wdteipen »

If they are being fitted over a briar tenon on the end of the shank (the right way) then most two part epoxies will work fine because there's no stress on the glued joints. Glued tenons present a different challenge because of the twisting and pulling the glue joint has to endure over time with a material (Delrin) that doesn't bond well with most epoxies.
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Sasquatch
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Re: Delrin tenon failure avoidance

Post by Sasquatch »

at this rate I could be buying better pipes than I'm making for less money than I'm spending to make them. :lol:

Well... yeah. I mean, my honest to god advice to anyone who says, "I wanna make my own pipes real bad, it's gonna be AWESOME!" is to take 400 cash, and just flush it down the toilet. Watch it swirl, really let it set in what you've done. And then go buy a Castello.

Cuz that exact same feeling is what you get making pipes for about... 3 years. Lots of money in tooling, lots of wasted material.

The only difference between the scenarios is that in the first one, you get a nice pipe. :thumbsup:
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n80
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Re: Delrin tenon failure avoidance

Post by n80 »

Rationalizing: Most of the tooling I've bought I can use for other stuff......except for the tenon cutter.

I'm probably in for over $500 already including tools and materials. I've made about 10 briar pipes in two months.

But I guess the thing is that I'm still having fun so far. And I'm enjoying a couple of the pipes I've made and so are a few other people.

It won't get nuts unless I buy a lathe.
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Re: Delrin tenon failure avoidance

Post by LatakiaLover »

Serious pipe involvement is expensive. I've got about $30K in it. Hell, a simple full set of chucking reamers---a necessity for serious repair work---is about $1300, and they just sit nearly hidden in a corner of two full-sized rooms filled with stuff.

Nice pipes CAN be made in a minimal shop (Baldo Baldi is a good example), but unless you become famous and your work brings a price to match, you'll never be able to work fast enough to make anything close to a profit. Some truly fine carvers have discovered that the hard way. Mark Price---a one-time active member of this board---being a good example.

The point? Only you know your own heart (so to speak), and it's best to be honest with yourself early on. If you just want a hobby spending time at it is the POINT, and pipe making is less expensive than many others, from golf to firearms to motorcycles. If you have aspirations of making an income from it, though, many spendy tools will be required.
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caskwith
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Re: Delrin tenon failure avoidance

Post by caskwith »

LatakiaLover wrote: Tue Oct 22, 2019 11:36 pm If you have aspirations of making an income from it, though, many spendy tools will be required.

Even with lots of spendy tools making a living is damn hard. I couldn't support myself on what I make alone.
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Re: Delrin tenon failure avoidance

Post by LatakiaLover »

Ah. The Other Thing.

Essential to high level success is either a trademark shape or a trademark look. Something that can be identified at a glance from across the room.

Eltang's router-finished cuttys and cherrywoods, Von Erck's loon and "spiral" variants, etc. are shape examples of this uniqueness; and Bang, Tokutomi, Joura, Cooke, and Roush are "look" examples.

Bottom line: Hang in there. Put out something unique that YOU like at every opportunity. Customer commissions of every shape and type might pay the bills, but are anonymous and will not "build a brand". Technical and design excellence alone, sadly, aren't enough.

After a while, if your specialty is good, collectors will want it just because. That's how humans work.
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caskwith
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Re: Delrin tenon failure avoidance

Post by caskwith »

Maybe I'll make it in another 10 years :lol:
n80
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Re: Delrin tenon failure avoidance

Post by n80 »

For a hobby this has been pretty inexpensive for me. Compared to photography/printing or sports car track days it is downright cheap. And for now i want to keep it that way. And I want to keep it fun. If I can keep it fun and relatively cheap and continue to improve I'll stick with it.

With a number of my hobbies, like cooking and photography, I am much happier not being a professional. That way I do what I want, learn at my own pace, fail at my own pace and produce at my own pace. That's how it stays something I do purely for fun.

As it is I have no customers and probably never will. And if I keep going I might even run out of people to give pipes to......and my wife is wondering where all these pipes are going to go.............
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