Pre mold stem question

For discussion of fitting and shaping stems, doing inlays, and any other stem-related topic.
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luttrell31
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Pre mold stem question

Post by luttrell31 »

For those of you that use pre mold stems and add a delrin tenon. What sort of device do you use to hold the stem when drilling it? Thanks.
LatakiaLover
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Re: Pre mold stem question

Post by LatakiaLover »

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luttrell31
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Re: Pre mold stem question

Post by luttrell31 »

Thank you and that is an amazing device but a bit out of my budget at the moment. I may try to rig something similar up out of wood for a temporary solution.
Flygare
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Re: Pre mold stem question

Post by Flygare »

Two pieces of some hardwood with the same triangular notches that George has in his vice will work fine. Just get the notches squared up relative to the upper part of the jig. Clamp it in your vice, face the stem with a forstner bit and then drill for the tenon without moving anything between operations.


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LatakiaLover
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Re: Pre mold stem question

Post by LatakiaLover »

Thank you and that is an amazing device but a bit out of my budget at the moment. I may try to rig something similar up out of wood for a temporary solution.
There's an engineering law that for every advantage/strength that a solution contains, there is a corresponding disadvantage/weakness.

In this case, avoiding the difficulty of machining an integral tenon by using Delrin rod creates the need to drill an accurate hole for the Delrin.

Also known as, "You can run but you can't hide" :mrgreen:

Drilling a centered & co-axially aligned hole in rod stock is a no-brainer, doing that with an irregularly shaped object like a molded stem is surprisingly fussy.

If you have a lathe, btw, here's how to cut a tenon on a molded stem with it, which is actually easier than drilling an accurate hole for Delrin:

https://www.youtube.com/playlist?list=P ... 3p2zAHIPJl
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luttrell31
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Re: Pre mold stem question

Post by luttrell31 »

That video is great thank you. I do have a wood lathe, it would be doable on one but not nearly as good as a metal one. Do you think it is easier to do it on a wood lathe or stick with delrin?

I plan to start making stems from rod stock all the time, i just haven't made them up to par quite yet.... practice....
LatakiaLover
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Re: Pre mold stem question

Post by LatakiaLover »

I know one of the top wood lathe guys in the world. Literally. He makes his living teaching lathe work, travels internationally to present seminars, etc.

He also used to make pipes. How often could HE hit a tenon bullseye by hand on a wood lathe? About 2 times out of 3.

Amateurs haven't much chance, in other words.

It is possible to "tweak" a tenon into shape with sandpaper & etc after cutting to a certain point, but that's not as easy as it sounds, either.

As I said before, the piper must be paid. When using pre-molds, that means having a clamping method regardless. Both cutting and Delrin require the blank to be firmly held and motionless.
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luttrell31
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Re: Pre mold stem question

Post by luttrell31 »

That's kind of what I thought regarding wood lathes. I plan to work on a clamping device to use until I switch exclusivity to rod stock. Thank you for all of the help. I appreciate it.
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Re: Pre mold stem question

Post by LatakiaLover »

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Blackbeltpipes
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Re: Pre mold stem question

Post by Blackbeltpipes »

In that video he talks a lot about leveling off the broken remnant of the tenon... and all the risk involved... if he’s going to re drill it anyway why not use a countersink bit and just level it that way? It seems too risky to put it anywhere near a sanding disk especially with an expensive piece. Even if you’re the beat sander ever, why risk it...?


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luttrell31
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Re: Pre mold stem question

Post by luttrell31 »

Perfect, that will work great. Thank you!
LatakiaLover
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Re: Pre mold stem question

Post by LatakiaLover »

Blackbeltpipes wrote: Thu Sep 17, 2020 10:47 pm
In that video he talks a lot about leveling off the broken remnant of the tenon... and all the risk involved... if he’s going to re drill it anyway why not use a countersink bit and just level it that way? It seems too risky to put it anywhere near a sanding disk especially with an expensive piece. Even if you’re the beat sander ever, why risk it...?
A countersink will not create a good surface on rubber or (especially) acrylic.

Plus, you do NOT want to shorten the stem by any amount. Besides creating a step up to the shank when fitted, you absolutely don't want to "erase" the outline of the old tenon on the stem base. If you do, all manner of technical dominoes will start to fall. Future problems would emerge like opening a bottle of demons.

FWIW, If you were in my shop and saw it done on a sanding disk you wouldn't be concerned.
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Blackbeltpipes
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Re: Pre mold stem question

Post by Blackbeltpipes »

LatakiaLover wrote:
Blackbeltpipes wrote: Thu Sep 17, 2020 10:47 pm
In that video he talks a lot about leveling off the broken remnant of the tenon... and all the risk involved... if he’s going to re drill it anyway why not use a countersink bit and just level it that way? It seems too risky to put it anywhere near a sanding disk especially with an expensive piece. Even if you’re the beat sander ever, why risk it...?
A countersink will not create a good surface on rubber or (especially) acrylic.

Plus, you do NOT want to shorten the stem by any amount. Besides creating a step up to the shank when fitted, you absolutely don't want to "erase" the outline of the old tenon on the stem base. If you do, all manner of technical dominoes will start to fall. Future problems would emerge like opening a bottle of demons.

FWIW, If you were in my shop and saw it done on a sanding disk you wouldn't be concerned.
Thanks... appreciate the insight. I knew there were good reasons but without messing a few up other ways it’s hard to understand why people do things a certain way. Glad I can learn from your experience. I’m finding in my woodworking that the easy way isn’t usually the best way and the best way is often the hard way which is why nobody wants to do it... haha. thanks again


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LatakiaLover
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Re: Pre mold stem question

Post by LatakiaLover »

Whoopsie

I just realized I was referring to tenon replacement (repair work), not initial stem creation for a new pipe.

In which case this specific caution does not apply:

Plus, you do NOT want to shorten the stem by any amount. Besides creating a step up to the shank when fitted, you absolutely don't want to "erase" the outline of the old tenon on the stem base.
UFOs must be real. There's no other explanation for cats.
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