@Copacetic , Thank you for your input and suggestions! I ended up using some of my off-time away from the batch 2 Nomads in the evening to experiment with some of these recent stem loading ideas.
I started with a prototype wooden capsule, as outlined in my previous post.... but ran into a number of issues. Most of the time I felt like the capsule loading/unloading was just too much of a hassle for me.
But most importantly, airway design is negatively impacted by any capsule system I tried.
From my pipe making daysvI know that airway design is the biggest design point for any artisan tobacco pipe. The airway determines how well the pipe will smoke.
Ideally, airflow through the chamber should be consistent from the center to the outer edge. The geometry of the airway before AND after the chamber will have a big effect.
With the more complex capsule systems, it's difficult to design a simple solution that maintains the best airway geometry. This trade-off doesn't seem worth it to me.
I landed on this idea, which is simple... but is working awesome so far.
It's a cherry-wood chamber liner that may come stock to improve performance, but can also double as a capsule system.
It fits snug inside the stem, but can still slide in and out. By pre-drying the wood before cutting on the lathe, any change in diameter as the wood is heated can be minimized.
Taste is altered for the first couple sessions, with a mild woody taste, but that disappears quickly.
Here is how I've been using it. With the two screens sandwiching the wooden liner.
I've also been using a 'push-rod' made from wood. This serves two purposes, to lightly tamp down my load, and also push the top screen out at the end of a session. Pushing on the bottom screen with the push rod pushes on the wood liner, which in turn pushes the top screen out. For people who can't use a fingernail to pick out the top screen, this is a great method. The herb is then easy to blow out, the wood liner stays put.
I keep my liner permanently installed, but it can also work as a capsule.
By removing the liner, putting it on a flat surface, and using a little funnel to load your herb material, you can then tamp down lightly to compress the load inside the liner.
The lightly compressed 'puck' of herb stays put inside the wood liner. You could load multiple wood liners in this way and store them in a case.
Now for the exciting stuff,
I found that extraction efficiency and evenness was improved over stock. Especially in the area close to the screen near the side walls.
Here is an illustration of why I think this wood liner is improving the performance.
On the left, we have a cross section of the stock stem with a screen loaded. Notice in the red circles where there is an interruption to the smooth side walls of the glass. The bunched up screen material obstructs airflow causing an outer ring of dead air flow.
On the right, we have added the wood liner. You can see how the liner creates a smaller diameter chamber... but maintains a smooth sidewalls.
Additionally, wood is my most preferred chamber material because of its thermal properties. I've noticed a significant change in heat-up time, and solid vapor production on the first pull from a cold start with a depleted battery and low-heat module. The glass stem stays cooler in extended use as well.
I think the combination of airflow improvement, chamber diameter reduction, and woods low thermal conductivity all work together to improve over-all performance.
@duff , That's awesome man! Looks great!
By having that groove cut into the ID of your wooden stem, you've created essentially the same airway design as what I've proposed here. I suspect that you've already noticed a difference over the stock stem. I'd be interested to hear your observations over time.
