Hey everyone!
I still keep tabs on this thread almost every day, I've just been in grind mode the last...oh man, feels like months, haha. So I haven't had much time to post!
Been trying out a new stem idea, really loving it so far.
Since coming up with the wooden chamber liner, I haven't gone back to the glass-only chamber. I find that the wooden chamber walls give better heat up time so that you can get nice thick vapor on the first draw without any pre-heat. With the glass-only chamber, I find the same vapor quality arrives on the second draw, when the glass is heated up a bit more. I think this is just a limitation of physics...
...If you started off with a higher temperature, you can quickly heat up the glass chamber walls, but at the expense of exposing the center of the herb load to higher starting temperatures.
I think it's much more effective to keep the starting temp on the lower side, but also use a chamber material that has both very high insulation properties and low thermal mass. This is also going to give you the most efficiency as far as battery use goes.
Wood is pretty much the perfect material here... it's safe, strong, machinable, and relatively inexpensive. High insulation properties, low mass.
The only issues is that it's dimensionally unstable, porous, and has a woody taste.
Back to the chamber liners... I find them to be slightly fiddly to use, and the bowl size is significantly decreased compared to the stock all-glass chamber option.
So, I've been trying to come up with a new wooden stem that gives better performance vs. the glass stem, but without the downsides commonly associated with wood.
So far I've got two options in the works. The first is this bamboo stem.
This isn't any ol' piece of bamboo, however, I've done a number of things that make this a pretty neat little stem.
First, the size... bamboo grows in a tube shape... but the outer most layers are the strongest and most densely packed fibers. These strong outer fibers are what I wanted to use as the outer walls. So I found a piece of bamboo cane that was almost the perfect size, only sanding off the outer "skin" to make this stem. That way I can make the walls as thin as possible without compromising the strength.
Second, I roasted the bamboo at 450 degrees. A lot of the volatile compounds that give wood it's "woody" smell, are driven off by the heat, and the sugars in the cane are caramelized to produce a harder, less moisture sensitive, material.
The stem will still smell like roasted bamboo, which smells a lot like caramel to me. But not for very long, after a handful of uses, it's pretty much on par with the glass stem in terms of flavor.
The roasted bamboo can also be cleaned with acetone on the inside walls to remove future smells.
The internal diameter can be greater than the stock glass, about 5% larger. And a whopping 27% larger than the glass stem with wooden insert. This gives some real noticeable differences in vapor quality.
As a bonus, the wood holds onto metal screens very well, so if you insert a screen, it doesn't go anywhere. By tapering the opening of the chamber slightly, it's possible to fit a basket screen in the tip so that it doesn't easily pop out... but isn't so deep as to be difficult to remove with your finger tips. This is a big advantage over the glass stems.
The outside surface glides against the o-rings, making for a much smoother stem insertion/removal. The glass has a little more friction against the silicone o-rings.
And, by roasting the bamboo (and the nature of bamboo itself), you don't have any stability issues, it won't shrink or grow with changes in humidity.
The one big downside is that finding bamboo that is perfectly round, and the correct size, is extremely difficult for me in Canada. You pretty much get one or two stems out of a bundle of cane. I'd need to special order hand selected bundles from China/Japan/west coast if I wanted to make these for sale.
But, I have a strong suspicion that boiled and then roasted straight grain dense hardwoods would be equally suited, but easier to source the raw materials.
Boiling will remove resins/oils etc.. and make the wood taste more neutral, where the roasting will give it more stability/hardness.
Anyhow, here is the bamboo prototype.
I love the look as well, very organic feeling.