t dub, I don't know if what you call tunnelling is what happens with a heavy load, or even if it's a bad sign like in the case of t-1.
What happens with my MV is that whatever the size of the bowl I take, some plant matter get stuck on the screen below the cone that's of top of the chamber. And this is normal I think. The unit needs a bit of cleaning after use. If I prepare huge bowls like that, I have sufficient material not only to get some herb on such screen, but to complete an entire dome like that. Probably before taking out the upper part of the unit it was complete, with no hole in the middle, if this means something.
In any case I'm happy to discover fails on the project if there is any.
Update: I had my first session without the basket, 600mg of dried plant.
After a few hits I have taken away the top to see the result. There wasn't any tunnel yet, just a complete cupola as I hinted in my previous post.
Then I messed up a little with the load to see its color. The bottom of my load was a bit brown and on top there was still a little bit of green matter. After a lot more hits the content was all evenly brown with a bit of darkish color. On top this time! But I have to keep testing because it could be due to me messing up with the load into the middle of things.
Anyone who wants to join me on this Huge Load miniVAP Contest is welcome (I know Roger will not approve
). It was enough overindulging for me now.