Very Impressive build. Appreciate all of the build photos.
Thanks for following 
Both cabinets are glued up and getting ready for the next phase, which is prepping them for filling them with epoxy/sand so each drivers get a individual sealed chamber.
Here is one of them set up for some better shots:
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filling them with epoxy/sand ? I’ve built speakers before and used acoustic batting inside but this is new to me. Please explain!
Indeed Epoxy/Sand (EG) is often used for machining bases (like CNC´s) etc to provide mass in order to reduce/eliminate vibration of it all. Which is also what we´d want for a speaker cabinet
You can see how I am gonna go about this on this pic, a test cabinet made with one single driver:
The EG will fill the entire cabinet, except for the volume the drivers themselves will use. Therefore the whole structure will have great mass, a rigid core (EG) which will prevent any sides of the cabinet to move/resonate.
Ideally you´d want a really high static vs moving mass ratio as this help eliminate structural resonance.
Image one driver and a card board cabinet. Ratio will be low, maybe 10:1
For this project I am getting close to 1400:1 which will practically make the structure immune to any forces excerted by the drivers. (Any force have a equal force in the opposing direction)
Each speaker volume will have batting etc.
Its gonna be a real handfull to move, but hopefully sound great!
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The mass/vibration thing makes sense. You’re going to fill outside that oval with sand/epoxy and inside it with batting? Have you thought about mixing the sand with epoxy so you don’t have sand working it’s way into places it shouldn’t or is that what your plan was?
The epoxy/sand is mixed together and used like a concrete filler outside the oval - which only act as a casting barrier.
Fusion360 is free for non-commercial use? Are you referring to the student/teacher option of which I’m neither. (but I do have 2 kids still in school 
Yes, and renewable.
First half of the project is operational and preparations for casting of #2 is done - mixing more EG this week
Left speaker is my old line source, the right tower is the new one.
To me a CNC is a side-hobby, enabling me to create components for other types of projects This time its a speaker build.
The imaged soundstage is as large as the speaker implies
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That is awesome! I’m sure the sound is as impressive as it looks. Well done sir.
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