Thanks for the reply !
I'm not quite done, and I haven't done any testing of tube lengths or anything, but I think I have it pretty much all assembled for a test run tomorrow. See pic.
None of my joints are anything other than twist-tight now, and I have many different length pipes so I can mix-and-match to optimise the flow once I start testing. I decided on a standard 90mm 45* angle join as the inlet, and I have a 22.5* angle before my leaf catcher (yep, I was in the same aisle at Bunnings
). I also put a sleeve inside the 45* join so that the beans can only flow in at a certain pace, and it should also help ensure airflow doesn't go up the angle. I have the 200mm fan and that has probably too much airflow in reserve so I hope I should be able to tune in a good balance of flow rate and still leave rocks behind.
The missus has been on my case saying I should get some clear PVC pipe so I can see the bean flow - yeah maybe, but haven't yet found some at a reasonable price to justify.
Still left to do is properly brace the main pipe to the baseboard.
Here's my rough costs:
$275 for fan
$25 for big rubber reducer
$14 leaf catcher/inlet funnel
$10 1m length 90mm pipe
$15 assorted pipe fittings
$9 mozzie stoppa
$12 pipe clamp for brace
$15 worm drive clamps for rubber reducer both ends
I think that's a bargain, as long as it works
Thanks again for the inspiration !