Spec me a grinder/belt for finishing aluminium.

[m_c]

I've got no idea if household soap will work or not, I just bought a bottle from Moleroda.

The way commercial systems work, is they periodically inject some water/soap in, and there's a drain plug at a suitable height to let excess run out.

I think the drain plug on the tumbler is at a suitable height for a similar setup, but you are correct in that the supplied tap is a rubbish fit. I bought new fittings to create a more robust setup, however it's still on my roundtuit list.

For filtering, letting the run off sit in a container would probably be enough to let the vast majority of debris settle out.

[JOGARA]

Before




After
Come back at 7pm :p

[JOGARA]

The sun went away so here is inside workshop. I should have taken a photo of them inside instead of outside but should show you the difference.
These 2 bits are just test pieces I did when I first got the 6040. So really bad edges and I left about 0.02mm on the deck then cut them from it using a knife.
Left a really sharp edge but as you can see it has taken most of it off.