On the rear of the drum I have placed a bead to indicate when the drum is in top dead centre, which now tells me the unloading hole is at bottom dead centre.

The unloading hole is just the threaded portion of a barrel bung cut from an old heavy duty barrel then welded into place, to close the hole any bung will do. The mill frame is on wheels making it easy to move around.

Hope this information helps to build a similar mill, the round shaft used for grinding media is five or more years old and shows very little wear.