Thought I post up some details of a DIY hammer mill I've been working on. Still a work in progress but I'm nearly there. The original aim was to make it semi portable, able to be driven by a 125mm cordless grinder so sampling can be done on site. It's a little bigger than I planned and the 125mm struggles to start (brushless motor issue I think) but it runs well once going. At home I run it with a 100mm corded grinder. The main reason for the size is that I got the steel pipe cheap. For a better portability and to reduce the abuse on the grinder I'd use 200mm ID pipe if it did it again. Wall thickness on the pipe could also come down a lot too.
Dimensions.
Pipe casing - 300mm ID with 12mm wall.
Side plates - 5mm mild plate.
Shaft 20mm with ball bearing either side.
Inlet and outlet both 90mm SHS 1.5mm wall.
Hammers are mild steel chain with 8.8 HT bolts in the outer link.
Outlet screen is drilled holes in the pipe casing. Originally 2mm but the milled dust was not exiting and the holes clogged easily. I rebored about 50% to 4mm and it works much better. I also added plates to the drive shaft that act as a fan to push the milled dust out the screen.
I've milled plenty of good looking mineralised rocks from old mine sites and found precisely zero gold. The struggle is real
.
Bidgee
Dimensions.
Pipe casing - 300mm ID with 12mm wall.
Side plates - 5mm mild plate.
Shaft 20mm with ball bearing either side.
Inlet and outlet both 90mm SHS 1.5mm wall.
Hammers are mild steel chain with 8.8 HT bolts in the outer link.
Outlet screen is drilled holes in the pipe casing. Originally 2mm but the milled dust was not exiting and the holes clogged easily. I rebored about 50% to 4mm and it works much better. I also added plates to the drive shaft that act as a fan to push the milled dust out the screen.
I've milled plenty of good looking mineralised rocks from old mine sites and found precisely zero gold. The struggle is real
. Bidgee
