The rollers are stainless but they don't touch each other. The rolling is very slow as well, by hand. A coffee grinder grinds, this thing crushes. I just cant see how this could possibly make a spark. I bought this some time ago but didn't use it until recently because you really need to build a structure to keep it bolted down and i didn't have the time or patience at that time. The structure I have now is still very basic and temporary. When the puck thickness is good, they just get sucked down between the rollers, if they are a little too thick, they don't and you need to push them. If they are much too thick, it just doesn't work. I really despised the whole hammer and grinder portion of the process and this takes care of that. I'm still learning about it but its a pretty easy thing to master. A few things that are draw backs but nothing to bad is that the powder sticks to the roller, especially when the pucks aren't fully dry. You need to rub it off or it eventually falls off. The other thing is the importance of puck thickness.
puck going in on its own in the coarse setting. One at a time.
Attachment 295458
end product, coarse and fines, the unwanted large grains are simply dumped into the hopper and crushed again. You can fill the hopper as much as you like and it will process the larger grains at this point. Make sure to adjust the setting BEFORE you dump in the grains.
Attachment 295459