Galvanized Steel Rollers for Grain Mill

[mvanwie]

Since my LHBS is now charging for crushing grain, I've used such as an impetus to finally get my grain mill project off the ground.

While browsing through the plumbing section at my local big box this past weekend, it struck me: why not use galvanized steel pipe for the rollers? It's relatively cheap and available in multiple combinations of width & length.

So is there a downside to using galvanized pipe? I assume it's food safe (since it's good enough for drinking water), but the only thing I can think of is whether knurling it would be of any concern (or is even possible).

 

[bja]

Knurling will disrupt the galvanizing allowing it to rust.

 

[Bobby_M]

How do you plan to add a center axle?

 

[mvanwie]

If the zinc layer is disrupted, basically I'm left with a steel roller, no? Perhaps I'm mistaken, but I assumed grain mills were made exclusively from steel at one point in time. Nevertheless, can you minimize corrosion (e.g. if it's kept dry) on a steel roller or is rust inevitable?

As far as the center axle, I was planning on turning the roller via a modded cap threaded onto the exterior of the pipe.

 

[Clementine]

When you consider the tolerances you require to use a mill, thousands on of an inch matter, water pipe is milled to very low tolerances hence you would be required to turn the pipe to get it true hence you would be back to a raw steel. The few dollars for some SS 1.5" @ 6 inches long would be worth the investment considering the time it will take to make the mounts etc etc. Stainless also works well with case hardening to make your project even more robust.

Not wanting to further throw water on your idea but a threaded cap on each roller would prevent them from coming in close contact with each other?

Clem

 

[mvanwie]

Clem... a thousand thanks for the input. As far as the cap goes, I was only going to cap one end on each pipe and offset them so that I could close the gap without interference from the cap. I was not aware of the tolerances, so this is good stuff.

This is just the info I was looking for... thanks guys. It's good to know ahead of time that my pipe dream is exactly that.