Q: I’m thinking of building myself a rolling mill for making silver foil out of tiny pieces of silver. Do you think I can use aluminum for the rollers? What about for the gears?
A: You’ve got to be kidding, right? Aluminum will deform as quickly, maybe even quicker, than the silver. Your rolls need to be steel. Not soft iron or cast iron, or brass or aluminum or cardboard: Steel, preferably of a grade capable of being heat-treated. You did say you want to make foil, right? That takes nicely flat rolls that won’t deform under pressure. And for the rest of the rolling mill, well, steel or heavier cast iron for the frame, and steel for the gearing. Aluminum gears will never hold up. They probably wouldn’t hold up past the first day of use. Bearings for the rollers can be brass or bronze if you like. Even with your proposed tiny pieces of metal, you’d be surprised at the loads your little mill will need to handle. Thus, steel is the required metal for most of it.
Frankly, making your own rolling mill isn’t going to be as easy as you think. To work at all well, even with small pieces of metal, it has to be fairly well engineered and made of decent metal. Rolls need to be very round and concentric with the bearing surfaces. That needs a high quality lathe at least, not a CNC benchtop mill. Even better would be centerless grinding after the lathe work is done. You might be able to have a local machine shop help you with this.
But frankly, I wouldn’t bother. High quality mills are indeed costly tools that need some saving up for and earn pride of ownership once you’ve got them. But you can get reasonably cheap mills. Frei and Borel has a cheap one for less than $300. Harbor Freight sells an even cheaper (in all senses of the word) mill for a bit over $250, if I recall right. All of these will get most of what you wish done. Yes, this is still some money to spend. But it’s less than the value of the time you’ll spend trying to build one yourself, not to mention the cost of hair replacement treatments you’ll also need if you try to build your own, judging from the level of equipment you’ve got available, and your apparent limited understanding of the engineering requirements for a rolling mill indicated in your post.
Now, if even these prices are too much, and you really only need to roll metal an eighth of an inch wide, then you’ve got another option—not great, but it might work. You can get a tool made to enlarge stone-set rings that basically is a micro rolling mill intended for rolling the metal of a ring shank. These usually come with a set of various profile shapes for different shank profiles, but can also handle flat shanks. They’re generally limited to about ¼ inch wide or so. Some resemble a sort of micrometer handle mounted to a base, with the handle adjusting the rolling pressure. Another I’ve seen actually looks a bit like a small rolling mill, with rolls on one side and hand crank on the other side of the base. This sort of mimics the costly Kagen ring roller, but for vastly less money. Check ebay for them. The cheapest of these little tools can be found for less than 40 dollars or so. And they actually are sometimes useful for more than stretching ring shanks, such as for producing various profiles of wire.
by Peter W. Rowe M.F.A., G.G.