Don Stauffer wrote:
The thread on millwrights got me to wondering about something.

I have seen one mill (I am sure mechanism was reconstructed) that
actually had wood crown and pinion gears (many mills required a right
angle change in shaft axis). And I see many diagrams of wooden gears in
history of technology books on mills.

Most gear sets I see are metal, from mid to late nineteenth century.

Now, I wonder if there was a complete, sudden transition from wood to
metal gears, or was there a transitional period with what we might call
composite gears- part wood, part metal.

For instance, we could have metal teeth mounted in a wooden wheel. That
to me would seem more reasonable than vis versa. Has anyone ever heard
of such a composite gear in a mill?

I've seen pictures of mill gearing where the teeth were wooden and the
bull gear itself was a cast iron "cage". I assume the tooth sockets
were tapered. The mill owner could then renew the teeth as they wore
out without having expensive tools, just simple wood working tools
would be all that was needed. The teeth would wear into each other,
too and bad meshes would eventually wear themselves in. Would be
farily quiet, too, compared to all cast iron gearing. I think the mill
itself was from the 1860s or so.

Stan