It looks like the shaft that goes through an old hand grinder, sometimes called burr mills.(the grinding plates are metal with burrs on both.) This would be for a small mill, like a kitchen mounted coffee, small corn mill grinder. Not a feed grinder. The handle would go on the threaded end, the "T" would go into the rotating bur and the setting would be on the end. Around mid 1800's. I have several mills and they are all different, but close. Just my thoughts. Tony