Menial tasks done for a blacksmith?

On our farm in the '50s, I graduated from the kid turning the crank to fan coals and putting new chunks of coal in the forge (slightly more modern than your situation sounds) to grinding off sharp edges on horse shoes and new or repaired machinery.

After hoes, sickles, scythes, plows, disks, etc. were fashioned, they had to be sharpened on a grindstone pedaled like a bike. I also assisted by holding items of metal while Granddad worked them. I tempered and refired pieces, too.

I don't know all the tasks a blacksmith would have someone do. But deducting from my own experience working in a metal trade, it would probably be a wild variety of things.

My official job is to drill/tap/polish/de-burr parts that come off waterjet machines; I am the "head finisher" at my shop. But when there are no parts for me to finish, my bosses will have me run the laser machine, answer the phones, mop the floors, sweep, take the rags to the laundry mat, pick up steel at the local metal mart (yes, they have 'em), update their website, paint the walls, fix things, organize things, water the plants ... even go on a cookie run. You name it. I pick up whatever slack needs to be picked up.

Typically, work flow in the metal trades can be very uneven - either you have a ton of metal that needs attention, or none. Therefore, a lot of "fill" work is needed. I'd imagine it would be no different for a medieval blacksmith.

Anyhow, hope this helps.

Depending on the set-up, there might be some water that needs hauling too.