The longbeard sat beneath the large clock in the crossroad cavern, nodding into his beard. His snore woke him and looked up sharply. "Oh yes, where was I?" he grunted.
"First time of the day is know as First-light. Now let me get this straight, it ain't sun up! All those forges and workshops need the furnaces hot and the boilers primed afore any work can start, so some bugger's gotta get down there a few hours early and light the fires first. That's while everyone else is still asleep y'see.
Course, some of the poorer lads can't afford clocks, so they pay a few coppers for a knocker-upper, a beardling who's job it is to wake 'em up. He'll run round the poorer parts of the Hold knocking on doors an hour or so before first shift. This is when they'll be drinking up breakfast and grabbing something to eat. Enough time for a quick preen of the beard, grab pick and duds and head to work.
Most dwarfs will be at work before the sun comes up over the mountain, and often be still at it after it's down. Five til Nine is a pretty standard shift across the board. A couple of hours in we usually stop for a smoke break, and mid-shift there's a yell of "Grubzup!", which is time to stop for a bowl of heartwarming stew. At the end of shift a steam-whistle or bell marks time. Often a night-shift will come in and take over, especially in busy Holds like Zhufbar. Then it's all off for a mug of ale on the way home.
Once back at the home-hearth there's time for an evening meal. As us dwarfs live in clan units even the unmarried lads'll have a communal meal waiting for them. Then an hour or so for leisure, usually unwinding at the forge after a long day at the forge. If y'don't appreciate the irony of this, we metal-smiths certainly do.
Then it's off to bed. O'course some of the more... err... "committed" artisans have been known to work for days without sleep if they're engaged in a special job. Runesmiths are well known for this, but many mundane trades can become an obsession as well.
As for measuring time, there's a few ways. When you're many leagues below the earth ye can't keep an eye on the sun, so we use geared clocks, marked candles, or a sand-glass. A few songs are around an hour long so you can mark a rough time in yer head. We split the day into it's hours and numbered them, and passed that on to the manlings. I hear the elves have given the hours each to their gods, which frankly I don't see much point in, some would have to be waiting all day for and others would be woken up early for. Very disrespectful if you ask me!
I suppose the truest dwarvish measure of time is the Age, great lengths of hist'ry named for what was happening at the time. You manlings will have heard of the Golden Age, the Time of Woes, or the War of Vengeance, but amongst our people are known the Age of Steam, when the Engineer's Guilds first approved commonplace use of the steam engine; the Age of Hydraulics, the Blast-furnace Renaissance, the Fire-Lamp Conflict, and not least, the Black-Powder Age. These all marked times of bitter conflict between clans as the changes rocked dwarven society.
Now, if you don't mind, I'd like to get to the pub afore I miss Last Orders!"