Dear Clayton, I can only get about 12 hours on a wind, but the (Genesis) clock is accurate to within about 15 sec during this time. I am temporarily mounted about 3 inches low, not enough for 12 hours difference. Any suggestions? Love the clock by the way.
Aloha Bob, congratulations, and I'm happy you love your Genesis. It really is a little wonder. So simple, yet such a great runner, and one of my quietest designs.
Things that cause short run time are generally related to how far the drive weight gets to drop before it hits the floor.
The height that the clock is mounted on the wall is of course the first consideration. The higher it is mounted, the longer distance the drive weight will have to fall.
The length of drive weight itself is important because an extra long drive weight will hit the floor before a short, squat drive weight.
Also if a larger diameter drive pulley than specified has been installed, that will mean the clock will run on less drive weight, but since the circumference of the pulley is much larger, the cord it reels out with each turn will be much greater and thus give us a shorter run time.
BTW, in my book the Practical Guide, I tell a story about how Thomas Jefferson mounted his clock at the peak of the ceiling in his dining room so that he could get an extra long run time. He ran the drive weight along to one corner of the wall and marked the days of the week on the wall so that his drive weight could also do double duty as a calendar showing the days of the week. The only problem is that he didn't calculate his drive pulley barrel radians correctly and had to drill a hole in the floor so that weight shows Saturday in the basement. The clock is still there in Monticello. This story always makes me feel better when I do my calculations incorrectly. Ha.
This story tells us that there is another possibility for a short run time - thick drive cord. The thinner the drive cord, the more turns your drive pulley barrel can handle. A thick drive cord will take up much more space as it builds up quickly on the drive pulley. Thus Jefferson could possibly have solved his short run time problem with some thinner drive cord. Maybe this will work for you, too.
However, considering that your clock is only running twelve hours, when it should be running thirty hours, tells me that something may be slipping inside the clockworks. Possibly some wheel or connector or pinion did not get glued tightly, or a glue joint has broken. A slipping joint would allow the weight to turn the gears, but also as it slips the weight will reach the floor sooner than anticipated.