A few months ago I acquired this Harder's Patent 400 day clock, something I've always wanted. After disassembly and cleaning the clock it ran for 1 week, keeping excellent time then stopped. This time I disassembled again and removed the mainspring and ordered a new one to the specs of the old mainspring in the clock. It worked and kept good time for two weeks and stopped again. I tried tracking down a possible binding issue with the wheel that corresponds to the great wheel, or mainspring wheel, so I very gently expanded those pivot holes in the hopes that would free things up. This time the clock worked for 33 days before stopping this past Saturday. I thought I may have corrected the stopping problem but apparently not. The clock was worked on by someone else as they had used small weights on the bottom of the pendulum to slow it down, I removed these. Maybe the previous repairman replaced the mainspring with something that is just not strong enough to power this clock for its one year duration. The measurements on the mainspring that I replaced are 3/4" wide, 61" long and strength of .012 inches. My question is should I replace this mainspring with a stronger one and if so, what size should it be. The clock should be in beat as it did run for a month. I have worked on 400 day clocks before but never one like this that is this old. I love this little clock and like to get it running and keeping good time as I know it can. Thanks for any help with this.
Last edited by a moderator: