SP3B running on 5.5lbs
After my success with the SP2B I wanted to build another clock for a friend so decided to build the SP3B. I had trouble with the pallet striking the edge of some of the escape wheel teeth, but some filing took care of that over several filing sessions. I found that a weight of 5.5lbs was about the minimum that would keep it going with some of the teeth dragging along the pallet as I was working on that issue, but it ran great once I had them all 100% clear. After fixing the escape wheel issue I put together a simple pulley hanger so I could test the clock in 8 day mode before printing the weight shell, and have found to my surprise that it runs very reliably on the same 5.5lbs. The pendulum swings on average about 1” either side of dead bottom, so 2” swing total. I haven’t yet taken the time to draw up a beat scale so am not sure how this translates into degrees. Running in 8 day mode on 5.5lbs is attractive to me as it minimizes strain on the frame. Does this seem reasonable? I want it to be reliable and as trouble free as possible for my friend. I plan to let it run “as is” through the weekend just to make sure it is stable, and possibly give it to her next week after completing the weight shell assembly.
It seems like you have everything running great. Not sure why the pendulum and pallet are interfering. Some designs have less clearance than others. I may take a look at it when I get a chance.
That clock has a 24.5" pendulum length measured from the pivot point to the center of mass. This likely gives around 28" to the pointer below the bob. 1" of swing works out to around 2 degrees, which should be enough. It doesn't hurt to add a bit more for additional margin. The frame can easily handle 10 pounds as long as the hanging procedure is followed to keep the top support beam from tilting downward.