Chapter 5: Finishing the BarrelNovember 29, 2004
In the book, this chapter is called "Dividing the Ratchet Wheel", but of course I actually did that in the last chapter. That left this chapter a bit shorter than the rest, and "Finishing the Barrel" is a more fitting title.
I made a simple slip washer mostly according to the directions in the book. I didn't actually have any 1" brass rod (and it seems pretty wasteful to have ordered some just to use a 1/16" slice off the end). It would have made things like chamfering the edge much easier, but instead I cut it out of 1/16" brass plate and just decided to leave the edge as-is. I can always make a replacement if I decide it's necessary. I did not find the sheet metal drill form described in the book to be very useful. I ground a nice 5/16" drill into that form, but was unable to get it to cut through the washer cleanly (and I destroyed my first attempt at the slip washer trying). I ended up using the drill mostly to mark the slip washer blank, and then cut out the 5/16" off-center hole with a jeweler's saw. It's slightly misshapen, but not too bad.
Here's a nice shot of the finished barrel and arbor assembly. I measured the distance between the plates, and cut the shoulders of the barrel arbor to length, trying to leave about .010" of end play. My lathe isn't easily set up for dividing, and I couldn't figure out a good way to mount the barrel arbor on the mill, so I ended up filing the winding square by hand. It turned out fairly well, considering I did it without a good file rest, but it is slightly out of square. Since doing this, I noticed that Sherline actually sells a tailstock you can mount on the mill which would have allowed me to machine the winding square using the rotary table to control the angles. It's smething to keep in mind for the future, but I'm happy enough with the square as it is.
I also drilled the two holes for the weight line. One small hole drilled at an angle in the threaded portion of the barrel for the line itself, and then a large one through the side that intersects the small hole and provides the space to tie the line knot. I hadn't realized this from the drawings, but the barrel endcap is actually thick enough that the small line hole is drilled through it, and not just through the 1/8" thick tube that forms the barrel itself!
Polishing the pivots was an interesting exercise, since I'd never done anything like that before. I was unable to get them as completely polished as I would have liked, but I'm not entirely sure what's reasonable to expect. I bought a combination pivot file and burnisher a while back in anticipation of this, and I spent a while working with it, trying to get a good finish on my pivots. The problem was that while the file & burnisher did a reasonable job polishing, it seemed like the edges of it would invariably leave scratches... and since my pivot is wider than my pivot file, I couldn't find a way to avoid this. Especially since the book indicated that proper burnishing takes "considerable pressure". The best solution I found was to use only light pressure, and even then there are visible scratches. Hmmm. I may come back again at the end and re-polish the pivots. Perhaps I'll bring the arbor to my clock repair friend, and ask for an educated opinion - I imagine he'll know if my pivots are acceptably polished, as well as how to go about doing the job properly.
All that's left for the arbor is to cut the slip washer groove, and that's done in the next chapter: "The Great Wheel".