Peter,
Spooling is the hard part. I've constructed a contraption to do this that works pretty well. I'll try to make up a series of d@##@$ital pics to show how it works but that'll take some time. Meanwhile, there are a couple of things to think about:
1. The tape goes on the wrong end. The tape that sticks the film to the backing paper has to be on the head ('start') end of the roll, so the film gets fed over the roller and into the exposure position. In order for the film to lie flat and not cause a jam, the tail end (usually marked 'stop' on the backing paper) cannot be taped down; if it is, the film will buckle in the camera and make a mess. So you need to begin spooling at the tail end of the roll, feeding the film in until it is caught in the backing paper as it rolls up. (I mark the end point with a little bit of tape that I can feel, then remove when I begin feeding the film into the roll.) Then, when you reach the 'start' point you cut the film and tape it to the backing. (I always leave the old tape in place so I can feel where the start point is, overlap the film on top of it and then tape it down. This means I use a bit more film than I have to, but it makes spooling easier.)
2. You need to keep tension on both the film and the paper to keep buckling to the absolute minimum. This is more difficult than it seems, but with practice it can be done.
3. Finally, 127 spools are not uniform sizes. The old all-metal spools are the best, with more clearance, and the backing paper rolls up smoothly on these nearly every time. The spools made of plastic with a brass pin on one end are almost as good, though I have experienced serious shredding of the backing paper and jamming of the paper as I tried to spool with some of these. Finally, the all-plastic ones are virtually useless. They're a full millimeter narrower than the metal ones on the inside (where it matters when you're spooling) and I throw them out. The all-plastic ones also jam in some of my cameras, which makes them useless for shooting too.
I'll try to shoot some illustrations soon!
