Hi Dave,
Gee, I seem to keep getting involved in your threads /ubbthreads/images/graemlins/wink.gif
Anyway, here's my technique for end-to-end stick packs.
1. Buy lots of extra shrink because you will have to play around to get the length just right. This is more important if you do lots of diferent length packs. If you do just a single length, get a length that works and cut several extra.
2. For a six cell pack, you'll want about 1/2" overhang on the bottom and 1/4" on the top. Note, this varies with the type of shrink you use. Some shrink in length more than others. Play around with it, see point 1 above.
3. Cut the ends as perfectly straight across as you can. This results in neater ends that are shrunk equally around the entire cell top or bottom.
4. Get the top overhang dialed in first since the bottom of the pack can always be trimmed with an X-Acto knife if too long. The overhang is my terminology for excess length beond the length of the pack itself.
5. Start at the top. One end should be "pretty" and it might as well be the end with the nipple on it. /ubbthreads/images/graemlins/wink.gif Do NOT start with the gun right at the open end of the shrink. Start blasting right below the top shoulder of the topmost cell and work to the open end. This helps set the shrink evenly around the circumference of the cell.
6. Work the heat gun slowly down the stick. I do lots rotating of the pack so it shrinks evenly around the circumference. Move the gun slowly down the pack turning the pack as you go.
7. When you get to the bottom, you'll have a good idea if you have about the right length of shrink. If it's too short, you'll still have a pretty good grip on all the cells though it won't look "factory perfect."
8. If it is too long, shrink the overhang until it forms a tube that sticks beyond the bottom of the last cell. Trim this back carefully with a razor leaving enough bare metal for spring contact.
9. I do the shrink in two passes. On the first pass, you set how well the shrink sits and grabs. On the second pass, you smooth out any wrinkles, buckles or bubbles you left. The important thing is to make sure the shrink grabs evenly all around on the first pass.
10. If the pack rattles in the body tube, depending on how much slop there is, you can add another layer or just a few short lengths as spacer/supports along the pack. If it's very loose, wrap a few layers of high quality acrylic packing tape around the stick then apply another layer of shrink.
In answer to Larry's concern above, a properly soldered stick built with flat top cells will have very little gap between cells. No intercell tape is needed. I have never, never had a stick pack snap a joint due to shrink shrinkage and I've made probably somewhere between 75-90 packs.
I know it seems like a lot to keep in mind, like with pack building. But the point is to get enough practice so it becomes like an automatic process. You get sensitive to it and then you get good, develop technique.
Wilkey