Working with Heat Shrink

Dukester

Flashlight Enthusiast
Joined
Jul 31, 2003
Messages
1,107
Location
Washington State
Never have worked with it before. Building a stick battery pack consisting of x6 Sub-C's coming in from CheapBatteryPack a long with the Heat Shrink, got extra coming in just incase. My question is this, can someone point me to a Link for Heat Shrinking Techniques. I briefly looked on the Net but did not see anything glaring out at me.

Thanks,
Dave
 

Darell

Flashaholic
Joined
Nov 14, 2001
Messages
18,644
Location
LOCO is more like it.
Can't point you anywhere - but you'd have trouble going wrong! Probably the worst thing you can do is get it TOO hot. At that point it'll tear and/or melt. Just sneak up on it with a hot-air gun until it begins to go and then gently let it shrink to where you want it. Less is more - and you can always go back and shrink it more if you want it tighter.

If you screw up, you just cut it off, and start over. Not much to lose. Good luck!
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
Dave, what Darell said! I've never stacked/heatshrunk cells before, but I suspect you might want to tape them to each other first with kapton electrical tape. The shrink tubing can shring smaller in the spaces between the cells and possibly increase the axial force required to maintain continuity. You might PM js, as he is one of the gurus with pack building.

Larry
 

Ginseng

Flashlight Enthusiast
Joined
Feb 27, 2003
Messages
3,734
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
 

cy

Flashaholic
Joined
Dec 20, 2003
Messages
8,186
Location
USA
wow,,, thanks Ginseng

this thread is added to my favorites.
 

Ginseng

Flashlight Enthusiast
Joined
Feb 27, 2003
Messages
3,734
A hair dryer will work with most types of shrink but is much slower (and consequently harder to do a good job) than a heat gun. They're pretty cheap to buy but if that's not possible, a hair dryer just might do the job.

Wilkey
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
For smaller diameter (wire sizes) heat shrink I use a cigarette lighter and hold the flame under the heat shrink. I suppose if you were desperate enough you could use a propane torch more a foot away for larger sizes but I don't recommend it.
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
Hi Wilkey, He didn't mention soldered stack. With a soldered stack, there should be no concern!

Larry
 

5150

Newly Enlightened
Joined
Aug 7, 2005
Messages
3
Location
Orange County, CA
Pop the pack with the shrink positioned on it in a toaster oven. Push the toast button and watch it pull up nice and tight. I have used this technique several times and it works sweet. Fast too.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
[ QUOTE ]
5150 said:
Pop the pack with the shrink positioned on it in a toaster oven. Push the toast button and watch it pull up nice and tight. I have used this technique several times and it works sweet. Fast too.

[/ QUOTE ]
You forgot to add butter and jam to complete the process! /ubbthreads/images/graemlins/grin.gif
 

KevinL

Flashlight Enthusiast
Joined
Jun 10, 2004
Messages
5,866
Location
At World's End
For smaller applications (heatshrink around wires) I use my Roar of the Pelican 30W incandescent to do the shrinking. For larger applications.. I'm waiting for my 100W USL /ubbthreads/images/graemlins/grin.gif

Heatgun indeed..
 
Top