Cam Buckle Assembly Instructions

[Akimbo]

The attached files contain step-by-step instructions, illustrations, and images for lacing webbing through cam buckles. There are some excellent videos on the Web, but there are times when the portability of a hard-copy, higher resolution, and the option of editing are desirable.

These files are in the public domain and can be edited, reformatted, translated, copied, and distributed without royalties or credits. Anyone including individuals, instructors, clubs, and shops can use all or part as desired. The content of all three files are identical:

CamBand-A4.pdf Adobe Acrobat file formatted to Metric A4 paper size. ~830 KB

CamBand-Ltr.pdf Adobe Acrobat file formatted to US 8½ x 11" letter size. ~830 KB

CamBand.doc This file is easily edited with most word processing and publishing programs. Illustrations are in vector format so resolution is not compromised by resizing. Images/photographs have moderate resolution to keep file size reasonable. ~1.77 MB

[HenrikBP]

Outstanding Thank you.

H

[fisheater]

My OW instructor taught me the mantra "metal, middle, inside, outside."

After that, I've never had a problem with removing and replacing cam bands.

[ItsBruce]

Thank you for such a worthwhile contribution to recreational scuba diving. Your document is very well done.

[TSandM]

Very, very nice work.

This issue is one of the reasons I counsel students against BCs with only one camband. If you have two, you have a) twice the chance of getting one set right, and b) if each is only half as tight as it ought to be, the tank is still likely to stay put.

[Sat Diver]

Never realised this was an issue. Very nicely done document. Valuable resource for the board.

[ianr33]

Threading a cam buckle at depth would make an awesome narcosis test.

[Akimbo]

…This issue is one of the reasons I counsel students against BCs with only one camband. If you have two, you have a) twice the chance of getting one set right, and b) if each is only half as tight as it ought to be, the tank is still likely to stay put.

We made a fairly strong statement encouraging two cam bands. It works out that the mechanical advantages are considerably more than twice what you might expect due to binding and alignment effects. We did a few unscientific shop experiments with two bands and found that they could be scary-loose with minimal tank slippage.

Based on instructor feedback, it turns out that there are a lot more issues than proper lacing of the buckle. Cam-over techniques that work for a healthy 180 Lb male fails for a 90 Lb female with long nails, a diver with arthritis, or has suffered injuries. Swapping tanks in an overloaded inflatable boat is another issue.

Perhaps the biggest factor is there are several ways to lace the buckle wrong but appear to function to the uninitiated. The fact that many divers have no need to think about it for years at a time doesn’t help either. Let’s face it; it can be embarrassing to admit that you are confounded by such an apparently simple device.

We tried to make the instructions Web-based but had to sacrifice too much resolution and formatting. Thanks to electronic distribution we weren’t constrained by printing or shipping costs due to document length. We felt that a hard-copy that people could use in the privacy of their own diving locker was important.

Hopefully, divers and instructors will improve the document and get it to people who need it.

[Hatul]

I think the explanation for Akimbo's more than additive effect of two bands, is that, if you watch how a tank slips out for a single band, it first twists sideways. That has a large lever arm on the band and stretches at with a huge mechanical advantage, and then it slips down. As it slips down and the band gets loose the tank twists more and finally slips out.

The second tank band not only adds extra friction but prevents the tank from twisting.

Adam

[Akimbo]

Never realised this was an issue...

Me too. Those of us with careers centered around rigging, lines, knots, and machinery forget what is common knowledge.

A friend and my computer guru in the 1980s was showing off his new Windows laptop to his 88 year old grandmother. After demonstrating some pointing and clicking he handed the mouse to her and said “try it”. She picked the mouse up off the table and pointed it at the screen like a TV remote. Funny story, but also a thought-provoking demonstration of the word “intuitive”.

This is one of those subtle oversights that can contribute to someone getting seriously hurt. It only takes a few divers out of thousands to make a senseless tragedy.