Delrin cam buckles?

[cool_hardware52]

I have broken a few over the years, but it happens in two situations:

1. The buckle is snugged up tight on a tank on the second dive where the strap is fully soaked and more prone to stretching, then the strap dries while still attached to the tank. The resulting contraction of the nylon strap can be enough to break a plastic buckle if it was tight to begin with.

2. The buckle is extremely cold - for example while gearing up for taking the gear apart after an ice dive with surface air temps pushing zero. When cold, and under tension, it does not take much impact to break a plastic buckle.

Both solved by adding a little compliance to the system.

Tobin

 

[Web Monkey]

Both solved by adding a little compliance to the system.

The other option would be to select a buckle that simply doesn't break.

Terry

 

[HenrikBP]

I should have specified; I'll be using these cam bands on my Freedom plate, so I'll be using 2 bands. I was also planning on using Tobin's strap pads for a bit of give. I have his wedge blocks on my DSS plate and really like them - no tank sagging and no struggling to "close" the cams.

Of course the argument could be made that the few ounces I'd save going with a Delrin cam buckle could easily be made up by leaving some clothing at home

Thanks again,

Henrik

 

[cool_hardware52]

The other option would be to select a buckle that simply doesn't break.

Terry

Stainless buckles are far more expensive, and heavy for travel, often scar tanks and they don't really solve the problem of tank slippage.

With a rigid system, metal plate + metal tank the only thing that gets stretched is the camband. 2" webbing is very strong and the leverage provided by a 2 1/2 inch cambuckle doesn't provide much stretch of webbing with a 2000+ lbs working load rating.

Consider two plates bolted together. One plate has holes in it and the second plate has tapped holes.

In one case we screw in a bolt using only our hands until it's as tight as we can get it. The plates are clamped together, but it the bolt is loosened even a fraction of a turn the plates are no longer tightly clamped.

In the second case we add compliance. A long compression spring is slipped over a longer bolt. This bolt + spring is also screwed into the two plates compressing the spring. Again just hand tight. The compressed spring clamps the two plates together. If this bolt + spring is loosened many turns the spring will still provide some clamping force.

That's the benefit of compliance, it maintains some load even as the strap stretches and or the cylinder gets smaller as the pressure drops.

Most successfully mechanically fastened assemblies have some element that can be preloaded. A torqued bolt is actually a stiff spring that is stretched.

Tobin

 

[redacted]

I should have specified; I'll be using these cam bands on my Freedom plate, so I'll be using 2 bands. I was also planning on using Tobin's strap pads for a bit of give. I have his wedge blocks on my DSS plate and really like them - no tank sagging and no struggling to "close" the cams.

Of course the argument could be made that the few ounces I'd save going with a Delrin cam buckle could easily be made up by leaving some clothing at home

Thanks again,

Henrik

Or you could replace that heavy (but very nice) freedom plate with something really light weight. I went with the Oxycheq Ulta-light plate which is all nylon and other fabric with a couple metal grommets. But I kept my 2 Scubapro straps. I was looking to save pounds (over my 5 pound aluminum plate) but not worried about a few very effective ounces. No problem packing and staying well under the 50 pound limit for the checked bags (wife and I). And the carry-ons are still quite manageable. But the brief case (my personal item) containing 3 regulators plus can be an arm stretcher.

 

[Eric Sedletzky]

Henrik,
You have the Aluminum version of the Freedom Plate as I recall.
I use those fiber plastic buckles on some of my loaner/demo plates and haven't had any trouble. I have a few left over from other systems I've robbed them off of.
It's really not brain surgery like some make it out to be.

Try using the plate without the rail and just put the tank on. If you sandwich the wing in place those roll control cushions should give you plenty of cushion to give you some suspension. Even with the rail on you're going to get a little cush with the wing material.


Just thinking to myself in response to everyone elses comments to Henrik:

How come I never have any trouble with this supposed problem?
I sometimes cam band the tank right down onto the rail and use the plate with no wing at all. Never had one loosen up or fall off or had plastic buckles break.
I use stainless buckles where I dive, but if I was travelling light I wouldn't even blink an eye about using plastic buckles.
Steel scuba tanks expand and contract enough to loosen or tighten cam bands!!! Really???
I'm going to have to look into that.

 

[HenrikBP]

Or you could replace that heavy (but very nice) freedom plate with something really light weight. <snip> But the brief case (my personal item) containing 3 regulators plus can be an arm stretcher.

I've looked at the various "soft" travel plates but *think* (since I've never tested one) that I would prefer a "stiff" plate. I really enjoy the solid feeling of a well adjusted HOG harness on a plate, and suspect (but again don't know), that the soft plates may feel less rigid than a full-on metal plate. I'd be happy to hear your experience.

My Freedom plate is aluminum, so the plate itself weighs only around 2 lbs. plus harness, hardware, straps and wing. Still less than my 6 lbs SS plate though

And yes, my carry-on also requires some muscle and pretending in order to get it through check-in and boarding as if it holds only tickets and a few personal items

My Hollis fins and my tools/spares kit are probably my 2 biggest weight "offenders".

Just saw your post Eric; yes, aluminum plate, so I've already shaved 4 lbs. right there.

Henrik

 

[cool_hardware52]

Steel scuba tanks expand and contract enough to loosen or tighten cam bands!!! Really???
I'm going to have to look into that.

Wrap a flexible tape around an empty, and then do it again when it's full. They "plump" when you fill em.

Tobin

 

[rstofer]

I've looked at the various "soft" travel plates but *think* (since I've never tested one) that I would prefer a "stiff" plate. I really enjoy the solid feeling of a well adjusted HOG harness on a plate, and suspect (but again don't know), that the soft plates may feel less rigid than a full-on metal plate. I'd be happy to hear your experience.

If you are talking about the OxyCheq Ultra-Lite Travel Plate (and I think you are), of course is seems floppy. It IS floppy.

OxyCheq Ultra Lite Back Plate reviews and discounts, OxyCheq

The question is, does it matter? I use mine in the pool with an Al 50. It is quite comfortable and works beautifully. I would absolutely use it to dive in some tropical location where I didn't need plate weight to counter a wetsuit. Singapore, Malaysia, Thailand and the Maldives come to mind.

This arrangement isn't much different than the old fashioned cotton harness that was attached to tank bands. Sure, the tank flops around a bit and can get completely sideways if the waist strap isn't tight but it all seems to work out fine when the straps are snug. I have this arrangement on a LP 72 that I also use in the pool. If I were younger, I might even try it in the ocean - after I bought a less compressible wetsuit - with or without one of those horse collars of yesteryear.

Richard

 

[dumpsterDiver]

I've broken several plastic cam bands over the years. most were attached to BC's that apparently have some compressible element. I've replaced all the plastic cam bands with Stainless steel on my gear. I've not yet broken a steel one and more importantly they tend to stay CLOSED!

I've seen probably 50 instances where the plastic cam bands are too loose (maybe people are trying not to break them) or for whatever reason they pop open. As a divemaster, I've had to re-close a plastic cam band on other divers tank while underwater dozens of times, literally. Normally just an inconvience, but if it occured at the wrong time, it could compromise someone's safety.

The plastic cam bands that Oceanic uses are particularly prone to poping open due to their unique geometry (but they are easier to close).

I view the plastic cam band as a very cheap solution for a pretty important application. It is a big flag for me and it lets me know that the manufacturer is more interested in cutting costs than providing a high quality and reliable product.

I use the plastic cam bands to attach small pony bottles, that is usually it.