The new Freedom Contour - The Rolex of backplates.

[stuartv]

I'm encouraging Eric to make an doubles adapter for his new plate. The latest design will be a lot easier. A quick & dirty version would be of a piece of metal that spans the bands with an extra set of holes for the 5/16" carriage bolts -- think metal strip with 4 holes. Two for the band studs and two for the plate. Longer carriage bolts and some spacers should do it.

I believe I am visualizing exactly what you're talking about. The question is, would it hold the tanks right up against the plate, just like with a "normal" plate? And, would it do so without having to adjust the bolts that go through the doubles bands?

In my mind's eye, it seems like the tanks would be just a little off your back, where they are right against your back with a standard plate.

Hmmm.... as I think about it more, maybe the worst case is the tanks would be further from your back only by the thickness of the plate itself - so 1/8". And, depending on the standard plate you're comparing it to, maybe the tanks would not be any further off your back.

Okay! I agree! Eric should make a really nice doubles adapter for the Freedom plate. Of course, then I would have to buy another one, so I could still have one dedicated for single tank...

 

[Akimbo]

The question is, would it hold the tanks right up against the plate, just like with a "normal" plate?

Depends:
From BCD to BPW: The Evolution, Post #12

For me, one of the great advantages of the Freedom Plate is you can use a one-piece strap that is inherently adjustable. You tighten by pulling the belly band, which pulls webbing through the lower slots and tightens the shoulders. After the dive you just unbuckle and push the shoulder straps away far enough that a polar bear could slip out. I never need a crotch strap, but YMMV.

The problem with bolting it like a conventional plate is the webbing is jammed against the cylinders. That's why I mentioned the spacers. Size the spacers so you get the +/- 3° angle... the bottom of the plate is farther off the cylinder(s) than the top. That puts the bottom of the plate in the small of your back, which helps distribute some weight to your hip bone.

As explained in the above post, here is the roller I added:

And, would it do so without having to adjust the bolts that go through the doubles bands?

The idea is to place the metal strip on the band bolts/studs (11" centers) and attach with wing nuts like a plate. There would be two more holes in the strip that clears the bands underneath so you can access the back to attach a nuts to the longer 5/16" carriage bolts. You could use a socket with an extension to tighten the nuts or make your own "T-handle nuts" that are long enough so the "T" will clear cylinders on the back site of the tanks. Does that make sense?

This wouldn't be nearly as elegant as some of the ideas Eric and I are discussing but would do the job for a DIY/garage fix.

 

[Eric Sedletzky]

Great!
Now I'm going to have to re- invest in a set of doubles just so I can fab and fit brackets, think, design some more, think some more, and come up with an ingenius way to attach a plate to doubles that's simple, not too complicated to attach, and fairly cost effective.

And I thought I was done with doubles and tech diving, sheesh!!

 

[Akimbo]

Now I'm going to have to re- invest in a set of doubles just so I can fab ...

I was hoping that post would suck you in!

If only it were that simple. There are 5.25, 6.9, 7.25, and 8" OD cylinders on 190 and 215mm manifolds. Then there's valve up and valve-down. I have computer models of all of them. You also have different preferences and body geometry that you can't model. That is why I suggest using spacers between the adapter and bands. That lets divers tweak it to find their own sweet spot.

The Freedom Plate is great for people that aren't satisfied one-size-fits-nobody.

 

[Eric Sedletzky]

One concern I have is when someone wants to use double steel 130's or some other immense set of doubles.
The Freedom Plate needs to sit against your back slightly more than the cylinders along side your back otherwise the whole concept of the form fitting benefit of the contoured plate is lost. In order to do this the plate must levitate out a bit from the tanks so that the plate can "sink in" where it needs to be on your back. This creates a stability problem with the mounting system and tanks. Little 5/16" bolts aren't going to provide enough mass to be able to withstand the side to side swaying and sagging that's going to happen with a set of water heaters. The bolts would need to be upgraded to 3/8" and some very heavy brackets with determined torque specs specified to be sure it won't fail.

Whereas with a conventional doubles plate, the plate pretty much gets jambed up against the wing and tanks, and at that point only really provides an attachment point for webbing. In the case of the conventional doubles plate, it's actually the tanks laying on your body that you feel, not really the plate. This is why many people recommend a very steep plate, to be able to get the plate channel in as close as possible to the doubles inner clamp spacers to shorten the 5/16" threaded rod as much as possible to avoid excessive rod length and the tanks sagging down.

This was always one of the design barriers trying to fit a set of doubles to the Freedom Plate. Like I said, I have in the past set up a set of double steel 72's on a Freedom Plate with acceptable results. The functionality and feel on a real dive in the ocean was fantastic!
But double 72's look like a little set of pony bottles next to some of these behemoth sets I see now!

 

[stuartv]

It seems to me that if the carriage bolts that hold the STA were of the style that has a hex key hole in the bolt head, then the STA (or doubles adapter) could simply have threaded holes for the bolts to screw into and you would tighten the bolts from the diver's side of the plate using a hex wrench. So, for doubles, mount the adapter onto the tank bolts using normal wing nuts. At that point, nothing would stop the adapter from pushing away from the wing nuts and into the V between the tanks. Then, hold the adapter up against the wing nuts and thread the carriage bolts through the plate and into the threaded holes in the adapter. Tighten with a hex wrench from the front (diver's) side of the plate.

I just received my plate and it seems like the current STA could be modified to work well for this. Weld in 2 plates between the rails. Put some holes in the top plate for the top bolt of the doubles and put a slot in the bottom plate.

If the STA needs to stand further off from the plate for doubles, use a threaded male-female standoff that screws into each of the threaded holes in the STA (the BP mounting holes, not the tank bolt mounting holes), then screw the carriage bolts through the BP and into the standoffs.

The biggest problem with this, as I see it, is that the current holes in the BP are (I gather - I haven't measured) 11" on center. So, the BP mounting holes and bolts would interfere with the tank mounting bolts and wing nuts. If the BP mounting holes were moved closer together, they could be out of the way of the doubles mounting bolts and still hold the STA on the BP just fine for single tank or doubles use. In fact, it might be nice if the carriage bolt holes were in between the tank strap slots, so that they would (possibly) be covered by the tank straps when diving single tank.

EDIT: I just realized that what I described is incomplete, because it does not put any tension on the tank bolts - unless the tanks are actually pulled up against the plate itself, which I don't think "works". Oh, well. Back to the drawing board.

 

[rhwestfall]

@Eric Sedletzky : Still awaiting the desire to do one for my 6'-7" frame...

 

[stuartv]

Anyway... here's some pics of my new arrival! Woohoo!!!

 

[Bubblesong]

Mine arrived today too! Still checking my porch for the anticipated Hog Wing to go with it.
Not sure how accurate my scale is, but in the ballpark.

 

[Akimbo]

It seems to me that if the carriage bolts that hold the STA were of the style that has a hex key hole in the bolt head, then the STA (or doubles adapter) could simply have threaded holes for the bolts to screw into and you would tighten the bolts from the diver's side of the plate using a hex wrench...

I'm confused. A carriage bolt has a domed head and a square extension under it before transitioning to the shank or thread:

It sounds like you are describing a Button Head Socket Cap Screw, Flanged Button Head Socket Cap Screw, or maybe a Hurricane Bolt.

Stainless carriage bolts are fairly easy to get in lots of different lengths but the others are less available in the 5/16" to 3/8" range typically used on double bands.