Double 45's, super tight bands issue

[tye1138]

Thanks for the video, yea thats exactly how I did it.

 

[Akimbo]

Bands like this are hand-made on minimal fixtures due to very small production. Variation is common. There isn't an easy fix if they are too wide for the manifold to fully engage like mine was. The spacers will fix too narrow and out of parallel, within limit of course. You should be able to find the right spacer size with a little imagination and minimal tools. You can have them cut to width pretty accurately at a plastics shop.

 

[tye1138]

So I tried several tricks and nothing worked. I tried the tape, the spacer and of course, turning the bands around so many ways, it got my head spinning what I had tried and not tried. Turns out I had a few issues, the setup was absolutely not right. So I got the right combo and found there was very little binding on the manifold, though still some. Honestly at this point, it seems like the bands are just bent in a strange way and thats the reason why its not perfect. They've been together for years and they were clearly put together wrong. So I'm just thinking new bands are the end all solution.

Any suggestion where I can get bands for double 45s? Kinda a strange one...

 

[Scared Silly]

5.5 Inch Stainless Steel Cylinder Bands

But they must be used with short cross over:

Modular Manifold Pro Type "190mm"

Look for a user mudpuppy who was making bands for 215mm cross overs.

 

[tye1138]

Interesting so there are multiple different manifolds eh... hmm... thanks for the links, time to do some research!

 

[Akimbo]

The bands I had to modify were from Piranha. Randy was apologetic and surprised. The photo I posted was originally taken to send to him. Maybe another batch of bands is better.

 

[Scared Silly]

What I found interesting is that the bands/manifold I posted above are for 190mm cross over. However, for the bands I have for my double 45s is they were for a 185mm cross over. For these, I used a thermo non-isolating cross-over:

Thermo 185MM (short) manifold cross bar [Val-TCNIN-s] - $56.00 : Tech Diving Limited, The Leading Source for Diving Equipment

Looking at OP cylinders it is hard to tell the spacing. They do not look like bands for 215mm spacing. As such, I wonder if he has bands for 185 mm spacing but the manifold which is a Blue Steel is for 190 mm spacing. 5mm (.2") may not seem like much but it could well be enough to cause the problems they are seeing.

Akimbo your bands are from Piranha what about the manifold? Is it the Blue Steel manifold listed above?

Here is a link which shows the 45 bands for 215mm and further below for 185 mm

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http://www.scubaboard.com/forums/tanks-valves-bands/321149-i-want-build-double-lp45s-need-help.html

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[Akimbo]

…Akimbo your bands are from Piranha what about the manifold? Is it the Blue Steel manifold listed above?...

Yep:
Manifold:
http://www.piranhadivemfg.com/item/Modular-Manifold-Pro-Type-190mm-170

Bands:
http://www.piranhadivemfg.com/item/55-Inch-Stainless-Steel-Cylinder-Bands-1988

I looked at my notes and I made the bands narrower by 0.309", which fully engaged all O-rings at the valve rotation I wanted.