Simple Question but Hard to Answer.

[shadragon]

Hi all,

I am looking for the thread specifications for the mounting bolts used on double tank configurations. That is the size and thread type / count for the two threaded mount bolts you typically use a wingnut on to secure the wing and backplate to the tank bands. If I can get specs for both the threaded bolt portion and wingnut that would be perfect. Picture enclosed with arrow showing the pieces I am talking about.



Thanks in advance.

 

[Dsix36]

The threads from all the Dive Rite ones that I have used are 5/16"-18 also called 5/16" national course

 

[Blue Sparkle]

I'm not sure which island/country you are located on.

Also, pardon me but I have not dived doubles, but these would be the same fasteners/slots where an STA would be attached, right?

I checked into this last year before I bought an STA from Agir-Brokk, because they offered to tap it to a more common US size for me if I preferred that. The Agir-Brokk comes with 8mm, which I gather is a common size in places that use metric.

Deep Sea Supply in California sells Delrin thumbwheels for those fasteners, and they carry 8mm, 5/16" x 18, and 3/8" x 16, so I figured that those three are common (I stayed with the 8mm).

https://www.deepseasupply.com/index.php?category=backplate_acc

Blue Sparkle

 

[shadragon]

Thanks Dsix36 and Blue Sparkle. We get most of our stuff from the US and that should do nicely. Cheers.

 

[divingtactics]

Some also use 3/8 UNC. But my preference is 5/16. 8mm works perfectly fine too. Just make sure you get 316 grade stainless, also known as A4 or marine grade. Some of the bolts/threaded rod that is supplied is 304 stainless or A2, but will not fear as well over time in salt water.