Another cable gland question.

[Klem]

Yes I did kind of wonder whether the real problem was people over tightening the gland, more so than it being due to how many cores the cable has.
.

If I can add something...

I don't believe you can overtighten a gland, unless it is a plastic one and you break it by jumping over the thread. It's all about compressing the cable to at least what the water pressure will compress it to at the maximum depth you dive. If the water pressure can compress it further than what you've tightened it to then there will be a gap, and water will leak in. How much is enough tightening? to be honest I don't know so I do it up as tight as possible without breaking and back it up like Lucca with Sikaflex.

What I also do is back it up with a second internal compression. I coat the end of the cable with Sikaflex and then tie a cable-tie as tightly as possible. Then coat more Sikaflex over the top of the cable-tie and pull all this black blob hard against the inside of the gland. Then do up the gland. The tie acts as a extra stop against tugging the cable.

One time I made the mistake of forgetting to put the nut on the cable before doing all this and the wand was sealed and dry before I realised. I ended up tying two cable ties in front of the open gland and covering it all with metal epoxy (JB Weld). Thankfully it worked and never leaked but looks very untidy. Don't do what I did and forget to put the nuts on the cable!

 

[JoelSim]

When aplaying sikaflex I get it before in little in warm water (45-50°C )to become more viscous . Point si to aplay thin film which made better seal (not hard gluing together) .To lubricate is just little silly expression .

Thanks for clarifying that Lucca. This is how I understood what you said, but I was unsure if I understood correctly.

 

[JoelSim]

If I can add something...

I don't believe you can overtighten a gland, unless it is a plastic one and you break it by jumping over the thread. It's all about compressing the cable to at least what the water pressure will compress it to at the maximum depth you dive. If the water pressure can compress it further than what you've tightened it to then there will be a gap, and water will leak in. How much is enough tightening? to be honest I don't know so I do it up as tight as possible without breaking and back it up like Lucca with Sikaflex.

What I also do is back it up with a second internal compression. I coat the end of the cable with Sikaflex and then tie a cable-tie as tightly as possible. Then coat more Sikaflex over the top of the cable-tie and pull all this black blob hard against the inside of the gland. Then do up the gland. The tie acts as a extra stop against tugging the cable.

One time I made the mistake of forgetting to put the nut on the cable before doing all this and the wand was sealed and dry before I realised. I ended up tying two cable ties in front of the open gland and covering it all with metal epoxy (JB Weld). Thankfully it worked and never leaked but looks very untidy. Don't do what I did and forget to put the nuts on the cable!

Klem,

Cheers for the advice and pictures...pictures are always good, lol.

I wonder a little if your advice stays the same with tightening the gland when it comes to using the AGRO glands, which are quite different internally compared to the one you have pictured??

I like the idea of the cable tie on the other side of the gland, I had been considering doing that as a "stopper", so to speak.

I will try my best to not forget the nut on the cable before sealing (good to know you got away with it though). I expect I have now jinxed myself....

 

[Klem]

Mate, you'll be fine...I make enough mistakes for all of us! :ironic:

Never used Agro glands so I cannot comment on the internals but I know several of the regular posters do. No offence to the other posters by I think the long Agro with its strain relief is a bit of overkill where it prevents cables from bending too much. I prefer to be able to bend the cable as close to the canister or wand as possible, especially if it's being jammed into a BC pocket. Strain relief can also come from using a thicker cable.

The internals of all glands achieve the same thing, a rubber ring compressed around a cable. What I will say is that while metal gives the impression of superior strength the parts appear to be less waterproof (to me anyway) than the nylon variety. I say 'appears' because I have never seen either leak...but you can't help wonder about water getting in between the grey plastic insert and the metal frame. Compared to the nylon variety which is seamless at that point and does not have a separate compressing section. The metal gland has 4 separate parts, whereas nylon glands have 3; one less seam to leak. Metal does look solid and 'commercial' though. I tend to use metal glands on metal surfaces, and nylon glands on nylon surfaces, but for no particular reason.

(Below) Back and front shots of the same canister plug. Gland fixed to the plug by its own screw but also Devcon (two part metal epoxy). Then the cable-tie and a bath of Sikaflex on the inside provides more than enough 'back-up'. There's no 'opportunity cost' to leaving that inside area empty so may as well fill it up with something flexible and waterproof.

 

[DIWdiver]

Mate, you'll be fine...I make enough mistakes for all of us! :ironic:

You can never make enough mitsakes!!!

 

[Klem]

You can never make enough mitsakes!!!

I know, it's hard...but I try! :naughty:

 

[JoelSim]

Mate, you'll be fine...I make enough mistakes for all of us!
Never used Agro glands so I cannot comment on the internals but I know several of the regular posters do. No offence to the other posters by I think the long Agro with its strain relief is a bit of overkill where it prevents cables from bending too much. I prefer to be able to bend the cable as close to the canister or wand as possible, especially if it's being jammed into a BC pocket. Strain relief can also come from using a thicker cable.


Then the cable-tie and a bath of Sikaflex on the inside provides more than enough 'back-up'. There's no 'opportunity cost' to leaving that inside area empty so may as well fill it up with something flexible and waterproof.

Hehe...I'm sure everyone on here wishes you did in fact make enough mistakes for all of us, lol. But where would the fun in that be??
Here's a little pic of the internals of the AGRO gland (I'll take a guess and say you won't like the amount of parts...I can definitely see your logic of thinking regarding the difference between the plastic and metal ones).

I don't have concerns with it going into a BC pocket (as I don't have any pockets). But again I see your logic. I chose to go with the strain relief option partly to do with water temp over this way (ie: if water is in double figures for degrees it's a 'warm' day). Thought with the cold water, stopping the cable from bending close to the gland was a good plan...don't know if this was logical or not, but ran with the idea:shrug: If I was back in Oz I may think differently.

I see that sealing in the back of the gland could be smart, so that'll be happening.

Hopefully I'll get it together and test dive it (without battery or electronics) on the weekend while diving on a new mark we have that are hoping for it to be a WWII wreck (2 actually..1 minesweeper, 1 plane).

Cheers again,
Joel.

P.S. My wife was a little concerned yesterday when she wandered past as I was typing my response to you beginning with Klem. Klem is actually the Norwegian word for hug, so she was wondering what on earth I was typing, hehe......

 

[lucca brassi]

@ Klem

I have whole box of metal glands , same as yours if you put some rubber grommet like http://uk.farnell.com/pro-power/60752/grommet-cable-11-30mm/dp/4326295 it looks like AGRO I have do that .

Sealing like AGRO is very simple do be done ( and I think Halcyon made that way at first proteus (SLA accumulator with acryl lid with no strain relief ) .

You have to have right ''THREAD ENLAGER '' like PG9 to PG13,5

under lower PG9 thread some O ring and inside big thread washer from some hardware (plumbing) store ( actually plumbing stores have right sizes with right washers ) but carefully .. washer should be high like cable diameter !

After washer inside thin SS round nut (instead of plastic cork in AGRO to equlize tighting pressure on rubber washer ) and on the top alo second reducer from PG13,5 to PG9 with upper rubber grommet

But that way is maybe more costly like ordinary gland ?

 

[JoelSim]

Well finally I was able to get all of this together and do a bit of a pressure test over the weekend. And the good news is....no leaks :thumbsup: (so far)

42m cold water (as in 2 inch thick ice on surface) and no issues.

Now just have to sort out my driver issues...but that's for another thread.

Thank you all for your input.

Cheers, Joel.

 

[lucca brassi]

new halcyon :
New for 2012
Polymer cord sealing glands now come with a built-in cord strain-relief :devil: :devil::devil:

 

[josb]

new halcyon :
New for 2012
Polymer cord sealing glands now come with a built-in cord strain-relief :devil: :devil::devil:

Well some people are stubborn, these glands with strain relief are already for sale for many years, I guess I'm using them since 8-10 years :naughty: :naughty:

 

[lucca brassi]

To be honest , i have seen several damage with these , mostly have broken in section between threads to enclosure and wrench nut , might be also to much torque at assembly , but I have also seen air buble in mould at broken cross section .

Special at PA (polyamide ) glands light gray .. there is another typ which is dark grey or dark blue are made from nylon which is much stronger. But these plastics are all sensitive on low temperature (ice diving) cca (-20-30°C) and might broke at accidently hit .

From that fact a become rule that all machines in factory have glands like Klem have .

That is only my view

 

[Doc Ed]

Forgive me if this has been asked before, but why did H shift from the metal Agros to these polyamide glands? Was it more of a cost cutting issue?

 

[350xfire]

Probably because they cost like $2 vs. the proper Agro for about $15...

 

[betti154]

Anyone got a link to a source if these polyamide ones? $2 sounds attractive to me.

 

[350xfire]

Anyone got a link to a source if these polyamide ones? $2 sounds attractive to me.

I don't think they will be $2... I was just saying Halcyon's priuce is probably $2.
There's no way I would spend all the time and money to build a light and cheap out on what is probably the most important (non-electronic) item!

 

[betti154]

I don't think they will be $2... I was just saying Halcyon's priuce is probably $2.
There's no way I would spend all the time and money to build a light and cheap out on what is probably the most important (non-electronic) item!

Fair comment. I don't want them or a light though. I need a smaller land or a different purpose.

 

[350xfire]

Fair comment. I don't want them or a light though. I need a smaller land or a different purpose.

LOL! Look at MacMaster Carr I think they have the plastic ones as well as some of the cheaper metal ones. Also, try home improvement stores, they usually carry cable grip type stuff not designed for high pressure but they will probably be galvanized.

 

[arek98]

Anyone got a link to a source if these polyamide ones? $2 sounds attractive to me.

Some are available here http://www.productsforautomation.com/nylonplasticflexfittings.aspx
Note that nut and oring needs to be purchased separately. They also have metal ones and without cable relief.
Watch out shipping while checking out, web is trying to convince you to get overnight.


More is available directly from Sealcon
http://www.sealconusa.com/strainrelief_index.htm
I contacted them and they sold me like 5 pieces. I wanted elongated metric thread and I could not find it anywhere. No problem, nice people.