Stress Crack in Meg lid

mattmexico

Yo there

I went yesterday for a dive, or at least tried to go. I encountered a stress crack, or that is what I believe it is, but you never know, I could be wrong too ... but it is a crack and it is leaking.

The unit has 233 hours on it, last dive in August, sitting in a safe place, lid in the body tube for one o-ring, no latches attached with no drastic temperature changes, no dives of the table, no dragging behind my truck kind of stuff ....

Did any one of you guys had some similar experiences ?. A photo should be attached to this post.

Greetings
Matt
www.protecdiving.com

Attached Images

meg crack01.JPG (187.6 KB, 615 views)

mverick

I'd give Leon a call.

I would say, you could inject epoxy into it. Or, Pull a vacume on the Meg cannister while it was put together and put epoxy on top of it. It would suck it into the crack.

But, I don't think ANY epoxy sticks well to delrin.

Mine looks fine though.

Ken

Ouch! You've got me looking at my Meg head too. I second the opinion to call Leon. I did a little Google search and came up with this info. about acetal plastics:

Small acetal parts can be attached with cyanoacrylate adhesives (CA), but what you're doing is surrounding the part, or a piece of it, with CA, which then holds it in place mechanically. You can similarly glue pieces made from Teflon, nylon, and other engineering plastics, but all of these joints will be very weak.

Good luck with your head.

schford

I cracked the carry handle on mine slightly but it did drop off a 4 foot bench onto a concrete floor fully loaded inc cylinders....I shat a brick!

Stuart

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PeteS

I seem to remember, from way back somewhere, that cyanoacrylate adhesives are not waterproof........

I think your only option is call the factory, and arrange replacement parts.

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Skipbreather

The head definitely has a crack of some sort. Several issues come to mind:

1. Why did it crack? One possible clue- the rust visible on both the QC4 fitting and at the base of the fitting where the crack starts. As most folks know, stainless steel is not rust proof- only more resistant to rust than ordinary carbon steel. Just maybe some rust began to form in the first few threads inside the top of the threaded hole. The added pressure of the corrosion enlarged part just might have precipitated the crack.

2. Can it be repaired? Depends on what you mean by “repaired”. If you mean returned to original strength w/ an adhesive of some sort, my experience w/ Derlin says no. It’s great stuff, but I’ve yet to find an adhesive that gives a good, reliable, strong bond- and I’ve tried quite a few.

3. Can head be salvaged? Depends on a lot on how warm & fuzzy you feel about diving a patched head w/ reduced strength. Biggest concern is that once a crack starts, it will almost ALWAYS continue to propagate unless arrested via what is commonly called stop drilling. The problem is that the tip of the growing crack is a very significant stress riser. The local forces keep feeding on themselves and force the crack to keep growing. A hole of modest size drilled at the very tip of the crack spreads the forces out and sometimes is enough to stop the crack from growing further. You could then seal outside, inside, & stop drill hole w/ sticky goo of your choice. 3M 5200 sealant or Scotchweld 2216 might be good choices. Stop drilling as a technique, though, is normally used in thinner sections where both sides of the material, and therefore the crack, are plainly visible.

I agree whole heartedly w/ others that you need to get Leon into the loop (no pun intended). With all the wiring that will need to be moved during removal of the stainless fitting to enable inspection of both the threaded hole and the stainless fitting, it most likely is a factory level repair job.

It’s a tough problem. Good luck- you’re going to need it.

Ken

abowie

Talk to the manufacturer. They make 'em and maybe they've seen a similar problem before and know how to fix it.

By the look of the corrosion I can see on various metal bits in the picture you're going to want to completely strip and service the head regardless.

As an aside, does anyone know if ultrasonic welding works on delrin?

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schford

Is it me or can any one else see rust in that crack too?

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Genesis

My best guess is that excessive load was applied to that fitting.

Whether it was due to the fitting being oversized for the hole (and thus it was just a matter of time) or whether there was an impact to the gland on that cable is impossible to determine from here.

Delrin doesn't take adhesives well at all. You could drill a stop as was mentioned and then fill the crack with 5200, which is about as permanent as you're going to get, but you have to consider the risks here and whether you want to take them or not.

The corrosion evident on those fittings needs to be addressed as well. Its StainLESS steel, not StainPROOF

I concur with the other folks - I'd talk to Leon about this one, and I suspect the correct answer is "you need a new lid".

denzel

For a possible solution, could you drill a hole over/ through the original and the crack, tap a thread in there, lathe-ee (the verb) a stop and screw it in, with the connector in the "bolt".
While using the same material, any expanding/ shrinking due to temp etc should not be a problem?

Or am I being dumb here?

denz

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