Poly tops breacking (quick question)

The breacking issues concerning poly tops on water blocks is coused by:
#1: Tension by the retention mechanism? (nuts&bolts&springs)
#2: Tension on the (brass/stainless threaded) barbs produced by turning the hoses?
(I'm allready considering thermal issues (expantion||contraction) by "on-off" cycles)

#1 sounds clear to me, now I've read in this forum 'bout cracks allways starting to grow from the barbs holes (#2).


thx 4 yer time.

i have a maze3 with a poly top (actually i don't know what it is but it's clear) and i've abused the fittings on it quite a bit and i've got ZERO cracks...

I mean i've twisted them, pulled them at angles, used them as handles while i lapped the base, blah, blah, blah... it's built like a tank, so i don't think that would cause a problem on my block. But i'm sure not everyone's is as stout as mine.

Im using a maze4 with a poly top. Been using it for nearly a year running on distilled water with a SLIGHT amount of isoprophyl alcohol and have abused it quite a bit. So far no cracks.

It's believed that the tapping process (cutting threads in the waterblock top's holes) causes micro-fractures (tiny cracks) that can open up with time, stress, or heat/cold cycling.

To me, that's very possible, but I think it's also from using machinery to tap the holes. A machine has little talent nor intuition for when to take it easy on the poor fragile parts.
When I tap holes in acrylic, I cut the holes by hand using a dremel and a fluted mill bit (not a drill) making sure the hole is actually a bit larger than normal (for metals). The finished threads aren't as sharp then.

Something thing I don't do is use an o-ring on them. The plastic tops bend too much when the o-ring compresses, causing alot of stress across the top.
I glue the top to the copper bottom with some Marine Goop.

I moved away from poly tops anyway, prefering copper or brass. They look nicer IMHO, and never cause problems.
Poly tops main drawback is that they suffer from Production Manager's productivity goals...they try to make them too fast (though cost effective) and the quality suffers.

crimedog said:

http://www.ocforums.com/showpost.php?p=3201937&postcount=5

Click to expand...

You guys r great!

it also depends on what type of material - some of the tops are hard and some are soft - the ones that have cracks from the barb holes are prob hard and are of course a lot easier to crack.

My dangerden gpu block has a poly top, BUT no barbs come through the top. They come off the side and top. So essentially its for looks. But since the block faces downward I consider it stupid. And it never cracked.