O-ring sucks. can't make it leakproof.
 

I got a 3mm o-ring, and I've tryed with 2,8 and 2,5mm channel for the oring.
When I tighten the block and the top it looks very good, like on the maze3block I also got, but the difference is that the maze3 is leakproof, my block aint.

whats the problem?

I've also used the maze3-oring, that is a little bit softer that mine, but without any progress...

I am planning on using an O-ring on my block as well once I mill it. And was wondering how big I should make the slot also. If someone could help us out that would be shagadelic.

Re: O-ring sucks. can't make it leakproof.
 

The problem is that you sandblasted the o-ring channel. It's easier to seal a soft surface.

what i've seen in ultra-vacuum chambers is an o-ring channel half its height. In your case try 1.5 or 2mm.
oh and if it's sandblasted, tough luck. Try a softer rubber maybe.

I haven't had problems spec'ing out an o-ring, but my block isn't built yet:p

I can outline it all (searching for notes...)

Here are some of the considerations:
1-Your channels must be smooth (if you sandblasted them, you're scre*ed). You can compensate for this with a softer o-ring (durometer rating).

#2-The channel must be wider than the ring, and the ring must sit perfectly in the middle of it. This of course applies nicely to round seals, but I believe that in your case, it's not; you'll have to calculate the length of the center of your channel, and make sure that it matches your o-ring.

I've got a couple more notes to add, but it'll have to wait... One thing at a time!

The first thing I did after the leak was to mill down the sandblastered area and milled the whole block down a little bit.
Its getting late, I have to sleep now, but the first thing in the morning, I will look here for some more helpful tips.

good nite!

All right!

The first thing to determine is your groove depth: the o-ring should be compressed by 20% (this can vary with the material of the o-ring).

Then, to determine your groove width, you want to figure out the area of the cross section of the o-ring, then make your depth so that the area (cross section) of the groove is filled by the o-ring by about 60 to 70%.

That's it! That's the theory, anyways...

I'll be using a 1/16 o-ring myself.:) It should be more than plenty, given the low pressure that it'll be facing (i.e. delta P between the blok's inside, and the outside (aka atmosphere).

Thanks for the notes, BigBen2k
 

I'm in the process of making my own wb and wasn't sure as to which O-Ring to use and groove depth, etc. I ended up getting a 1/16 diameter Buna-N Oring with a 70 durometer (relatively soft)... BigBen, I think you saw my bock design over at overclockers.com
Here's the link again!

I always just go with silicone.seems to hold up better.

I went with silicone too, but only because a lot of the materials aren't 100% compatible with my cooling solution (windshield wiper fluid). EPDM would've worked too.

The standard for the O-ring says that :

H=0.67*D to 0.7*D and L= 1.18*D to 1.2*D

Channel MUST be wide tan O-ring because O-ring must be deformed to ensure the sealing ! :)

Silicone... as in liquid silicone that is applied between the block and the top or a silicone o-ring... if you are using liquid silicone that hardens, can you please explain the procedure :)
Also, regarding the O-ring groove in the previous picture, I plan on making mine circular for the best fit!

No, not liquid silicone.

A round groove is possible, but it complicates (a little bit) your area calculations, to optimize the compression. Not sure it's a good idea.

Many links on this. Dove tail groove is actually an improvement over square.

BigBen, can you post links on the O-Ring groove issue?
Also, where can I buy silicone O-Rings? (or am I totally misunderstanding you here)
Excuse my denseness!

I got my silicon o-rings from www.mcmaster.com . As for links, I'll let you Google, it's not terribly hard to find (search terms: +"o-ring" +groove )

ah, yes.....everyone should have mcmaster.com in there favorites!
super fast shipping, and very difficult to NOT find something that you would need there.
I love em'

Its best to get an oring cord kit(?), so you can make any length(and virtually any size) that you require.

Most O-Ring kits don't include sizes (between #030 and #040) which are commonly used in most waterblocks.
I'm a mechanical engineer, so I love McMaster-Carr. However, they are rather pricy! (I think one has to buy packages of 100 O-Rings there, and who needs that many? :))

Actually, it depends. My pack of silicone o-rings contained 25 units. Prices are OK, but I'm sure someone could find anything cheaper somewhere else. I think they were #27 or #29...

Actually, McMaster doesn't always have what I'm looking for, but they have a lot of stuff I have no use for too!:D

McMaster's silicone rings are red tho, right? I just don't like that color :)

have you ever read the specs on O-ring sizes? I Beleve the groove hasta be BIGGER, not smaller, otherwize it wont squish down and fill the gap, itll overfill it. so Im just guessing, but I beleve your groove should be 3.5mm or around that, or at LEAST 3mm.

on my maze3 it has a .125inch oring, and a .155inch groove.


hope this helps ya out a little

Jon

Yes, they're red.