The block will be slightly modified for accomodating the O rings, channel depts, screws to hold the block together AND MOST IMPORTANT, to force more water through the central channels. Keep in mind, these will be slight modifications In the meantime, BigBen, Don't forget this:

One thing that bothers me is this:

1/2" id pipe cross sectional area: 113mm^2

My slit area: 17*2mm = 34mm^2

That's quite some restriction!

Cathar, what advice can you give me?

Same thing (see graph).

As for the fittings, it's ok. Cathar has 8 channels, with a final opening width around 2.0 mm, for 16 mm^2.

Here's an update. By modifying my design a bit, more water is forced to pass throught the 3 central channels. It is difficult to see, if you wish I can attach the cad file.

A new wide channel has been made in the empty space.

From the other side. Copper stock should soon be with us...

I don't know about the thermodynamics, but I'm wonering if something like this would help balance flow:
http://members.sigecom.net/unloaded/shot5.jpg
If you came down on both sides of the "divider" with a ball end mill you would have a bit of slope directing the flow towards outlet, likewise with the bottom opening in the top-plate. Anyway, just a thought, it came to mind while looking at morphling's block too. It just seems to me it would be better having the water directed rather than colliding below the outlet.
I'm not sure how the block will perform but the little I know about milling tells me it will be expensive to make. Also your drawings don't reflect the roundness of the tools on outside corners and such. Probably won't make much difference, but you should take that into account.

peace.
unloaded

Thanks,
As for the roundness, I think it'll be better that way (rounded) :D
I'm sure It'll be expensive to machine but it is not a commercial block.

Have you got hints on how to machine this? Guess the microchannels will have to be cut with a thorn. A mill would also have to be used.

Something tells me nobody's interested in the outcome :shrug: :cry:

We're interested, but it's looking like you're about to hit a wall, and share the experience, so we all wait in anticipation.:(

You've got a flow balancing problem:
1) you'll find that there's more flow through the fins closest to the outlet (how much, dunno, probably not significant)

2) your nozzle plate doesn't help getting more flow in the central channel, the deepest, even though each channels exit is the same size.

You haven't addressed the heat distribution issue. This design might work just fine, assuming that the central channel's extra heat can be picked up by the surrounding channels; it's hard to tell.

Big ben,
1) The top compensates for distributing the flow evenly by acting in the opposite way of the bottom.

2) true :( I'll see what I can do

How?

water will tend to pass through the fins fartest from the outlet

Update
 

This is an update. My friend "got" (stole) enough copper to make four of these blocks :) 1cm thick.

Next problem: Cutting the b1tch :mad:

What endmills should i use to cut it? Material and size

2 0r 3 flutes, TIN coated, if possible.

Go with a high helix >30 degrees.....prefferably 45.
Im a solid carbide kind of guy myself, but the more flutes you use..the stronger the end mill is. But also, the more flutes, the less chip clearance and they have a tendency to "gum up" quicker.

HSS Tin coated bits are pretty hard also, but they dont hold their cutting edge as long as carbide does in my experience..and carbide can be had for as cheap as HSS plain bits if you shop at the right place.

Be very very patient with copper. You WILL break alot of bits if you try to cut too much at once when in a hurry.(youre going to be breaking quite a few anyway)

When you do buy your endmills....buy about 3 times more than you think the job will require......youre going to need em'!:D

Pretty much sumed it up. I am not sure they make a 45 degree helix endmill that small though.

I can get 60 degree in 1/4", 45 degree in 1/8", but havn't seen anything under 1/8" above 30 degree. I maybe looking in the wrong places though. :D