The "Cascade" - mini-cup directed jet-impingement block design (56K warn)

[bigben2k]

For something a tad easier, go with my original idea: glue small copper tubes into the middle plate.

A bit more labor intensive, but DIY.

[utabintarbo]

Originally posted by Since87
I'm fairly confident that it could be done, with the right plastic.

The biggest problem I see, is that when injecting the plastic, the plastic is going to have to 'flow past' the tip of the nozzle, in order to ensure that that part of the mold gets filled. This will tend to leave flashing at the nozzle tip which might be a pain to trim off.

...

Actually, I don't believe this would be a problem at all. The real issue would be air bubbles at the tips of the nozzles. But this could be alleviated somewhat by using a low viscosity plastic which does not "set-up" too fast for the air to exit the tips. Unfortunately, this would adversely affect yields due to longer cycle times.

Also, there would be some possible flashing at the nozzle entrance (at least as I envision the mold). But the impact (and the cleanup) would be substantially decreased.

If you add some type of ejection from the nozzle bottoms, this would mitigate both of these issues, at a somewhat higher cost.
See cheezy MS Paint pic:

Bob
(Mold Designer in a previous life)

[Since87]

Originally posted by utabintarbo
Actually, I don't believe this would be a problem at all.

It sounds like you know this stuff far better than I.

I'm not understanding the purpose of the ejection mechanism. Would you elaborate?

[utabintarbo]

Originally posted by Since87
...

I'm not understanding the purpose of the ejection mechanism. Would you elaborate?

Well, the problem with little bitty pieces like those nozzles is that they tend to bind in the mold. One way to stop this from happening is to create a mechanism to "push" the piece out. That is what the ejection pin does. Also, there is enough space around the pins that air bubbles have someplace to go, yet not enough so that the plastic can follow. (Air is relatively non-viscous.)

The other way is to draft (angle) all "vertical" walls so the piece essentially "drops" out of the mold. That might be a problem in this application, since that would restrict water egress from the base plate.

Bob

[utabintarbo]

Originally posted by Cathar
Not entirely sure if injection molding could get that level of detail. It's something worth looking into.

...

If you do wish to go that route, I may be able to help!
LMK!

Bob

[Blackeagle]

I'm wondering if you could use fewer, but larger accross, tubes to reduce head loss due to wall friction?

For increased strength could you avoid machining away all the material from between the holes? Perhaps leave 20-30% now being machined out? Relize you have to remove a good deal to allow the water a escape route. But any not removed would increase the strength.

Is the top plate also made of polycarbonate for best strength?

I like the fact you again bead blasted the base. Another little detail to gain all performance you can get. May not help as much in this design, but any increase in surface area of the base in contact with the water should help some.

Sence87 or utabintarbo,

What plastic injectionable material would match the strength of polycarbonate? Unless high strength can be maintained the savings could be at the cost of dependability. My understanding is that polycarbonate is about the strongest of all plastics.

BE

[Since87]

Originally posted by Blackeagle

What plastic injectionable material would match the strength of polycarbonate? Unless high strength can be maintained the savings could be at the cost of dependability. My understanding is that polycarbonate is about the strongest of all plastics.

I don't see the need to match the strength of polycarbonate. What is the purpose?

I'm thinking nylon, high density polyethylene, (HDPE - plastic cutting boards) polypropylene...

Look at poly barbs. They are molded. Is there a characteristic that a waterblock top needs, that the material in a poly barb doesn't have?

[funktional]

I had problems to get my Block soldered together as i told here (I fixed it with using Epoxy now). The Block is based on the basic idea of BB2K and Cathars suggestions in that thread.
Because of the Problems I wanted to use that one for testing and build another one once again. The block I thought about is exactly what Cathar postet here. Honeycombed and with pipes as jets not just wholes in the middleplate.
This shouldn't be a big Problem. Use a Copper middleplate and drill holes in it. In these holes we can easily attach small copper pipes. A little Hammer is all we need

[LiquidRulez]

Cathar........ how did you get the nozzles in the array the shape of a polygon on the outside, when they appera to be round in the actual opening??
Or am I just having flashbacks from the ol' days?

[Blackeagle]

For a large long term builder of blocks your injection idea might be cost effective, I can't say. But I suspect for a small maker the cost of the molds would be prohibative. It would just take to many sold blocks to cover your outlay.

As to the plastics to use and the advantages of polycarb. I see these +'s to polycarb.

1) stiffer
2) stronger
3) clarity
4)short term cost effectiveness

If Cathar is interested in long term building of blocks now, your injection molding may well work & be cost effective. But if he intends to build a few hundred as before for direct retail, then sell the rights to the design for future royaltys and other considerations then no I don't see molds as cost effective.

The greater stiffness of polycarb will reduce the chance of water getting past the O-rings due to softer material being used. And a block top can't be to strong. Polycarb is known to be the best currantly used plexi for block tops. These other materials will raise concerns as to dependability with buyers. Even in the face of extensive testing proof showing other materials such as nylon to be dependable. And there is the issue of the cost of such testing.

Last clarity of the material used will matter to the general market. There are large numbers of people to whom looks count for a good deal in the purchases they make. A clear plexi top would, I think, aid CAthar in sales. A solid colored plastic top of nylon could be taken as "cheap" &/or unattractive in the retail market, regardless of the real truth regarding dependability.

The more I think on the issue of top materials to use the more problems I see in implementing the use of alturnative top materials. As I said at the start of this post, molded tops could prove a good way to go for a large long term maker of blocks. But I don't see it for small makers or short term.

Reading this over I see I'm really more concerned with how well a alturnative top material would sell for Cathar. Although all the reasons given would be raised, regardless of true impact on performance.

BE

[jaydee]

Originally posted by LiquidRulez
Cathar........ how did you get the nozzles in the array the shape of a polygon on the outside, when they appera to be round in the actual opening??
Or am I just having flashbacks from the ol' days?

Looks to me like he drilled the holes, then milled around the holes with just strait cuts to make the stop sign shaped "pipes".

[Blackeagle]

I liked the stop sign description best. But has Cathar ever seen one of our stop signs? Hehehe

Jaydee nailed how it came about I think.

[Cathar]

BlackEagle sums it all up pretty well.

Due to the extra cutting, I absolutely had to move away from an all-copper block. The cut the block out of copper would require a tremendous amount of machine time. It could be done, but the block would cost around $150US straight off the mill.

So polycarb it had to be, also because it's fairly strong, and better yet, it offers what people seem to want, which is a shiny clear block. The machinists have been playing with different grades of polycarb and after talking to me this morning seem to have found one that machines "clearer" and more consistently than the material used in the pictures.

Injection moulding would be a way to cut costs, but also the machinists are just at the very first stages of machine tweaking, and it may be possible to whip through the blocks considerably faster than at present. Or it may not. Gotta suck it and see.

So it depends. It's only after 50-100 blocks will the machining process be refined and tweaked enough to give a good idea of the ongoing machining costs. Only then can the decision be made as to the cost effectiveness of going with a mould approach (which would still require drilling the holes) versus just machining the polycarb.

If the difference works out to $5 US/block but the clear polycarb appearance is lost, then that may actually turn out to be worse in terms of sales. Desirability is an important factor, and people will happily pay $5 more (out of say $50) for something that looks much nicer, but they won't pay $20 more.

All this supply/demand talk though is a bit premature. I'm still trying out stuff to see if I can get it to beat the White Water. Right now it's very close, but still just behind, but there's still a few tricks left up my sleeve. Just submitted a tweaked base-plate design to the machinists based upon what I've learned from the base-plates I have here presently.

I tell ya, the White Water is a very tough act to follow. I really believed that it was possible to get ahead of it by at least 1C somewhat easily, but even after all this time and quite a few behind the scenes attempts, I've only had limited cost-prohibitive success.

[Cathar]

Originally posted by Blackeagle
I liked the stop sign description best. But has Cathar ever seen one of our stop signs? Hehehe

Jaydee nailed how it came about I think.

I've lived in the USA and visit there a few times a year. The Stop signs are the same as in Australia.

Yeah, jaydee was pretty close.

[utabintarbo]

Originally posted by Blackeagle
...

Sence87 or utabintarbo,

What plastic injectionable material would match the strength of polycarbonate? Unless high strength can be maintained the savings could be at the cost of dependability. My understanding is that polycarbonate is about the strongest of all plastics.

BE

I have use clear urethane for many applications where clarity was necessary (headlight lenses, for example). It works well.

Bob

[satanicoo]

Originally posted by Cathar
I really believed that it was possible to get ahead of it by at least 1C somewhat easily, but even after all this time and quite a few behind the scenes attempts, I've only had limited cost-prohibitive success.

Could you post the best, or one of the best, cost-prohibitive solutions you have came across?

[Blackeagle]

Ah, urethane a interesting idea.

Just how close does it come to polycarb for strength? Can't be to bad if it's used for headlight lenses.

[Blackeagle]

I didn't know that stop signs were the same shape in both countrys. I'll bet having been both places offers some interesting comparisons.

[utabintarbo]

Originally posted by Blackeagle
Ah, urathane a interesting idea.

Just how close does it come to polycarb for strength? Can't be to bad if it's used for headlight lenses.

Well, these were prototype lenses. Urethane is strong, but brittle (like carbide). For real lenses, other, more difficult, materials are necessary. But, in this application, I thik the pros would outweigh the cons.

Bob

[Cathar]

Originally posted by satanicoo
Could you post the best, or one of the best, cost-prohibitive solutions you have came across?

White Water design, but slightly finer/smaller. About 0.5C better, or what amounts to diddly squat given the extra cost to machine that small (using slitter saws). Once you get below 1.0mm for either milling or sawing in C110 copper, tool wear becomes an increasingly larger proportion of ongoing costs, especially if you want to make it with any real speed.

I kinda feel that the White Water design is at a near dead-end with respect to improvements. Yeah, you can eke out about another 0.5C for a hot (a real ~80W) CPU, but getting something like 1.0C better on a hot CPU isn't going to happen through further tweaking of the White Water design. At least that's the conclusion I've come to after banging my head against that nut for too long. The current WW design just happens to be a happy balance between performance/cost, and pushing the design further yields dramatically diminishing returns, and further, pressure resistance starts to climb fairly dramatically (and quite unacceptably) if we drop too much below 1.0mm channels.

[LiquidRulez]

Originally posted by Blackeagle
I liked the stop sign description best. But has Cathar ever seen one of our stop signs? Hehehe

Jaydee nailed how it came about I think.

Sorry, I must have glossed over that detail, as I didnt even know that they were piped down just above the "cups"......I thought they were drilled straight thru the poly jet array plate, as the impingemnt nozzle was on the WW.

[funktional]

Cathar, which pump do you use for testing? The I used 6x7 holes with 2mm in diameter in the middleplate and the streams coming out of the holes are not very strong, even with a 1600lph 2.5meter Head Pump. So I think this Block would benefit more from a huge Pump than the White Water.

[Cathar]

Originally posted by funktional
Cathar, which pump do you use for testing? The I used 6x7 holes with 2mm in diameter in the middleplate and the streams coming out of the holes are not very strong, even with a 1600lph 2.5meter Head Pump. So I think this Block would benefit more from a huge Pump than the White Water.

Incorrect conclusion. The problem lies with your implementation.

Your pump would probably push around 8 to 9lpm in a full setup at a guess. This is dependent upon the restriction of the block, but let's say 9lpm.

Your total jet-hole orifice area is 132mm^2. At our guesstimate 9lpm, the pump is pushing 150ml/sec, for an average nozzle velocity of around 1.1m/s.

1.1m/s is pretty sedate, and is slower than the rate with which water will flow through something like a Maze 3, which would typically be up around 1.6m/s for a pump like yours in a full system.

Compare that to my block where with an Eheim 1250, the average nozzle velocity in a full setup is around 4.5m/s. With the Iwaki MD-30RZ, it's up around the 7m/s mark.

ie. your holes are too big. Make them smaller.

[msv]

Originally posted by bigben2k
LOL! That's got to be the most original source of inspiration!

Eeeh... Feels like I´ll have to get miself some metal cutting gear. I´ve started to angle my coffee cups differently while rinsing them after dishing, just playing around with the waterwhirl...
regards
Mikael S.

[hara]

Great work cathar!

How about milling the small pipes with ballmills so that the water would have a smooth path?
Also, what would happen if the holes on the base were closer to each other?

Did you experiment with different style drillbits? Being a good machine shop, I would say they would have the tooling to make you a customised drill bit. I think optimising the base "cup" shape will be a key to squeeze more performance.