"Radius" by BigBen2k

[utabintarbo]

Originally posted by nicozeg
Hey Bigben you should reconsider the new cuts on the center fins, it seriously compromise structural stiffness of your block. If you keep connected the central crossing fins they make the base far more "unbendable", not needing an ultra stiff top. The 18 lbs. of vertical load you are aiming are simply a yoke to copper capability.

I sketched two cross sections of the fins of your block, yust wuess who is more able to bending?

As the center fin treatment is my suggestion, I will attempt to defend it...

I suggested that to ease machining (going in one direction is easier/more reliable than going around corners). I also suggested going to a solid top concurrently. If Ben had decided to stay with a plastic top (this was originally my idea, as he didn't specify anything about the top in our initial communication), I would have suggested going back to the original setup. I hope this alleviates your fears.

Bob

[BillA]

Ben
invest in a calculator, and get some practice using it
and make dwgs to scale, may help you to 'see' what's going on

to compress an o-ring 30%, what is being done ?
- it's cross-sectional diameter, relative to the longitudinal axis, is being reduced by 30% (or 40 if you prefer)
[this will tend to slightly increase it's diameter, Roark describes the deformation calcs]
- is it's volume being affected ? nooo
[not at the stress levels involved]
- so if the o-ring's volume was 70% of the groove's (or 60 if you prefer), has it changed ? nooo

so what then is the cross-sectional area of a 1/16" o-ring ?
so what then is the groove volume ?
now you 'know' that the depth of the o-ring is 70% of 1/16",
[find out the tolerances, and use the lower 'limit']
what then will groove's width be ?

this is pretty basic arithmetic, eh ?

now why cut a groove that small if such is not necessary ?

BTW, the bearer of bad tidings here; your design is quite seriously flawed
- Cathar's thread identifies the salient considerations,
which you are ignoring in favor of what you like the appearance of

build it, test it - many to go

[bigben2k]

Thanks Nicozeg. Do you have any calculations/numbers to back that up?

[nicozeg]

Fins in a waterblock are like small structural beam, where it strength increase linearly with the thickness, and by the cube of the height.

That is double width = double strength; Double height = eight times strength.

If you have 2mm base and 5mm fins that makes an effective beam height of 7mm, so base against fin ratio is 3.5. the cube of 3.5 is 42.875.

Conclusion: A fin crossing the center of your block makes it about 40 times stiffer than just the base

If you look at cathar`s block, he has several parallel fins that make it very strong in the fins direction; but perpendicular to them he has only a very thin base that would be easy to bend. That’s why he needs a supporting top.

In your case with only one pair of crossing fins you can have all the strength needed because they cover the two main directions.

[utabintarbo]

Originally posted by nicozeg
Fins in a waterblock are like small structural beam, where it strength increase linearly with the thickness, and by the cube of the height.

That is double width = double strength; Double height = eight times strength.

If you have 2mm base and 5mm fins that makes an effective beam height of 7mm, so base against fin ratio is 3.5. the cube of 3.5 is 42.875.

Conclusion: A fin crossing the center of your block makes it about 40 times stiffer than just the base

If you look at cathar`s block, he has several parallel fins that make it very strong in the fins direction; but perpendicular to them he has only a very thin base that would be easy to bend. That’s why he needs a supporting top.

In your case with only one pair of crossing fins you can have all the strength needed because they cover the two main directions.

And given the fact that a solid top was deemed to be most appropriate, your point is...?

Bob

[myv65]

Originally posted by utabintarbo
And given the fact that a solid top was deemed to be most appropriate, your point is...?

Bob

His point is that the top may not be required for structural purposes. What's described is the method for calculating a moment of inertia, which largely determines bending "strength". While the relationships are correct, they only apply to a solid member. In short, a fin crossing the base doesn't make it 40X stronger. It's a little more involved than that.

In summary, you must first determine the neutral axis, which will correspond to the center of gravity. Since the fin is "thin" compared to the width of the base, the neutral axis will be very close to the center of the base. Then you calculate each member's area moment relative to its own center (this is the 1/12*base*height^3 portion). Finally, you add the member's area multiplied by its distance from the neutral axis^2. This is the composite area moment. It's basic strength of materials stuff, but pretty much greek if you haven't studied it before. The Roark book I mentioned earlier goes into just a tad more detail and tabulates copious loading conditions for plates, beams, cylinders, etc., etc.

[MadDogMe]

:shrug:Mistook

[pippin88]

Originally posted by utabintarbo
Ben,

If you recall, I posted my idea of what your block would look like in the "Ultimate block? Theory" thread. Since then I've come up with a few ideas, which I will post, if you like. A couple of q's come to mind:
1. Have you given up the idea of the fins at the bottom imparting a "swirl"? ie. curved vs. straight radial fins.
2. Are you wedded to the idea of a uniform thickness baseplate? Recall that Cathar's fins brace the baseplate against the cover, effectively giving him a stiffer bp to compensate for his lack of thickness. Also, his has a higher density of "finnage" than yours will at a given point, I believe. Refer to my posts in the "Ultimate waterblock" for the direction I am heading.

As to Cathar's block, I believe he said that he had the fins EDM'd into the copper. When I talked to one of my co-workers about machining 1mm channels into copper, he wasn't particularly enthusiastic. PITA!

I also have an idea or two re: mounting. If you prefer, I can contact you off-line, but that might be considered bad form. In any case, any help I might be able to give re: CAD and NC Programming is available.

Bob

Sorry if this has been said, but the fins are milled, none of it is EDM

[utabintarbo]

Originally posted by myv65
His point is that the top may not be required for structural purposes.

Agreed. But since it was decided to go copper top, I thought it would be easier to machine with the center-post configuration. In that context, his point is informative yet not totally relevant. If Ben wants to go Lexan top, things could be different...

Bob

[bigben2k]

All right, before everyone gets all huffy and puffy, I'll clarify:

As of now, a copper top is my preferred direction, because I'm not able to resolve the resulting structural integrity: it's out of my league. I have noted however that the resulting strength would be cubed if the crosshairs are not chopped up.

As you all know, the fins are part of the structure of the block i.e. they are what prevents the 2 mm baseplate from caving in. This is done in 2 ways:
1-having solid fins, which by torque only help keep the baseplate flat
2-Having a solid top, where the fins rest up against it.

The load applied comes from the clamping pressure, which would be in the 20 lbs range.


That being said, a clear top would be nice. I believe that the polycarbonate would be best.

What I don't know is what kind of stress points either configuration (copper top, poly top, solid fins/chopped fins)creates, but it is clear that there would be some pressure applied against the top.

I also don't know what kind of deflection I can expect from any load applied against a copper bar.


What also concerns me a great deal is the clamping mechanism. As per AMD specs, the clamping pressure should be applied longitudinaly over the core. I believe that preferably, the clamping force should be applied centrally, but this design makes this near impossible.

What we have so far is this:

Note: there would be a spring effect from this copper extension, and I don't know how to calculate this either. I do need those numbers, in order to select the proper clamping pressure.

[bigben2k]

Originally posted by unregistered
Ben
invest in a calculator, and get some practice using it
and make dwgs to scale, may help you to 'see' what's going on

to compress an o-ring 30%, what is being done ?
- it's cross-sectional diameter, relative to the longitudinal axis, is being reduced by 30% (or 40 if you prefer)
[this will tend to slightly increase it's diameter, Roark describes the deformation calcs]
- is it's volume being affected ? nooo
[not at the stress levels involved]
- so if the o-ring's volume was 70% of the groove's (or 60 if you prefer), has it changed ? nooo

so what then is the cross-sectional area of a 1/16" o-ring ?
so what then is the groove volume ?
now you 'know' that the depth of the o-ring is 70% of 1/16",
[find out the tolerances, and use the lower 'limit']
what then will groove's width be ?

this is pretty basic arithmetic, eh ?

now why cut a groove that small if such is not necessary ?

BTW, the bearer of bad tidings here; your design is quite seriously flawed
- Cathar's thread identifies the salient considerations,
which you are ignoring in favor of what you like the appearance of

build it, test it - many to go

Yeah, I'm told that I have my days, where I'm just "dense".

I think Utabintarbo understood what you were trying to convey. I'll double check (using my trusty calculator ).

I still haven't been through the entire thread (Cathar's). I wouldn't go as far as to say that the design is "seriously flawed", but it certainly does have a number of limitations, and a couple of non-sequitor sections:

1-The purpose of this radial design is primarily to reduce the overall flow restriction. Pending a full cube-res design, I believe that this has been accomplished.

2-The added benefit is that because of the channel design, the coolant will flow at a higher speed over the critical area (over the core), but the nozzle (center opening) does not reflect this. If it did, then the opening would be in the order of 1/4 inch (diameter), but that in turn affects the throughput through the fins. I am still working on this, but in the mean time, the design does allow for a drop-in nozzle, so for construction purposes, I believe that we are still on track.

3-I have made some templates to fit over my hand drawn fin pattern, and have found that a 3/8 inch opening would allow the flow to be seperated into 16 channels. In this configuration, the equivalent opening is (16 * 5 * 1 = 80 mm^2) at the channel area, where the nozzle opening is 3/8 aka 72 mm^2, which isn't much of any kind of nozzling.

4-With a 3/8 nozzle, there is a certain flow restriction, which may counter point #1, but strictly for cooling purposes, where it is critical. A small pump may not work well here, but I am certain that my Little Giant can handle it.

5-I have made many references to the core being 11 by 11 mm, when in fact it is smaller, more like 8 by 10 (rough approx). I have a template for this too.

6-The fabrication of this block is a very large factor. EDM is out, due to cost. I have yet to be able to reproduce Les' calculations on Cathar's block, and I am somewhat limited in calculating the thermal numbers for this block, as most tools do not account for a circular pattern, but it's not impossible to figure out, using a little averaging (adds error, but that's ok, I just want an idea). The numbers change at different radiuses (?), hence the name.

7-There is a flow optimization issue over the very center of the block. It has not been resolved to my satisfaction, yet.

8-There is a flow distribution issue, where the channels on the outside of the fin pattern won't have the same flow rate, but it's not a very large difference (depending on nozzle), and I plan to attempt to balance this by selecting the right openings on the top.

Overall, I believe that the block design will function, regardless of what's inside, so again, to call it "seriously flawed" is, IMO, out of touch. Since I'm still optimizing/calculating, it can be called "work in progress" (to Fixittt's frustration: he can't wait to get started!).

Note: my original idea did not have a top plate, but didn't have any fins either (except to hold the center barb). In that configuration, I believe that the design falls somewhere along with the Swiftech type blocks (open/flat plate category).

[BillA]

good to see that your mind is not closed to doubters

Cathar's thread can benefit you, but only if you read it - eh ?
suggest making 6 or 8 notes
some points are essential to the process, the sequential development of a design
truly, some choices FORCE others

you are trying to kiss all the girls at the very same time
ain't gonna happen that way

your #7 is the real #1

your words are obscuring your vision

a 'good' design is not a trip through a market, selecting the best of this and the best of that
rather it is the identification of the primary influences, their prioritizing, and their sequential optimization;
understanding which tradeoffs may be beneficial - and which less so

your design IS seriously flawed, and that you fail to see this means – to me – that you have not yet understood the design process itself

[nicozeg]

Just relax Bob, it was only a suggestion. It seemed to me that the only argument for deciding copper was being afraid of weakness. When Ben asked for glass, it make me clear that he prefer a transparent material; so my point was that the block could easily be made strong enough to use plastics for the top.

Myv is right; I made a very brute simplification of the problem. My intention was to do some quick numbers to show the advantages of fin continuity. I didn’t want to spend a lot of time in more precise calculations, because I’m very confident that for the small loads involved, it’s stiff enough by a big margin.

As for the added complications in the machining stage, they are by far compensated if machining a copper top can be avoided.

Further simplifications of the model can be made when using a plastic top. The o-ring channel can be eliminated and use that silicone film sealant someone mentioned. Even more, it could be used silicone adhesive and eliminate the need of bolts. It can give the block a cleaner look and avoid hole taping. I think this is ok with the KISS concept

I’m sorry if the only added work my suggestions imply is Bob’s drawing time.

[nicozeg]

Ok, I can do some real numbers calculations but I need that someone provides me with copper´s mechanical properties, mainly "elastic limit" and "elasticity module" (not sure about the correct name in english)

[utabintarbo]

Originally posted by nicozeg
Just relax Bob, it was only a suggestion. It seemed to me that the only argument for deciding copper was being afraid of weakness. When Ben asked for glass, it make me clear that he prefer a transparent material; so my point was that the block could easily be made strong enough to use plastics for the top.

This too was my original contention. And if I were any more relaxed I might soil myself!

Originally posted by nicozeg

As for the added complications in the machining stage, they are by far compensated if machining a copper top can be avoided.

Further simplifications of the model can be made when using a plastic top. The o-ring channel can be eliminated and use that silicone film sealant someone mentioned. Even more, it could be used silicone adhesive and eliminate the need of bolts. It can give the block a cleaner look and avoid hole taping. I think this is ok with the KISS concept

But this does not correlate with the KILL concept (Keep it looking 'L33t).

Originally posted by nicozeg

I’m sorry if the only added work my suggestions imply is Bob’s drawing time.

What?

Bob

[utabintarbo]

Originally posted by unregistered
good to see that your mind is not closed to doubters

Cathar's thread can benefit you, but only if you read it - eh ?
suggest making 6 or 8 notes
some points are essential to the process, the sequential development of a design
truly, some choices FORCE others

you are trying to kiss all the girls at the very same time
ain't gonna happen that way

your #7 is the real #1

your words are obscuring your vision

a 'good' design is not a trip through a market, selecting the best of this and the best of that
rather it is the identification of the primary influences, their prioritizing, and their sequential optimization;
understanding which tradeoffs may be beneficial - and which less so

your design IS seriously flawed, and that you fail to see this means – to me – that you have not yet understood the design process itself

Obscure references aside, what exactly are you talking about? I mean for the less-informed among us.

[myv65]

Originally posted by utabintarbo
Obscure references aside, what exactly are you talking about? I mean for the less-informed among us.

For a switch, Bill was relatively polite and I get to come in a say what he was really thinking whilst sounding like the hard case. Sorta like good cop, bad cop if you will. As an aside, Bill must not be feeling well today. Get well soon. LOL.

Bill means that Ben doesn't yet get how everything works together (or against each other). Ben has looked at many designs and noted the relative merits of each. Now he's trying to take all the "good" ideas and combine them into a single block. The various "good" traits are irrevocably tied to other traits and it is not so simple as merely "using all the good ideas at once".

As for Ben, few approaches beat hands-on experimentation to learn how things work. At best, this block of his is a starting point rather than a destination. A lot more experience and education in heat transfer would likely lead to a different first step. Believing that it will be the greatest thing since sliced bread would be naive.

Personally I wish Ben all the best in making his block a reality. I believe, however, that you need the mindset of "it's nothing more than a learning experience". Once he's made it, he would need to study how it works, where it falls down, how he could make it better. It's a refinement process and it's rarely if ever right the first time out the gate.

[utabintarbo]

Originally posted by myv65
For a switch, Bill was relatively polite and I get to come in a say what he was really thinking whilst sounding like the hard case. Sorta like good cop, bad cop if you will. As an aside, Bill must not be feeling well today. Get well soon. LOL.

Bill means that Ben doesn't yet get how everything works together (or against each other). Ben has looked at many designs and noted the relative merits of each. Now he's trying to take all the "good" ideas and combine them into a single block. The various "good" traits are irrevocably tied to other traits and it is not so simple as merely "using all the good ideas at once".

I guess my problem is one of style. Merely saying something is no good without saying why it is no good conveys nothing. It is merely pissing on someone elses idea. There are very few people here who are unwilling to take constructive criticism, key word being constructive. But criticism for its own sake makes one appear merely sanctimonious.

My 2 pfennigs...

Bob

[BillA]

Originally posted by unregistered
Ben
. . . .
build it, test it - many to go

from some posts back

and the only way you will shorten that cycle is to start actually thinking about what's going on

utabintarbo
sure seemed clear to me
1) read the references given
2) think about it until a measure of comprehension is attained
3) do it

the process I'm seeing here is a verbal circle jerk
a whole lotta talk
with minimal thought
all eye candy
no thermo or fluid mechanics (must get back to the basics)

-> hit the library !

(better form now myv65 ? - switching keeps 'em guessing)

Bob - posts crossed

no, I do not agree
something is worth what YOU pay for it, easy come - easy go
if I give you the answer it is worthless because it was free
BUT
if you have to read a 30 page thread, which has 6 or 8 real pearls hidden in it
then you have paid perhaps enough to remember 'the lesson'

on forums all posts have the same appearance, good or bad
as I said to Ben; if you don't care enough to read, why should I type for you ?

[bigben2k]

I am glad to see the animosity dissipate...

I have to confess, to BillA's remark, that this thread is somewhat representative of the process through which I am going, to develop this block. It is chaotic, approaches many aspects at either the same time, or in no particular order. As with software development, 80% is planning, 20% is coding (under the best circumstances). Since this is a part time effort on my part, I will certainly not make any scientific claims of any kind of breakthrough. As myv65 pointed out, I'm trying to use "the best of the best".

In this particular design, the aim is to optimize the flow where it is needed, and I believe that it is achieved with the "tube-in-tube" approach, combined with the radial pattern. As Cathar pointed out, the optimal copper to channel ratio he found to be ("between 1.5 and 0.8") is entirely applied here, where the ratio will vary between 1.5 and 0.75 . My numbers may turn out to be slightly different, but I won't know this until I've completed my calculations.

In the mean time, I view this thread as having what I call a "hack-and-slash" approach (a D&D expression refering to a simplistic "kill everything" campaign). There are many parts here, and some more in the e-mail exchanges between Utabintarbo and myself. Utabintarbo has made significant contributions (Thanks Bob!). All in all, I can see that there isn't a clearly defined approach to this, but most of the design has been inspired from an idea of mine, and from some of Cathar's results. That's where it all comes from, the rest is merely the details of an idea.

If this was an ordered development, the first thing for me to do would have been to recruit a specific number of people, so that we can list the parameters, define an approach, set up a schedule, and since this would become a collaborative effort, assign each member a task (except for non-participating team members). Then, and only then could I claim any kind of pseudo-scientific approach (Now tell me honestly BillA, would you have responded positively to such an invitation?)

To point the obvious:
this is a ProCooling forum, not NASA.


This entire effort is revealing of the many constraints a block designer faces, the most important of which is the construction. I have dreamed up many other blocks which were unfortunately impossible (or too expensive) to make.

Back to work.

At this point, I think that we should send Fixittt some kind of drawing, even if it's preliminary, because I have many unanswered questions in that area, and Fixittt doesn't appear willing to budge without one!

[Cathar]

Originally posted by bigben2k
This entire effort is revealing of the many constraints a block designer faces, the most important of which is the construction. I have dreamed up many other blocks which were unfortunately impossible (or too expensive) to make.

You know, I spent a lot of wasted time worrying about what was not possible based on what people were telling me. "Can't use mill bits smaller than 3mm or 1/8", etc. Plugging through the simulator I found that this was in fact the major limitation to making blocks any better than what they are today.

I gradually reduced the channel/wall thicknesses, down to 1mm which I knew was the smallest mill bit that is commonly available without getting into aerospace quality machine (and the huge cost jump that goes along with that), and knew then that I wanted to get my block made with 1mm channels.

Then I must've rang about 40 machine shops asking them

1) could it be done (in pure copper)
2) will you do it
3) how much

90% said no to #1
5% said no to #2
Of the 2 places who said yes to #3, only one was relatively enthusiastic and they were willing to try it out.

Was it expensive to get it prototyped? Hell yeah. It took a pretty large leap of faith to commit that kind of money just merely on an idea.

However I will say this. I learned more about structural and machining limitations in 1 hour of face to face talks with these guys than I could've learned through a few days of reading. There's the real engineer's approach to a design by looking at all the variables which involves design it right on paper the first time, and then there's the "on the ground" human intuition assessment of a design from a machinist with 40 years of experience in taking the jobs that everyone else said was too hard to do. Both work very well. The engineer's approach will be guaranteed to work, while the machinists approach will be correct 99+% of the time.

I never professed to have a full understanding of every stress variable in my design at the time I took it to the machine shop, but by the time they looked it over and made a few changes, that took about 1 hour of their time.

So basically, use the tools that are available to you. If you like your design, and want to see it get made, and have enough faith in it then the best thing you'll do is pull out the yellow pages, ring around to find someone who's willing to take the job on, then head down with your design in one hand and a cheque book in your back pocket that you're not afraid to open, and benefit from years of experience that you could never hope to pick up in a few days.

Sometimes you've just gotta take the leap.

[bigben2k]

Here here.

However, since I haven't resolved the central flow issue (#7), I don't feel that I have anything to even show to anyone right now (huh? what about this thread?) so until it's resolved, I'm not ready to put it into production. Otherwise, I think I've pushed Fixittt to his limit (maybe?).

The mount is becoming a larger issue. Utabintarbo pointed out to me this morning that my drawing doesn't work, but I haven't explored why yet.

The top material issue is "to be resolved", pending a sudden increase of knowledge on my part, or a structural engineer popping in here.

Also pending is my thermal calculation. In the spirit of "good science", I will try to recreate Les' numbers first, before I commit to calculate Radius' properties, but this takes time, which I have little of right now. Maybe in a week or so.

In the mean time, here's the latest drawing:

[bigben2k]

For the central flow issue, I have been looking at this (in my head) for some time:

blue: cutting wheel
orange: copper

As ya'll can see, the circular disk would leave a pointy pattern in an unfinished cut. If this was done from all four sides of the center, the result would be a "pointy pyramid", with 4 walls.

But I can't visualize it without some kind of 3D render (Utabintarbo?).

The original intent was to use an endmill, which would leave a completely different pattern in the middle.

The original idea had a perfectly square cut, which is not possible without some manual effort and/or special tools.

Without any feedback from the miller, I'm at a standstill on this issue.

[gone_fishin]

There is much to be said about making and testing and seeing for yourself. Cathar went through a refining process as his design progressed, blocks in hand, physical testing. That's the next step after theorizing. BTW, congratulations to you Cathar on finalizing a product

[BillA]

Ben
I spent 10 years on committee work at the national level (ASTM, API, etc)
I have very definite ideas about how I will NOT spend the balance of my life

I still don’t think you’re hearing what’s being said

I gave Cathar not a single answer (that I recall anyway)
but suggested areas of ‘interest’
which HE followed, and came up with HIS design

if I tell you what to do, are you then going to think its ‘your’ design ?
(I know the answer to this question, and its depressing)

why solicit answers from others ?
spend the time, learn it yourself, answer your own questions
(independence, initiative, self-reliance, blah blah blah– that’s my song, always)

#7
address the flow issue
THEN worry about machining it
you're still bassackwards