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Project: The C Case

Discussion in 'Project Logs' started by Zds, 6 Nov 2005.

  1. Zds

    Zds What's a Dremel?

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    Thanks! :)

    This is possibly something you want to check: http://www.fischerelektronik.de/index.php?id=52&L=1. They have distributors all over the Europe, but no prices on the Web, so it's up to your local distributor and luck what they stock and at what prices.
     
  2. Zds

    Zds What's a Dremel?

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    1:2.5 scale model

    As I have the overall shape and component placement now fixed, it's time to check that my vision about the look can be implemented.

    As I have 0.8mm thick aluminium sheet and 3mm thick acrylic sheet handy, I chose to make the second scale model to 1:2.5 scale. This way the effective thickness of the aluminium matches the 2mm I have planned for the final product and acrylic thickness simulates closely enough the planned 8-10mm full scale thickness.

    Especially in bending to concave shapes scale is fairly important. As with the first version it proved out to be fairly difficult, I try now to tackle that risk early on.

    Enough talk, here are the images:

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    As it's already quite late, I decided to leave rest of the hammering, filing and dremeling to tomorrow. The finish of the edges leaves lot to be desired, but the perfection of the finish is not the point of this model. The point is to verify that the materials and shapes I have planned work together so that I can produce the same shape with same materials in full scale.


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  3. Zds

    Zds What's a Dremel?

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  4. Zds

    Zds What's a Dremel?

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    Tearing the TEC PSU apart

    As you saw in the blueprints, I plan to rip the standard fans off of the PSUs and make them leaner, while offering straighter and less restrictive airflow path and external heatsinks and fans.

    The first victim was the Antec 480W TruBlue PSU, which will power the TECs and some of the lights and microcontrollers.

    It's a dual-fan model, 92+80mm:

    [​IMG]

    To make room for the two fans, the main PCB is split into two parts, the smaller one raising almost to meet the opposite cover:

    [​IMG]

    This is bad, since I want to squeeze the PSU (sans cooling) into 150x140x60mm box.

    Fortunately it's fairly straightforward to detach it and move it to the space once occupied by the rear 80mm fan. This just means I have to lenghten the five wires connecting the two PCBs:

    [​IMG]

    This PSU convinced me of Antec quality. It feels robust and solid, and has more features I could have understood to ask for. For example, it had an external Molex connector covered with plastic cap:

    [​IMG]

    I remains a mystery to me what this tiny PCB between main +12V, +5V and 0V lines and external molex connector does, but it looks like Antec has tried to actually make sure the external one and internal ones will not mess each other:

    [​IMG]

    And naturally there are some leds. In fact, these blue leds are the only blue element in the PSU, PSU that comes with name "TruBlue".. I have my doubts about how that brown goo used to glue them affects the effectiveness of the heatsinks:

    [​IMG]

    And here they are cut off, the external connector and its PCB and the leds along with the legacy 6-pin 3.3V connector that never actually got popular:

    [​IMG]

    This PSU had more and longer connectors than any PSU I have had this far. Naturally it also had two fan only molex headers:

    [​IMG]

    I didn't cut them, since if the Antec fan controller is of any use, I might still have some use for them.

    The two Dynaeon Industries fans were detached and saved for future use:

    [​IMG]
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    The rear 80mm fan sports also RPM sensor wire that was made available externally:

    [​IMG]


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  5. Zds

    Zds What's a Dremel?

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  6. Zds

    Zds What's a Dremel?

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    Tearing the TEC PSU apart, part 2

    The backplate and its screw mounts are sturdy enough that I consider cutting it out and using in the final assembly. This way I also save the pain of trying to find fitting metric screws to replace the original ones:

    [​IMG]

    This shows why this is perfect PSU for TEC use. 70% of the rated maximum power is available in a single 12V line:

    [​IMG]

    It seems that I do not want to remove the original heatsinks. They are made of single piece (each one) and screwed with some dozen, half of which are behind soldered components. Here are the only four screws I _could_ remove easily:

    [​IMG]

    This component it a bit of mystery to me. It was screwed to main heatsink separately. OTOH, I have not been able to find anything resembling thermal diode:

    [​IMG]

    The scalp! As I will not use any standard connectors, I cut them all away:

    [​IMG]

    I also cut away lot of the power cables to reduce the clutter:

    [​IMG]

    What I left is 8 +5V cables (red ones), 7 +12V cables (all there was..) (yellow), few 3.3V cables (orange) and 12 ground cables (black). The thinner ones that are together separately are standby power cables:

    [​IMG]

    There was some 16 ground cables in total, but as the TECs will draw power from either 5V or 12V line at any single moment, never from the both, it's enough to have one 5V, one 12V and one ground line per TEC module. Thus the six TECs eat up 6+6+6 wires in total, leaving all the 3.3V wires, two 5V wires, one 12V wire and six ground wires for whatever other needs I will find.

    I also played with idea about replacing half of the remaining ground wires with one very thick one and using it for all the TECs.. lets see.


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  7. Zds

    Zds What's a Dremel?

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  8. Zds

    Zds What's a Dremel?

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    Scale model 1:2.5 update

    Proceeded with the second scale model. I let the images do the speaking:

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  9. Zds

    Zds What's a Dremel?

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  10. Ravimade

    Ravimade What's a Dremel?

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    I really love this amazing project.

    Hope your will success the mod

    Big support and good LUCK ;)
     
  11. Zds

    Zds What's a Dremel?

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    Thanks a lot!

    I'm still sick, so no much progress on modding field, but.. I found a place to sell me black anodized aluminium in single sheets and at tolerable price. Nice! It's been a real PITA to find proper aluminium, as it's usually either too thin and too expensive per kg, or then sold in amount of one metric tonne.

    And as I need some 30 kilos of it, price starts to be a valid concern.

    More details if I get the deal done, but now I at least have an offer from them. It's for three sheets, 0.5mm, 2mm and 3mm ones, 1000x2000mm each.
     
  12. Lazarus Dark

    Lazarus Dark Minimodder

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    i think i remember seeing your other log

    this is an interesting form, I'm actually still having trouble visualizing the final product, but I anticipate it will be something to see.
    keep up the good work.
     
  13. Zds

    Zds What's a Dremel?

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    More detailed heat transfer plans

    As I’m sick third week on a row, no chance to get anything physical done. Instead I have done some math and drawn some pretty pictures.

    As you might recall, the plan this far was to have water flow in thin layer between TEC hot sides and backplate, from up to down, and distribute heat to backplate while flowing. Well, I started to calculate the thermal conductivity performance and heat distribution along the heatsink and quickly decided to change the plans.

    Here is the new plan:

    [​IMG]

    The new thing is that the heat exchanging part (where cool and warm loops flow over the TECs) is now narrower and I have added copper pipes (the red lines) that will be embedded inside the back heatsink.

    Cross section showing the two water loops and TECs (from top to bottom: cool loop, TEC, warm loop):

    [​IMG]

    Here is how the copper pipe will be mounted. The idea is to take 12mm OD, 10mm ID copper pipe and squeeze it to 10×10mm groove in the heatsink:

    [​IMG]

    The bottom grey part is the heatsink, top grey part is the backplate. Thus copper pipe is sandwiched between backplate and heatsink. If my calculations are correct, the pipe should fit just as well as in the picture; it’s in the exact scale. By forcing the copper pipe to deform I hope to get better contact between the heatsink and the pipe.

    Here are gross estimates about temperature gradient over heatsink in the old and the new model:

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    Each step represents 2.5°C difference in temperature when the total heat load transferred is 250W. As the heatsink will be constructed from vertical aluminium pieces, I have assumed thermal conductivity of 150W/m/°K to the horizontal direction and 200W/m/°K to the vertical direction.

    This is basicly optimization between flow resistance and maximum temperature gradient: more pipes mean less flow but better thermal transfer..

    What I hadn’t realize before was that while flow resistance is roughly linear in relation to the lenght of the pipe, thermal transfer increases squarely with the pipe length. If I have reasoned properly, this is due to the fact the when you add more piping, you both decrease the average distance from each point in heatsink to the closest point of hot water _and_ increase the amount of conducting surface. The latter means that there is less thermal energy per cross section area of the heatsink to transfer.

    And the last image shows how the heatsink will be constructed. The top of the image is the outer side and the bottom is the inner side. Note that most of the inner surface will be flat; this depicts the part where there is also internal heatsink:

    [​IMG]

    The outer fins are optimized for passive heat transfer, thus they are thick and sparse: 2mm per fin and 10.5mm between them. Inner fins, where present, are supposed to be cooled via forced airflow, and there fins are 0.5mm thick and have 4.5mm worth space between them.


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    Last edited: 19 Apr 2006
  14. Zds

    Zds What's a Dremel?

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    Hehe :D.

    Thanks, I will. Slowly but surely..

    And some pretty pictures about what's to come:


    More detailed heat transfer plans
    [​IMG]
     
  15. Whelan_999

    Whelan_999 What's a Dremel?

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    Hey Zds
    This is the first time I've read your post, very long, but a good read. I'm on 56k so the long read gave my internet time to catch up with the pictures.

    I think the whole concept of using acrylic is pretty cool for making shapes. You said you were trying out different ways of making this look real. Try taking different objects to poke the heated acrylic with and see if that does anything, or rough textured stuff to give it some skin tone. Another idea I had was pouring warm water in, or cold and seeing if it forms a weird shape, just some ideas I dunno how well they will work.

    As for the body internal structure of the project I think it looks great. The motherboard case is sweet looking, the idea of the Volvo radiator is cool too. Anyway I can't wait to see the finished project, I'll be waiting patiently. Keep up the good work.

    Cheers,
    -aaron
     
  16. K.I.T.T.

    K.I.T.T. Hasselhoff™ Inside

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    hi Zds....just read you work log and its awsome i really like the idea of incorporating the volvo radiator to give you a huge cooling surface. great work and keep it up.

    also...this strange compnent (pitured below) is actually a 10 Watt resistor that is placed so that there is always a load on the PSU when it is turned on as most PSU's these days will shut down if the load drops below a minimum level.
    [​IMG]
     
  17. Zds

    Zds What's a Dremel?

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    Scale model v3

    Starting again with foamcore:

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    Remember kids to sand the foamcore sheet before gluing.

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    Here you can see the size difference between the first iteration and the current:

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    I "maybe" overdid "a bit" the polyurethane foam part:

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    But there's few problems that cannot be solved with sharp enough blade. Now looks a lot better:

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    Add some artist's clay into the mix:

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    I saved some money and used the kind of clay used mostly to do ceramics and not the one used by sculptors. This means it's more sticky and coloring, so I didn't dare to touch the camera while sculpting.

    Anyway, here's what I ended up with:

    [​IMG]

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    It's too bulky to my taste, but otherwise it's in the right direction. Lots of work still to do, but the basic concept works. I just have to make it look leaner..

    The finish of the clay model is sub-standard, but once again, I wanted to see the shape, so the finish does not matter. It'll end up to trash can sooner or later anyway.


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  18. Zds

    Zds What's a Dremel?

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    Scale model v3

    Hmmm, interesting idea, gotta try it :) . Too bad the acrylic has tendency to bounce back to original shape when cooling.. Needs some careful planning and materials that can stand the heat of the plastic acrylic.

    Ah, figures. Thanks for the info!

    And sorry to disappoint you guys, but most likely I will leave out the Volvo radiator.. I have learned a lot during this project and now I think I can cool the system very well with massive heatsink and TECs. In the beginning I was unaware of the fact that peltiers can work with high CoP, so I did some redesign along the way.

    And thank you for your kind words, they help a lot in keeping up the quite challenging project!

    Here's some update:


    Scale model v3
    [​IMG]
     
  19. Zds

    Zds What's a Dremel?

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    Mini-update

    Yesterday I bought some aluminium-capable blades for my jigsaw, a drill press and router. Unluckily I didn't have time to pick up my aluminium sheets and rest of the week goes into long weekend snowboarding in Lapland and preparing for it.

    But on the bright side, I've made some progress on the case shape front:

    [​IMG]

    The rightmost is my vision per today, middle one from Sunday and leftmost from Saturday. Definitely getting better.

    The clay model did it's job - it helped me to see which parts worked and which did not, resulting in a sleeker model. Huzzah.

    But I better get the shape fixed soon, as I do not want to cut 130€ worth aluminium into something that does not satisfy me :-].
     
  20. Big SturL

    Big SturL What's a Dremel?

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    Did this mod ever get finished?
     

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