brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Simple Pi Rack 3

Mon May 02, 2016 6:42 pm

Hi,

Below are images of the latest in the Simple Pi Rack line (following on from Simple Pi Rack and Simple Pi Rack Mk II). The Simple Pi Rack 3 features a set of six Raspberry Pi 3 on top and one embedded. The embedded Pi is connected via GPIOs to a SainSmart relay switch, which is used to switch power on/off to the Pis on top. Power comes from a 50W (5V x 10A) PSU. Inputs to the embedded Pi can also by made through a menu using the AdaFruit 16 x 2 character display with Up/Down/Left/Right/Select buttons (front right) or using an I/R remote (sensor top front left), there is also a realtime clock inside. The Clock and the Display share the i2c GPIO pins. All the Pis are connected to wired ethernet via a 8 port TP-Link 5V (0.6A) 100Mbps switch. The embedded Pi is mounted to expose its ethernet and usb ports to the front and has its HDMI port extended and exposed to the left side, ensuring that the rack is usable over the network and locally as a workstation. On/off switches have also been provided at the front to physically control when the Pis have power.

Here is an image of the rack assembled and running:
DSC06219.JPG
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and here is an image showing the internals immediately before final assembly:
DSC06218.JPG
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and finally here is a view from the rear showing PSU air venting and power lead connection:
DSC06220.JPG
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The bottom and top were constructed in a similar manner to the Simple Pi Rack II, but using off-cuts of twin-wall polycarbonate sheets, instead of wood, which helped greatly with embedding the HDMI connector to keep the Pis upright and USB power shim, and for keeping the wiring neat.

The case was made from the white plastic underside of a lid, shaped like a tray (the photocopier part) of an HP all-in-one printer, split into four sections (front, back and sides) to form a casing around the rack top and botton. Front/Back/Sides/Top and Botton are screwed together using small self-tapping screws into small lego blocks shaped, inserted and glued into the polycarbonate, making it solid - I'll supply more pictures soon!

I hope you like it!

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DougieLawson
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Re: Simple Pi Rack 3

Mon May 02, 2016 8:24 pm

And the point of building that is ...?
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kena
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Re: Simple Pi Rack 3

Mon May 02, 2016 10:10 pm

Hey... if you enjoyed doing it, that's all that counts. You don't need a reason to do something...

peterlite
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Re: Simple Pi Rack 3

Tue May 03, 2016 12:08 am

Where are the blue LEDs?

I can see the point of a cluster. Would you get faster communication between the cluster members using an Ethernet switch or a USB hub?

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Gerd
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Location: Europe

Re: Simple Pi Rack 3

Tue May 03, 2016 9:35 am

Great craftsmanship! I Also like that the Pis are stacked up vertically. I have a question concerning:
brigo wrote:All the Pis are connected to wired ethernet via a 8 port TP-Link 5V (0.6A) 100Mbps switch.
Why do you use a 100Mbps switch? I see no storage attached and somehow that cluster needs to get data in and out. So 7 Pis are competing for 100Mbps, while with at least 1 Gbps port there would be no competition at all. Of course assuming that your external Networt is 1 Gbit.

robotsandcake
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Re: Simple Pi Rack 3

Tue May 03, 2016 11:24 am

That looks absolutely awesome, it's been a long time and I've been really ill which is why I haven't followed up on any of this stuff ages. But would you be willing to make one for me please, all of this the pay for materials and your time. I'm quadriplegic and obviously can't put these things together myself but I don't have anybody in my social circle has the skills to do what you've done, but what I do have is a rapidly growing collection of of Raspberry Pis.

Seriously, if I don't get them under control soon I don't think I'm going to have a wife for very much longer! ;-)

*Posting this here in case you didn't see my message on the other thread.

brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Tue May 03, 2016 6:44 pm

Gerd,

I'm glad you appreciate the work that's went into it. You make a very good point about the switch, I think my concerns with 1 Gbit switches were around power, size and weight. At the time I started this I don't think there were any 1 Gbit switches at 5V, they are always a fair bit larger overall in volume, and tend to be in metal cases (is that because of radio emissions?) which makes them considerably heavier.
Gerd wrote:Great craftsmanship! I Also like that the Pis are stacked up vertically. I have a question concerning:
brigo wrote:All the Pis are connected to wired ethernet via a 8 port TP-Link 5V (0.6A) 100Mbps switch.
Why do you use a 100Mbps switch? I see no storage attached and somehow that cluster needs to get data in and out. So 7 Pis are competing for 100Mbps, while with at least 1 Gbps port there would be no competition at all. Of course assuming that your external Networt is 1 Gbit.

brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Tue May 03, 2016 7:12 pm

I'd love to get one of these together for you, somehow! I'll be posting images with short descriptions of how this one is constructed, and hopefully you'll appreciate the effort that went into it and why it took time to put together. I really enjoyed doing it, but mainly from a hand craft and recycling perspective in that I enjoyed making the different pieces of otherwise wasted materials that make up the rack and its case into something useful. I can't commit to building one of these for you, but if anyone can, or if someone can see a better way of making one of these for you quickly, and more efficiently, and frankly better, then they should feel free to do so, and I will provide any details they may need from me. I actually started putting these racks together to help me with my job and to that end there is a fair bit to be done on the software side, and I'd like to return to concentrating on that goal.
robotsandcake wrote:That looks absolutely awesome, it's been a long time and I've been really ill which is why I haven't followed up on any of this stuff ages. But would you be willing to make one for me please, all of this the pay for materials and your time. I'm quadriplegic and obviously can't put these things together myself but I don't have anybody in my social circle has the skills to do what you've done, but what I do have is a rapidly growing collection of of Raspberry Pis.

Seriously, if I don't get them under control soon I don't think I'm going to have a wife for very much longer! ;-)

*Posting this here in case you didn't see my message on the other thread.

brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Wed May 04, 2016 6:37 pm

The frame of the rack was constructed from some off-cuts of twinwall polycarbonate, the kind of stuff now being used for garden cold frames and greenhouse glazing. I started with a single top and bottom sheet help separate by 6M nylon studding, joining screw plastic ends, nylon nuts and washers (all available at DIY stores). This makes an incredible light and surprisingly rigid structure:
DSC06223.JPG
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Other advantages of twinwall polycarbonate are that it is clear (you can see all the wires and lights inside), easy to work with, especially if you don't have lots of power tools, you can cut it easily with a sharp knife, bore holes with fine files, and the channels mean it is easy to keep the structure square.

The other use made of the channels was for the vertical fixing of the Pis using the HDMI and micro USB power ports. I started experimenting with U-shaped aluminium extrusions and spacers, to get the correct positioning and fixing of the HDMI connector support and micro USB shim:
DSC06226.JPG
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brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Wed May 04, 2016 6:46 pm

Eventually the correct positioning was found, and along with a cut-down jack in the sound port acting as a supporting peg, the arrangement is square and true and the Pis can easily be slipped in and out with no problems:
DSC06221.JPG
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blaablaaguy
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Re: Simple Pi Rack 3

Wed May 04, 2016 9:06 pm

peterlite wrote:Where are the blue LEDs?
Exactly. No electronics project is complete without a blue led
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robotsandcake
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Re: Simple Pi Rack 3

Fri May 06, 2016 10:29 am

blaablaaguy wrote:
peterlite wrote:Where are the blue LEDs?
Exactly. No electronics project is complete without a blue led
This. If you've made an electronics project and it doesn't have blue LEDs then I'm afraid it's not quite finished! ;-)

brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Sat May 21, 2016 8:32 am

On thinking about adding the internal Pi, relay and power supply to the rack, concluded that the bottom level was too flimsy, so added an additional layer of twinwall, with the channels running length ways:
DSC06229.JPG
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and from underneath you can see the cross ply effect, a lattice of polycarbonate i-beams. A bit like cross laminated ply-board, the effect of crossing the polycarbonate walls substantially increases the strength and stiffness, with not a lot of extra weight:
DSC06228.JPG
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the cross-channels running length-ways and cross-ways also proved useful when running the individual power leads, improving the internal neatness.

brigo
Posts: 52
Joined: Sat Oct 06, 2012 10:01 am

Re: Simple Pi Rack 3

Mon Sep 05, 2016 8:11 pm

I had a slight set-back with obtaining the same switching power supply as the original rack, which I particularly liked for its dimensions (this one https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1), took some time to find and test another (settled on this one https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1). Here is a picture of the rig, with relay switch, 7 Pi 2bs attached, and a D-Link Gigabit switch (model GO-SW-8G), that I used to help test it before starting to form the the rest of the rack around it:
DSC06228.JPG
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brigo
Posts: 52
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Re: Simple Pi Rack 3

Tue Oct 04, 2016 7:44 pm

Having decided on the PSU and knowing the dimensions of the other major parts, and the rack itself, we can make some decisions on the layout of the bottom layer to avoid problems with wire and connectors. Have decided on the following layout:
DSC06228_640.JPG
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This shows the PSU, relay switch, controlling Pi, power socket, the 6 physical on/off switches, terminal block for power distribution, the stripped down HDMI swivel cable adapter for external connection. Some things may change a little, however based on the experience of building the first one, not by much!

robotsandcake
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Re: Simple Pi Rack 3

Wed Oct 05, 2016 9:18 pm

This is looking really cool, and definitely something I could do with.

I will leave this here but I would be willing to pay for somebody's time to assemble one of these for me (as I am quadriplegic), I would even pay for detailed instructions that a non-technical but skilled workmen could build.

Fair wages for fair work and all that!

All that being said, it's a really interesting project that I'm enjoying following along regardless, keep up the excellent work :-)

brigo
Posts: 52
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Re: Simple Pi Rack 3

Thu Oct 06, 2016 6:24 pm

Relax, this one has your name on it!

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