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Diesel Engine

Chris Howell

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Hello everyone - Welcome to my build log for my current project, a scratch-built PC / Games Console designed for the living room.
About the Build:
After my previous project was primarily built from used components and recovered materials, I wanted to design and build something new and bespoke, with materials sourced for the purpose of the build. The move to smaller cases and living room PC's was also an area that I've found really interesting recently; lots of great designs from both big manufacturers and modders alike. So this is my attempt at the same challenge. I'll be including as much of the design process as I can, as well as the actual building (the design phases pre-build were very important!)
The Build Spec - Primary Requirements:
- Powerful enough to play games and compete with other living room systems
- Small enough to fit in a unit under the TV and not look out of place (i.e. flat)
- Quiet enough that it doesn't ruin the gaming/TV experience
- The design must represent a visual showcase, one that provides Diesel Engine with a unique and clear identity.
Secondary requirements:
- The software must boot directly into a gamepad-navigable state. No Keyboard + Mouse
- The case must not light up like the sun (this is very distracting when sitting under the TV)
- The case should not use or require any specialist or custom hardware
- Be able to support both 1080p and 4K system setups
- Not require an external power brick
Oh... (and this should go without saying) but the build shall not call itself an "ITX case" and still support full size ATX hardware and all the trimmings.

Concept Artwork

I drew and modelled a range of concept pieces first, free from any technical limitations, just so I could see where the art style was heading. Once the style was chosen, only then would I start to figure out if the design was technically feasible.


A similar half and half design to the Xbox One and PS4, which have matt and gloss surfaces. 
A chunky hexagonal design in copper plate also sounded great
A very slim, long and simple design. Minimising or hiding all controls and inputs from the front
I explored some of the same shapes and colours in 3D, using Sketchup to create some quick and dirty mockups
By this point I was aware of the size of ITX and SFF components and had a rough case size in mind.
This helped me work with some units when modelling
Technical Design


I decided to pursue and modify Concept 2#, it was a simpler design and there were areas of Concept 1# would be technically more difficult to implement. I needed to determine what parts of the design were feasible and the layout of the components within the case. There were three main parts of the design up for negotiation: orientation of the graphics card, form factor of the power supply, choice of supported components and airflow solutions.
It's worth mentioning here that I had also started investigating materials and fixtures. Like many cases, sheet steel construction would provide the strength and simplicity that I required for the inner shell. I planned on using premium materials to cover the steel shell and where possible, be fixed from the inside of the case so that no screws would be on show. My technical designs started to consider how the pieces would be made from bent sheel material and fit together.
I had experience using graphics card riser cables, so I knew that I would be able to re-orientate the card how I liked. Many other HTPC cases that I had seen use rigid risers and have the card fan facing downwards. I really didn't want this, it was important that performance cards get fresh air from outside the case so I wanted the fan to be as close to the console lid as possible. I planned to incorporate a design into the lid that provided direct airflow to the components.

I built a bunch of scale models to check the real-size of components. SFX and Flex ATX power supplies here. 

I'd recommend this technique since 3D models can sometimes detach you from the relative size of objects.
An ITX motherboard and a SFX/short graphics card.
Side note: the questionable meatballs are NOT mine ;)
I chose the Flex ATX form factor for its tiny height, just 40mm! The SFX power supplies were around 80mm and up. I started modelling and worked on translating my concept designs into a technical design
I decided the simplest layout of positioning the components next to each other would allow me to keep the case in a flat console style.
I explored a bunch of different front port options
Investigating ways that the Graphics car mounting would work in the simplest way
I started mapping the mounting holes for Flex ATX PSUs
The front panel assembly for the USB's + power button was something that I would have to create.
This was an early solution I came up with.
The tolerances were going to be tight. I learned that folding very near holes in the sheet would likely compromise the shape of the hole, so I had to redesign some sections several times.
I was having the same problem with the graphics car supports and was unsure if they would still hold thier shape after being bent

Final Design


I combined the learnings from my technical design investigation and produced a final concept design of what the case was going to look like and how it was going to work. The final design includes ventilation in the lid, mounting for all components, a front panel assembly and cable management solutions. I was also able to find solutions that would allow me to construct the case from the inside, hiding nearly all of the screw heads.
Having a solid technical design also allowed me to go back and design the asthetic parts of the console, knowing that it would be feasible to create. I had started searching online to see what kinds of parts were freely available: thin panels of real wood, thin and affordable premium metal panels, fixtures.





....And there you have it! During the design of the final concept I also nailed down a lot of the technical details that you see in the images above. I'll go into more detail about the shell design next post and explain the role the of the spacers and also why I chose to separate the case into several different pieces. Other small decisions like the position of the power button were finalised, I really liked the idea and look of cutting the corner off the case.
I also began using CAD software to translate my sheet designs into something that can be fed into a machine and made. I have many tips and learnings from that exercise that I can share here.

Before I leave the first post, I should probably show some work in progress right? Oh okay, can you tell what it is yet?





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CAD Packages & Sheet Metal Design

As I started to reach a final design for the case, I needed to think about what software I was going to use to translate my Sketchup model into a sheet metal design that could be read by a machine somewhere to manufacture. I didn't really consider creating the case by hand, the design was going to be tight and required the precision that only a laser or CNC can provide. I needed the confidence that I could create the parts separately and know they would come together and fit perfectly. Part of the process was defining how the case was going to be fixed and compare the benefits of having the case as 1 large folded piece or made up of several smaller and simpler pieces.

After a broad internet search I came across an American company called eMachineShop that actually have thier own softwate which can model sheet metal bends and also privide instant pricing and ordering from within the software. I didn't actually buy anything from them in the end, but I found the software and simulation of bends very useful.

An early attempt into creating a CAD design of the case pieces

I explored different layouts within the software to evaulate the price difference for the part.
This design was never going to work! Not sure what I was thinking... :D


Here's the design coming together a bit more. You can define bend lines & give them an angle.
I also added tons of notes for myself and the machinist


A 3D render shows the parts after being bent. A useful instant-visualisation

This is my final design in CAD format. The 4 panels, the brackets for securing the shell to the wooden base,
the SSD bracket and the Front I/O assembly bracket


The 3D render of those parts


There is definitely something to be said about modelling the bends of individual pieces to check thier position after being bent. A 100mm sheet strip for example, bent across 90 degrees, doesn't give you two 50mm lengths (measured on the outside of the angle) because of the radius of the bend itself. If you're still interested, keep reading :P. After a bit of searching, it turns out every type of bending material has a "K-Factor" which is a value applied depending on the material and the thickness of that material, to calculate the length of material needed before being bent, so that your measurements (screw holes etc..) remain correct after the material has been bent. This effect is magnified the thicker the material.

I used a tool to calculate the sheet material required so that it would be correct after being bent.
You can see an example of the calculation and values for this below.
Note that to get 50mm after being bent, each length needs to be slightly less than 50mm (49.045mm etc..)


Origami Time

The next part of the journey was to create a version of my shell in card to check that it was going to fit together and to try out my card-components that I had made. Now, this method turned out really well (and I consider this a top tip actually :D) but I searched and found a CAD package that allowed me to print the CAD design at real scale onto paper, which I then glued to card and cut out with a craft knife. For the printing I used DraftSight.


The print didn't fit on one A3 sheet, so I had to improvise!

Glued on...

Cut... and assembled with some tape

You can see the relative height of the case shell. Those meatballs again...

I set about placing the components in the shell

I got out an old bracket and tried the fit. Pretty chuffed that it was spot-on

An old I/O Shield. The card broke at the thinnest parts, but it was enough to verify the fit was solid

The mounting holes for the PSU - lined up like a dream too

And the USB ports! ... very important that a comfortable fit was made

Seriously, all this was great to build confidence in the measurements before I put any money down to have the case made. Nothing worse than being disappointed.



Additionally, you might be wondering about the measurements for the all of the screw and I/O apetures. I created the design based from a small selection of technical specs that I saved from various sources. They are here if you want to check them out. The Motherboard one was particularly important because it not only defines the size of the apeture, the the relative position and mounting holes for the motherboard itself - which is usually fixed to another part entirely and needs to line up perfectly.

-  The Motherboard I/O Apeture
- The double height PCI bracket dimensions
- SSD Mounting positions
- Flex ATX  Power Supply Mounting holes

An illustration of the dimensions.

That's all for now...

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A big part of building small form factor computers seems to be about figuring out how much power you will actually need, before trying to pick from a wide array of power options. I think there is a general trend where people over-estimate how much power thier system uses, insisting that anything under 500W isn't going to cut it. It turns out that is mostly wrong, especially if you choose efficient components and also strip away all of those bits that you probably don't need (optical drives, hard drives, additional PCI cards + case parts that require dedicated power).

After reading a bunch of bit-tech articles on CPU and GPU power consumption of various similar components, I calculated that anything above 300W should be sufficient, but a 400W or 500W would give my system more 'wiggle room' and operate more comfortably.

Pico PSU - I discovered Pico PSU early on. They have an external power brick that converts the AC mains to DC. Then an adapter inside the case splits the voltage to the required components. I think though, that the highest Wattage they support is about 160-200W, which simply wasn't going to be enough for me. Though, this looks like a reasonable choice for anyone with a HTPC-type system and doesn't have a dedicated GPU (or has very low power GPU). Seen here is an example of the power brick and adapter. Note the power brick isn't very pretty either!


SFX Form Factor - On the other end of the scale, Silverstone have some super powerful supplies in a small form factor. The smallest volume they have is 100mm x 125mm x 63.5mm(I think!), which is available up to 600W! For quite a while I contemplated using one of these supplies and was trying to figure out how I could orientate the supply and components inside the case, without wasting valuable space. Positioning the PSU next to the other components would waste space in at least two dimensions. Event positioning the PSU behind the other components would add extra height and depth to the console that I didn't want.


Flex ATX / 1U Power - Then I came across the standard form factor for server power supplies. These come in wide variety of shapes and sizes and you'll see the names "Flex ATX", "1U" or "2U" used to describe server power supplies. While I do know 1U and 2U refer to single and double height supplies, I'll admit I'm still unsure if flex ATX is the same as 1U!

Either way, they're all 40mm in height, which is very close to the 'flat' height of any GFX card you might see and also pretty close to the height of a motherboard with stock cooler and standard RAM. The width and length of these power supplies vary A LOT, but the smallest comes down to about 81mm in width and 150mm in depth - which again, is pretty close to the 170mm depth of a ITX motherboard and the 150-170mm length of a graphics card. They also come in Wattages from 100W up to about 500W (if you can get your hands on one). The 350W and 400W specced models are quite common though, and sufficient for what I wanted to do.

A 40 x 81 x 150 Flex ATX PSU

Be Aware that many 1U supplies are the larger 100mm Width or are very long!

Other 1U supplies also do NOT ship with standard cables or are hot-swappable units. Check before buying!

In the end I purchased a 400W Flex ATX supply from FSP. The power should hopefully give me enough room to operate comfortably without over-burdening the PSU. The manufacturer also came highly rated, so we'll see how it fares!

Last Note: I discovered HD-PLEX after I purchased the power supply. Which seems to be the basis other modders have built small form factor PC's with dedicated graphics. Another power brick style solution that provides much more power than Pico PSU. Something to consider for the future!


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Manufacturing the Shell

I started researching companies that would be able to take my CAD files in DXF format and manufacture the case parts for me in sheet metal. I started looking at a few big companies in the US, including the company who's software I was using. But after a few emails to thier rep, it became clear that they would require the design to be as flat-packed as possible, otherwise the shipping cost for the parts was going to be huge. I got some advice from a fellow modder on this forum and contacted in a bunch of smaller companies in the south of the UK, where I live.

After chatting to a few local sheet metal manufacturers, it became clear I had a few options regarding how much work I wanted them to do. Generally, the less work that needs to be done by the manufacturer to setup the file and the design, the cheaper the cost. As a result, I did all of the design work and took all the responsibility for the fitting and measurements of the parts. I found there were 3 main options:

Most expensive: You provide a 3D model or non-technical drawing. The company re-creates the design in 2D CAD and translates your idea into a complete product

Average cost:You provide CAD designs that require tweaking/modification before manufacture. The company products the final product

Lowest cost: You proved exact CAD designs that require no additional work. The company doesn't build the product, but just produces the finished parts

I spoke to a few guys that would take my files and supporting documents and produce the parts for me at a reasonable cost. It turned out being able to have a few phone conversations with a local company was great. They even recommended the specific type of mild steel (Zintec) and the thickness required.

A few weeks later, I got an email that the parts were ready and a very excited me went to go and pick them up :D

Seeing something real for the first time, after it only existed on my computer screen for many weeks. Totally awesome...


The stainless steel spacers take standard M3 screws. They won't be seen when the panels are on

The metal was laser cut directly from the DXF file, so matched perfectly to my paper model

The PCIe bracket bend. Worked out really well!

The button bracket assembly

The SSD Bracket. Driving a PC case screw through the holes created the thread itself.
The holes turned out to be a great fit for this purpose

I started to test-fit the components that I had

The Motherboard I/O panel. Looking better than my paper case fitting :D

I threaded the holes for suporting the PCIe card

I purchased some 12mm deep M8 hex brass bolts to try out. I created the thread and slotted them in to test the fit

And there it is. Naked, and with no lid or base. But it's coming together! It feels great to see the edges and angles in real life.
I'm also super chuffed that everything fit together so well.
It's going to be so small! ha ha.

In the next update...

This is what I was up to while I was waiting for the case to be completed. More detail on the wooden lid and base soon. I spent a bunch of time trying to find thin-solid wood. It's so much better looking than plywood and other man made boards.
This was my first attempt using guess-timated laser power settings for the etch + cut.

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  • 2 weeks later...


Wooden Lid + Base

When I started searching for materials to use for the lid and base of the console, I knew that plywood and other man-made boards weren't going to have the look that I needed. The problem with that was, natural wood boards aren't usually supplied in the very-thin thicknesses that I would require for the console. I also found that nearly all suppliers sold natural wood boards in standardised plank widths (usualy between 100mm-200mm plank widths), which was pretty frustrating because the console measures about 207mm across the short edge.

In the end, I found a company that sells 'furnature board' for furnature makers. It comes in Pine or Oak and is professionally glued end-on-end to provide really wide (and thin) natural wood boards. The thinnest sheet that they had was 6mm thick - which was about right for what I needed, so I purchased some of this in Pine.

Lasers - I also spent a bunch of time figuring out how I was going to actually make designs in the lid so that it both looked great and allowed enough airflow for the components. Since all the components are layed flat, the airflow of the lid was crutial to allow the heat to rise up and escape. I searched online for laser cutting services, which threw up a bunch of results in the UK. But a friend told me about a local 'hackspace' where the idea is; you pay a monthly fee and gain access to a whole range of support and machinery that would cost any individual a lot of money (too much for a single project). It turns out they have a couple of laser cutters, a small CNC machine and a bunch of other metal and wood working machinery that I could use myself - result!

I cut a sample of the boards to 450mm in length to try out my first lid design

The wood is great. It's great quality and looks and smells like fresh pine

Before I got the board cut, I wanted to check the total height quickly

With the 6mm pine boards, I'm at 62mm high in total - not bad! :)
(so thats 50mm internal space plus two 6mm boards)

This is my first design for the lid. I'm going to take it down to the Hackspace and see if we can cut it!

Annnnnd, we did it! The pine was a odd material to cut because it varies in density around the knots and grain of the wood.
Some parts took a couple of runs before the laser made it through

The contrast of the black lasered edges against the fresh wood looks great. You can also see to the right here, some of my curves were not actually cruves, but very small straight lines - I need to fix this before I try again.

The base was also cut. It contains mounting holes for the shell and the hardware
Exact-positions I might add! If I've done all my measurements correctly, everything should slot into place

I did a test-build to check everything fit together OK. First the L-brackets

A close up of the L-brackets

Then I slotted the shell onto the brackets and screwed it in

A close up

I placed the lid on and was happy to see the lid screw holes lined up for my brass bolts

It's still 'naked', but I'm chuffed that it fits together so well

The back view

And the scale shot against those meatballs

A Quick Graphics Check!

To finish up this post: I borrowed a small form factor Graphics Card off a friend, who had a few lying around. I just wanted to check the fit and see how much room I had when I pulled a random card off the shelf.

The mounting at the back was really tight, but I got it in and it feels really solid!

Space inside the case pretty-much lines up with my 3D model and expectations, which is great.

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PCI-E Riser Cables

I had a bunch of options when choosing a riser cable and I continued on research that I had started when I built my wall-mounted PC. The difficulties with the console build would be bending the cable into the small space and making sure that it actually worked, operating so close to the underside of the graphics card and edge of the motherboard.

Option 1 - Buy another Premium Shielded Riser from 3M. However, they are very expensive and I was concerned that I simply wouldn't be able to bend the cable into place in such a small space. My wall mounted build had big bends in the cable and I was able to appreciate just how thick the cables are.


Option 2 - Try to manually shield, an unshielded cheap cable again. These cables are super cheap. But when I tried this before, it worked fine, then didn't work, then worked fine again, then stopped working completely. These cheap cables are so hit and miss. I don't think this would work so close to my other components. Also, the contacts aren't very strong, which is something that was immediately obvious when I got my hands on the more premium cables


Option 3 - Buy one of the cheaper, but still premium shielded cables that exist online. I was tempted by these ones that are sold on ModDIY.com . They look to have re-enforced contacts and thick shielding

Option 4 - I discovered another brand of premium shielded cables from a few members of the small form factor forum. Li-Heat cables seem to be reasonably priced and they come in a couple of different styles that have 90 degree angled ends in a few orientations. This seems to dramatically reduce the space required to bend the cable around and into place. This was looking like it was going to be perfect for what i need, so i ordered a 285mm length B. type cable through facebook directly from the company.


I tested the fit inside the case to see how tight the cable can be against the edge of the case. I have to say, it's pretty dam close! I think it's going to fit really well. The only thing left to do with the riser is design a few strips that will pin the cable to the bottom of the case below the GPU.


More small updates soon!
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Woody McWoodwork

I started the process of staining the wood to get the antique effect that I wanted. The fresh wood was a nice start, but I needed something that would complement the brass. After searching online for coloured waxes, I found out that the most common technique for colouring wood was dye or 'stain'. There is a bunch of videos on YouTube of guitar makers using wood stain to sunburst thier guitars. So I purchased some small sample pots and gave it a go!

At the same time, I had to work out some weaknesses in my first lid design. Some of the holes were too close together and were causing the top-left section to be rather unstable. I needed to adjust the distance between each of the holes and redesign the location of some of the pattern.

I purchased some "Light Fast Stain" and used a rag to apply the dye to the wood


My first session with the watered down 'Antique Yew' colour, plus a bit of after-sanding

I came back the next day and wacked some 'Black' around the edges, then applied some neat Yew to blend it in

A bit more sanding to achieve the weathered look. And I wiped it down with a sponge to get rid of the excess

After I was done, I really liked the look of it. So I went down and lasered my V2 lid design into it.

The V2 lid, back on the console


The design gets lost quite a bit amongst the black, but it looks great here. Nice knots!

I spent quite some time looking at the second version of my lid. I looked great, but I lost a lot of the laser design in the black dye and I wasn't sure it was going to match the brass panels when I put them on. I realised the 'burnt and weathered' look is quite modern and I failed to make it look antique-ey and steampunk-ey. Lots of the sunburst guitars I looked at used the black, orange, white sunburst. It was just too modern!.

So I bought some 'Rosewood' dye and set about my lid v3 design. This time I would sand it less and not distress the wood as much either.

First layer of the 'Antique Yew' again


About to cut the lid. You can see a softer colour transition and less sanding

Mid way through the job

Aaannnnnnd. The final result for V3. I think this is the one

Both lid and base together

A close up :) Looks good!

Another close up!

I finished the job by covering the inside of the console panels with the 'Rosewood' colour

A close up of the base. The colour really IS nice. It looks very antique to the point where you wouldn't recognise the original colour.

After the stain dried completely. I sealed both parts with some clear oil. This prevents stain and protects the wood.

.......Meanwhile in another part of town..

Brassy McBrassface from Brassville

I ordered some cut-to-measure brass sheet for my panels and they arrived while I was waiting for my wood dye to dry. I ordered two thicknesses (1mm and 2mm) to see how they would fare asthetically and structurally. I was conscious the 1mm might be way too bendy.

My brass sheets! 2mm on the left. 1mm on the right


The 1mm looked cheaper in appearance and wasn't the same grade as the 2mm.
I chose to scrap the thinner material and begin work on the 2mm

I started by sanding the sharp edges of each panel. They had been guillotine cut and had blemishes and nicks.
I then began using ebrasive paper to polish each sheet. I had 120, 240, 600, 1000, 1500 and 2000 papers

I can't remember what grade this was, 600 maybe.

This was 1000

And the 2000 grit

A before and after comparison

All three after the work had been done

These guys need to go through a mill to engrave the name into the front panel, then they'll get some antiquing treatment before being fixed to the shell. Very cool! The material itself looks great when working with it.

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  • 2 weeks later...


Supports + Brackets

So - I spent a bunch of time trying to get the front panel I/O assembly right and trying to get the USBs and power button to line up perfectly. I changed the design a few times after trying different options that appeared OK in the 3D model but had movement when built for real.

I also designed a few pieces to form a bracket that pins the PCI-E Riser to the bottom of the case and also supports the furthest end of the graphics card.

Remember this? it turns out, the smallest stand-offs I could find (5.5mm) were too big.
Additionally, I found that attaching the cables via the back of the connectors and then
bending the cable into place was swiveling the front of the USB out of place!

So I came up with a design that provided more support and sandwiched the USBs together.
3mm acrylic sheet in the middle and 4mm sheet on the bottom. Secured with a single 30mm PC case screw

It wasn't a big deal to create the shape in CAD and go through some trial and error
if the thickness wasn't perfect first time

And.... assembled. Looks like this is going to work

I may also finish the assembly with 3M tape or adhesive to align the pieces together

Here are the pieces I created for the PCI-E cable bracket

A test fit using an old cable. Looks like they will do the job

The thick strip will be covered in self-adhesive foam strip (3mm thick) to stop the screws from interfering
 with the Graphics card and also provide support

That's all I have for now. I've been waiting to get access to a milling machine to get the brass sheets engraved. I also need to sort out some finances and then I'll order all the components :)       Soon!...

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