Log Björk 10L - University design project

Hiraeth

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Nov 20, 2020
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I'm on my 4th year of my masters degree in Mechanical engineering with specialization in Industrial Design. As part of the program is to find a need and create a design to be produced in a short production of 10 units and sell. I've always been the aluminum-fan and never really worked with wood. Something I wanted to change. My aim was to make a case that was simple to the design, looked exclusive without being too expensive. I also did not want to hide the hardware and go with an open design. I wanted it to be something that you would like to have on your desk. This is 9L.

Because of covid and the length of the course I have limited time, resources and tools. I will therefore go for routes that I can do with handheld tools. The presentation is in two weeks, and I am yet to get hold of tools.

I began trying some kerf-bending of plywood, just making bends in different directions.
Kerf-bending is done by making kerfs (cuts) through some of the veneers and with force/hot water bending it in place with glue.



This went easier than I thought. This is of course just a quick draft. I like the look of it, however it can't quite practically fit a PC.
With proper tools the cuts wont show at all.



I went to SketchUp and Creo in order to make sure to get a design where everything would fit.
I wanted to keep the S shape, however it made it very weird to route the PSU cables, hard to attach the PSU and did not leave enough room for the cables.
Below are two rough drafts of how I would like it to look.





This is a sub 10L, 330x150x200 open air case, fitted hardware is mITX motherboards, SFX-PSU, and most tower-coolers, but preferably the BeQuiet TF cooler (108 mm above motherboard).

This week I need to get hold of tools, and make better drawings so I am able to make the cases efficiently. I am also looking into staining the birch wood to a darker look.
 

Hiraeth

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Nov 20, 2020
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I always make a sanitycheck when it comes to durability. Especially since I'm working with wood that is not as strong as metal.



In the simulation above, I have calculated with a single point 40N load in the position of the cooler. This is a rough estimate of the normal weight with some margin. As you can see on the left image, the maximum stress is 2 MPa. The yield strength of plywood is about 15 MPa. This is of course affected by the kerfs and glue, but at least it shows that it is viable. On the right you can see the deformation, which is 2mm in the top. This will be less in reality as the components will provide rigidity.
 
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Hiraeth

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Thanks for your kind words! The one thing I wish I had access to in order to elevate the design would probably be a CNC and a laser. Would be kind of dope if the buyers could choose an artwork to laser-etch in the front piece or such.

I just ordered the SF600 from Corsair, as well as the BeQuiet TF cooler and Asus 570X motherboard. I already have some nice 64 GB DDR4 and a 3070 that will fit quite nicely. Update in some days!
 
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Skripka

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I like the draft.

The only thing you might consider/address is electrical grounding. Since you're dealing with organic media, there's no path to the PSU grounding for the surfaces of components as they are not 'networked' by a metal chassis.
 

rfarmer

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Thanks for your kind words! The one thing I wish I had access to in order to elevate the design would probably be a CNC and a laser. Would be kind of dope if the buyers could choose an artwork to laser-etch in the front piece or such.

I just ordered the SF600 from Corsair, as well as the BeQuiet TF cooler and Asus 570X motherboard. I already have some nice 64 GB DDR4 and a 3070 that will fit quite nicely. Update in some days!
Not sure if you have ever tried mounting the BeQuiet TF before but it is very hard to install on almost all itx motherboards. The Asus x570 is listed as incompatible on BeQuiet's site. It will usually collide with either the ram or the vrm heatsinks.
 

Hiraeth

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Not sure if you have ever tried mounting the BeQuiet TF before but it is very hard to install on almost all itx motherboards. The Asus x570 is listed as incompatible on BeQuiet's site. It will usually collide with either the ram or the vrm heatsinks.
Thanks for the headsup. I have some really low profile RAM, but I will investigate this... I would like to have a pretty large cooler, but not that goes out of the case or past the GPU.
 
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Hiraeth

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Nov 20, 2020
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I like the draft.

The only thing you might consider/address is electrical grounding. Since you're dealing with organic media, there's no path to the PSU grounding for the surfaces of components as they are not 'networked' by a metal chassis.

I have thought about this, however the PSU and motherboard should be grounded by the wiring in any way needed. As they are connected with ground cables they are effectively grounded. There is no need for a metal case really. All components are connected to the motherboard, and the motherboard are connected to the PSU. Can't see any components voltage run off there.
 

Hiraeth

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Nov 20, 2020
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Not sure if you have ever tried mounting the BeQuiet TF before but it is very hard to install on almost all itx motherboards. The Asus x570 is listed as incompatible on BeQuiet's site. It will usually collide with either the ram or the vrm heatsinks.
I found this video , it seems like they are using the same motherboard with the BeQuiet TF! A tight fit but should be doable.
 
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Hiraeth

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Update! The weekend is closing in and I want to get started on the cases. I've been waiting for my new cooler and motherboard to arrive in order to get some final measurements. My month long search for an open workshop has been in vain. I had to get this done one way or the other, so I went shopping.

This will come in handy in later projects. I can't wait to have my own house with my own workshop. For this project I need a plunge saw and a router. A sander would probably be nice too, however I think the one I have should do the trick.



There is something special with small motherboards, this one was a bit expensive, but my old Gigabyte has been nothing but issues, weird noises and the PCH fan broke down after some weeks.



Assembly time!



As @rfarmer had warned me about, it was a real close call with the cooler. However it fit perfectly, not one millimeter wasted!



I also picked up some standoffs, and a nice SF750. This build is running benchmarks completely silent. 900 RPM only, can't hear anything from it.
Next update in some days!
 

Hiraeth

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Yesterday I began making my first kerf-cuts in the actual wood to be used for the cases.
It's a time consuming process, but also a scary one. Hours of work could be ruined by one skewed cut, or a too deep one.



There were quite some residual stresses in the wood, probably from the gluing process, which ment that it was bent in every weird way.
I am trying to fight this by putting some weights on for a couple of days.

55 kerfs later and it seemed it went fine. There are things I would have done differently that would have made the process easier, but those are changes I might do for the next batch.



Kerfs look cool, didn't think you could do such things with a saw and a rail.



To give you an idea of the tolerances here, the thickness of the last layer is about 0.5-0.8 mm thick, but fibers are strong and with glue it makes a very tight bond.


I decided to also try out the router, which was a new tool for me too. I 3D-printed some templates to use and given it was the first time trying it went very smooth.



Now for the bending, it's a part where I've spent hours with trial and error.
Too thick last layer and you must soak the entire thing in water for hours before I could even try to bend it. It would almost always snap from the stress.
Too thin and the layer might break of that reason. I figured out that it's better to be "too thin" than "too thick", as the thickness almost always ment that it broke, while the thin ones never did, although they felt fragile with no glue. Putting water in the kerfs is also something I want to avoid as the glue probably works better on a dry surface (even though there are glues and epoxies that work with water).



Next time I hopefully have somewhat of a full case to show you! I am also looking at certain stains in order to darken the wood.
 
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