New 5.25 bay HDD Box project - alleycat/sandwiching/copper??

Dimwhited · Post by **Dimwhited** » Sun Mar 09, 2008 6:55 pm

Llllooooonnnnnggggg time reader, first time poster! Starting project!

I'm buying a lian-li pc-a05b soon, and need it to be silent!

I wanted to use one of alleycat's boxes, but there won't be enough room in the case

. I'm working on a solution for that right now, and wanted you guys's input

It needs to fit into a 5.25 drive bay, and it needs to work really well. here is my current idea:

buying six peices of 1/8 inch copper online, and making a box the size of an optical drive, but a little narrower. There would be about .4 inches of vertical space with the hard drive in there, so I would make cold packs(annother forum member did it, said it was easy) .2 inches thick and have them on each side of the drive. I would also make or buy thicker cold packs for the sides. I would then attach some kind of rubber to the sides that would allow me to soft mount it in the drive bay.

I'll put four quarter inch vertical copper posts in each corner to screw into those. I think welding or soldering would be hard (never done it), so screwing is best option (unless you really think its not. I'llcaulk or (gulp) soder the edges together to make sure the enclosure is airtight.

Here are my questions:

1.)Would it be better to skip the gelpacks and use .25 inch aluminum in direct contact with the drive? (deffinately not paying for .25 inch copper) The enclosure won't be transferring vibrations to the case, so the coldpacks aren't needed to dampen vibrations in that respect. But would the vibrations be transferred to the aluminum plates, and cause them to act like speakers? Like when I hold my vibrating phone to a table, the whole table shakes and produces a low, hollow sound. Should I do .25 in direct contact or .125 with thin coldpacks?????

2.)Would .25 inch thick aluminum be too thick to disipate heat? Would it not be able to move through the metal fast enough, and fry my drive?

3.)Are there any other DIY alternatives?

--I wanted to use copper because I might put a raptor in if the new ones come out soon enough!!

Thank you guys so much!!! I love this forum and I love this website! I had a bad run with a 500 watt x-finity psu, and have been here ever sense!! (seasonic energy plus rocks!)

merlyn · Post by **merlyn** » Mon Mar 10, 2008 12:00 am

greetings

just a couple of things to consider.

Why build the enclosure out of Cu ? I haven't priced it up but I'd guess that Al would be cheaper. Cu might look prettier but from your post I'm guessing whatever you build isn't going to look pretty when you're finished!
If you use solid Al internally make sure you isolate the electronics.

1) Interesting question, I'm no expert but I'd say there was a chance so the coldpacks seem like a good idea.
2) this question suggests that you don't understand thermo-dynamics. bear in mind you're looking to dissipate less than 20 watts, Al will be fine.
3) Seriously, how much is your time worth? have you looked at the scythe quiet drive? they can be modded in minutes for suspension. I'm using two right now. they're effective and look a damn sight better than anything i could build! I dunno how much one would cost in the US but can't be far off the Cu you're looking at.

Dimwhited · Post by **Dimwhited** » Mon Mar 10, 2008 9:24 am

my time is valuble; I like to spend it doing things that are fun

I was thinking about putting a raptor inside... I did price up the copper. Then I realized that I can't afford the raptor AND the copper. I can get one or the other... so I'm switching to Al. Its supprisingly cheap - and you can get it pre cut.

I have a good undertsanding of thermodynamics from textbooks... but I havn't had to apply it outside of a physics class. Learning is good.

My understanding was that alleycat's enclosure worked ALOT better than a quietdrive. Alleycat's reduced temps, AND reduced noise. Both are important to me.

Yeah, I could buy a quiet drive, but this seems like so much more fun!!!!

BillTodd · Post by **BillTodd** » Mon Mar 10, 2008 12:32 pm

Cu v. Al - As previously stated, thermodymanically there'll be little difference in this application (the principle thermal resistance is the gel pack). Copper has the advantage of greater density (the greater mass will help to reduce vibrations) and it would be easy to solder the joints (if that's what you were proposing). It's important to seal the enclosure to stop air (and thus sound) leaks. Using a ready made (di-cast) box saves a whole lot of work!

Gel packs will not suspend the drive (the drive may seem to 'float' but it will eventually sink against the metal) , so you'll have to find some foam 'rubber' to keep the drive off the metal work.

I made my own gel packs for my original enclosure, but I am now using a medical/cool pack with some of the fluid drained off, which works as well as the homebrew ones and has stayed dry for the best part of a year (seal the hole well!).

You may not need to add extra gel-packs for the sides, as they tend to wrap around the HDD anyway.

Dimwhited · Post by **Dimwhited** » Mon Mar 10, 2008 5:17 pm

I was actually thinking about draining cold packs while I was sitting in an incredible la-z-boy chair in my livingroom. How I love that chair....

Glad to know someone did it without having it leak!!!

There is a good chance I could get aluminum scraps from one of my friends, so this whole project could ring in under ten bucks!!!

I have annother question however:

Would it be better to use .25 inch aluminum, and a very thin coldpack on the bottom? If I suspended the entire enclosure, vibrations wouldn't matter with the case. I was thinking some more, it doesn't seem like .25 inch solid aluminum wouldn't produce sound if it vibrated. I would still use a cold pack (very thin) on the bottom because the bottom wouldn't be flush.

Price not a factor, would .25 inch AL with the top of the drive in direct contact with the enclosure be better?

I would LOVE a die cast box... but they don't come in a size small enough for a pc-a05. Just a little too long

BillTodd · Post by **BillTodd** » Mon Mar 10, 2008 5:54 pm

If the drive touches the box, it might as well not be in a box. The whole idea is the suspend the drive in the box, so the drives sound (air vibrations) & mechanical vibrations don't make it to the outside world.

The gel-pack mearly helps to reduce the temperature by filling the gap between box and drive with something that conducts heat better than air, while being compliant enough not to tranmit too much vibration. (The gell coincidently provides some damping. Before coming up with the water based gel-pack, I considered a copper or aluminium wool made from fine turnings).

The only advantages that I can see to using thick ally (a dicast box has a wall thickness of about 2mm ), is that it might be easier to screw into the edges and, of course, it'll be heavy, which will help reduce vibration.

Dimwhited · Post by **Dimwhited** » Mon Mar 10, 2008 6:44 pm

That doesn't make any sense?!?!?!?!?!?

There are three types of sound that come out of a hard drive:
idle whurr
seek noise
vibrations

Idle whurr is from the platters in the drive rotating at 7200rpm. This noise has nothing to do with vibrations. My drive is currently suspended, and I still have this type of noise. It happens completely internally, and is simply escaping through the drive housing, through the case, to my ear. With the enclosure, it would have a quarter inch of aluminum to go through as well, which would significantly reduce the noise. Its like putting a brick wall between me and the hard drive - would deffinattely help.

Seek noise also happens internally. It has nothing to do with vibrations. The enclosure helps this kind of noise in the same way a brick wall does.

Suspending the enclosure would get rid of vibrations. The reason vibrations cause a problem is because the entire case vibrates, and acts like a speaker. The aluminum enclosure would be the only thing vibrating.

If I put the enclosure on a peice of foam, the foam would dissipate all of the vibrations.

Is all of that right? It sounds right to me? Instead of suspending the drive in the box, I want to suspend the box... same idea, right? kinda?

...I'm just trying to understand why it won't work well. Please correct me where my logic isn't valid.

BillTodd · Post by **BillTodd** » Tue Mar 11, 2008 4:57 am

This noise has nothing to do with vibrations.

Where do I start???

Sound is just vibration of the air, if it's fast enough we hear it as sound, if it's too fast we don't.

You'll probably be surprised to know that, because the HDD is itself a closed box, ALL the sound you hear from the drive comes from the surface of the HDD moving the air around it, even if the source of the sound is inside.

When you attach the HDD to anything else, i.e. a PC case, this will also vibrate . You can reduce the higher frequencies that are transmitted through the mounting mechanism by using a compliant suspension (i.e. something that will flex enough to absorb the vibration but strong enough to take the weight of the drive.) But, it will not stop the vibrations transmitted to the air from the surface of the HDD.

By enclosing the HDD in an air tight box, the air-vibrations (sound) cannot directly make it out to your ear. The air-vibrations WILL couple to the enclosure but, because the enclosure is Massive i.e. 'heavy' (compared to the air), the transmitted vibrations will be tiny (thus inaudible).

The lower frequencies from the HDD will make it past the suspension (because the suspension acts like a low-pass filter) and they WILL be attenuated by the mass of the enclosure, but by adding another filter, i.e. suspending the enclosure, we can reduce the resultant vibration of the PC case to negligible levels

Dimwhited · Post by **Dimwhited** » Tue Mar 11, 2008 1:22 pm

Thank you so much, I'm learning alot!! I think I'm starting to understand... but one thing is still escaping me...

If the main purpose of having the box airtight is to keep sound waves in the air from coming out, then the main reason thicker aluminum would help is because it has more mass.

Why not get a heavy material... like steel, lead, or whatever else I can find on line thats dense

and use that for the sides of the box? That way I have the cooling properties of the aluminum where it matters, but still have the benefit of a light material.

Thank you so much for your time (and patience!), this is a great hobby... so much to learn!

BillTodd · Post by **BillTodd** » Tue Mar 11, 2008 2:11 pm

If the main purpose of having the box airtight is to keep sound waves in the air from coming out, then the main reason thicker aluminum would help is because it has more mass.

By George! he's got it

Why not get a heavy material... like steel, lead,

lead is dense but poor thermally (worse than steel)

Silver would be good

(better thermal resistance and greater density than copper)

or whatever else I can find on line thats dense and use that for the sides of the box? That way I have the cooling properties of the aluminum where it matters, but still have the benefit of a light material.

I doubt the enclosure material will have any great effect on the drive's temperature as the greatest thermal resistance is from the gel-pack (the main job of the box is to silence). Giving the enclosure the greatest possible surface area will help cooling some.

i.e. make your box out of a finned heat-sink

(This wasn't a great success; there wasn't room for gel-packs and barely enough room for the drive!)

Dimwhited · Post by **Dimwhited** » Tue Mar 11, 2008 7:32 pm

How thin can coldpacks be and still be effective?

In order for my box to fit in a 5.25" bay, it has to be 1.625" tall. If my hdd is .75 in tall, that leaves a maximum thickness of about .2". I'm assuming it would be best to have something like .25" on the bottom and .15" on the top, because the bottom would have to be supporting the weight of the hdd. Would this be enough to sufficiently dampen vibrations? Would it be more effective if I reduced the thickness of the Al on the top and bottom, and used thicker heatpacks?

Where did you get that heatsink material??? I searched google and McMasters, couldn't find anything.

Thank you!!!! Your extremely helpful!!!!!!

BillTodd · Post by **BillTodd** » Wed Mar 12, 2008 4:27 am

How thin can coldpacks be and still be effective?

In terms of cooling, the thinner the better (they have poor thermal conductivity, so the less distance the heat travels the better)

Would this be enough to sufficiently dampen vibrations?

While the gel does help to dampen vibration (they are fairly heavy, being mostly water), they will also help to couple (transmit) the vibration from the HDD to the enclosure, so it's all about balance - it helps to cool the drive (which was the only reason I used one) and adds some mass.

To make a thin gel pack, you'll have to drain most of the gel from the pack, but don't remove too much, you need enough gel so that when it finds its own level it will fill the space between the drive and box.

Leave a little air space in the gel bag to allow the gel to expand and move about.

You may find that you only need a small gel-pack under the drive (near the motor) to keep the thing cool enough. [most modern drives run cooler and quieter than the original one I was using with my home brew gel packs]

Where did you get that heat-sink material???

It was just a lucky find at a radio-rally (a sort of electronics garage sale)
It looked perfect, but there wasn't enough room in it to suspend the drive successfully.