Build your own case

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Three more pictures

Fotios
 

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The amplifier completed

In the attached pictures, it is the first amplifier that i made. This moment i construct just the second unit, which will be exactly of the same appearance. I sold the first for 1200 euro, because some deficiencies in the external finish of ALU plates which are not anodized as well. You can see that, although the parts that i use inside are of Hi-End class, i feel ashamed to sell it for more money, because the above. :(
I build the current unit with more care as for its external finish, and i hope to sell it for 1500 euro.

Fotios
 

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Hi Fotios,

That is a very nice looking amp. Thank you for contributing your knowledge to this thread.

I see that on the back you have used the angle similar to what I was proposing. Your's appears to have been bent in a brake instead of extruded. That works just as well, but many here may not have access to a brake. What I present here are suggestions, not rules. You have shown another way to do the same thing that works just as well.

It appears you have attached the front panel the same way I was going to suggest. Did you drill part of the way through the panel and tap the holes? If someone plans to do this there are several guidelines that should be followed. You should use a flat point drill bit. They aren't really flat, just flatter than the other types. A 118 degree point is the flattest you are likely to find. You should use a slow spiral for soft materials such as Al or Cu, however this mostly applies to deeper holes. You should use some type of drill stop to ensure you do not drill through your panel. Do a test hole on a scrap piece first. Use a bottoming type tap to get as much thread depth as possible. As a very general rule, the threaded hole depth should be equal to or greater than the major diameter of the screw you are using. The screw length must be sized to use as much of the threaded hole as possible while still holding the panels firmly together.
 
Since there are no questions, the next logical step is to show a design example. Does anyone have a case size to suggest? Perhaps something you might want to build? If someone doesn't have a suggestion, I will just select some random size. Are there preferences for either amp or preamp?
 
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Hi Steve,
I find a pleasing size for most any amp/preamp is close to standard commercial products. Low power amp or preamp maybe 3 to 4 inches high, 17 inches wide and ~12 inches deep. This give plenty of room for most transformers, height wise.
A high power amp could be taller, to accommodate higher heatsinks.

Nice idea and thanks for the guidance/effort.
:)
 
Hi Steve,
I find a pleasing size for most any amp/preamp is close to standard commercial products. Low power amp or preamp maybe 3 to 4 inches high, 17 inches wide and ~12 inches deep. This give plenty of room for most transformers, height wise.
A high power amp could be taller, to accommodate higher heatsinks.

Nice idea and thanks for the guidance/effort.
:)

I agree in general with your recommendation. I find 17" to be a very practical width. The 12' depth does give plenty of room for most projects other than large amps. I have never liked being locked into the "rack unit" height increments. Why should you be forced to choose a height that is a multiple of 1.5"?

I will work up a drawing by tomorrow (hopefully) and we can begin to walk through the building process.

I know that all of this can be done more easily in a machine shop, but that is not in keeping with the DIY spirit. We are showing how to do it on the cheap, and get great looking results. I say we because I hope other people continue to contribute ideas and share results of their projects.
 
Nice thread

Nice thread.

As an aside, one thing you can do with a chassis is to use an old broken component and recycle it.

Here is a link to how I did it for my DX amplifier-

DX Post 6071

Now back to Steve's original thread.

I have thought of doing it Steve's way and not attempted it for a number of reasons. Its easy to come up with the sizes and brackets but really the details of the parts order can derail this (at leat for me it did). I don't know much about metal or anything else for that matter and I hate to buy something that may be wrong.
Could you think about answering these questions-

- what type of aluminum do you order? (what are the differences between different types and which ones cost more and why?) When you get to these onlinke metal suppliers you get a big list of metals as the first option, its confusing.
- The cutting from these metal suppliers are not very precise, I know I've ordered from them before. They lay the material out on a big saw table and let er rip. Would you spec oversize or undersize and what do you do if the panels are cut with a slight diagonal or something? Would you file, dremmel, sand or do something else?
- how do you finish (round the edges, smooth the faceplate, etc???) or label the aluminum?
- for whatever example chassis you describe, can you post the price and exact ordering specifications you would send to the metal suppler (online metals I believe is your example supplier)? An example order with parts specified would be of immense help.
- How would you incorporate lage heatsinks? There are a number of heatsink issues, if you mount them inside the chasis you need venting in to the top and bottom- how do you DIY this without a drill press making them look nice and even (I have tried using template and it failed horribly)? What is the best way to mount? If you mount them on the ouside of the chassis how is this done? Do you hollow out the 'walls' to make the heatsink area available? How do you color match external heatsinks to you diy case?

These are just a number of issues that have prevented me from doing a full DIY case. Some have common sense answers so you don't have to answer them all in detail; but I think these issues should be of interest to all.
 
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!

Could you think about answering these questions-

- what type of aluminum do you order? (what are the differences between different types and which ones cost more and why?) When you get to these onlinke metal suppliers you get a big list of metals as the first option, its confusing.
- The cutting from these metal suppliers are not very precise, I know I've ordered from them before. They lay the material out on a big saw table and let er rip. Would you spec oversize or undersize and what do you do if the panels are cut with a slight diagonal or something? Would you file, dremmel, sand or do something else?
- how do you finish (round the edges, smooth the faceplate, etc???) or label the aluminum?
- for whatever example chassis you describe, can you post the price and exact ordering specifications you would send to the metal suppler (online metals I believe is your example supplier)? An example order with parts specified would be of immense help.
- How would you incorporate lage heatsinks? There are a number of heatsink issues, if you mount them inside the chasis you need venting in to the top and bottom- how do you DIY this without a drill press making them look nice and even (I have tried using template and it failed horribly)? What is the best way to mount? If you mount them on the ouside of the chassis how is this done? Do you hollow out the 'walls' to make the heatsink area available? How do you color match external heatsinks to you diy case?

good questions!
many of us will want to know these:)
my project will be 15"x7" x 4"high
can't build it soon enough for posting here, but if you can give an example of how to change the above 17'' i think it would help anyone wanting a different size.

my only other thought is how to reinforce for weight.
 
Weight

good questions!
many of us will want to know these:)
my project will be 15"x7" x 4"high
can't build it soon enough for posting here, but if you can give an example of how to change the above 17'' i think it would help anyone wanting a different size.

my only other thought is how to reinforce for weight.

Great!

Here is one idea on how to reinforce for weight, use an angle for the bottom sides of the case (or other thick metal structure) so that you can put some holes in it to place screws in the bottom panel which will connect up through the sides, pulling the bottom up to reduce sag and provide reinforcement.

Below is a before-and-after of such a situation on my krell clone.

An externally hosted image should be here but it was not working when we last tested it.
 
It looks like I have a few questions finally.

Procuring the metal: The link I gave lets you order the number of each part that you want and adds them to your cart. There is a running total that includes the fees for cutting to size. Once your order is complete, you enter your zip code and shipping is added. The cuts are guaranteed to be +.125"/-0". Once a cut is set up, all pieces will likely be the same size. The actual tolerances I have encountered were closer to +0.05"/-0". Each person will need to check with the dealer they buy from for their tolerances.

I prefer 6061 for parts that need any type of work such as drilling and taping.

6061 Aluminum is, by most any measure, the most commonly used aluminum alloy. It is specified in most any application due to its strength, heat treatability, comparatively easy machining, and weldability. If that were not enough, it is also capable of being anodized, adding a layer of protection for finished parts

Think about what you need. For the inside frame, use 0.5" angle. That is second under the Al heading.

The cuts you receive should be straight and square. Take sharp edges off with a file.

For the outer parts such as sides, front and back I like 6061 flat bar stock. This is available in sizes from 0.062" X 0.5" up to very large. 1" X 6" should do for most audio applications.

For top and bottom or very large flat panels, use 6061 Al sheet/plate. This is available in thicknesses from 0.02" up to 4".

Your parts should arrive with very few scratches. Choose the side to show just as you would with wood pieces. 6061 can be filed, sanded and buffed. I will get to finishing later in the thread along with heat sinks and venting.
 
good questions!
many of us will want to know these:)
my project will be 15"x7" x 4"high
can't build it soon enough for posting here, but if you can give an example of how to change the above 17'' i think it would help anyone wanting a different size.

my only other thought is how to reinforce for weight.

For the size changes, just order the size you need. This will be more clear after a design example.

I will cover the reinforcement issue latter also. I can't do everything first.
 
I can't do everything first.

Obviously you gotta work on that ;)


Regarding aluminum alloys, I think that once people get the right tools, and the hang of how to use them, the alloy is less important in most of the applications in a chassis.
What should be noted though, is that copper content is not welcome, if you want to anodize the parts. Also if wanting to anodize, all parts should be the same alloy.

The only alloys that a kitchen table craftsman would like to avoid in general, are the 7XXX types, as they are hard, brittle, and need special attention to anodize. Frequently the 7XXX series alloys are also called "airplane aluminum" or "duraluminum". Both names are just a lay mans term for high grade alloy, and nothing to go by if you actually need such alloy, but good enough if you just need to avoid it.


Magura :)
 
Hi to all
1) Size: I prefer 17" width like John, because is standard for most Hi-Fi devices. For the height, i prefer 100mm because i like slim line. Moreover the heatsinks that i use, are Fischer SK93-SA100 (400mm length X 100mm height). So, the inner depth of case it is 400mm.
2) Plates: The front support plate and the back plate are from 2mm ALU sheet. The decorative front panel it is from 4mm ALU sheet. The top and bottom covers are from 3mm ALU sheet. I use thick covers to support heatsinks in thermal dissipation. I have ascertained that a heatsink removed from the case can touch a temp of 49-50 deg C in idle state, instead when it is mounted on the covers the temp drops down to 35-37 deg C. It should be noted that this amplifier in pics operates with +/-60V supply rails and that the power x-former it is 500VA. You can estimate approximately the power dissipation.
3) I find the ready offered extruded angled profiles some impractical; you can't find each time the size that you want. For this reason i prefer to make by alone the angled pieces. I have a custom made bending press, but to bend ALU sheet it is not so complicated. ALU is soft. You can use a usual bench top vice. First, you cut the ALU piece in the dimensions you want. With a sharp tool you engrave the bending line enough times, say 10-15. Grip the piece in the vice at the engraved line, and with a wood piece and a hammer bit the piece until is bended exactly in a right angle. That is all.
4) For the front plate: I open holes with a 3,5mm slot drill (this which is used in milling machines and its cutting surface it is flat) and i don't open threads with tapper. I use the bolt itself (M4) to open the thread. For a 4mm thick front plate, i use a press drill with stopper to obtain a depth of the hole about 2,5mm. The bolt when screwed, push out the surplus of ALU creating thus a "volcano" around the thread. This volcano adds 1mm in the thread, thus total 3,5mm depth. In the support plate, i open 6mm holes so as the volcano can contained and i add in each bolt (M4 X 6mm) two washers and screw down. If the thread destroyed and the screw does not tight securely (a rare thing) i add epoxy glue on the screw.
I know that these things are difficult to explained with words. Some pictures are better. I will try to take and post some.

Fotios
 
What should be noted though, is that copper content is not welcome, if you want to anodize the parts. Also if wanting to anodize, all parts should be the same alloy.

That is why I am recommending 6061.

Here is an exploded view of the case from the front. To keep the drawing less confusing, I have left out the 4 angels that go from side to side in front, back, top and bottom.
 

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Very good. I was hoping to bring together the builders with experience in building their own cases and to get as many links to other building threads as possible in one location.

Here is a drawing of what the cut pieces for the front or back frame would look like if you miter the ends. Notice that these pieces are shorter than the case dimensions. I am using 0.125" side, top back and front pieces. This must be subtracted from the outside dimensions. You may need to cut these pieces an additional 0.01" to assure they clear each other when assembled.
 

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Here is the same thing with square cuts. I feel the best look is obtained with a combination of the two styles. I like to use miters for the front and back with square for the sides. If you cut your pieces closely you get an almost seamless frame.
 

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As requested, here is the pricing for the case. This does not include shipping or hardware to assemble. All pieces are precut to size with the exception of the extruded angels. If you want the mitered corners, you have to cut these yourself. I also substituted 6063 for 6061. This is because the 6061 is not available in the 0.5" angel. The 6063 anodizes very well also.
 

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