Build your own case

[fotios]

Fotios

[fotios]

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

[Steve Dunlap]

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.

[Steve Dunlap]

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?

[MJL21193]

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.

[Steve Dunlap]

Originally Posted by MJL21193

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.

[lgreen]

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.

[myhrrhleine]

Originally Posted by lgreen

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.

[lgreen]

Originally Posted by myhrrhleine

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.

[Steve Dunlap]

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.