Working with Aluminium

[Nordic]

Hey, been looking at cases for my 5.1 channel gainclone amp, but quite frankly the prices just don't justify the material costs over here... and then you still need a heatsink.

So I picked up the phone and phoned an aluminium sheetcutting place localy (well at the time I only asked for a price for a 10cm x 30cm x 2cm piece of Alu... to use as heatsink), turns out its quite a bit cheaper than I thought (about $10).

So now I am thinking that I could reasonably afford to have all panels cut and make the case myself.

<<<The real question is, >>>
Would I be able to make my own screw holes or do I need to ask someone to put it in with some kind of machine or something?

If you can point me in the right direction or give me a google search term that's actualy usefull I would be very gratefull.
I's going to be one heavy amp, the trafo is just shy of 9kgs, and I still need another smaller one for a preamp to go in there too, so I don't think wood is an option..

[Peter Daniel]

Check this thread: http://www.diyaudio.com/forums/showt...9413#post69413
It contains lots of info on tapping, drilling, cutting and finishing aluminum.

[Nordic]

Ahh so thats what those funny drillbit thingies are for....

My dad had a litle box with things like those, think it had little round rings it fits to and i think there is some kind of handle thing which you stuck through it... but how do I know if the thread is the same as the screw's?

Think I should ask the sheetcutting place if they can do this for me... looks very daunting

[Emiel]

Originally posted by Nordic
(well at the time I only asked for a price for a 10cm x 30cm x 2cm piece of Alu... to use as heatsink)

Please keep in mind that the amount of heat a block of aluminium can dissipate is lots and lots smaller than an actual heatsink with fins and stuff!

If you have the right tools (especially a drill and the right drills to make holes and taps for tapping threads), a good design and the patience it's not that hard to make your own case!

Good luck!

Kind regards, Emiel

[Nordic]

Will definatly try my hand at it with some PC heatsinks for practice (lol will have to avoid the copper core by the sounds of it).

[AndrewT]

Hi,
a counterbore for the bolt heads looks really neat.
Even if the plate is not thick enough to get the bolt head at or below the surface, it is worth doing. Black screws on black plate are O.K. but gold or silver on black plate is something else.
You can grind a flat ended drill to get your own counterboring tool, but you have to start your drill turning after inserting the drill into the predrilled hole or else the drill corners will chew up the plate edge if you do not centre it correctly. Practice on some scrap.

[Peter Daniel]

Or simply get DeWalt drill bits, they are perfect for that: http://www.diyaudio.com/forums/showt...5896#post45896

[AuroraB]

Peter..
How much do you use helicoils ( or similar )..?

In my work ( sounding rockets), - helicoils are used everywhere in alu structures, - not a problem as such for hobby work, except for the money.....

[Emiel]

Hi!

I believe helicoils are used in aluminium if the bolts have to be tightened with high torque and/or tightened and loosened often. Normally they are used in plastics.

Ciao,
Emiel

[Peter Daniel]

When I was working on aircrafts, helicoils were used only to repair damaged threads (pending engineering approval). Otherwise, special nutplates have been used, whenever screws where applied in aluminum: http://airbolt.com/nutplates.htm