Hand-made aluminum heatsinks

[Petter]

Nice pictures. Nice work.

1. Can you write up a short "recipe"? Did you for example mill the complete thing flat after assembly?

2. How are you planning to attach the transistors?

Petter

[grataku]

Does anyone know how well these heatsinks will work in terms of heat transfer since they are not one piece alluminum?

[vdi_nenna]

...I guess these two go hand in hand. I was planning on trying to attach the trans. directly to the heatsink. But, I don't think this is the best way, because no matter how straight and perfectly lined up the pieces are, you still get gaps.

A way around this is to attach a solid rod across all the fins and seperators, or an L-bracket. But first, add liberal amounts of silicon grease to the rod or L-bracket. Then, attach the trans. to the rod or L-bracket. This will also give you slight more surface area.

Lou tells me that Aluminum is dirty. I guess he means when working with it it get diry because of the cutting grease. He said to use 2 part water and one part clear vinegar to clean the parts (if milled).

On this site, look under Amplifiers> Construction> Massive Class A Heatsinks. The plans are nice. The guy who set it up is a nice guy, very helpful too.

I decided to try this because I'm tired of looking for large heatsinks. This method allows me to have 2 sides of the case already finished and provides an easy way to attach a front and back panel.

I'm going to assemble these sinks around my Zen amp, that runs on two amps right now. I'm going to rise that to 3 amps. I did some basic calculations and they are more then enough for that design. When I'm done, I'll put the whole thing on my site.

Does anyone know the proper way to take case temps from a trans.??

Vince

ps, they were not milled flat after assembly. They are however very flat just by quickly putting them together, as they are in the pictures. I could probably get a flatter surface by making minor adjustments and then torquing the ends. My brother says there is a adhesive that can be applied to the end where the bolts are attached. He said that high temps don't effect the adhesive. The aluminum would melt before the adhesive does. His words, not mine...

[Edited by vdi_nenna on 03-23-2001 at 01:39 PM]

[Petter]

For rods and nuts, please consider not using anything with Iron, and if you do, check that it is not magnetizable (you get stainless in magnetizable and un-magnetizable). Parts with iron in them are not recommended at all. Brass is a much better alternative if it is strong enough for you.

Most cases are made of steel, but steel is crap. Use aluminum or better still copper since Aluminum does not have perfect magnetic properties either (it is in fact paramagnetic)

Goint into a detailed discussion on magnetism is beyond my scope of expertise, but Iron content is certainly always an enemy (ferromagnetic), particulary since there will be large currents in the output stage.

[vdi_nenna]

What are the effects, Petter? Most mid-hi fed. audio equipment uses sheet metal. I understand that most of it isn't high current apps, but how much difference can 12 bolts and 4 rods have? Wouldn't the surrounding case be more of a concern?

I checked and they are magnetic. Brass parts wouldn't be that much more in price, I guess, if I can find them. I have to check my sources...

thanks!!

[Petter]

If you look inside even very expensive audio equipment, you will find a lot of cheap parts. One of the most expensive portions of an amp (and let's face it, they are ALL designed to a budget) is the box.

Building boxes out of Al is a pain in the butt. They are expensive, and box manufacturers don't necessarily have equipment for this.

Folding some cheap strong iron is easy, and if you paint it afterwards, nobody can tell the difference anyway.

Anything magnetizable is bad in the box, end of discussion. Ideally, you would put transformers externally as well.

[vdi_nenna]

Thanks for the info. I think some things are unavoidable, especially when we trying to save a buck and cut corner in construction methods. Ultimatly, I'd like to obey every rule that will make a beneficial difference in the sound.

[Petter]

This is one of those rules you should seriously consider following.