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custom heatsink machining

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You might want to consider posting some of your works here...just to show people what you can do. I'll bet if you can machine a whole chassis...have it look good, be simple to put together etc....you'd have a ton of customers. Hundreds of people just bought aleph x boards. Group buy on chassis as well? just a suggestion :)

-Matthew K. Olson
 
Hi guys

Not to be a paty killer.....Ive machined custom parts for a few(read hundreds) DIY projects (anything from amps to loanmovers). Its something you get done if you have a GOOD friend thats able to do it for you, or if money is no issue.

A custom heatsink will set you back approximately 4 to 5 times and up, of what an off the shelf heatsink would cost you of the same type/- size.

Ive just made 12 heatsinks (200*200*80mm) for myself, and i sure am happy i didnt have to pay somebody for doing that, it would have been outrageously expensive. Just the raw material (100 euros a piece) is too expensive to be considered for such purposes if you have any other option.

Besides the cost of the material.....each heatsink took more than 5 hours of CNC machining on a dedicated aluminium CNC center.

I dont know how much a CNC hour is in the states, but here you would find it hard to find anybody willing to sell you a CNC hour for less than 50 euros....do the math :(

I have been asked to machine a lot of different things, since i have acces to any sort of modern machine i could imagine, but i have come to a point lately that i usually say no, if i dont intend to do it for free. Most people have no idea how long it takes, and how much raw materials really cost.....especially when people hear the magic word "CNC", they think anything in the world is made in seconds....and virtually for free.

So after spending loads of time explaining people about the options/- limitations of machining, and you explain that you dont intend to work for a cup of tea a day ( just the price of the raw materials is usually enough to do this) , they usually find out that an off the shelf ithem is just fine.

All that said, if you want a pro looking amp, custom machining is the ticket, ive made a few boxes for people according to their own design, it sure does make it stand out of the crowd :)


Magura
 
Custom Heatsink Machining

Material cost is expensive. A 1 inch thick 8 by 8 inch piece of aluminum is about 40 U.S. dollars. If I had a large order I could reduce cost by buying material in bulk. I have a small machine shop behind my house. I don’t make my living at it therefore I have no overhead and I able to keep machining cost low. I have a friend who has a larger shop that has a CNC. We sometimes collaborate on projects. I can use his CNC to machine loudspeaker cabinets and create unique cabinet designs or elaborate heat sinks. I would love to get into making heat sinks or manufacturing speaker cabinets on a routine basis. A routine product would be great. I can make about any size or shape heat sink but it can get expensive for larger pieces. I could also machine smaller copper clad circuit boards for crossovers or amplifiers. The cost wouldn’t be too bad. Programming time can get rather lengthy for complicated boards and increase the machine time. If the circuit layout was in the form of a CAD file I can convert it automatically to a CNC program. A uniquely design custom heat sink and chassis does make an amplifier a distinguishable piece.
 
Hi Jason

As i wrote...been there, done that. It dosnt pay of if you dont do it for fun. Nobody (or a VERY limited number of persons) will be willing to pay for your hours. If people came with a working (working in this case means a model possible to machine, ie. finns not too thin, no undercuts with no room for the tool, etc.) 3D model in a format thats compatible with your cam software...it would be closer to going around, but they usually dont. On top of that im sure your friend will not let his CNC mahine run for free. I get the machine time for free.....and even then it usually scares off people that they cant pay in banas of biscuits for my hours and the material.

About material cost:

You mentioned a 8*8*1 inch piece of aluminium....if you go measure an 8 by 8 inch heatsink, youd find that its between 2 to 4 inches thick...lets just do the math again then : 8*8*1 inch piece = 40$, an 8*8*3 inch piece.....material alone 120$, and thats before you have even thought about cutting as much a one single chip of it.

I machined some copper heat spreaders a while ago....state of the art, just the material cost was enough to make people use words like ripoff and robbery, and that even i get the material at a very good price.

Have you ever actually made a heatsink of a reasonable size? Im not asking this way to put you off of making one, but i guess you should try once before you offer making heasinks as buisness. Its rather hard to do if it have to look good, and on top of that you have to choose the right alloy to be able to make the thin finns at all.(7075T6).

What have you machined till this point? Maybe i can help you out if you want to make heatsinks/ complete boxes, ive made a "few" :)

Magura

P.S. ohhh btw, in this buisness there is no such thing as a large order. Nobody want to have the same as somebody else, if they have gone as far as paying for custom machining ;)
 
Re: Custom Heatsink Machining

Jason Watts said:
A 1 inch thick 8 by 8 inch piece of aluminum is about 40 U.S. dollars.

It's not expensive if you imagine what you could do with that piece. I don't think machining aluminum heatsinks for big amps makes any sense, but you could do platforms for CD-Pro (like Flat Fish for instance), nice small enclosures for GC amps (you could even use copper for more exotic appearance and better performance), interesting looking knobs (there's not too many of those arround), CD and LP clamps, push buttons (like Mark Levinson), acrylic platforms, speaker baffles...

Possibilities are just endless and the above examples are much harder to source than heatsinks, so the demand might be greater, even at premium price.
 
I'm sure Magura already knows what I'm talking about, in fact, his CNC centres probably already have it automatically performed on their G-Code, but I know of at least one piece of software used specifically to reduce the number of pointless, or time wasting moves a piece of CNC machinery makes before you send it the codes.

However, I do think you're going to have a tricky time finding lots of customers due to the machining time per heat sink even with such software running.

You might be better trying to find problems unique to certain tube amp configurations and making a diverse heat sink. Machine a positive, have a negative made in investment and then cast the heat sinks. You could even have it done using inject molding if you could secure enough customers. Both methods would give a very nice finish! Even high quality Petrobond sand gives incredible detail; I saw someone cast a coin's face using it once.

You could scale it up to entire cases. That way you could cast the entire case with heat sinking properties and then just machine specific parts out that each customer wants to use, such as spaces for valves to sit on the top. Rather than working from A to Z, this would start you off more than half way thru and save a disturbing amount of machining time.

For instance, you could mold a simple case, but cover the entirity of it's outer surface in fins. You'd need to keep the cases roughly the same size to futher reduce the manufacturing costs. This way you could have a jig set up on the mill ready to go. Have the custom send you a picture of the transformer - cap - tube layout they want, drop the case into the jig, lock it in, run the code.

You could even have strategically placed locking points on the cases so that would lock neatly onto the mill's table.

It's obviously just an idea, but I'm sure you know what I'm talking about.

I'd have tried this myself but I don't have a CNC mill at the moment, and I feel like my CNC lathe is about to go soon anyway due to space problems.

You could still create some really interesting designs, but just keeping them uniform enough that you could apply them to a number of different layouts.

I'm sure it would massively increase the sinking abilities if you etched the surfaces in some form of acid or sodium hydroxide. You could anodise them and have them look really cute.

This would massively cut down on material costs as you wouldn't be machining huge amounts of base material away; which must get added to the cost of the end product eventually.

I believe scrap metal is worth practically nothing compared to the plates it's bought it. First of all, unless you have a compactor, it has a stupidly high volume to weight ratio relative to the original form it was in. Secondly, it's covered in machine coolant, which makes reforming it messy.

You would also need to use less material in the first place since you could design in structural patterns to reinforce the case, while removing some of the, virtually useless, bulk mass; like drilling holes in iron I beams to reduce their weight without mechanically weakening them to any major extent.

First of all, I would suggest you have an amature caster or hobbyist try casting a case for you. If you have it cast in Petrobond sand you should get quite a nice finish.

There is a group on Yahoo called Hobbicast. It's for people who cast bits and pieces at home for fun. I have been a member of it for many years and know that almost everyone in it will be eager to help you out if they can. Perhaps one of them lives close enough to you for you to pay them a visit and try casting a heat sink. Most of them would probably enjoy the challenge.

The aluminium alloys with silicon in them are well known for having very fluidic flow characteristic, that would help ensure the aluminium flows into the fins correctly. I would also recommend you make the fins quite thick to start off with. As even with proper venting and silicon alloys it's unlikely the aluminium will flow correctly through every single fine if they're too thin. Under pressure, this shouldn't be a problem.

Sand blasting the finished prototype will make it sparkle and help smooth off any bits of leafing. Leaving the surface slightly rough, alternatively, would mean you needn't etch it later.

You are at an advantage as you already posses the CNC machining capabilities needed to make molds. If you want to have the cases die molded under pressue, you will need a mold. Probably made from stainless steel. If you can make this yourself, you could save quite a lot of money during start-up.

Alternative, you could have the cases cast in investment material by hand if you will be making a smaller number of them. You'll just need to be sure that the mold doesn't need destroying to get the cases out.

Just some ideas.

And of coarse, if you decide to go ahead with casting them... I get one for free right?

:D

Kind regards,
John
 
This heatsink ( 11 x 11 x 2.3) can be bought at $50 (black anodized and cut to size). Do you still think that making heatsinks is profitable, unless it's special order (according to customer specs)?
 

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Peter Daniel said:
This heatsink ( 11 x 11 x 2.3) can be bought at $50 (black anodized and cut to size). Do you still think that making heatsinks is profitable, unless it's special order (according to customer specs)?


Just my words :)

You have to be in deep s*** to machine anything like that yourself.

About casting:

First of all cast aluminium dosnt conduct heat very well.

Second, as you that have tried (ive done a few fairly big casts) casting anything of aluminium already knows, casting is also fairly expensive to do.
Pressure casting was mentioned as well. Great idea, if anybody needs about 10.000 pcs of a specific part, else its waaay too expensive. The material cost of the mold alone is on the wrong side of 1.000$ for a fairly small mold. Dont even think about tooling cost.

Peter, you mentioned a few options that pays off. Im sure they do, if implemented in an amp that retails around 2.000$, but both you and i know that there is a huge difference between a guy that spends 2.000$ on an amp, and a DIY'er.
Just look at the projects people have made, the wast majority looks like a 25$ budget project.

Magura
 
Custom Heatsink Machining

Not to get off topic or anything. I have made heat sinks. I have several years experience machining aluminum and copper. Aluminum and copper machine rather well under the right conditions (speeds, feeds, proper cutting fluids, etc.) I have spent a lot of time as a machinist. I have built plenty of molds, and dies. I have spent many hours programming 250,000 dollar machining centers, turning centers, EDMs etc. Many of the items I have made are floating around in space in satellites or contain nuclear fuel for reactors. Heck I even use to work in a foundry a long time ago. I am familiar with most general manufacturing methods (injection molding, vacuum molding, extruding, stamping, casting, etc.) and I am well aware of what it takes to enter into the manufacturing business.
 
Re: Re: Custom Heatsink Machining

Peter Daniel said:



Possibilities are just endless and the above examples are much harder to source than heatsinks, so the demand might be greater, even at premium price.


Anything you want....as long as people have understood that virtually nothing is machined for less than a few hundreds of dollars......and they mostly dont :(


Magura
 
Go for a 'shelf' custom

Jason,

Maybe make a 'shelf' custom design, one you could make in 2-8 qty in one evening and small. The perfect project for that would apparently be a GainClone or other chip amp, as they seem to often be small projects. Grab some E-bay (or better yet, local recycle center) copper and aluminum bars, come up with a neat look and sell them for $20-40 each and you might be able to sell a few units, I'd wager. Front panels for the APOX kits or other items similar 'complex' kits could also be a niche.

I have a small home shop and enjoy checking out the chaski.com site from time to time. I'm not into about anything those guys talk about, but enjoy looking over the wild stuff they do, sometimes with next to no equipment. Plus, they made me happy I didn't sell my shaping attachment. . .

Thanks for the offer. If the right people have an open mind and do the research on raw material costs (i.e. understand nothing is free) it can be a good service.

Sandy.
 
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