Its not usually so much the $ as it is the time. Believe me, I see your point, but it takes me a dang long time to do work like that, even w/ help. My grandfather helps me...he was a prototype toolmaker and really knows his stuff, but that doesn't mean that everyone has time to put together a case. Maybe rather than spend 5 hours+ building a case it'd be more efficient for someone to buy the case instead and then go from there. I'll shut up now and let someone else weigh in on this. But believe me Peter, I do see your point, which is why I'm shutting up :-D
-Matthew K. Olson
-Matthew K. Olson
Okay, first of all... why machine the front panels?
If you cast in an investment or plaster based mold they'll look just as nice. Precious metal jewellery is investment cast. The surface of the molding is incredibly smooth and will give nice sharp edges if needed.
The kind of casting most people are used to is done in water based clay sand. I have some of this myself, it's like lumpy sand and isn't particularly great.
I also have a bag of Petrobond sand. It's almost uncomparable. The Petrobond smells like a kind of sweet oil and the sand it's self is like squishy play dough. It's very soft, almost like skin, not gritty like river sand. This is because it has been squashed together, while mixing, under quite a lot of pressure. The sand is bonded with a rare organic clay, which is expensive compared to normal clay, but nothing in the long term picture. It's the same clay as used in expensive paints actually.
I have pushed wooden patterns into the Petrobond sand and seen the grain of the wood in the resulting piece of metal. It is very accurate. Investment casting is even more accurate.
Please not that by investment, I do not mean under an inert atmosphere using pressurised molds. I simply mean the mold is made from investment material, you could pour the metal by hand.
There is a big differences between investment casting and the nasty sand pitted iron castings you see that have been cast in water based (wet) sand.
Casting metal is not expensive if you do it yourself. I have seen tens and tens of guys do it in there yard with furnances they've made themselves. If you're in, or near the US, you could probably buy a perfectly sized kiln or furnace from ebay in a liquidation sale for next to nothing.
Say I wanted to cast the one half of the face plate on the case, I wouldn't expect to spend over $100 on refractory material. Sand... $20 for Petrobond, less if you can find one of the Hobbicast guys willing to mull some for you. Heating equipment, you can make yourself in an afternoon. Gas handling, $40 maximum for a new propane regulator off ebay?
If you're even moderately intelligent and practical in nature, you can easily make this stuff yourself. I cast bits of aluminium on my own when I was about 16.
The grill on the top well take forever to cut on a CNC mill, especially the kind of CNC Bridgeport knee mills every DIY'er buys. Have it laser cut for you, or plasma cut. It will take about 2 minutes instead. Or even better, look for somewhere producing it in bulk already. I have even seen plans for attaching a plasma torch to a knee mill, forming a plasma table from the mill's table movements. Like a pantograph.
Buy the heat sinks to go on the side, it's pointless trying to machine them cost effectively. Buy a case to base it on underneath.
You're making this all far too complicated. That case is seriously impressive to look at. But if you spend another few minutes looking at it, you can see that there are a number of things that have been done which needn't be if you were to produce a number of them.
What's the point in hand casting the casing underneath if it's almost totally unseen?
What's the point of spending hours and hours of time machining the front panels when they're simply enough to cast at home? It takes minutes to set up a mold once you have the parts ready. I am quite confident that anyone here who's as used to working metals as you are could replicate that front panel in an investment casting with nice sharp edges on it.
Before you question how well you could cast metal at home, I should tell you I have seen far more than one or two of the guys I know who cast in their yards who've used furnaces built from empty propane tanks to cast entire desktop machine tools. A number of these have been lathes or drill presses, although one was a shaper. The quality of the end tool was absolutely evil.
You're not looking at this in the right way. Only manufacturers like Audio Note would think 'Lets machine the heat sinks', because they know the guys buying their high end systems can afford to pay hundreds of dollars without even thinking about it most of the time. If you're buying a Hi-Fi worth $200,000 what's $300 extra?
It's like paying an extra $1000 for a small improvement in sound quality. If you have the $1000 spare, you can warrant spending it much more easily. If not, you question whether or not you need that almost undetectable difference.
Rather than picking up any bits of junk aluminium to melt down, you could ask at alloy working yards if they have any continuous output of scrap alloy in a usable state.
For example, they may only be able to get three lengths of usable material from each bar of aluminium they buy, leaving a short amount spare. This would be exactly the same as buying it in it's original length to you. In fact, it may save you the effort of cutting it up.
Have a look into investment and plaster based molds. You will be seriously impressed with the kind of quality you can produce with them!
I dont know about the rest of you, but there is no way a surface that isnt either machined or extruded gets in my livingroom.
I do casts frequently in steel molds, even in steel molds the surface is somewhat un-appealing.
If anybody want a cast version, thats sand blasted.....sure it can be done for next to nothing.
I allways machine my casts on all surfaces. First of all for the dimension stability, and the surface quality.
Aluminium must be anodized to avoid oxidation of the surface. Fact is that you cant anodize a raw cast surface with reasonable results. Even a machined surface of a cast is not allways turning out perfect.
To make something like what Peter have made sure wouldnt be a big deal, but if you have to buy the heatsinks off the shelf, they too would turn fairly expensive.
What Peter have made there is sure not very time consuming to make. I would guess such could be made in about 1 hour if a reasonable number is to be made...like 50 or so.
Magura
I do casts frequently in steel molds, even in steel molds the surface is somewhat un-appealing.
If anybody want a cast version, thats sand blasted.....sure it can be done for next to nothing.
I allways machine my casts on all surfaces. First of all for the dimension stability, and the surface quality.
Aluminium must be anodized to avoid oxidation of the surface. Fact is that you cant anodize a raw cast surface with reasonable results. Even a machined surface of a cast is not allways turning out perfect.
To make something like what Peter have made sure wouldnt be a big deal, but if you have to buy the heatsinks off the shelf, they too would turn fairly expensive.
What Peter have made there is sure not very time consuming to make. I would guess such could be made in about 1 hour if a reasonable number is to be made...like 50 or so.
Magura
I wouldn't even have the heat sinks on show unless they were pointing downwards; as per the case in this example.
I can't stand having to, every few days, wipe dust off expensive electrical things to keep them looking neat.
Heat sink fins are the ideal place for dust / muck / hair / bits of pizza / biscuit crumbs and crisps to gunk up, especially if you have kids I imagine.
I can see where you're coming from. Gas turbines are investment cast and can be amazingly accurate right from the mold though, and these have to be very secure mechanically otherwise they'll fail when they're spun up to their operation speed, so I'm still sure you could achieve something at least good looking.
To kill the cast heatsink idea once and for all....cast aluminium is no good for heat transger(unless its pressure cast, that helps a lot).
Any heatsink have to be either extruded, machined from solid billet, a combination of the former 2 or pressure cast.
A frontplate could be cast, if it wasnt for the problems of the later surface treatment. Then youre back to machining again, if you have to machine the surface of the cast....you may as well machine the whole thing from scratch, since theyre not all that big anyway.
BTW, youd find it hard to get convection cooling to work properly if the heatsinks are facing downwards...they need to be out in the open...hence on display (counting out forced cooling systems)
Magura
Any heatsink have to be either extruded, machined from solid billet, a combination of the former 2 or pressure cast.
A frontplate could be cast, if it wasnt for the problems of the later surface treatment. Then youre back to machining again, if you have to machine the surface of the cast....you may as well machine the whole thing from scratch, since theyre not all that big anyway.
BTW, youd find it hard to get convection cooling to work properly if the heatsinks are facing downwards...they need to be out in the open...hence on display
(counting out forced cooling systems)Magura
No no no no... I don't mean cast the heat sinks!
I mean investment cast the face plates, and other bits that aren't too complex.
My version of pointing downwards was like the ones attached in the picture, so any muck hitting them would just run down the fins and onto whatever the amp was sitting on, rather than into the base of the fins.
I mean investment cast the face plates, and other bits that aren't too complex.
My version of pointing downwards was like the ones attached in the picture, so any muck hitting them would just run down the fins and onto whatever the amp was sitting on, rather than into the base of the fins.
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