From: Jasen Betts on
On 2008-12-20, Rich Grise <rich(a)example.net> wrote:
> On Fri, 19 Dec 2008 22:15:43 +0000, Eeyore wrote:
>> Rich Grise wrote:
>>> Eeyore wrote:
>>> > John Larkin wrote:
>>> >>
>>> >> Hint: smart people machine the heat sink *before* they anodize it.
>>> >
>>> > Who said mine need any machining ?
>>>
>>> If it's extruded, it needs to be machined, especially if you're
>>> intending to use the hard anodize as the insulator.
>>
>> Who said anything about extrusions ?
>
> Every sizeable heatsink I've ever seen has been extruded. What are
> you doing, having them cast? Maybe machined from a solid block?
>
> Please, tell us more about these magic heatsinks that don't need
> any heat grease/paste with your magical pads, of which you seem to
> be the only happy user in existence.

I've seen heatsinks where the part contacted the cut end of the
extrusion, but I expect Graham is thinking of the kind that are
stamped from rolled* sheet.

From: Archimedes' Lever on
On Sat, 20 Dec 2008 09:07:03 +0000, Eeyore
<rabbitsfriendsandrelations(a)hotmail.com> wrote:

>
>
>Archimedes' Lever wrote:
>
>> Rich Grise <rich(a)example.net> wrote:
>>
>> > Plain aluminum has very poor emissivity.
>>
>> It varies with surface finish differences.
>>
>> Grit blasted matte finish and 36 grit rough polish emit pretty well
>> compared to average extrusion finishes.
>
>And when you're using conduction it matters very little.
>
>Graham
>

I make military satellite hardware. I do not need a twit like you
expounding on conduction cooling techniques, nor principles. Nor IR
emissivity.

What little you know about radiating surfaces fits onto the tip of a
molecular probe. So I am quite sure that you also have little knowledge
about conduction cooling.
From: Eeyore on


Jasen Betts wrote:

> On 2008-12-20, Rich Grise <rich(a)example.net> wrote:
> > On Fri, 19 Dec 2008 22:15:43 +0000, Eeyore wrote:
> >> Rich Grise wrote:
> >>> Eeyore wrote:
> >>> > John Larkin wrote:
> >>> >>
> >>> >> Hint: smart people machine the heat sink *before* they anodize it.
> >>> >
> >>> > Who said mine need any machining ?
> >>>
> >>> If it's extruded, it needs to be machined, especially if you're
> >>> intending to use the hard anodize as the insulator.
> >>
> >> Who said anything about extrusions ?
> >
> > Every sizeable heatsink I've ever seen has been extruded. What are
> > you doing, having them cast? Maybe machined from a solid block?
> >
> > Please, tell us more about these magic heatsinks that don't need
> > any heat grease/paste with your magical pads, of which you seem to
> > be the only happy user in existence.
>
> I've seen heatsinks where the part contacted the cut end of the
> extrusion, but I expect Graham is thinking of the kind that are
> stamped from rolled* sheet.

You are correct. It makes them very lightweight and they can be stamped or
produced on CNC presses.

Graham


From: Eeyore on


Archimedes' Lever wrote:

> Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote:
> >Archimedes' Lever wrote:
> >> Rich Grise <rich(a)example.net> wrote:
> >>
> >> > Plain aluminum has very poor emissivity.
> >>
> >> It varies with surface finish differences.
> >>
> >> Grit blasted matte finish and 36 grit rough polish emit pretty well
> >> compared to average extrusion finishes.
> >
> >And when you're using conduction it matters very little.
>
> I make military satellite hardware. I do not need a twit like you
> expounding on conduction cooling techniques, nor principles. Nor IR
> emissivity.
>
> What little you know about radiating surfaces fits onto the tip of a
> molecular probe. So I am quite sure that you also have little knowledge
> about conduction cooling.

Your comment does not apply to the OP's question and is thefore entirely
redundant.

Graham


From: John Devereux on
John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes:

> On Thu, 18 Dec 2008 20:39:54 -0800, Capt. Cave Man
> <ItIsSoEasyACaveManCanDoIt(a)upyers.org> wrote:
>
>>On Fri, 19 Dec 2008 03:29:21 +0000, Eeyore
>><rabbitsfriendsandrelations(a)hotmail.com> wrote:
>>
>>>
>>>Now do the sums kiddie ! Heatsinking is an expert area that clearly no-one else
>>>here has much of a clue about. I've been studying it for over 30 years.
>>>
>>>Graham
>>
>>
>> You're an idiot. My last large sink product was a 1500W supply for a
>>CAT scanner for Philips. We used a custom extrusion
>
>
> What's amazing is that you can tool up a die and buy a truckload of
> custom extrusion for nearly the price of the aluminum, which may be a
> fifth the price you'd pay for a similar stock extrusion from a
> "heatsink" company.
>
> Ditto sheet metal. We can do a custom chassis, exactly the way we want
> it, with all the pems and spacers and connector holes and vents in
> place, and have it fabbed for less than buying an unfinished
> "standard" chassis.

Do you mean for the external case, or an internal subassembly?

> Weird.

I have found this in other areas. We had a common "passive" LCD (8
digit "triplexed") where we needed the polariser rotated 90 degrees
from their normal type (don't ask).

The "special" was about half the price of the "standard", even for
just 100pcs! Apparently it went to a different division or something,
who I guess were organised for huge orders of custom displays instead
of catalog items.

--

John Devereux
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