Cpu heatsink modification

Elektrotechniker · Nov 13, 2010

Okay so I got this stock cpu cooler which I replaced with a better one. I want this modified to fit an aixiz module so I can make a nice 445 labby. Unfortunately, the local machinist said he cannot make a 11.9 mm hole, so I have to send it to someone to do the work for me. Since I am in need of some money to pay an argon, I will accept the best offer in terms of the service. Here's the cpu cooler.

HIMNL9 · Nov 13, 2010

You can also keep the heatsink horizontal, and just fit an aluminium block on the copper face (with thermal grease and screws, or with thermal glue) ..... probably in this way your machinist can just make the hole in the aluminium block ..... then just place one side on the heatsink, and, voila', lab-style heatsink done

.....

AUTO XX · Nov 13, 2010

Why not just get the machinist to use a standard size drill bit + reamer then spin the aixiz module down to that size on a lathe.
I have done it before and it is a hell of a lot faster than trying to bore the exact size.
I also believe the heat transfer is better without the extra thickness or chrome in the way.
It is so easy, I didn't bother with a set screw on the the module and just pressfit the last one directly into the heatsink.
If the diode ever dies, the back of the heatsink is drilled for the wire anyway and so I also tapped it 1/4"nf thread and can push the diode + module out with a bolt to reuse the same heatsink.

HIMNL9 · Nov 13, 2010

Maybe the machinist just don't have a lathe or lathe holder (chuck ?) big enough ..... or, more probably, he fear to ruin all the outside (those fins are not the better thing for close them tight in a holder, they bend easily)

It can still be done on a mill, anyway ..... lever blockages can be placed where there is the step, around the center, without ruin it, if the worker know how to do ..... or on a column drill (press drill ?) ..... 4mm guide hole, then 11,75mm hole, then 12mm reamer, at slow speed (copper is a bad beast to work), may take care about it

EDIT: ALWAYS blocked with levers, don't try to do it keeping the part at hands

Blord · Nov 13, 2010

I like the idea using a CPU heatsinking for cooling. These heatsinks are designed for heat dissipation around 100Watt. They should easy cool a laser diode of few Watts.

The copper in the middle is not massive. The other side is hollow. I think a vertical drill with 12mm diameter should easily make a hole.

HIMNL9 · Nov 13, 2010

^ true ..... but remember that a drill bit always "wobble" a bit in the drilling process, making the hole few bigger than the bit diameter ..... and also, copper plaque (usually are 5mm thick or similar) it's a bad metal to work ..... if possible, is always better to hook the heatsink on the plate, then start with a small bit (3 or 4 mm) as "guide hole" ..... then go for bigger holes (if the drill assembly is robust, can also be passed directly 11,75, or 11,5 mm bit) .... then do the last pass with a 12mm reamer, or, if not available, with a 12mm drill bit at slow speed and slow pressure ..... or 11,9, if want to pressfit the aixiz module .....

The problem can be, that these copper discs are usually pressed and bonded in the central space with glues, not with metal-metal soldering ..... an excessive effort or stress / deformation can detach the parts .....

Elektrotechniker · Nov 13, 2010

HIMNL9 said:
^ true ..... but remember that a drill bit always "wobble" a bit in the drilling process, making the hole few bigger than the bit diameter .....

That's what the machinist said. I am too worried to assign the work on him. I don't know the process and how it's done to tell him. Even if you guys explain it to me, I doubt he will listen and make an effort to drill this thing. He has a lathe, but he can only drill 12 mm holes, which after the drill are a bit biger, thus, there will be serious gaps between the module and the copper. I just need someone to make a hole in the copper...

Lasers and Masers · Nov 13, 2010

You can drill the hole your self, you need a carbide drilling bit, coolant/lubricant, and a variable speed hand drill. I've done it my self, although a carbide drill bit is gonna cost a pretty penny where I have solid carbide bits for other purposes. So I would suggest a carbide tipped bit like this and drilling very slowly stopping every time it heats up too much (when you feel it's too hot to hold your probably past the point of to much heat, your bit will break if it gets too hot. This is the main purpose of having a solid carbide drill bit, not only a tipped one...

AUTO XX · Nov 14, 2010

I really doubt this HEATSINK is going to get too hot for the carbide *especially in copper* ^_^
If you do it with a hand drill, your chances of getting the hole perfectly perpendicular are pretty slim but you probably don't need to worry about that.
A reamer is a great idea though, I'd still say get the machinist to drill the hole for you.
Spin the module down if he doesn't have the right sized bit/reamer but pressfit is the best option. I just finished another heatsink with a modified aixiz module ~an hour ago.

Elektrotechniker · Nov 15, 2010

Can't mess with this guy, sorry. Thanks a lot for the time you spent to explain what I can do with it but I don't have the right tools. I do have a a drill with some drill bits though, dunno if they can do the work. Will take a look later and tell you what I have in hand.

Lasers and Masers · Nov 15, 2010

You just need to do it slow and a little at a time, I have drilled through thick solid copper poles with a regular drill bit... No it cant be done in an efficient manner this way, nor would you want to do it more than every once in a while.. But with patients, it Can be done.

Benm · Nov 15, 2010

I suppose you would need a drill press to make the required hole, drilling one out of the hand is just to wobbly to get a good result.

That said, you should be able to get a decent 12mm hole drilled using some pilot drills to guide the final effort. I suppose you get the best result with a 3mm pilot hole, then a 10 mm drill bit, and finishing it off with the final 12 mm bit.

One disadvantage of this particular heatsink is that it would be very difficult to make room for a set screw, so you would have to work within press fit tolerances. This will probably mean you will need thermal compound to fill the final gaps, but its entirely doable as long as you have a good drill press.

Elektrotechniker · Nov 15, 2010

@Benm Yeah I was thinking of it as press fit.

@Lasers and Masers, Indeed, it will be done no more than once in a year lol. I just happened to have one of these for spare and thought it would make a good heatsink for a 445 labby. Cmon, someone please take this for machining

I need a good press fit finishing.

AUTO XX · Nov 15, 2010

there is no way to press the copper part out eh? Throw it in the freezer and then tap it with a hard plastic hammer?
That would make the job SO much easier!

Elektrotechniker · Nov 15, 2010

AUTO XX said:
there is no way to press the copper part out eh? Throw it in the freezer and then tap it with a hard plastic hammer?
That would make the job SO much easier!

I guess I could try, but it seems like it's glued in there.

Benm · Nov 15, 2010

You can count on the copper being bonded to the aluminium somehow, otherwise i think it would make a lousy heatsink. But you could put the whole thing in a drill press clamp, provided its big enough. You risk damaging some of the fins a bit to get enough pressure, but that shouldnt affect performance much.

If you get it right, the can give these a run for their money:
http://laserpointerforums.com/f39/maxsink-ultamate-lab-style-hs-50590.html (sold out, but check the pics)

Cpu heatsink modification

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