Building a custom heatsink

Hey folks!

Currently I'm building a custom heatsink made out of
one single aluminium piece , but i've got some troubles with lathing the place for the diode and I hope someone can give me advice:

First off, the diode will be a 9mm diode like the NDB7875,
I have got access to a lathe (for sure) and some tools.
So now i have problems creating the fit for the 9mm diode (9H7 fit?)

But as I don't own a 9H7 reamer i have to lathe it manually.
Unfortunately I havent got the money to buy appropriate tools like that.

My question is: How can i be sure to get exactly the right diameter lathed out of the aluminium?
My idea was to first bore a hole with less than 9mm in diameter.
Afterwards removing some µm several times while checking constantly if the diode fits in.

But for that i would need a broken 9mm diode which i havent got here..
Is there a better solution or does anyone know where i can buy some broken 9mm diodes?

Thanks in advance!
:thanks:

In my experience it is very difficult to make a direct press heat sink, I typically go slightly over the desired size and it ends up becoming a module heat sink. I prefer to buy the modules from someone else and drill a 5/32" (11.9063mm) hole. Give it a little wiggle and you'll have a perfect direct press 12mm module hole. Definitely not the right way to do it, but it works for me

There are other benefits to just fitting a 12mm module instead of direct press. For one, you can use those diode presses made for those 12mm modules. Otherwise, you'll need to make the back-side of your module accessible so that you can press the diode into your heatsink. Fitting that head into the vice and lining it up is sometimes a pain too, and can potentially marr the surface. I had to deal with that on a Kryton Groove, and I'd just rather use a 12mm module anyway. Hell, some people don't have a proper vice + diode press kit, which could add another $50 to the overall price (assuming you're reselling the host).

The 12mm module can also be copper which will spread out the heat faster to more "surface area" before it interfaces with the aluminum (assuming proper coupling between the two). In 12mm modules, both the head and the back side are made of copper, further spreading out the heat. It probably makes little difference in the overall picture, but is still overall more efficient.

Plus, you'll also need to add threading to your direct-press host for your lens. It may be rather tight.

Thank you both for the quick answers!

The thing is, I'm uncertain about the efficiency when i use a module press.
Even if it is a copper module, wouldn't it be better to have only one piece of metal as heatsink? Or is the difference that low that it doesn't matter at all?

But at least I think its a pretty good solution. I inteded to use a fixed lens so I might have to chop off the focusing end of the module - should not be a problem.

Only two things left:
1. Do you know (or does anyone else know) the precise dimensions of those modules (or is there a datasheet available)?
2. Is the outer diameter the same for 5.6mm and 9mm modules? (I hope it is)

Schnizel said:

Even if it is a copper module, wouldn't it be better to have only one piece of metal as heatsink? Or is the difference that low that it doesn't matter at all?

Click to expand...

Yes it would, but once the heat is spread
out to the larger surface area of the
module, it doesn't make a whole lot of
difference. What most people do (including
myself) is just buy a module and press the
diode into there. Then bore out the
heatsink to either give 1-2mil of press or
a mil over for a nice tight slip fit.

Schnizel said:

1. Do you know (or does anyone else know) the precise dimensions of those modules (or is there a datasheet available)?

Click to expand...

The modules sold by DTR are around 470mil
on the O.D. Other modules can vary quite a
bit.

Schnizel said:

2. Is the outer diameter the same for 5.6mm and 9mm modules? (I hope it is)

Click to expand...

Yes

Thanks! That helped me a lot!

The Lightning Stalker said:

Then bore out the
heatsink to either give 1-2mil of press or
a mil over for a nice tight slip fit.

Click to expand...

I tend to use the tight fit, should result in better heatsinking.
Would you recommend some thermal compound between the module and the aluminium?

Yes unless it's a press fit. In that case
no thermal compound is needed. Also with
press fit be careful. Too tight a press
will shrink the module and make the lens
threads tight.

Best thing to do is buy a reamer. Or you can just bore it but be careful because before you know it will be oversized.
Chucking Reamer 9 mm Shank Round Flute Length 1 3 4" | eBay

Not really being helpful but heres my little ramble,

I have a shocking amount of PC heatsinks, lots of which are nice for mounting my small 8mm modules into and coupling with a old PSU, problem is that 90% of the time no matter how hard i try my 8mm bit (Using a drill press) will also drill about 8.3-8.5mm, has anyone got a suggestion for a better method to achieve a 7.9-8mm hole with a drill press.

I've tried starting small and building up (4mm, 6mm, 8mm) and using lubrication as i cut but still no luck.

Get a reamer and use an undersized pilot.

SyKo said:

Not really being helpful but heres my little ramble,

I have a shocking amount of PC heatsinks, lots of which are nice for mounting my small 8mm modules into and coupling with a old PSU, problem is that 90% of the time no matter how hard i try my 8mm bit (Using a drill press) will also drill about 8.3-8.5mm, has anyone got a suggestion for a better method to achieve a 7.9-8mm hole with a drill press.

I've tried starting small and building up (4mm, 6mm, 8mm) and using lubrication as i cut but still no luck.

Click to expand...

Drillbits don't drill round holes get yourself a reamer.