Laser cooling

After having a 3 watt die on me after only 700 or so hours I cannot help but think that these tiny little heat sinks are far from sufficient for long jobs like raster engraving.

So that being said I am on a mission to design a low cost solution using a TEC and a TEC controller. I know OPT Lasers makes a driver and TEC controller all in one but that is a little rich for my blood. I ordered a 15 AMP TEC controller and 2 9AMP TECs today for $25 CAD… Good thing I have a beast 750 Watt Dell server power supply running my MPCNC. Gonna need some juice.

So far I have a large aluminium heat sink from an old AMD dual core system for the hot side of the TEC. A 60mm fan screw directly to it. I figure the heat dissipation required should be pretty close to what this CPU cooler can provide. The CPU I believe was around 90 watts and the 6 Watt laser is probably some around 30 watts to guestimate on the high side (5V at max x 5amps) not that I run my laser driver a max amps. Over design for safety.

I am thinking that the small Chinese diode heat sink will be sufficient with a TEC glued to it and set to hold 20 Celsius.

The mount is what is going to be a little trick… My 3d modeling skills are not the greatest LOL.

Interested to see where this goes as my parts come in. If anyone has anything to add I would appreciate it.

You have to remember to be conservative on your current settings regardless of how you decide to cool the diode. I think i remember you mentioning that your last diode was running at 2 amps. That’s a really high current setting for that diode. Even if someone on a laser forum says it’s OK, you have to remember that those guys enjoy lighting cigarettes from across football fields and stuff like that. They don’t run engraving jobs for hours at a time. Keep that in mind when you decide how far you want to push that new beast of yours;)

I have not run the 6 watt beyond 4 amps… otherwise it seems like the driver will go nuclear. Is that still too high?

Hard to say, I haven’t seen a datasheet for it. It sounds a little high. If 2 amps is too high for a 2.8w diode then I’m guessing 4 amps is slightly outside the comfort zone for a 6watt diode. I did find a little info on the OPTlaser site that mentions an operating current of 3 amps. With active cooling you can run it a bit higher. You’re new driver has a thermistor input so you should try to incorporate that into your TEC housing so you can monitor temps. The diode is rated for a 10000 hour life but that’s only if you run conservatively.

The dudes over at pic engrave talk about their 6 watt in a thread and they are running at 4 amps. Once all my stuff for the holidays is complete then
I will be encorporating a thermistor in the the laser diode heat sink my goal to keep it 40 degrees Celsius or less. Not entirely sure I want to know how hot it’s running right not my new longer Chinese heat sink came in today so that little bit of extra aluminium should help a bit.

Oh ok, It’s probably ok then. I’ve read that the NUBM44 can be pushed pretty hard. I just don’t want you to burn it up.

I am looking for one of those large square heat sinks. The 50 x 50 x 100mm ones. I cannot find the heat sink separately only in kits that are pretty pricy. See the attached pic. That one is smaller but just so you can get an idea what I mean.

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This is the exact one I am trying to find