Not Just Another Laser Engraving with PVC

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Re: Not Just Another Laser Engraving with PVC

Postby JJWMACHINECO » Thu Sep 13, 2012 8:22 pm

Actually there is a thermistor sandwiched in between the heat sink half and the laser diode housing. He uses thermal epoxy and I had a heck of a time getting apart without damaging anything. I did all of this before I sent it back last time. When he said he was going to charge me, I knew the warranty was over so I cracked that egg open to see what kind of animal was inside.
Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
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Re: Not Just Another Laser Engraving with PVC

Postby dlgabry » Thu Sep 13, 2012 9:23 pm

Hmmmm. Was the bottom heatsink epoxied to the box? It looks like the thermometer readout was epoxied in place on the top cover too?
My junkbox had a whopping big aluminum heatsink from an old mainframe supply - 5x5x1.5" with large fins on both sides. I can mill a flat area near one end to accept the existing heatsink with some heat transfer goop. I knew that if I threw it out that I'd need it someday. :wink: Now to find a big fan/blower and a box to put it all in. Maybe remount the thermometer so I don't have to do handstands to read it.
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Re: Not Just Another Laser Engraving with PVC

Postby JJWMACHINECO » Thu Sep 13, 2012 10:55 pm

No, the heat sink is just screwed to the box, but had some kind of heat transfer material in between. When I mounted it in my new box, I was not sure if the heat sink should be grounded. I have read somewhere that the diode housing should not be. I thought the thermal epoxy on the diode housing was isolating ground and I did not want to take a chance. I mounted the heat sink to a non conductive circuit board material and the screwed that to the housing.

Here is where I bought the thermometer to replace the other one that was epoxied in. Yea it was no fun standing on your head trying to read it. :roll: http://www.ebay.com/itm/230435834419?ss ... 1439.l2649
Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
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Re: Not Just Another Laser Engraving with PVC

Postby dlgabry » Fri Sep 14, 2012 3:09 am

Thanks Jeff. I think it's probably grounded to the case given the two screws, but I'll meter it when I open it up. Sounds like it's also using the case as an additional heat sink with the goop underneath helping to transfer the heat.
I'll put this one second on my list while I try to get the counter scheme working. Parts for that should be here next week.
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