WE SHOULD REPLACE THE LASER CHILLER


  • Member

    After trying to hunt down and repair the leak in the water chiller for the laser cutter, I think it will be a better to buy a premade chiller. After doing some research with Morgan Gosse we can get one more that adequate for under $600. Morgan is also willing to apply for grants to fund raise for it.



  • From what I understand the leak isn’t from the refrigeration system but from the cooler that was chopped up to clear the refrigerant lines in order to make a chiller?

    At a quick look, I think replacing the cooler with an inexpensive plastic tote would suffice. Buy a pair, use one lid for donor material to provide a proper lap at the pierce point. Use a quality two part epoxy and fillet around all the seams instead of silicone. You could double up the totes for redundancy.

    A proper job would be to build a vessel out of some plastic panes and with trim, but costs all in would probably get close to that of a off the shelf chiller.


  • Member

    @GHunter That could be a solution, and that was the original plan with the current setup. But due to the resealing part not quite working out, it leaks. I am concerned that doing the same DIY build will risk running into the same issues, and I think it will be worth getting a manufacturer chiller solely for the reliability factor. We will save so much energy, time and money in the long run never having to worry about it again. I will try to get it at least limping along by next Monday.



  • I can speak to the chiller design as it is. There are reasons for choosing a cooler. It is insulated. The double wall construction allows for it to be fastened to the plywood with short screws from underneath that do not pierce the inside layer. I had originally wanted to make the tub with painted plywood but was overruled as seams can become leaks. The cooler is also the right physical size and not brittle. Single wall totes may be difficult to source in the right premade size and they are either too flexible or too brittle to use. If you choose to replace the cooler with a different container you will be right back to the same issue, sealing around the lines.

    Least effort option would to pick the old silicone off, dry the area with a hairdryer, and replace it with new silicone. This is the second one of those that I’ve built. There is a lot more work that goes into it than it seems. The next steps with the chiller were to install high and low level sensors (we have them).

    If someone wants to replace it with another one my feelings won’t be hurt.


  • Member

    @Grant-Fraser My plan is to try resealing the current cooler with some flex seal and silicone. Me and dave had already tried this once last tuesday but i don’t think we got it dry enough before putting silicone on it, so i ripped it up today, put some moisture observant in the cooler and am leaving it there overnight. Hopefully this will seal it up enough for reliable use, but i still feel it be worthwhile to get a better chiller.



  • My best recollection is that we might have put down spray foam first, then siliconed that on the first one?


  • Member

    @pierre Yes, there was a lot of spray foam in the cooler. It had gotten water logged and was ripped out. I have given everything a few coats of flex seal, and siliconed up what areas couldn’t be reached with the spray. The leak has still been persistent but i have made progress and will work on it tonight until it is fixed. I expect it to be fixed by tomorrow morning


  • Electric



  • From an earlier post “1040 watts go into the tube. 119 comes out as a laser. 921 is removed as heat by the chiller.”

    Unless we have a 1000 watt Peltier cooler we won’t be able to keep up with the heat generated.

    Here is a good explanation of why an AC is a better idea. First page is relevant. Next three are a flame war. Somebody made FTL data cables?

    https://www.electronicspoint.com/threads/cheap-peltier-air-conditioner.130381/



  • Difference between the case posted there and the chiller is that is specific to AC, and air has terrible thermal capacity.
    Looking at peak numbers is misleading unless the laser is running non-stop, and doesn’t account for a holding tank.

    The current set up just pumps water through the laser tube into the cooler, that the AC in turn keeps at a lower than ambient temp?

    Any volume of water is going to have a huge amount of heat capacity. You need to dump 4100 Joules(W-s) into 1 kg of water to raise it by 1deg Celsius. The existing cooler is about 27L or 27kg when full, so it takes 111,000 Joules to raise that 1 degree. 120 seconds of continuous cutting.

    I don’t know the efficiency of the chiller, say the 180W runs @ 50% efficiency that would take roughly 10x the amount of time as the laser cutter runs to bring it back down to temperature.

    Factoring in time for movements without cuts, time to change stock, programming etc I doubt that the cutter is actually working for much more than 1/10 the time it’s being used.



  • A fairly common situation is doing a raster scan… Where the laser cuts continuously , almost without pause for tens of hours.

    Relying on the water as a thermal battery, and expecting a peltier unit that is an order of magnitude to small to make up the shortfall during the down-time is much riskier than I’m comfortable with when it comes time to replace laser tubes.

    Incidentally @HunterVogel did a great job on the chiller repair.



  • That makes sense… I’ve only done quick cuts not drawing fancy patterns.

    Does that mean the chiller is good to go again, or is the fix more of a temporary one?



  • Hunter’s fix is good enough to last until the window rattler breaks down I think. Which is likely several years from now at the rate we run it.

    I hope to build another, better chiller, and have a spare ready to go well before then. We could knock one together with not much more than $60 in parts… but we usually recycle donated parts for them.

    Ideally, I’d use a mini-split rather than a window-mount… That would let us just strip the cold-side and plunk it in the water bath. We could even mount the hot-side outside the building on a wall, if the hot-side was big enough, we could even strategically air-condition a few of the upstairs rooms.




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