K40 running Grbl

[Imtippmann]

Here is my k40 running converted to an eccentric Grbl board. Moderately easy swap that allows me to run lightburn. Also pictured is a few of the things myself and my wife have made with it. I am currently sitting in front of it running the second batch of 500 tokens for my First Lego League students to give out at a competition. I run 12 hours nearly non stop with no troubles, I do have a refrigerated chiller to keep the tube cool.

[icarus525]

What kind of chiller are you using? Although I think they're aimed at the hydroponics market I'm pretty keen on the Active Aqua chillers. At work (i'm an 8th-12th Engineering Design teacher) i have a 100w laser and a 40w laser both plumbed into a 12 gallon tote that i'm using as a reservoir and the 1/4HP Active Aqua chiller keeping the whole reservoir cool. 12 gallons of water is a lot of thermal mass.
I like your coin idea... i might make up a batch for our school's upcoming First Lego Robotics league match.

[Imtippmann]

I'm actually using a lab chiller. It is not ideal as it runs the refrigeration system non stop and pulses a 1500w heater to maintain a very accurate temp. Its a bit of a power hog. 12g is a nice size thermal mass with an active chiller pulling as much heat off as it can, my system has maybe 1.5g to the whole system