Hello everyone.
Following the demise of my Glowforge basic, I recently purchased a K40 Laser. I’ve upgraded the lens and mirror on the head and am waiting for the other mirrors to arrive.
Ive an Omtech Control board due to arrive any day. I want to run Lightburn with a camera to make it more user friendly. The problem that I’m currently having is that its getting very hot, its not cutting even 2mm ply. I’m thinking of getting an aquarium chiller as the way I’m currently cooling it isn’t working.
Any advice would be more than welcome.
The Glowforge was pretty much press and go but this is a bit different although I am more excited about it, if I can get it running right.
Thanks in advance
Kirsty
Make sure the final lens is in correctly. Concave up, dome down. Also make sure you are at the correct focus height by doing a ramp test.
How do you know it is getting hot?
Are you monitoring the tube current?
If it’s getting too hot and you are drawing too much tube current you will ruin your tube.
I thought it was flat side down?
Excuse my ignorance. I’ve tried it at various heights. It makes a nice line but doesn’t cut. that’s at 1mm/s 100percent.
The temp on the machine is going above 30 degrees celcius. The water is coming out hot and not getting cool enough when it goes back in. When I pause the machine the temp goes down.
I need to get a bigger resevoir and try that. I put ice around my current reservoir yesterday. It didn’t make much difference.
Yes, flat side down is correct for plano-convex lenses.
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Have you read this article?
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I apologize for my mistake. I should have gone back and read what I wrote!
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Thanks all.
The lens was in correctly. I realigned the mirrors and got a large bin for the water (a bit overkill) but it brought the temperature down and kept it down. So I think I am okay for now. The new control board has arrived so I will install that this weekend. Hopefully I will get it right 
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Some people freeze water filled plastic 2L bottles and just drop them into the coolant…
Might want to invest in a refrigerated chiller.
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without a milli Amp meter installed I would not run the machine over 40% because as Don pointed out, you can over drive the tube and quickly ruin it. And if it’s a stock K40 with stock tube, the general rule is to only put less than 18mA through it and never run it hotter than 25C
There is a K40 Into link at the top right corner of this page and look at the FAQ on http://k40.se so you understand what you have and how to operate it. Unlike the Glowforge, the K40 is a DIY laser cutter/engraver and there are few protections in place to keep you from destroying the machine or harming yourself.
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… while we are providing advice…
You should add interlocks to that machine to make it safe.
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So I’ve installed the Omtech plus board and am running Lightburn, what a pleasure. What a difference it makes to the machine.
Now I just need air assist and a camera
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… and interlocks! 
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What do you suggest? Also I saw that someone installed a Beam finder: LED added to the laser head is there any you tube videos that you know of?
Add switches to the front and laser compartment covers wired in series with the LPS enable circuit.
If you decide to do it we can provide more details
There are multiple beam finder designs on Thingiverse like this one.
I am sure a Google search will lead to more ideas.
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