Here is a collection of my K40 shop tips that you might find useful.
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can you let me know where you bought your laser or what person selling them on ebay?
I bought mine on alibaba. The seller seems good enough.
I cannot speak to the quality of the machine yet. I have only had it for four days.
US $422.75 5%OFF | Digital 3020 Woodworking 40W Engraving Cutting CO2 Laser USB Machine with Update Control Panel
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I think the simplest option for the moment is a lab jack. I know that there has to be stuff in here but all that I have really found is people asking about them, not in how to make them work with the k40.
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Hmmm…it’s been awhile since I’ve seen anyone use a labjack. I think @funinthefalls may have used one at one point?
Essentially you will need to mount a bigger bed to the top of the lab jack platform. I think I remember someone using a metal plate mounted to the top of the platform. You would then want something to stand the work off the surface of the plate to avoid flashback on your workpiece and prevent buildup of oily wood residue. I think I remember the person using metal studs in the lab jack build? Can’t find the build in question. Might be able to use magnets as standoffs if your plate is steel.
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After more review, I don’t think a lab jack is a good idea. The adjustment knob moves in the vertical axis so you need a hole in the case that accommodates that.
Instead, I think that I am going to build or buy a manual z-axis table like this one:
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I have been happy with the Lightobject powered table.
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I looked at that. For now, I am going to save a bit of money and buy the manual version from above. It can be converted to powered if I choose to do that in the future.
I am thinking about trying to add better LEDs to the interior of the cutting compartment. I need to see what kind of information I can find online about that. I have not messed with LEDs before. The entirety of my electonics experience revolves around amateur radio.
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Pretty much any LED light strip will work.
There are many choices on amazon look for ones with the best customer scores and adhesive backing. I use 12v white.
You will need to decide what voltage you want for your accessories as you cant add any more load to your LPS.
I chose 12V for my accessories as most of the less expensive add ons (like gauges) were 12V.
I added a 12V supply (https://amzn.to/2LB4L4C) which are also pretty inexpensive with lots of choices on amazon.
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Thanks, Don. I am looking at a secondary power supply for added electronics and such. My air assist is working out great. I need to work on my ventilation. Right now I have just run 16 feet of semi-rigid duct out of my garage (under the door, so it is freezing) and around the side of my house. I have to find a 6" hole saw to cut through the wall to install a vent.
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I am also happy to report that during the extended period (around 90 minutes) that I worked on the hippo engraving, the water temp in my 27 gallon tote (with 20 gallons of distilled water in it) rose only 2ºF.
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Mark a hole and saw it. A 6" hole saw wouldn’t be manageable with a hand drill. What kind of siding do you have?
It blows my mind that the closed loop belt goes under the laser beam. I mean, I guess it must work OK but it’s not what I would have expected! I still plan to route my Z belts away from the laser beam. 
If you make your own lift table, I can recommend zyltech.com as the only consistent and reasonable US source I’ve found of single-start metric trapezoidal rod. single-start doesn’t back-drive, and metric is nice because of cheap bearings. I’m using T8x2 because 8mm shaft diameter lets me use very cheap and widely available 608 (“skateboard”) bearings. I just got a set of 4 400mm T8x2 and they came well packaged (survived UPS puncturing the box) and straight.
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I have brick on one wall and vinyl on the other. I plan to go through the vinyl. Yea, I was concerned about it not being doable with a drill… I have an cordless drill and a heavy duty corded drill but I don’t know that either could do it. Could I use a jigsaw? I don’t particularly want to mess it up.
I completely understand that concern. I have seen a lot like that though. Do people think that because it is so far below the focal point that the beam is unfocused (and therefore does no damage)?
I’d suggest looking up advice on installing dryer vents through vinyl and scale up. I’ve seen warnings that the vinyl needs to be able to “float” behind the vent and that it’s easy to let water through by doing it wrong. May need J-channel to flash the edges? I don’t have vinyl siding and have never installed a vent through it myself.
That must be right. I don’t have the experience to know. I’m also not going to assume that what works with a K40 will be appropriate with my 100W laser that I’m building. 
I’m a nutcase; I have zero actual laser experience and am jumping straight up to 100W self-designed scratch-build for my first ever laser. (I got here by accident by rescuing 3D printing content from Google+, and it is helping run this site that got me interested in lasers as well…)
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I know nothing about 3D printing but want to learn and get into that too. I don’t want to have to order parts from someone else when I could just as easily do it myself. Plus, I want my kids to learn as well.
I will look into the vinyl stuff. I have watched a number of videos about it but I want to do it right, the first time.
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Normally that is the case, especially if the beam is going through something first so that most of the energy is dumped into the workpiece. The thing to watch out for is if you run the beam over an empty space by accident, especially at high power.
This sits about 1.5" under my bed on one of the supports. Was doing a bunch of deep engraving at high power and didn’t realize that I had miss measured the wood and part of the engraving was off the wood.
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Yikes. Could I potentially put a sheet of non-reflective metal sitting just above the belt/pulleys that wouldn’t interfere with their movement?
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Absolutely. Could even make a foil tunnel.
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