I bought a second hand K40 laser and I need help!

Hello Everyone,
This is my first post so I suspect it will take some time to get approved however when it does I would really love some opinions and help.

The laser came with an Anywells 608 controller, a broken bed, air assist, no lights, an aquarium pump for cooling a new actual 40-watt laser tube, the old 35-watt laser tube and no fan.

My brother in law is an engineer and so far he has:

Added LEDs
Upgraded the air assist
Upgraded the wiring systems so that they are future proof (he added boxes and wires that are better because)
He also added a drag chain (drive chain) I printed to stop the air assist and laser cable from getting caught up.

After he was done I added a laser pointer and added a camera (which I have mounted to the bottom of the door because I cannot find a better solution which means I cannot see inside when cutting).

I also purchased a better bed, decided it still isn’t easily adjustable so I have purchased an adjustable bed that uses a large key and a 2GT belt and wheels to move the whole bed at once.

I also bought a CW3000 chiller so I can cut continuously as I want to start a business making and selling things.

To date I have cut some boxes to hold the cards for Star Wars Imperial Assault, I have cut some player dashboards for the same. I also engraved some black slate tiles (which is why I want an easy solution to raising and lowering the bed) and I cut a couple of phone holders.

I was happy until yesterday when I tried to do an engrave/cut of 3mm birch plywood for my first paying customer.

I used Lightburn to send the file to the AWC608 and the engraving began, I was using 4 different colours, an engraving, a deeper engraving, an internal cut and an external cut.

The first part of the engraving was going fine until it got to the 4th of the 6 separate designs. There was a grinding noise but also a grating sound and the head jumped and carried on engraving but obviously had lost its place so was engraving in the wrong place.

It had happened before but I assumed it was because I was trying to engrave in too large an area.

From what I have read I may have to do something to my belt, either loosen it or tighten it.

So how do I do that and how do I know if I should loosen it or tighten it?

Also, I have some further upgrade questions, should I upgrade the motors, I have read people saying that brushless motors are better.

Should I upgrade the mirrors & what are the benefits?

Is there anything else I should do to the machine to make it better?

Thank you for looking and for any help/guidance you can give.


Use a CW-3000 “water chiller.” There are lots of these on ebay for US$150 and up, marketed for cooling lasers. The problem is that they are not chillers. They are radiators that blow room temperature air over your cooling water. If your water is cooler than room temperature they will actual heat your cooling water.

It should “sing” if you pluck it. It’s more likely too loose than too tight, since belts stretch rather than shrink.

In general, there’s a lot of really good info in the K40 Intro pages.


first thing to do is to determine the VALID working area of your machine and set that in your design software( LightBurn?) so that you do not put designs outside your valid working area and grind belts or worst break things. If you don’t use software which provides these limits then design a vector graphic of a box having those dimensions and use it in every design you make so you don’t go outside the limits of your machine. You use layers or colors or whatever your software allows you to use to disable the actual machining of that box. it’s just for layout purposes.

Next, there are tons of videos and FAQ’s on tightening belts on the K40 laser cutters so you really should familiarize yoruself with google and some of these sites. I think there’s even a huge FAQ here on Maker Forums. k40laser.se has one also.

The next thing to do is to get an analog current meter on your machine so you know what kind of current you are pushing through your laser tube. Maybe that new tube is a “real” 40W tube and you can push 24ma through it for maximum 40W of power. You should determine if this is the case because if it is not then pushing 24ma through an underrated tube will greatly shorten the life of the tube.

BTW, if you are sending your laser head into a wall and it’s grinding the belt, skipping steps, etc you do not adjust the belts to help with that. If you lost steps without hitting something then you could have a number of things to look at:
loose belts
speed is too fast
stepper motor driver current is too low or too high
stepper motor belt drive gear grub screws are loose

Also, pictures of your machine go a long way to help us understand what you have to deal with.
K40 machines can be vary different.


Thank you very much, I will add pictures tomorrow.

Thank you very much, yes, the temps of the water are hitting 25c so I will be sending back the chiller. Having read a little more it looks like something I could do with a bucket and decent pc fan!

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Well, bucket and ice is better. :relaxed:


Yes, their marketing of that CW3000 is really bad and sooo many purchase those thinking they do refrigeration type cooling instead of just blowing room air over radiators for the cooling.

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I use a 5 gal bucket of water. I have ~ 16 0.5L frozen water bottles in the freezer that I can rotate out in pairs to basically run all day if I need to. Works good if you have the freezer space to spare and don’t want to pay for the more expensive refrigerated unit.


I built a secondary cooling system by getting a coil of copper wire from HomeDepot(packaged in a coil for use in connecting fridge water supply) which I drop in my 5 gal tub of distilled water. The coil is connected to plastic tubing which connects to a pump which circulates from the cooling chamber of an old office water cooler. Others have used dorm refrigerators for the secondary cooling source.

It’s just tough dropping that kind of money on a CW5000 when the K40 laser itself was only $350.


Thanks so much for the replies everyone, I really appreciate it.

I will be returning the CW3000 as not fit for purpose but I want to start a small business so I think a chiller is going to be an essential purchase.

Would this one be adequate https://amzn.to/3xgcCqV? It’s a CW5200 and it has refrigeration so should keep the temperature constant right?

After I solve this issue would upgrading the mirrors make much of a difference to the cutting ability? I am mostly making things from 3mm Birch ply but for longer cuts, it takes three passes at 15mmps and 80% power (according to Lightburn and the AWC608 display) and I would like to do less power if possible and still get through.

The CW5200 has more cooling capacity than the CW5000 (that’s the difference). I’d think (not an expert here) that especially if you think you might upgrade to a larger laser later, the extra for a CW5200 over a CW5000 would make sense. When asking for purchase suggestions, it’s a good idea to Display your national flag with your user name Since you linked to a UK supply, I assume you are in the UK — otherwise I’d be suggesting to also look at the Lightobject chillers.

For cutting plywood, I’d suggest searching the site here for experience cutting plywood. Different batches tend to cut differently, knots in inner plys can make for incomplete cuts, and some plywood has metal in the glue (on purpose!). In the US, there is now a specialty plywood supplier that makes plywood expressly for laser cutting, with no knots in any ply and glue that’s appropriate for laser cutting. If you are going to make a business out of this, it might be worth looking for this in the UK.

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Thank you, Michael, really helpful. I am indeed in the UK, I will add a badge shortly. For anyone else in the UK with the same question, I have been using a company called Kitronik who sell items specifically for laser cutting. The prices are reasonable for A4 sized sheets which are all I can handle at the moment but I am certainly interested if someone has a lower-cost alternative. I don’t want to buy cheap wood I want to buy wood cheap if that makes sense.

I think I will need to save for the CW5200 as its around £400 here which is a fair price but more than I have currently so I may need to cut in the middle of the night as that is the only time the ambient temperature drops enough for me to cut at the moment.

Thank you for the help and advice.


I cut 3mm birch ply in a single pass at 9-10mm/s and ~8mA power.

  • What speed are you using?

  • To get the best cutting the focus point of the laser should be halfway into the work piece. For 3mm ply that would be 1.5mm below the surface.

  • Also make sure you have a solid alignment of the beam from all 4 corners and that the beam is cleanly exiting the air assist nozzle.

  • It’s also possible that since the laser is second hand you might need a new tube. When you do the alignment do you see a single spot from the laser or multiple / distorted spot?

  • Upgrading from stock mirrors and lens is always a worthwhile investment IMHO.


My solution, too. I don’t have the inclination to buy a separate cooling unit, and I have run my unit for hours at a time. Full disclosure: I generally don’t run my laser very hard (in terms of MA), and sometimes I have to double up cuts, but I’ll take it as long as I get some longevity out of the tube. I’ve run my laser like this in the heat of a Texas summer for 3.5 years.


Hi Matt. I am UK based and do a lot with 3mm ply. I get mine from Daisymoon a UK company via Amazon. I looked at going direct but the prices were the same. I find their ply cuts well. I use 8mm sec, 43% power or 14m/a. I have fitted a m/a meter for a few quid from ebay. Is worth it. The ply works out between 50p and £1 a sheet. Some do have patches on but if you check the boards first you can disguise them on the rear of things.


A good tip is to keep the ply flat and somewhere dry. I used to leave mine in my outside workshop and the good old British weather made it warp and damp. When the ply is damp it is harder to cut.


Thanks for all the replies it really helped me get dialled in. So, I bought the CW 5200 from S&A and the temperature problems are all sorted, stable at 14-15 degrees for as long as I want to run the machine.

I contacted Vevor and told them that their machine (the CW3200) is not fit for purpose, I also got my bank to refund me and I still haven’t heard back from them. All I can say about them is that in my limited experience, they are not a good company to deal with.

After reading elsewhere I bought new mirrors and a lens and found one of the mirrors that was in the machine was cracked inside if that makes sense, it looked fine from the surface but when I removed it there were two pieces.

Adding the new lens and mirrors I am able to cut 3mm birch ply at 8mms at 65-72% power. I have an AWC controller so there is no milliamp meter however, I will fit one soon.

I have discovered Engraving is more art than science but I am starting to figure out power and speed settings for different depths.

I do still have another issue but I will start a new thread as its probably a simple solution that could well help someone else who is searching.

Thanks for all the help


Hiya, glad you are getting the hang of lasering. Just a tip on mirrors. I use a spray I got from the opticians to clean my mirrors. One day I sprayed and didn’t dry one of the mirrors. I fired up the K40 and had a nightmare trying to cut/ etch. It turned out the mirror was in 2 pieces, right down the middle. What happened was wet mirror/Laser beam, liquid got very hot and cracked mirror. Won’t do that again.
I’ve just posted an article on etching on stainless steel which seems to work well.
With regards to engraving I keep a book with material type - wood, slate, rubber etc, the power setting and speed setting. It really helps as I use my K40 for a multitude of materials. Initially I write it on the inside of the lid in pencil until I have perfected it.