40W Laser Engraver & Cutter Review (K40)

November 30, 2020

One of if not THE most popular budget CO2 lasers is the K40. The combination of price (under $500) and power (40W CO2) make this an attractive option to anyone's shop. But it has always comes at a cost. Over the years, people have had quality issues with these Chinese imports, but OM Tech is a new US supplier offering the quality control that the K40 has been lacking. Let's check out their unit and see if it's a good fit for you!

Note: OM Tech supplied this unit to me for free for review. They have not directed anything I saw, and I'm giving my honest opinion. If you decide to purchase this machine through my link, I do get a commission but feel free not to use my link as well!

If you do decide to purchase, you can save 5-10% with my code: MAKEORBREAK

Disclosure: All opinions expressed here are our own. This post may contain affiliate links that at no additional cost to you, I may earn a small commission. Read full privacy policy here.
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40W Laser Engraver & Cutter Review (K40)
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K40 Features

One of if not THE most popular budget CO2 lasers is the K40. The combination of price (under $500) and power (40W CO2) make this an attractive option to anyone's shop. But it has always comes at a cost. Over the years, people have had quality issues with these Chinese imports, but OM Tech is a new US supplier offering the quality control that the K40 has been lacking. Let's check out their unit and see if it's a good fit for you!

Note: OM Tech supplied this unit to me for free for review. They have not directed anything I saw, and I'm giving my honest opinion. If you decide to purchase this machine through my link, I do get a commission but feel free not to use my link as well!
If you do decide to purchase, you can save 5-10% with my code: MAKEORBREAK

Let's jump into the features of the K40. This review is specific to the unit provided by OM Tech, but you will find similar features with most 40W lasers from Orion Tech and/or imported from China.

Construction

Overall the K40 has a solid metal construction. Other than some of the buttons, there are plastics, and the machine is very robust. You still won't want to bang this thing around because of the glass tube on the back, but overall I was surprised that the build quality was on par with my bigger 50W Orion Tech laser.

The top door consists of a metal frame with a tinted acrylic panel. Unlike the more expensive machines where the lids are glass, this did feel like a piece that might need to be replaced in the future. I'm not sure how much added safety you are getting from the tint in the acrylic vs. just clear, but having any extra protection between you and the laser is a plus.

40W laser

The K40 gets its name from the 40W laser tube. One of the biggest positives for purchasing from OM Tech is their quality control process after imported these units from overseas. I've read horror stories of people who have gotten their units with cracked tubes and haven't been able to replace them.

Everything I've seen from OM Tech has been great in terms of customer support. They also include a one year warranty on the laser tube itself.

Size and Work Area

The K40 comes in at an overall size of 32 x 20 in with a workable engraving area of 8 x 12 in. Now, this could be perfect for your situation primarily if you mostly work with smaller parts. When I got my very first laser, this was the main reason I upgraded to the 50W unit. I was able to engrave and cut much larger items (like cutting boards).


Also, the exhaust duct protrudes a good way into the back work area of the machine. A pretty popular modification is the cut that away to give even more room.

Speed

It's a little hard to talk about speed when it comes to lasers. It is mostly dependent on the material, what type of operation you're doing (cut or engrave), and what you want the laser's final effect to be.

The most significant factor for this is the power of the laser. This is a 40W machine that is more than able to cut and engrave lots of materials. In my tests, I found that the max I could cut 1/8 in Birch plywood was 25 mm/s. Sometimes I would need to do this in multiple passes.

For engraving, the speed could be ramped way up. I did a few tests at 150 and 200 mm/s at pretty low power settings. But I've seen other people run the laser at higher power and push the machine up to 300-400 mm/s.

Materials to Cut and Engrave

The materials you're able to cut and engrave are specific to this machine but, just like the speed are dependent on the laser tube's power. For engraving, you'll easily be able to use wood, leather, paper, cardboard, acrylic, glass, and coated metal.

For cutting, the K40 will be able to go through wood, leather, paper, cardboard, and acrylic. The settings in terms of speed and power will vary greatly depending on the materials' type and thickness. The vast majority of stuff I cut is 1/8 plywood, and I found I could cut through it fairly quickly with one pass. I did run into a fair bit of charring, but we will get into why on that later!

Fume Ventilation

In addition to the main machine, you'll need to deal with exhaust and cooling. For exhaust, the K40 includes an internal fan to help vent the fumes and smoke out a port on the back. OM Tech also provides some flexible tubing that is used to vent out a window. I'm set up in a garage, and I found just venting it out the garage door worked fine.

More expensive machines often will include an external fan (like a giant inflatable fan), which also helps pull the machine's exhaust. But I found for most of my tests that this fan, the small internal fan did a pretty good job.

Water Pump for Cooling

For cooling, you're given a simple aquarium water pump and tubing for both water in and water out. You will need a container as well as distilled water to complete the system. While other lasers have this as a more comprehensive integrated solution, this simple set up still gets the job done.

Laser Pointer

The K40 does not come with any integrated cameras to help line up your workpieces before cutting/engraving. These are big selling points for other lasers like the Glowforge or Full Spectrum Muse.

Instead, a secondary laser is included, a low power laser pointer attached to the gantry. You'll be able to line up your workpieces using the laser pointer in conjunction with the trace function in the K40 Whisperer software.

Unlike diode lasers, which can fire a much lower power setting, the K40 needs a separate low power laser instead of firing the CO2 laser at the lowest power settings. Even in my testing, I found that running the laser at 1% could result in light engraving on the material.

I also found that I needed to align the red laser dot to the CO2 laser, but that was a pretty simple process.

Power Control

Unlike most other lasers (both CO2 and diode), you won't control the power of a K40 from the software. Instead, there are physical controls on the machine that let you vary the laser power as a percentage of max power.


This was reasonably easy to use once I figured out some of my speed and power settings. One widespread upgrade is the addition of a mA meter that allows you to monitor the unit's actual power. This is very helpful in dialing in your settings.

It also means that the laser can't vary its power when running. This is most commonly seen in raster engraving, where the different shades of grey are made by changing the power.

The K40 creates the same effect using dithering. Dithering uses dots spaced at different distances apart to give the illusion of different shades of grey. I've found it tough to see the difference, especially when running it at a high DPI setting.

Assembly

Unlike other machines, the K40 from OM Tech isn't a kit. Everything comes preassembled, and all the accessories are packed inside the laser.
The only thing you'll need to set up is the power, water pump system, and exhaust. You could be up and running in less than an hour.

K40 Whisperer Software

K40 Whisperer is the included software with the machine. This is a pretty significant upgrade over other software I've gotten from Chinese imports. K40 Whisperer is from a US developer and does a great job sending commands to the machine.


You'll easily be able to align artwork and set engrave and cut settings. The most significant difference between K40 Whisperer and something like Lightburn is generating the artwork itself. You will need to use other software that can create a .svg file to import into K40 Whisperer.

I typically use Adobe Illustrator for this, but Inkscape is a free solution that works cross-platform. I tested out the workflow of Inkscape + K40 Whisperer and found it was straightforward to either convert artwork or create something from scratch and then send it to the machine.

Laser Cutting and Engraving Tests

I didn't do extensive testing on this unit since I've done many general CO2 tests in the past. The biggest thing I wanted to check was the reliability and ease of use for the OM Tech unit.

Here are some tests I did on my larger 50W laser.

The most significant difference I found with the K40 vs. the other lasers I've used was the lack of air assist. Air assist is a stream of compressed air that is pointed at when the laser burns the material. This is continuously putting out any small flare-ups that you'll get when using the unit, plus it helps to clear smoke that can obscure the laser beam and cause lower results while in use.

I found when cutting plywood that I would get some pretty severe burning on my final piece. It's pretty easy to see how this could spread to the machine itself if you weren't carefully monitoring it.

There are relatively cheap and easy air-assist upgrades that can be added to the unit, but the current lack of air assist is the biggest detractor for me for a K40, especially if you want to do a lot of cutting.

On the engraving and raster side of things, you can engrave up to 1000 dpi, which is comparable to more expensive machines. My quick Baby Yoda tests turned out great on birch plywood!

Not so much on Basswood, although that's more an issue with engraving Basswood vs. the machine.

How much does a K40 cost?

So why is the K40 so popular?

Two words: The Price.

OM Tech sells several different units at 40W power. The one I tested is $429.99, but the price goes down to $390.00 for one with a smaller control panel.

This price is higher than what you could find on eBay, but those don't come with the warranty, quality control, or customer support from OM Tech. Which I think is well worth the premium you would pay to get a unit that wasn't broken right out of the box.

K40 Upgrades

So why is the K40 so popular? The second only to price is the community and upgradability to the unit. More than any other laser I've seen, the K40 has a ton of resources that allow you to upgrade it. I'm planning on a follow-up video that will feature some of the top ones I would recommend, but here are some quick recommended upgrades:

Air Assist

If you were going to upgrade anything on the K40, it would be this. You'll have a stream of compressed air always putting out any small fires from the laser engraving or laser cutting process by adding air-assist.
This also does a great job of removing small debris from the workpiece at the point of contact with the laser. You'll need an air nozzle, air pump as well as tubing to connect one.

Current Meter

To save your tube's life, it's pretty common to not run your laser over 50% power. The best way to measure this and compare settings to other units is with a current meter. These are cheap and pretty easy to install.

Adjustable Bed

The inability to move the bed makes it annoying to cut different material thicknesses. You'll need to add spacers underneath the material to raise and lower it. Lots of people will add a scissor lift style bed and remove the current one.

This is a good option.

Upgraded Control Board

One of the most significant upgrades you can make in terms of functionality is to change out the current board that runs the laser. I would recommend checking out Cohesion3D. You'll get way more functionality, including the ability to use your laser with Lightburn and the ability to control laser power through software rather than the controls on top of the unit.

Lightburn

This is my favorite laser software. You can set up multiple machines with one account, create graphics, and directly control the laser. You will need an upgraded board to use it. It is paid software, but you only have to pay once!

Camera

Lightburn can add a camera, and they sell one. If you've liked the idea of positioning your artwork on top of material that is already inside the laser, this is a great option.

Honeycomb Bed

The included slatted bed works fine for engraving, but if you plan on doing lots of cutting, a honeycomb bed design will give better results. Since most of the bed is open space, the machine will have better airflow leading to much better cuts.

A few other upgrades include different lenses for better optics and cutting out the majority of the exhaust port to extend the bed of your machine. If you love to tinker, then these upgrades don't have to happen all at once and are projects in themselves.

If you add up the cost of all the upgrades plus the cost of the K40, you are getting a lot closer in price to a 50W CO2 laser. That was the biggest reason I went with the larger unit when I was first starting.

Who is the K40 for?

If you want to both engrave AND cut materials for as cheap as possible, then the 40W CO2 laser from OM Tech is a great starting point. In the past, I would recommend the larger 50W unit because of concerns around safety and quality control. But OM Tech is doing a great job checking their units, giving support, and offering a two-year warranty on the machine and one year warranty on the consumables (laser tube and power supply).

If you only need to cut and engrave on the smaller side of things and like the idea of upgrading the unit as you go, then this is a great option. I would highly recommend adding an air assist if you plan on doing much cutting.

If you need something with a bigger work area and an upgraded control board, then stepping up to a 50W unit might make more sense.

Finally, if you want all the bells and whistles and ease of use of an integrated system, then the much more expensive Glowforge or Full Spectrum Muse lasers might be a better fit.

You can check out a full breakdown of my current laser recommendations here.

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