OMTech Preenex K40

I cut my teeth in the CO2 laser world the same way most other people do……..with a Chinese eBay K40 laser.  Hobbyists love them because they cost next to nothing (about $350 and up) and they are pretty powerful devices.

That being said they are Chinese, are cheaply built, with not the highest quality parts.

Much of the allure here is in the hacker installing upgrades and building it into a much more capable machine.   At the end of the day though the machine has some serious limitations.  Here are some that got my attention:

• Very small work area – 12 x 8 at best.
• Doesn’t interpret g-code which means you can’t use some of the better software out there for it (i.e. Lightburn).  You must upgrade the controller card.
• Upgrading the controller card renders the control panel basically useless.  All controls are now software controlled.
• The z axis (up and down) is fixed.  The machines are basically configured to cut or etch 3mm materials.  There are things that can be done to provide some z lift capability but I don’t think it is worth the time, effort, or money to do.
• The machine I own isn’t really a 40 watt.  Probably more like 30.  It is a “Mini” with a shorter tube.  Essentially, the longer the tube, the more powerful it is.

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Laser + Poodle

Got my new OMTech 50 Watt Laser today.

I also own 2 Ortur Laser Master 2 – 20 watt diode lasers and a K40 Laser also from OMTech.

After tons of research I have decided that your best bet on buying a Chinese laser system is to buy it from OMTech.  Your mileage may vary and in fact some people’s mileage DOES vary.   That has NOT been my experience.

The K40 I bought from them and now this 50 watt machine………JUST WORKS. Right out of the box. No damage.  Not one scratch.  Not one dent.   The machines both came aligned right out of the box.

Shipping was fast,  the price was competitive albeit you could save a few dollars by buying from other dealers.  I don’t recommend it unless you are prepared to take a machine out of the box and spend time aligning it and making it right.  If you posses those skills then by all means…….save some money.  Me. I posses those skills but it isn’t worth $50 or $100 to me to do all that quality assurance and work.

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Well the unthinkable happened.  My K40 fouled up.  I’m not sure what happened but my working theory is that my accidentally dropping the laser tube door really hard caused a retainer to fall out, which in turn released spring tension on mirror #1.

Retainer and Spring on Mirror Assembly

Laser beams were firing all over the place.   The dreaded realization came to me that I had to do a mirror alignment on the K40.

Okay, I removed the #1 mirror and reinstalled the spring and retainer and remounted it.

To my surprise I got it back real close to where it was just by using a sharpie to locate orientation.

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Here is a common occurrence on laser forums and groups.  Post a picture of something cool and within about 4.1643 seconds someone will ask, “What Are Your Settings?”

Unquestionably a valid thought from someone who saw what you did and seeks to emulate it.   And most of us want to help answer that question.  We really do.

But there are a LOT of variables involved in a burn.  My settings could produce great results but could start a fire at your house.  Here’s an example worth noting that happened to me just today.  I have a K40 laser and have settings saved for Baltic Birch Plywood.  I bought a new lens and cleaned all the mirrors and ran a job.  That which was supposed to etch my plywood burned slap through it.   New lens was a heck of an improvement, I guess.

Here are some variables:

1. The type of wood or material you are burning on.  I may have 3 layer Baltic Birch and you may have 7 layer.  My plywood may have glue made by virgins with harps and your glue may have been produced by the Communist Chinese.
2. The direction of the grain.  Lasers etch and burn better in some directions than others.
3. Air Assist.  If I have an air assist and you don’t then my settings may not be relevant to your setup.
4. Focus.  I may be focused using a microscope and you may have no idea of what the actual state of your focus is.
5. Temperature.  If using a CO2 laser, cooler water temps can produce more efficient burns.
6. Lens cleanliness.  If my lens is clean and yours is dirty my settings are useless to you.
7. Diode intensity.  I may have a brand new diode laser and you may have been burning at 100% power for 6 months.  Diode lasers wear out.  CO2 in a laser tube depletes.  Also you might have a 4.5 watt output and I might have a 5.5 watt output laser.

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I have an Ortur Laser Master 2.

I have determined that it is now an essential piece of equipment that must have minimum downtime.

That lead me to purchase a new Laser module and a new Motherboard.  These two items and associated parts are the lions share of the machine.

Ortur seems to be really trying to be open about issues and also seems to have pretty great customer service.  And they’ve done something that I think is remarkable.  They have created a Product Advisories web page.

One of these advisories is about a batch of defective motherboards.  My Ortur Laser Master 2 is working perfectly but I was concerned about my spare board that I just received.  They specifically said if your board failed some previous tests to look for the markings OLM-MAX-V10

Ortur Product Advisory

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OMTech K40 Laser

The Chinese laser often referred to as the K40 (40 watt) is an entry level CO2 laser at a magnificent price point.  They can be had for around $350 to $450 dollars depending on where you get them and how you get them configured.

I got mine from a place called OMTech for about $420.  It is also were well configured and has many upgrades already included.

Right out of the chute these things engrave and cut well although the 40 in K40 seems to be a bit of a gimmick.  A lot of the included laser tubes are actually 30 to 35 watts.  It’s really not enough to kick a fuss up over.   It’s just the way it is.  So that kicks off the upgrade discussion.  You can buy larger and more powerful laser tubes.

Once you use one of these things a bit and learn your way around one you’re going to want to upgrade some things.  While they do indeed come at a magnificent price point the old adage applies.  You get what you pay for.

Let’s go over a quick list of things you are going to want to upgrade.

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I have an Ortur Laser Master 2.  Very, very nice low powered diode laser rig capable of making some great craft items.  I also have a larger K40 Laser however sometimes it is like trying to use a sledgehammer to drive a nail.   The Ortur has great flexibility because of how open it is and the fact it can be set on any surface or pass materials through it or raise it way up high.

Make no mistake though, the Ortur Laser Master 2 is NOT a production machine.  It was not meant to be run full power, all day, every day.  It is a hobby device for hobbyists.  If you push it beyond that…….well…….good on ya.

There do seem to be some issues with the laser though.  Some users report 100% laser power 100% of the time and frequent disconnects, not to mention the fact they can’t connect at all to the computer.  So there are issues going in……………

It CAN be a production device though with some pre-planning and regular maintenance.

Let me tell a somewhat unrelated story.  I like solar power and solar powered generators such as the company Jackery makes.  Every time they release a new one about 50 clowns on the internet say “This is bullshit. This will only run a refrigerator for 14 hours and my heart transplant kit needs to run for 15 hours.”

My response to that is always this:  “So buy two of them!”

Do you see where I am going with this?

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A K40 with a digital control doesn’t actually indicate actual laser power.  The only way to reliably measure the current from a laser tube is to add a milliamp (mA) meter to your K40.  While there are a lot of differing opinions on max power draw most agree it is somewhere between 18 and 20 mA’s.  Some people even pull short at 15mA to improve tube longevity.

Adding a meter is SIMPLE.  Locate the Black wire on the EXIT end of the laser tube.  That is the end closest to the mirror.  That black wire will be spliced to another wire that runs all the way to the L connection on the Power Supply.

LASER END

K 40 Laser Tube (L) wire

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I recently bought a K40 Laser from OMTech. Most people use a free software mix for the K40 utilizing Inkscape and K40 Whisperer but there is a far better software solution (not free) called Lightburn.

I liked K40 Whisperer and was getting the hang of it.  It’s actually pretty powerful and it really is a good hunk of software but it just isn’t Lightburn.  No knock at all on K40 Whisperer intended.

Most K40 lasers come with a control card called an M2Nano which is not compatible with Lightburn.  The only way to run Lightburn on a K40 is to purchase a new controller card.  There are several options out there but I went with the Mini-Gerbil from AwesomeTech.  I just got the card and installed it and as always took notes while doing the installation and ran into a couple of noteworthy things that I thought was worthy of a blog.

There are SO MANY K40 variants that it is hard to say that anything I took note of is a problem.

“Let me just throw this out there…….If you bought a K40 laser and realize you need a new control card and aren’t scared in the least to change it then nothing I note here is above your skill level.  I don’t view anything as a mistake or documentation error.  There are simply SO MANY K40 variants out there it is tough to cover them all.”

Let’s roll.

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I recently bought an Ortur Laser Master 2 which is marketed as a 20 watt laser but it is truly about a 5 or 5.5 watt output power diode laser.  It’s an amazing device for engraving wood and cutting thin materials.  In other words it has some limitations.  I’m having so much fun with it but the forums are full of stories of parts failures.   If you have a hobby device and it fails it’s not the end of the world, however if you are making money with the device you probably should have a 2nd one at the ready, or at least buy spares, such as another controller board and laser module.

So that’s where I’m at.  I made my first couple of sales and I realized that if I can make a buck or two I’ll lose credibility real fast if my machine goes down and I can’t deliver.  So I decided to pick up another machine.  After all they are cheap.  Around $300 or so.

K40 Mini Laser

Then I (re)discovered the K40 Laser.  K40 isn’t a name brand but rather a gigantic swoosh covering a range of inexpensive cloned Chinese 40 watt CO2 lasers.  K40’s are made by several manufacturers and sold by untold number of secondary retailers especially on the Chinese electronics websites (Aliexpress, Banggood, etc.) and eBay.  The quality range varies from great to absolutely horrific.  You need to carefully source your supplier and do lots of research before buying one of these things.

That being said, these machines are a platform for upgrades and lots of the people who buy them don’t much care if they work or not.  They will make them work and improve and upgrade them in the process.   In fact I’d love to find one broken that someone was selling for a song.  After 48  hours with this thing  I’m pretty confident I could rebuild one and repair parts can be sourced cheaply.

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