Replacing Crap Water Flow Sensor – Shutoff Switch in Chinese Laser

CO2 lasers are water cooled.  If the cool water stops flowing the laser tube will die.  That’s all there is to it.   To prevent the laser from firing when there is no water flowing most lasers incorporate some kind of switch that chops power to the laser circuit when no water flow is detected.

My new 50 watt laser has such a switch but forums are FULL of reports of failures and especially the fact that the switch will begin leaking.

Crap Water Flow Sensor

While this may not be the exact switch, it is darn similar. There is no outlet port on these things.  The switch is hooked to a Y valve.  One side is inlet, the other is inlet flow and the top opening goes to the switch.

In my mind that doesn’t really measure “Flow”, rather the fact there is water pressure present on the switch.

Let’s say you had a fancy water chiller and the chiller was setting up higher than the laser.   Gravity and shit, would put head pressure on the switch allowing it to fire EVEN WHEN THERE WAS NO FLOW.  I’ve seen several reports of this already.  That renders this switch USELESS.  And again, even if it is working right I’ve also read MANY reports of “this failed after a month” or “this started leaking right away”.

Continue reading

Spares, spares, and more spares for Lasers

There seems to be an epidemic in LaserLand™ where people buy really expensive, and large CO2 lasers for their home business and experience component failures and become frustrated with the re-seller for selling crap.  I’m sorry to keep harping on this but it’s like watching a car crash, paint dry, and grass grow all at the same time.

These lasers are so capable, and so fun and provide the ability to make the owner some money.  But they are not without issues.

Let’s be clear about these CO2 lasers.   They come from CHINA.  That is about all one really needs to know as it relates to product reliability.

The blue power supplies in these lasers = Crap that will fail

The Water Flow Sensors = Crap that will leak

The Air Assist pump is in a special category of crap = Crap that crap calls crap.

Look.  I dig laser etching and cutting.  It’s fun and its a great way to make continuous $20 bills.

But I spent a career in the US Navy and as a Gov’t Employee fixing equipment that costs a lot of money.  I’m an Electronics Tech Rep for DOD that supports the Navy and Marine Corps.   I know how to fix broken things and I can smell a crap component a 100 yards away with the wind blowing away from me.

Continue reading

Random Musings About Lasers

I’m not sure what is going on in the world of Home/Small Business Lasers.  Just a couple of months ago they were relatively easy to get, and now suddenly they are nearly unobtanium.  Kind of like last year when Coronavirus hit and you couldn’t buy a bicycle to save your life.  Everyone all at once decided to buy bicycles.  So it goes with the larger CO2 lasers right now.  I think a lot of folks have decided to do the side hustle thing and laser engraving from home is a viable and sometimes profitable endeavor.  I refer to my lasers as “$20 bill vacuums”.

I belong to several forums regarding lasers, and software and they are filled with first time users who have no idea at all what they are doing.  And, let’s be clear……..there is nothing wrong with that.  That’s what forums are for………helping each other and learning.  When I bought my first laser I had no idea what I was doing either.

If you buy a Chinese Laser …… YOU ARE ESSENTIALLY ON YOUR OWN.  You might get some limited support, but you better be able to be self-sufficient.

Laser engravers and cutters are pretty complex systems that require at least some technical skill.  Larger CO2 lasers consist of a few different subsystems such as:

  • High powered laser
  • Precise Optical Alignment system with mirrors
  • Water cooling system
  • Air Assist system
  • Electronics – power supply, controller, switches
  • Machine settings in firmware and software
  • G-Code – you may just have to pass some G-Code settings to your machine manually

And I’m really oversimplifying things here.    Once you ship a machine half way around the world, it may or may not have problems upon arrival.  Your choices are then:

  • Send the Machine back and wait for the reseller to fix it or provide another machine, which by the way is unobtanium at the moment.
  • Deal with the problem, whatever it is.

Continue reading

First Week With A Bigger Laser

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.

Continue reading

OMTech 50Watt Laser First Impressions

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.

Continue reading

K40 Updates

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.

Continue reading

Network Security – Part Deux

Your network probably is comprised of the modem/wifi router provided by your Internet Service Provider.  Most people I know are configured this way.

This is the ABSOLUTE, WORST POSSIBLE security scenario there is.   It is typically extremely old, and unmaintained in terms of software / firmware.  And you probably lease the equipment from them for $10 a month or something.  That $50 hunk of hardware has already netted them hundreds of dollars from you……..if not thousands.

So the smart play is to go buy your own router and modem.  Walmart and Target sell them and it’s more than likely that is where you will go.  Or Amazon.   First of all you cannot just hook a modem to your home.  You have to call the cable company and ask them to “provision” it.   They have to apply the settings to it to allow it to work on their network.  There is NO WAY for you to do this.  They have to do it.   if there are firmware updates for your modem you have to call the cable company and tell them to apply them or “re-provision” your modem.   You can have a secure router (HA!) and have a crappy modem which will allow you to be compromised.

Continue reading

Revisiting Routers and Security and Alternative Firmware

I get on a network security / router security kick every now and again.   For the last week or so I have been reconfiguring my main router.  I have a Netgear R7800 that was running a firmware called OpenWRT.   I prefer to run Open Source firmware on my routers for a couple of reasons.

  1. Users can view the code.  When you buy a router at Walmart or Target or from Amazon or wherever it comes with the manufacturers proprietary firmware.  You have no idea what is in the code.   Also their goals are to make money, and make the router as simple as possible so you don’t call their paid support centers.  Complex configurations that are safer cause connection problems.
  2. There is a community of people who submit security and performance changes to the Open Source firmwares.   When exploits are discovered they are patched.   When is the last time you got a firmware update on your home router?

Router exploits and bugs are SCARY and all too frequent.  Here is a good resource where recent bugs against routers and modems are listed from news articles.  Scroll down that list.  I bet you won’t get far before you see a recent exploit discovered against your home router.

Continue reading

Prusa Mini+ Upgrades – So Far

The actual goal of 3D printing is to make your 3D printer unrecognizable from its stock form is less than one week.

Seriously, who hasn’t owned a 3D printer and “upgraded” it instantly?

It’s not like a Prusa Mini+ or i3 Mk3S+ isn’t good enough right out of the box.

I’ve had my Mini a week now and I have built the perfect beast.   Nothing I have done has actually made the printer print better though.  At least I realize that, huh?


First of all I love me some Wyze Cameras and smart outlets.  I can VPN into my network and watch my cameras.  In the event something horrible went wrong with a print I can go into my Home Automation and just chop power to the outlet.  Not real elegant but better than letting a print run for 12 hours with nothing actually stuck to the bed.  And, yeah, I know about Octoprint.  Again, not elegant but it gets the job done.

Wyze Cameras

Continue reading

Prusa Mini+ Kit Review

Prusa Mini+ Kit

First of all I have to say I have been 3D printing since 2015 and bought my first Prusa in maybe 2016 or 2017.  So I’ve been around the block a time or two.  No, I’m not a super expert like some folks but I do have some experience that lends me to share a thought or two.

My Prusa experience kind of shakes out like this:

  • Bought i3 Mk2
  • Upgraded i3 Mk2 to Mk2S
  • Bought i3 Mk3S+
  • Upgraded i3 Mk2S to i3 Mk2.5S
  • Bought and built Mini + kit.

Okay, I have no huge print farm, just three printers and 5 builds and upgrades.  But let me tell you this……..The Prusa Mini + is IMPRESSIVE.

You expect a lot from an $800 3D printer like the i3 Mk3S+……. that’s a no-brainer………but you don’t expect as much from a $349 3D printer.

But there’s the rub…….The Prusa Mini+ is a CRAZY GOOD 3D PRINTER.  I can’t believe it.  Not a lot impresses me but this printer is incredible.

Okay, what are the downsides?  Number 1 it isn’t called a “Mini” without a reason.  The build plate is much smaller than the other offerings.  That being said there have been very few times I have stretched the limit of the size of my 3D printer bed.  Most of the things I print will fit on the Mini build plate.

Continue reading