80W Chinese Red and Black not cutting succesfully through

Still learning tips and tricks to make my machine run smoothly
I have the 80W 700 x 500 Red and Black machine I purchased from Ebay a few months back (Ruida.) Currently running it in my garage in Florida (not air conditioned … yet) we have created a water cooler of our own using just a regular Igloo cooler to try to keep the water cool, as well as keeping ice packs in the water. I am struggling because the cuts aren’t going all the way through my plywood 1/4" inch thickness. I have been making things for a while now and I have experimented with all different settings that I have researched or read on multiple forums. I recently tried speed of 5 with pwr 66, and it burned the edges of most of my items pretty drastically. I have experimented with many many different settings I am just wondering if the machine is getting too hot. In the past I have done a speed of 35 with pwr of 45 but with about 3-4 passes to get through. However lately neither of those settings have been successfully cutting through. I don’t know if I provided enough information however I am looking for any advice! I am looking into getting the garage air conditioned to try to keep everything cool. I have also read about getting a better air pump as I have the one that came with the machine. Any other suggestions would be greatly appreciated! Thanks!

I assume you mean mm / sec when you state the speed. (please be sure to specify). Here’s some points to go through that should get your cutting improved:

  • Calibrate your Laser Tube’s Power Supply if you have not done so already (otherwise you really don’t know if you’re within the ideal long-life current draw of the laser tube)
    Could this be a sign of a bad laser tube?

  • Get a Quality ZnSE lens with a longer throw if you want to cut
    Which lens to use

  • Upgrade to an air compressor and increase the air flow and pressure
    Air pump recommendations appreciated?

  • Ensure laser beam alignment is tuned in
    How to align your laser beam a handy guide

  • Check that your bed is plumb to the Gantry

  • Provide effective fume extraction
    Problems with Baltic Birch Plywood

  • Keep your mirrors and lens clean. Build up on these surfaces will first reduce power. Then over time, the film will gradually absorb more and more light until finally they are destroyed and need replacement. For cleaning, some denatured alcohol, soft cotton swabs, and some latex gloves (while handling the lens) should clean well.

You don’t mention what controller your red&black has.
If it’s Ruida, be aware that for speeds less than (usually) 10mm/sec, the controller defaults to whatever MIN power setting you’ve entered. For low speeds like that make sure that your MIN power is set the same as your MAX power.

1 Like

What focal length? Are you set up for engraving or cutting?

I have roughly the same machine, and it was set up for engraving with a restricted air flow as it shipped. There is a physical difference between the set ups. I could barely cut 1/4" Premium MDF as shipped. Got a cutting set up and good air flow and 1/4" was no problem. Got a 2.5" lens / lens tube set up and now 3/8" is no problem. Will be interesting to see what I can do when I get the 4" nozzle and lens tube in place.

Thank you! This is all so helpful!

The first two pics on my mod page are of the nozzles. You can see the difference, especially in the air fitting.

Glad that I found this thread, I also just got an ebay laser, the new blue and black 60w that actually has a 50w tube in it. Have had some success with cutting 1/4 baltic birch ply with settings at 8mm on 45% power, but it isn’t consistent every time so I will be looking into the recommendations above.

Thank you

The longer focal length lens the more ‘usable’ cutting depth you have. What length lens you can use is totally dependent on your head and lens tube combination.

You didn’t mention whether you were ever able to do this. I ask this because most of the cheap imports lack a current meter, and if you run the tube too hard (easy to do) they die quickly. Hope this isn’t the case for you, but from how you are describing the problem, it may be. Replacement tubes are expensive!

I always urge users to install an ammeter (carefully) and stay within the tube’s safe operating range.

mA meters are cheep, $12 on Amazon, and extremely easy to wire. A coolant temp gauge is the second must have.

You have two ways to cook your laser tube. Too much current and too much heat. Do either one of those, and you will have a nice shiny EXPENSIVE glass paper weight.


You will want to pay attention to what Dave and Niel mentioned here. It is very important, Specially if you are new to laser cutting and experimenting different materials

“I always urge users to install an ammeter (carefully) and stay within the tube’s safe operating range.”

“mA meters are cheep, $12 on Amazon, and extremely easy to wire. A coolant temp gauge is the second must have.”

Our first laser tube lasted about 2 months

Personally, I got a dual digital aquarium gauge on Amazon. It was $1 more than the single and will run on anything 5V to 80V DC, and let me put a probe in the in and out of the tube so I can see just how much heat the laser is dumping into my coolant. I get around a 3.5 to 4 degree bump if I’m running at a full 80W.

Mounted my probes in my new bulkhead fittings. I also moved my fittings. Straight out the back let the silicone hose partially kink further reducing my coolant flow. I have some pics in here.

I did have to send the first gauge back, wasn’t paying attention and clicked on the C instead of the F and they don’t switch.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.