Laser with MPCNC

Good day! I was very interested in the opportunity to build my own CNC! But in my case, I need a laser with which I want to cut sheet plywood. If I am not mistaken, there are 2 versions for implementation: Based on MP and Lowrider. And the question is which laser to choose Diode or CO2? I would like to hear advice from you dear forum users

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Cutting thin plywood with a diode laser is possible. You need air assist. If you are ok with about 24"x24"x3.5" work area, then the MPCNC is the right choice. If you want bigger, then the LR. But there is less info for lasers on the LR.

There really isn’t a good way to do CO2 on either. At least no one has made it easy. The MPCNC can get a little out of square and the laser can get away from it’s mirrors. Someone posted about putting the co2 laser along the gantry of a LR, but I haven’t heard anything in a long time.

If you need to cut through anything but the thinnest plywood, I think you need to get a CO2 laser. But you’ll be doing a lot of work to make it work on an MPCNC or a LowRider.

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I have a pretty powerful diode laser and can only get consistent cuts in 1/8" plywood.

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Curious how powerful laser it is to cut the 1/8" ply?

Depends on how fast you want to cut I was cutting 1/8" ply with a 1.6W diode laser. But it took 8 passes.

The limiting factor is the glue, the diode lasers have a hard time cutting through the glue in plywood. Because a co2 laser runs at a different wavelength it cuts the glue better.

@Lurgot But if you are looking to cut through thick ply (>1/4") in a reasonable time frame for larger projects, you will need a very powerful co2 laser that I would not recommend building yourself. Can I ask why you need to laser cut rather than mill the ply?

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Need? Not really.

But new tools to play with? You betcha! :grinning:

I’m in no hurry, trying to learn what’s involved. Looking to get as close to plug-n-play as possible. I’ll turn wrenches all day but would prefer electronic simplicity.

Thanks for the reply!

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Sorry I should have been more clear that question was aimed at the OP. he said he needed to laser cut ply I’m just curious what he plans to do with the laser that can’t be done with the router.

Lasers are very simple devices. No more complicated than a light bulb really. For diodes the biggest diffrence is that they are a current device, Like the motors. But if your looking for simplicity I would choose a pre-assembled laser in the 4-7W output range. Should give you a good amount of power while not breaking the bank.

Ahhhhh, I have to say I was impressed with the etching on tile as well as some of the markings on wood. And if the laser’s in the mount when you want to cut some thin ply? Why not? The burly cuts thin ply very well but even baltic birch has ‘fuzzies’ that need to be removed. I’m guessing that may be less of an issue with a laser.

No fuzziness with a laser but smoke stains instead, especially when cutting though thicker pieces. And the process to remove it is the same as removing fuzziness (light sanding). The only application I can think of that needs a laser is if you needed to make a cut with very thin walls. A laser can cut out a toothpick, a mill tends to chip when you get walls that thin.

Exactly what I’m thinking, I put a pic of a piece I did of ‘The Great Wave’ in the MPCNC gallery that’s 8" in diameter and has some very delicate areas to try and sand. And being painted, no problem with smoke stains. And the tile etching was something I’d never heard of, it’s a step down to my backroom and I could see some interesting tiles making a nice facing.

~7w is what I’m using. It’s sold as the NEJE 30w, but that’s not true diode power.

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I know you’d had some from Banggood? and see the link in this posting mentions Amazon. Do any of these come with enough documentation to allow someone who can hook things up as instructed but isn’t terribly well versed in electronic theory to be successful? I wouldn’t mind buying something US made and was looking at the EL Cheapo but they hit one of my pet peeves. I really don’t understand why companies put links on their sites saying they’d be happy to answer questions about their products and then never answer.

The fact is that when cutting with 2 lasers, there is no shavings, there is no need to build aspiration with which I have problems and the speed is better. Well, the biggest bonus: Cutting out very thin parts, which, if processed with a 1 mm cutter, is very long

This is not true at all, in fact there is a greater need for good ventilation with lasers. Lasers burn or vaporize the material rather than cutting it. This creates smoke and soot. If your burning through solid wood then it’s no more dangerous than a campfire, but plywood has glue that is quite toxic when burned and inhaled. Also the smoke and soot will interfere with the lasers operation and reduce its power or even damage it if not removed.

This depends largely on how powerful of a laser you have and how thick your cutting. Just for reference, cutting 1/4" birch with a 150W co2 laser is usually done at a speed of 10mm/s. That may be faster than milling but not by much and will cost much more than the mill.

Yes you can cut very thin pieces of thin wood but because lasers cut with a conical shape the deeper the cut the less thin you can cut or your thin piece will be charred and brittle.

In the end all my research has told me that home lasers are great for cutting thin (~1/8") detailed designs or engraving. The lasers required to do more than that are either cost prohibitive (as compared to a mpcnc mill) or extremely dangerous to build at home (one wrong mirror angle and you will light things on fire or blind yourself) this led me to ask what your planing on cutting/making. Your original post just said “sheet plywood” witch you can get in 1/8" thickness and have no problems. But if you want to cut 3/4" ply, I’m just not sure how you could go about doing that safely. Especially on a machine like the MPCNC or Lowrider.

If you want to cut metals rather than wood you could build one with a fiber laser, that would cut faster, more accurately and be (relatively) safe to put on a home built machine. Though they are still quite expensive.

If you have info contrary to what I have said here I would love to hear it. I love lasers and would be very interested in your solutions to these problems.

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Added negative of using a laser to engrave solid wood… burning maple and walnut tends to make me hungry.

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I am new to this field and I have absolutely nothing to oppose. It sounds like advice to me) And I’m glad of that. It turns out that it makes sense to take only a diode laser of the highest possible power in order to cut a maximum of 4 mm of plywood at a low speed? Or just put a router and cut it as I am cutting now on my cnc machine …

If your only cutting 4mm than a 5 to 7W diode laser should work pretty well. Still might not cut faster then the router but you could definitely get more detail at the same speed. I would strongly recommend an air assist of some kind the most basic would be a fan blowing across the work area. Better yet would be compressed air delivered through a tube near the optics of the laser.
If your running it in a confined space than air filtration or a good respirator would also be a good idea (I haven’t ment anyone with COPD that has said “it was worth it”).

Keep in mind if your going to use it all the time the diodes will wear out adventualy (I would say in 3 to 5 years with heavy use). And don’t leave it unattended for any real period of time (I consider my laser safer than my router but far more dangerous than my printer. I will leave it alone long enough to run to the bathroom or grab a can of bear from the fridge but no longer than 5 minutes) and have fun with it. You can do some really cool designs with lasers(I like making Christmas ornaments with mine).

Thanks a lot! I have heard that diode lasers have a maximum power of 7 watts. 15, 30, 40 is all marketing. Although I saw some kind of 40-watt laser on aliexpress, which cut 5 mm plywood in one pass and cost about $ 200 …

Is it worth considering such samples?

Sure the 15,20,30,and 40W lasers are being rated by input power rather than optical output power. A 40W input should be right around a 7W optical output. Though keep in mind that cheap Chinese products aren’t always the most durable. And vary rarely have good documentation/instructions.

In this case, where can I buy a high quality 7 watt laser? In the sense that it is not Chinese