K40 and hardwood

I was given a K40 (all stock), and I want to use it to cut out some earrings from different exotic woods. I have it set up and etching the woods ok, did some nice Rosewood stuff last weekend.

So far, my attempts at cutting 4mm Sapele or Cocobolo have failed terribly. I've done some reading here, and seen some conflicting information. From what I have picked up, I need the air assist. What about the focal lens? I've seen posts stating the 50mm is fine, others say get the 38mm. Or should I just use this lower quality laser for etching, and pick up something else for cutting?

I hate the moshidraw which comes with it, but I see there's controller board/software upgrades. Without breaking the bank, what's the most universally used?

Thanks for reading the newb questions.

The K40 is 30-35W and not powerful enough to cut 4mm hardwood, anything more than 3mm laser ply or laser mdf is pushing machine beyond its abilities even with better lenses and air assist.

That's what I was afraid of. What type of wattage would I be looking at to do this?

I would recommend a minimum of 80w for your current needs but to prevent disappointment and need for further upgrades 100-150w would give you a better range of uses for your machine and increased cost going from 80w to 130w would worth while in my opinion. Remembering that with Co2 lasers your going to extend tube life dramatically running between 20% & 70% of max power and decrease tube life running above 70% for any length of time.

Awesome, thanks... now it's time to start reading reviews, and spending money.

I have a 50w with a 52mm lens and would have no problem with 4mm. Would cut it at 30mm per min. 19 ma power. It's not a K40 which might get to around 13 ma. You will need air.


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I cut 6mm mdf in 2 passes with my k40. 1/4" poplar too. Use air assist. 10ma.

Well, I have an air assist in route to me now... Just need to figure out the whole focus thing (finding sweet spot). The Rosewood I use is a lot different than poplar, but hey, since I already ordered the air assist, I might as well try again.

If not, I have to explain to the wife that I'm about to make her broke again. haha

Correction up to 400 mm/min in case someone gets picky. Yea you burn wood to cut it and it needs oxygen, more the better.
Never cut rosewood tell us how it goes


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The original post is regarding the cutting of hardwoods not softwoods like PLY and MDF even with PLY and MDF the type used must be compatable with laser cutting, some are treated with flame retardants and many others use resin in their construction incompatable with laser cutting.

Louis do you have a k40? If you do, check your mirror alignment. I just cut some 6.5mm Cherry, which is considered a hardwood. It almost cut through with one pass at 10ma and 5mm/sec speed. Had to do a second pass for it to drop out completely. I have no doubt it will cut 4mm Cherry in single pass. I've cut plenty of different 1/4" woods/ply/mdf/hardboard etc. never really had an issue. It may take 2 passes but it cuts just fine. I'm not sure why you say a k40 isn't powerful enough to cut 4mm material. My machine is stock except the air assist.

If you are cutting that slow and more than one pass you are burning your way through not Vapourising material for a quality cut.

Used properly a laser vaporizes materials to cut, this process should go as quickly as possible, to minimize heat being imparted to the material near the cut.
Lasers that don't vaporize quickly will take longer to cut through an area, resulting in more heat which causes burning.
High peak power so parts are vaporized much faster is needed for acceptable edge quality, lower watt lasers can't accomplish this quality because they cut too slowly, burning rather than vapourising.

Dean448 air assist is used to provide oxygen to promote burning or that you burn wood with a laser tis not how a laser should work wood should be Vapourised leaving clean edges and not BURNT leaving charred mess!

Cuts just fine for my purpose. We all wish to have a high power laser but for $366, it does it good enough. I have no issues with the cut quality. It's faster than using a scroll saw and more accurate to. That works for me and no one is complaining.

Most of the time the pieces are decorated or painted. It doesn't matter if the sides are a little black. It's certainly no worse than the stuff I see on etsy all the time.

The OP requested advice for cutting Earings from hardwoods, not boxes or anything to be painted, the finish for small items of jewellery require sufficient power to vapourise the cut, and yes this is going to cost more and you will only ever get what you pay for. When advice is given and people disagree because they can burn their way through materials eventually leaving a poor quality charred edge its not helpful advice. People thinking that wood or anything else should be burnt by a laser are ill informed, I am not trying to put anyone down just passing on relevant and reliable information to enable someone to make an informed choice. Having made the same mistake as many I started with a K40 burning my way through materials, I learnt the hard way too, then I saved money and made money by spending more money to do the job correctly, if you ever get the chance to see a pro laser cutting machine at work you will be amazed at how poor the K40's really are at cutting anything more difficult than Acrylic.

Well most earrings I see are not just flat cut. Anything nice looking will likely be shaped, carved, sanded and worked on before final finish coat. It doesn't take much time to sand off any burnt edges especially if you use a dremel. I do plenty of small pieces that are rough cut on my cnc or laser and then hand shaped for a more pleasing/artistic look. As a woodworker for over 30 years, lots of stuff has been made in my home shop, even earrings too.
It's not that hard and don't try to make it more difficult than it has to be.

My guess is the OP needs to just align and find the focus for his laser before spending any money on a multi thousand 100watt laser that you are proposing. That is just silly and isn't really helping the OP.

http://uploads.tapatalk-cdn.com/2016...f6925f8800.jpg

I made this just now for my nephew. 2 minutes to cut on laser, about 7 minutes sanding off the dark edges with dremel, 2 minutes putting on a coat of wipe on finish. It's not that hard working with wood.

Can't say I've thought about burn vs vaporize. Sound similar. When the cut struggles like in plywood with many plys it looks burnt. Balsa cuts easier and looks brown to tan. I think as power and as air increases it cuts fast and less burnt.
To prove that no burning is involved in laser cutting try running with argon.
The goal is tan cut walls which shows a good power and focused beam.


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OP this is my focusing jig. It's placed on a couple of 123blocks. Then laser a line on a piece of thin wood. Measure the height where the cut line is the thinnest. That is your ideal focus spot. Mine is 3.3" from the BOTTOM of the laser box.
http://uploads.tapatalk-cdn.com/2016...f97062557b.jpg

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Originally Posted by jfong

OP this is my focusing jig. It's placed on a couple of 123blocks. Then laser a line on a piece of thin wood. Measure the height where the cut line is the thinnest. That is your ideal focus spot. Mine is 3.3" from the BOTTOM of the laser box.

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Thank you, that's helpful.

Spent today working on a commissioned furniture piece, I hope to get back to the laser tomorrow. I went ahead and ordered the air assist, should be here next week. I will use something like your rig there to find the sweet spot.

Quote:

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Originally Posted by jfong

I cut 6mm mdf in 2 passes with my k40. 1/4" poplar too. Use air assist. 10ma.

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As stated use an air assist to limit charring and make multiple passes. 4mm hardwood is doable on these machines. Make sure your lens and mirrors are all aligned and focused properly and your material is at the correct height (distance from the lens). It may simply take 2 or 3 (or more possibly) passes to cut completely through. Your edge finish will depend on the speed, power and type of wood/material, so if may take some practice to find the best settings.