Cutting Speeds and LASER Power

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Cutting Speeds and LASER Power

Postby wdyasq » Sat May 14, 2011 11:27 pm

Greetings,

I found this site through 'MakerSlide'. I want to first thank all who got that project underway. I will be purchasing some long lengths and having them shipped to about 80 miles SW of Dallas if it is possible. If anyone in the "Fort Worth/Dallas" area wants some long lengths or, just wants to bundle shipping with my batch, let me know by PM and we shall make arrangements to achieve that goal.

I am primarily a woodworker. My present project is a series run of 22' John Hacker inspired runabouts. These will have a hull of 2 layers of 4mm marine plywood covered by a linear layer of "African Mahogany", also near 4mm. All of this will be vacuum laminated over forms using epoxy as the primary adhesive. I plan on CNC cutting all of the plywood and mahogany, at least on the first two.

I plan on building a 'better' router with the MakerSlide extrusions. While reading about the project, it occurred to my not so nimble brain if the wood were cut with a laser, all of the kerf would be smoke, rather than sawdust. I would not need to sweep the sawdust up or carry it out and dispose of it.

The question is how fast will a laser of "X" power cut wood of "Y" thickness. Is there a 'rule of thumb' one can use to determine what speeds might be possible? On this site I have seen things like % speed with apparently power pulsed at another rate. Both of these are near Greek at my present LASER education level. On commercial sites I have found rates of up to several meters a minute ..... but they seldom tell the power used. In my short amount of research I have found solid woods cut faster than laminated products and the mash of glue and cellulose they call MDF does not cut well at all.

So, what speeds can one expect with a 40W .... or even a 100W LASER and 4mm solid and ply? Do I need even more power? From what I read at times it will take several passes to cut thicker material. My level of ignorance tells me this must be from the smoke degrading the laser beam and/or the glue.

Thanks for your help,

Ron
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Re: Cutting Speeds and LASER Power

Postby r691175002 » Mon May 16, 2011 12:35 am

You aren't getting many replies because it is really hard to estimate cutting speeds. It depends on the laser power, optics, material and thickness.

I'd say that if you are doing reasonable amounts of 4mm plywood you would probably want more than 40W. It would cut, but it would be slow.

To be honest, it sounds like a router would serve you better than a laser.
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Re: Cutting Speeds and LASER Power

Postby metalman » Tue Aug 02, 2011 11:46 pm

I'm in the process of gathering parts for my build and I am trying to get a feel for what the cutting speed of the 40W laser will be on 1/8 plywood and 1/8 acrylic. I'll either be using Bart's driver card and Mach3 or a DSP controller. The parts I need to cut have about a sixteen inch perimeter, made up of twelve straight segments.

Another issue is the time it would take to engrave a simple fill pattern in a one inch square on both the plywood and acrylic. Would one of the controllers have an advantage over the other?
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Re: Cutting Speeds and LASER Power

Postby twehr » Wed Aug 03, 2011 12:21 pm

metalman wrote:I'm in the process of gathering parts for my build and I am trying to get a feel for what the cutting speed of the 40W laser will be on 1/8 plywood and 1/8 acrylic. I'll either be using Bart's driver card and Mach3 or a DSP controller. The parts I need to cut have about a sixteen inch perimeter, made up of twelve straight segments.

Another issue is the time it would take to engrave a simple fill pattern in a one inch square on both the plywood and acrylic. Would one of the controllers have an advantage over the other?


On 1/8 craft ply, I cut at 3 mm/sec. On 1/8 acrylic, I cut at 2 mm/sec. Both at near full power (about 18 ma continuous).

On craft ply, I engrave at 100 mm/sec, scan spacing of .10 mm. Means 254 scan lines per inch. Takes about a minute or so (as I recall - no actual time tests)
On acrylic, it will be a bit longer, I think. I run about 75 mm/sec on acrylic.

The controller you choose will not influence the performance speed of the machine. It will have a great effect on the quality of the output (especially engraving) and the overall time it takes to run your job. If the controller allows you to run all cut and engrave operations at once, your throughput will be much faster than if you have to make individual passes with each type of operation. For me, the DSP has always been the go-to controller for ease of use, convenience, quality.
tim
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Re: Cutting Speeds and LASER Power

Postby metalman » Wed Aug 03, 2011 2:11 pm

Thanks Tim! That is just what I needed to hear. Would a 60W laser be better for that type of work?

Thanks again,
Jay
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Re: Cutting Speeds and LASER Power

Postby twehr » Wed Aug 03, 2011 4:09 pm

metalman wrote:Thanks Tim! That is just what I needed to hear. Would a 60W laser be better for that type of work?

Thanks again,
Jay


For cutting, extra power is usually a benefit - you can cut faster. If you are cutting delicate materials (paper, cloth) you could reach a point where more power is not helpful.

For cutting acrylic and plywood, the 60watt option will certainly give you faster cuts than the 40watt. If you are trying to do any type of "production" work, then faster = $$$.

For engraving, the 60 watt should still do a good job for you. Again, some materials don't like higher power, but doubt this will be an issue at 60 watts. Higher than that could cause some concerns. The ply (and wood in general) and the acrylic should still be fine for engraving at 60watt.

I have a 40watt and do a lot of cutting. I certainly wish I had 60 for the speed it would give me. But unless I had two machines, I probably would never go above the 60.
tim
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Re: Cutting Speeds and LASER Power

Postby metalman » Wed Aug 03, 2011 11:37 pm

Thanks again Tim for your help. Being new to this I'm not sure what I will be using the laser for the most. I will probably do some sporadic production runs, but mostly odd lots... I don't think I will be cutting much paper or cloth, mainly plastic, wood and foam. I also plan to do some engraving on glass and stone as well as wood, plastic. I'd also like to try engraving on some anodized aluminum and maybe coated steel. As soon as word got out that I was building a laser, "friends" started coming out of the wood work with things for me to do.

I usually lean towards "bigger is better" but versatility is the most important thing. If anyone else has experience with a 60w I know several of us would be interested in your feedback as a comparison against what a 40w will do on cutting 1/8 plywood and 1/8 acrylic, and engraving a simple fill in a one inch square.
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download cutting speed calculator

Postby Mike-f » Fri Aug 05, 2011 2:17 pm

Just found this useful? calculator on the Synrad site

http://www.synrad.com/LaserFacts/Aboutlasers.htm

Calculator installs then you can choose laser power, material and thickness and it gives you and idea of cutting speed. Might be useful to someone!
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Re: Cutting Speeds and LASER Power

Postby metalman » Fri Aug 05, 2011 2:51 pm

Thanks Mike! That will come in handy. It is just what I was looking for.
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