Tell me about laser power

[Dave Johnson29]

Hi people,

More questions than answers. :)

Is a 50 Watt laser twice as powerful as a 25 Watt?

I mean if a 25 W will cut 1/4 pine, will a 50 W cut 1/2" pine?

[Scott Shepherd]

Not really, no.

Your beam is shaped like an hourglass. The focal point of your lens (2.0 as an example) is where the beam is the thinnest and most concentrated. As the beam gets further away from the cut (in this case, the bottom of a 1/2" piece of wood), the beam is much wider and less "focused".

You can get beams like the 4.0 lens, which has a greater length the beam stays closer together on, but no, that's not always the case.

[Darren Null]

A 50W laser is twice as powerful as a 25W one, yes, but that's not the whole story. The depth of cut in a given material isn't a linear value (ie, twice the power, twice the depth) because there's other effects to consider. You are pumping twice the energy into a given area, but the ability of that material to absorb the energy is a factor. Wood, for example, will catch fire beyond a certain point. Marble, after a certain point just melts, so within the range of 'domestic' laser engravers (<100W) more power doesn't make a great deal of difference.

It'd be more accurate to say that the 50W laser could cut your 1/4 pine faster than the 25W but that's not a linear value either. Double the power is not equal to half the job time.

So, lens (beam shape), material, speed, machine, and brand of laser are all variables that you have to consider.

As a general rule of thumb, more power = shorter job time = increased depth of possible burns = more expense.

[Scott Shepherd]

Well said Darren, and I'd also add the following example- it you have a material that takes 100 speed and 10 watts of power to break the cap sheet, or surface, then a 25W and a 125W will give the same results. However, if it's taking 40W of power at 100% speed to break the cap sheet, and you have a 25W, then you'll be decreasing the speed to break that cap sheet. However, with the 50W, you might very well be able to run 100% speed.

It's all tied together as Darren says. That's what makes me a little crazy when I hear salesmen talking about how fast things are. If a machine will run a 150 inches per second, what does it mean? What's it cutting at 150ips? Air? 2 ply plastic? Marble? Granite? What? How much power? 25W? 60W? It's all tied together so blanket statements about speed are more of a sales tatic than anything else, in my opinion. Certainly some machines are faster than others, but overall, it's more dependent on the material and the conditions than most sales reps will tell you while trying to pitch their machines.

[Dave Johnson29]

Thanks Scott and Darren,

I understand more. :) I have had my very old 25 Watt ULS going for less than a week and already I am hot for more power.

I have an unused glass 50 Watt ex medical I bought surplus some years back. When I made the aluminum enclosure for it I used Synrad's mounting pattern and that is what this old ULS has so it will be a straight drop in.

The 50W intensity is driven by 0-10v so I will have to make an interface board to use the ULS driver PWM output.

First pic is a bit dark as I wanted to have a shot of the thing in operation. Water cooled.

[Larry Bratton]

Somehow, the word "laser" conjurs up visions of extreme speed. Since I have owned the Epilog (some 18 months now) I have been utterly frustrated at times as to how long it takes to do some things. I suppose it is fast, compared to cutting with a handsaw or the like, but I can cut most things on my CNC table a whole lot faster than on the laser. Just my two cents worth.