Beam width question

[David Fairfield]

I guess this falls into the theoretical, but I'm curious. Why is there a kerf of .007" when I vector, but I can raster marks with a narrower width? Maybe my eyes deceive, but I can raster marks down to around .002" What's going on with the beam that allows me to do that?

Dave

[Matthew F Kirwan]

Dave, I'm guessing it relates to the power of the laser. Are you using a higher power in vector mode than raster mode? If so, the higher heat generated may be burning away more material, increasing the gap? Hope this helps, Matt

[Tom Bull]

The beam is an hour glass, your material has thickness when cutting. There are some old threads on this subject that might be helpful.

[Gary Hair]

The beam is an hour glass, your material has thickness when cutting. There are some old threads on this subject that might be helpful.

The beam will burn away more material than the width of the beam. Even if you could calculate the maximum width of the beam based on the thickness of your material, it would still end up with a wider kerf.

Gary

[Dan Hintz]

The first question that comes to my mind when I read your question is "Are you talking about vectoring material as in cutting or are you talking about vectoring as in marking?" If it's the former, then Tom and Gary have you covered. If it's the latter, there should be no difference unless the power is different.

Either way, you're guaranteed not to get a 2mil mark with a 2.0" FL lens, no matter how long you spend focusing it (unless you have a thick substrate and you're not burning the edges of the beam as sharply as the middle, but that's highly dubious).

[Richard Rumancik]

. . . Why is there a kerf of .007" when I vector, but I can raster marks with a narrower width? . . . I can raster marks down to around .002" What's going on with the beam that allows me to do that?

Kerf is generally thought to be the width of a cut through a material. That is making people think that you are cutting through with vector and trying to compare with making a scribe line using raster.

I assume that you are really comparing vector marking and raster marking.

My guess is that when you are using vector, you are just delivering more energy per unit length of line to generate a wider "trough" in the material. Even if you set the power and speed the same, raster speed will not necessarily be the same as for vector. Thus the net energy delivered per inch changes. With many lasers, you need to set PPI (pulses per inch) for vectoring but this does not apply to raster. So the PPI setting may also affect the result.

There may be some "hidden" things happening within the driver/firmware that are not apparent. For example, with my laser, if I set 100% speed in raster mode I get 42 ips max speed. But if I tried to set 100% speed in vector mode it would IGNORE this as it just can't achieve 42 ips in vector mode. It actually ignores settings above ~30%. It would probably run 12 ips. In this case, even though my "settings" may appear equivalent the laser is fudging with the inputs . . . and not telling me.

It is possible that your laser just cannot go as fast in vector mode as raster mode, resulting in more energy being delivered along a given length for the vector. Thus, a wider mark.

[Dan Hintz]

resulting in more energy being delivered along a given length for the vector. Thus, a wider mark.
Yeah, I probably should have used the word "energy" instead of "power" to avoid confusion.