Laser cutting

[Dave Sheldrake]

Beam profilers straighten the beam after focussing and before final focussing, they are usually finely adjusted multi optic systems Dave It's all about manipulating the beam before it hits the target

cheers

Dave

[Dan Hintz]

Dan - since you seem to be deliberately misreading my posts I've done a drawing to explain exactly what I mean.
It is a little exaggerated, but not by much.

Deliberately? Uhm, no... I just could not envision what you were suggesting. There is still a kerf to either cut in your diagram. Again, to my point, it doesn't matter if the beam is acting like the top or bottom, both have an angled kerf at some point on the object being cut. Your picture just makes my point more clear. You may have a perpendicular cut on one side of the object with your second diagram, but the other side of the cut object will be twice as bad. Without high-priced optics, it's a downside we all have to live with. Not much else I can say about it...

[Michael Hunter]

The point is that Chuck (the OP) was complaining that his supposedly symmetrical pieces could not be rotated and still be put together. I think this is something that most would find odd. Just saying "its kerf" and that there is nothing that can be done is not very helpful.
The ***axis*** of the beam being out of perpendicular may possibly be the reason for his complaint.

Look again at my drawing - the whole cut is angled one way.
I have had 6mm ply come out of my machine looking just like that and spent a long time wondering how it could have happened, thinking that the ply must have been angled up on something until I re-ran the job and got the same result.
That's when I had the idea of checking using the red-dot pointer and found that (although not perfect) this gave a simple way of ensuring that the beam was sufficiently perpendicular to the bed to get the kerf evenly balanced each side of the cut.

The problem on my machine is not one of gradual change. It seems as though passing through a certain ambient temperature range "sproings" the turning mirror on the beam to a new position. After adjustment it normally stays good for up to six months.