Versalaser spot size is now bigger

[Mike Mackenzie]

Harry,

I will e-mail you the instructions on how to check the alignment and to re calibrate the Z axis. You will do this for each lens you have. I will try to get it to you by this evening.

[Mike Mackenzie]

Rodney,

I am not sure how your systems get aligned however all of the ULS systems have a fixed 90% mirror mounted above the lens. So the beam comes straight down. In your diagram this mirror would not be perfectly set to 90% if you get the angle you are describing. This would not be the case on these systems. The alignment adjustments allow for the beam to adjust up and down and left and right. There really is no way that the beam would change the angle that it hits the focus lens unless the lens itself was incorrectly mounted or the surface was not properly ground. The possibility of this is slim especially with the problem happening with both lens.

[Rodne Gold]

Oblique is probably not the right word and my diagram is too simplistic, if the beam does not hit the focussing optic dead centre , which can easily happen with a fixed last optic , the lens does not work as it should and bends the beam. The focal point thus changes and the spot becomes eliptical as the cone described by the focus becomes oblique or slanted and when it hits the flat object its focussed on it loses energy as the spot size becomes bigger for the same energy.
Apart from that , if the beam is not 100% aligned , the beam wanders about the focus optic as the head changes distance in the X and Y direction and the spot and focal point vary with that making the engraving or cutting somewhat inconsistent. You would see that if you have a red dot pointer and move the head about the table , the red dot pointer will not hit the last fixed mirror at the same point all the time as it moves (assuming the red dot pointer is aligned with the beam)
The problem is actually with the lens itself , the types we use are generally very simple lenses , plano convex and arent ground to cater to a beam hitting it at anything other than dead centre. Heres a better diagram. The ideal situation woud be if the lens diameter would be exactly the same size as the entry beam diameter , but this would mean that alignment would have to be 100% spot on all the time , impossible to achieve with these type of lasers with their multiple mirrors and mirror mounting systems.

[Rodne Gold]

Ideal lens scenario

[Harry Radaza]

I just recently noticed that under my driver ... VL300 ADVANCED DRIVER
Under Advanced tab, there is a a setting that says

Tuning.... -15, 0, +15

It was set to 4. I dont know why. Could this have something to do with the z axis setting?

[Scott Shepherd]

Tuning has nothing to do with the Z Harry. I seem to recall reading in the manual when we first got our laser that it should be a value in there, so I'm assuming the 4 is a valid factory setting.

Tuning helps refine the burning (as I understand it). When the head travels back and forth, the motion is to the left, then to the right for the next line it burns. With every laser, the beam has to ramp up and down before it turns on and off. If the head is moving at 140 inches per second, and it needs to fire at X 8.000, and it's coming from the right to the left, then at some point, the beam has to be turned on prior to the X8.000 position, since the head is moving at 140 IPS. Otherwise, the burning would start somewhere less than 8.000. Now, on the same note, go to the next line in the burn, it needs to stop at 8.000, and it's coming from the left to the right, so the signal to stop burning has to coming prior to actually hitting the X8.000 number on the encoder.

It's really clear when you're doing ascenders and decenders on text, for example the lower case "g". You can run into problems with those areas since it's a small area and it's burning one line from the right, one line from the left.

If you look at most engraving done on a laser under a magnifying glass, it you can clearly see a pattern. The edges of every other line are lined up, but the one's in between are shifted a little. This comes from the left/right burning.

Tuning allows you to adjust for each material (materials are all different) and you can tune the burning so that there isn't this mismatch. If you look at the burning after it's been tuned, the ends of the lines will all be dead in alignment.

That's the way I understand it. I've tuned a handful of materials and it certainly makes a difference in quality.

I could be wrong about the tuning in the "System" area of your control panel, but I think it's all similar. I'm sure someone here knows exactly what that one is and can expand on it.

[David Lavaneri]

This is kind of on topic.

I had a friend engrave some coated aluminum for me and I noticed the vertical lines of the image were wider than the horizontal lines, making a Helvetica Regular look more like Helvetica Bold.

What could cause that?

Thanks,

David "The Stunt Engraver" Lavaneri

[Scott Shepherd]

I've seen that happen with a dirty lens.