Switching 2" lens with a 2.5" will affect autofocus accuracy?

[Dan Sobel]

Hi Pete,

Sorry I'm a bit green on operating a laser. From your I see that you are using RDworks, I'm using LightBurn the parameter labels are a little different, I have found a focus parameter in the Miscellaneous section of the machine settings called "Focus Distance" with a current value of 10.900 is that the focus value for the 2" lens I need to change?

And if that is correct is the Focus Depth value of 7.500 the correct focus value for a 2.5" lens?
Where do I find those depth focus values or how is that calculated?

[Gene Uselman]

I don't think that Pete uses Lightburn... Here is a graphic that may help- what you want is for the distance from the nozzle to the work surface to remain [close to] the same by using different nozzles and spacers. You may be able to suss out what the LB focal distance is referring to. I have always measured the nozzle/work distance myself.

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Lens focal length.jpg

[Dan Sobel]

The Boss manual shows only a picture of the provided different nozzles for different lenses length saying, that each nozzle will correlated with a specific size lens, but it does not explain how it correlates to the auto-focus.... you can see it here https://www.bosslaser.com/Download_pdf/ ... chines.pdf at page 14.
Can be that by just changing the nozzle (which for a 2.5" lens is longer than a 2") for a specific lens size, the table will offset correctly in relation of the length of the nozzle ans correctly set the lens focus?

[Gene Uselman]

Nice manual- does the spring on the laser tube retract and trigger the autofocus? If so then the longer nozzle would be accounted for. Most AF are a slide affair alongside the laser lens tube which would have to be adjusted for the longer nozzle. If I were you... I would have tried it a few hours ago and we would both know now

[Dan Sobel]

Yes exactly, the auto-focus on this machine works that way, you place your material and position the nozzle over it, you then select the auto-focus function from the machine console and press enter, the motorized tables will rise up until the material touches the nozzle pushing it up a bit on its spring and then moves back down and stops to the correct focus distance.

[Dave Vigness]

Not positive, but I believe the Boss set up is a lens tube and nozzle package with the lens in the right place from the nozzle tip. If that's the case, then the auto focus wold be the same no matter what lens tube / nozzle set you have in.

[Pete Cyr]

Hi Pete,

Sorry I'm a bit green on operating a laser. From your I see that you are using RDworks, I'm using LightBurn the parameter labels are a little different, I have found a focus parameter in the Miscellaneous section of the machine settings called "Focus Distance" with a current value of 10.900 is that the focus value for the 2" lens I need to change?

And if that is correct is the Focus Depth value of 7.500 the correct focus value for a 2.5" lens?
Where do I find those depth focus values or how is that calculated?

I am using a 2" lens - I determine my focal length for this lens by performing testing until I found the smallest dot size - the smallest dot size with my 2" lens in my machine was 7.5mm - so that is what I set as the focal distance.

I do not use lightburn - it is excellent software but I do all my formatting outside of RDWORKS - I only use RDWORKS to assign power and speed to my layers and send the info to my laser.

[Pete Cyr]

Not positive, but I believe the Boss set up is a lens tube and nozzle package with the lens in the right place from the nozzle tip. If that's the case, then the auto focus wold be the same no matter what lens tube / nozzle set you have in.

In theory you are correct. in practice I have found that it will be close but not always optimum - I prefer to tweak the focus until I get the smallest dot size.

[Dave Vigness]

Pete,

I believe that, no matter how hard they try, the two will never be exact. I was referring more to the tube / nozzle set though.

[Dan Sobel]

So, technically by switching the proper nozzle for the 2.5" I should be ok with the auto-focus as a starting point, and than eventually fine tuning the beam focus.
But once I find the optimal focus for that lens can I save those setting without having to repeat this process every time I need to cut something? So the auto focus will always position the nozzle with those optimal setting for each lens size I would like to use?
Anyways I was planning to call Boss on Monday and asking about this.