Fiber Laser Question

[Terry Wade]

I have a BEC 50 watt fiber that I have 2 lens' that I got when I ordered with the laser. The lens that was installed on the fiber when I received it was the 110mm, I have the need to install the 300mm lens for a job that I have coming in a few days. If I understand what I am looking at I think that both lens' have the same focal length, am I correct? And what is the best way to set up my computer so that I can use both lens' ? Should I install EZCad2 with another name for the new lens?

Thanks
Terry Wade


20220930_122414_resized.jpg

[Kev Williams]

Those 2 lenses are about as far apart focally as you can get with a fiber!

The "short" lens is, as printed on the lens housing, a 112/163 lens, the "long" lens is a 300/420...

Now I don't know the exact calculation as to focal length, but what works out really close is to do this:

In Corel (or AI or whatever you use) draw a perfect circle the size of the larger number on the lens, in this case, a 420mm circle and a 163mm circle--

Now draw a perfect square that fits perfectly inside each circle...

You'll find the square within the 420mm circle measures APPROXIMATELY 300mm (I got 299 just now),
and the square within the 163mm circle should be APPROXIMATELY 112mm (I got 115--)

The square within the circle represents the 'practical' working area of the lens. In practice you'll find the beam can be used to engrave within the limits of the CIRCLE, but be careful because (1) the galvo mirrors have their movement limits and won't fully extend to all areas within the circle, and (2) 'lens abberation', or distortion, comes into play when outside the practical limits, as in actual sizes of things engraving outside the boundaries tend to grow larger than they are--

So, that all said, how to work with 2 lenses:

Somewhere on your computer is the EZcad files and program, which, if I understand correctly, is set up for your 110 lens, yes? And those files are all within a specific folder, which were originally copied off a flash drive...

So what you need to do is, either make a NEW folder copied from the original flash drive, but name it differently, OR, my preferred method, make a new folder from a copy of EVERYTHING in your CURRENT folder, and name it differently--

example, I have 5 lenses that will fit 2 of my fibers, same physical sizes as yours: 70mm, 150mm, 190mm, 220mm and 300mm.. I have program folder for each size lens, and a Windows icon for each on my taskbar.

You need to try this:
Rename your current working folder by simply adding "110" to the [folder name]
Now create a new folder, named "300 [folder name]
Now, go into the original folder, copy EVERYTHING in it--
--go to the new folder and PASTE everything there--

What this does is preserves all of your current job and machine operation settings--

Now the fun begins: Go into the new folder and start EzCad from in there...

Now you need to change a few settings: In the F3 menu, your field size should be "110"mm or close, that's for your original lens. Change that number to 300--

Next, you need to find the actual focus "working" distance of the new lens, which may blow you away a bit, as the approximate working distance from the lens head to the work with your 112/163 lens is going to be roughly 6" or so-?? I don't know since 110 is one size I DON'T have! - however, the working distance of the 300/420 is somewhere around 18"-! Best "quick" way to find the focus point is to draw a 3" or so box, hatch fill it big, like .2mm, then run it slow at ZERO POWER on some anodized or painted aluminum, and crank up the lens tower until it starts marking, then tweak the focus best you can right between the upper and lower focus points you find... Now, FIND SOMETHING TO MAKE YOURSELF A FOCUS TOOL OUT OF! I just use scrap pieces of aluminum or plastic, and fit it between the lens housing and the workpiece...

NEXT, draw an 8 to 10 inch perfect square, and while in focus, run an outline of it, to determine how close to actual size it's engraving-
-if engraved size is too LARGE, then go into F3 and RAISE the 300mm "field size" number to 310 (raising the number will reduce the output size), then test again, then tweak the field size until it's real close. To fine tune the size, you'll need to tweak the percentages in the galvo adjustments at the bottom of the F3 menu. Once you get the square to engrave the size you want,
NEXT is to test the red-light square to see if it matches up to the actual engraved square; if not, fix that in the "F3/Other/Red Light Pointer" options...

That's about it! Because you copied all your old settings which worked ok I'm assuming, they should be pretty close for the new lens. There will be minor differences that you can tweak later, but for all intents and purposes, using each program for each lens lets all other settings you've saved remain the same, and from then on just tweak as needed! All "new" saved settings will be specific to the lens you're using and it's program...

Just a note, that long 420 lens is much more forgiving as to focus distance than the 110 will be, AND, the actual power output will be reduced, due to the fact the longer focus length can't be focused as tightly as a shorter length lens, and that equals a reduction in power, so plan for that!

Hope this helps!

[Bill George]

This video helped me a lot..... https://youtu.be/FZT9zOp9Sl8

And I am doing just the reverse going from a 220 to 110 lens!! The guy in the video does as Kev suggests and what I am going to do also have two different folders, one for each Lens size.

[Kev Williams]

my fiber folders look like this--

My "main" folder is the "Fiber New" folder, on my -C- drive, amongst other engraving-specific folders...
laptop-c-fibernew.jpg

in the "Fiber New" folder is all my different lens folders-
fibernew2.jpg

inside the "EzCad 300x420 lens" folder, is the entire basic EzCad
2:14:10 working program;
fiber3.jpg

click on the first folder and everything else opens up-
fiber4.jpg
Note I changed the name of the running program by adding the lens name,
probably not really necessary, but this keeps them all separate on your
tasksbar or desktop, and hovering the mouseover each icon will reveal the
name-- I just keep the icons in order on my taskbar--

[Terry Wade]

Thank you so much Kev I think I can get this set up and then be able to take on the job.

Terry Wade