How does the focus test work?

I saw a reference to a new feature in LB and also located it in the menu system. The online docs have not yet been updated to include the focus test option and a determined search of the system doesn’t say much either.

What might one expect if one selected the focus test? Would the laser immediately begin to fire out a pattern of a certain size? What preparation should be made for selecting this task?

It’s pretty straightforward. You need a controlled Z for it to work - the software produces multiple lines with varying Z height, labeled. You specify a start and end height, speed, and power, and it will let you preview or frame as well as run the job.

Well, shucks. No controlled zed on my machine. I kinda hoped there would be a programmed pause/resume option to allow for the equivalent. That leaves as the only practical option Russ’ cheese wedge focus tester, I think.

Can someone describe this process more (I do have a controlled z). Do I put the laser head touching the material and select “0” as the focus test start? I’m experimenting with it and can’t seem to really figure it completely out. The laser keeps returning to whatever z position I start it at a zillion times during the test (instead of moving down .5mm to go from 14 to 14.5 for example, it does the 1, moves z back to the start, does the 4, moves z back to the start, does the ., back to the start, 0, back to the start, does the line, back to the starting z… you get it.

So, can somebody give a step-by-step on how to get the most effectiveness for the focus test, and also tell me if there’s something I did wrong that is causing it to move the z about 100 times more than necessary?

The Z moves the way it does because I don’t optimize Z moves yet for DSP systems (the feature is still in test for GCode systems, and DSPs are next).

The test itself is simple - it draws a bunch of lines at varying Z heights so you can tell where the optimal focus point is (the thinnest line).

For the range, I suggest using your normal focus method as a starting point, then using the “Get Positions” button on the Move window to figure out the Z height that gives you, then make a focus test of Z-5 to Z+5 or Z-10 to Z+10 (for example) to figure out if your existing focus height is ideal or not.


Do all values need to be entered using metric units even though I am using imperial for everything else?

At the moment, yes. I work in metric, so when writing new features I often forget to add all the unit conversion stuff necessary to handle both. I’ll make a note to circle back and fix that.

Focus test has been updated to support inch measures as well. This will be in the next release.