Focus Height

I’m confused by “Focus Height.”

This indicates that changing the Focus Height will directly the laser’s focal point.

However this seems to indicate that the Focus Height entered doesn’t do anything except allow better visual placement. And that the head comes over and does a depth analysis before printing.

Can somebody help clarify?



Material thickness is for the camera placement. Focus is an overide for automatic focus.


There is a material thickness you put in when you enter a material (proofgrade’s are set automatically). That’s what changes your camera focus. The focus height you input into each cut/engrave step is what changes your laser focus.

Edit: @rpegg beat me to it. And explained it clearer.


Thanks! I have a better understanding now! I didn’t even see that manual entry for material thickness!

So that leads me to my next point of confusion… If I tell the GFUI that I’m using .25" :proofgrade: plywood, for example, it sets the Focus Height to .197". Why wouldn’t it set to .250"? But let’s make that a practical question… If my material is .25", wouldn’t I want to set the Focus Height to .25" as well?


Normally you don’t need to set the focus height on any material. The head will slide over and take a single height measurement and use a new value unless you typed something in for the entry. You enter it when you want to overide the automatic setting. Material height always needs to be entered for non-proofgrade.


Thanks. I’d think that once I enter the Manual Engrave option, all settings are considered manual even if I don’t change them. So the height measurement wouldn’t apply at all in Manual Engrave mode even if Focus Height isn’t changed. Is that correct?

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No the automatic height (material) measurement is always taken by the head and used for Proofgrade or non-Proofgrade unless you have manually typed in a focus height.


Nope. Still autofocus.

I previously asked them just to fill that box with something that says “autofocus” in greyed out letters or have a little symbol next to the box titled autofocus that is lit up until you manually enter something. I think that would provide more clarity


Interesting. Thanks!

I definitely agree. Clearly. :wink: There’s no way to intuit that.


Two possible reasons I can think of: If the engraving is a lower LPI than the beam width it may defocus to make the beam wider.

If it is cutting or engraving to a significant depth it may focus half way into that depth.

Who knows? I think we will have to study the machine for a long time to find out what it actually does.


And… One last topic-related question…

When it does its height measurement, does it pick the center point of the object that’s about to be engraved? Or some other specific point? Or some arbitrary point?

For example, I’m about to do a partial engrave. I’ve done a few on this piece of scrap. If I were to let this etch the entire object, it’d overlap my previous tests. But I want to make sure the auto-focus height isn’t going to mistakenly sample an earlier engrave.

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Interesting. Thanks!

Just checked. It seems that the interface has changed since I last manually adjusted focus. When I use non-Proofgrade and tell the app that the material thickness is 0.187" the manual focus entry was also set to 0.187". Now the confusing part is we believe that unless you change the value that the focus height will still be automatically taken by the head before the print. But if you change it the focus will be overridden. But the fact that the entry is now populated with my chosen material height entry just confuses me.

The system seems to function just fine. The user interface entries are confusing.


Great… If you’re confused about this, I don’t stand a chance! :wink:


I think this is on purpose based on proofgrade tested settings. If it isn’t proofgrade it’s going to show material height and autofocus.

I think what is happening with proofgrade is that as long as the autofocus scan comes in within a certain margin of error it will use the value show in the focus height box, as it has been predetermined to be the best focal height for that operation for that material, to give optimal output results.


Torn between a “Like” for the answer and saying, that’s really a messed up way to make a user interface." I’m only 75% confident in your answer. Better than mine though.

So I allowed my finger to hover over the Like button with intent.


This notion comes from watching the progression of the software from one point where it would only use those settings if proofgrade was detected, and autofocus was not working yet.

Later it started using autofocus, but autofocus only worked at the center of the bed at that time. So I know if your material wasn’t in the bed center the value shown wouldn’t work.

Now you can manually select proofgrade even if a sticker doesn’t exist, and autofocus moves to the center of your shape to gather height info. [insert previous post here]

It seems this functionality we’re speaking about is a bit vestigial and could use another look at some point in the near future.


Thanks for that insight!

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Don’t think we tried to answer this question… When I’m doing a cut it usually picks an area on or very near a cut line in an object. Not sure about the engraves. Somewhere within the engrave. If you have multiple objects to cut and engrave it seems to be pretty good about picking an area within an object but I have seen it pick a point between. The material thickness intelligence is ever changing for us.

So all that said it’s always important to watch where the red pointer measurement is attempted. I’ve seen it try to pick a spot that is technically within my object but has a hole where a previous cut was made. So essentially it would be ranging off of the crumb tray and not the material. If it ranges over the wrong spot then cancel the print and rearrange or use manual focus entry.



I watched it earlier and something interesting happened… My engrave would have gone off the edge of my material if I’d intended to let it complete. But this was just a test for depth/shading so I planned to kill it after a couple minutes. When it went to check height, it completely missed my material and just shined the red dot on the floor of the 'forge. It didn’t seem to care in the slightest bit. It just said I was ready to go. Which I thought was weird, but it engraved just as expected.