Cutting type-high material


#1

I want to engrave material that’s exactly .918" thick. (Type-high.) What’s the best approach? Is it possible to put in a negative focus depth? What’s the focal range of the machine?

It looks like I’ll need to raise up the material somehow? Risers to Make Lasering Thick Materials EASY

Looking at those files, it seems like the bed is 1.383" tall. I have spacers that are exactly .918" high already. (Using existing metal type.) I’m thinking if I put them under my material, that would give me 1.836" total:

0.918" spacers + 0.918" material = 1.836" total height.

Subtracting the expected bed height, this would give me:

1.836" total height - 1.383" expected bed height = 0.453" focal height.

Is this correct? Is there a simpler way of doing this?


#2

Yes and not that I’ve found. :grinning:

Seriously – you’re spot on here. It really does require a bit of math the first time, but in your example, once you figure it out, you’re set for all Type-high engraves. :+1:


#3

Cool, thanks!


#4

I’m hoping we eventually can choose a focus height from the bottom of the Glowforge, so all you have to do is add the height of the object plus the height of the support. Easily measured with a ruler or calipers.


#5

Or be able to specify it as an offset from the surface (as PG materials do) so the GF can simply measure the surface height.


#6

Well, we can already do that. If I put in a slab of wood 1.75 in high it would be convenient to simply enter that as the focus height.


#7

Yes but the machine can measure the height of the surface to 0.1mm (we are told) so why do we need to measure? Just specify where we want the focus relative to the surface instead of relative to the crumb tray. It should always be relative to the top surface but the user input is always relative to the crumb tray.


#8

Agreed. Having it be relative to the material would make so much more sense. Unless we need to override the system for some reason, it should be able to just measure the height automatically.

In fact, it would be nice to have a checkbox that said “automatic”, and if it was checked, it asked for a focus offset instead of height.


#9

Yes. That would be nice. I’m not sure what their choice was there either. I’m guessing so the initial camera shot is more or less correct, but yah, it does have the ability to take the load off the operator.