Running a program twice on a single material?

Hopefully I’m not covering something already discussed but I couldn’t find anything so if I have please link me and i’ll remove this thread!

As the wait continues i’m toying with my list of ideas and projects and a question has emerged that i’m not 100% of the answer.

I have used a 30w laser in a local maker space in the past but have never had chance to really sit and trial methods so my question is:

If for example a laser’s max cut on plywood is 10mm…if you run the program and cut 10mm on a 20mm thick sheet, then run the program again, on the same material, will you cut the remaining 10mm or is there a deterieration on the power based on depth of material? So at 10mm it’s 100% power but 11mm and deeper the laser natural gets weaker?

Any and all input welcome to cure my curiosity!


The problem you are going to have is with the hourglass shape of the beam. It might be possible, but you would have a wider kerf and slightly angled walls. for that depth, it would probably be easier to flip the part and cut from the backside.
Here is a link for another thread.


Perfect Joe, thanks for the reply and the link.

I had expected as much and had seen something about the hour glass shape hence my skepticism on the idea alas I had to check.


one thing I don’t know if has been covered is if your design tolerates the width at the maximum of the hour glass, it should probably work to a degree.
There is a maximum depth you can cut to due to focal length and getting in the way of the laser head. Also might have issues once the depth of your cut line gets too deep with the air assist being able to clear debris.

I have seen videos of people cutting 1/2" wood with a k40 Chinese laser but it requires a lot of passes and causes quite a large kerf.

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1/2in is anticipated to be doable by 1/4inch engraving, then flipping and re-engraving the other side. So really would only be looking at thicker than 1/2

Yep sure is. I look forward to seeing this in action.

I was simply explaining what would be seen by doing multiple passes as @jamiecross asked.

It typically requires more than 2x as much power to go 2x as deep. At some point, you can’t go deeper without basically engraving a canyon in the material. For most materials 1/4" is as deep as you want to go on one side.


Thanks Dan! I expected as much as I say this was as much to validate my own logic as much as to cure my curiosity!

thanks, my thoughts where that deeper would be a more narrow beam so it would fall inside the pre existing cut and wouldn’t need to carve out any more of the previous cut so still being able to use just as much power as pass one given that it has a 1/2 focus length ( unless I don’t under stand the focus)

The lower focus point will still be narrow but the portion of the beam at the top of the material will now be wider and cut more of a channel. Think of it as a V beam. The point of the beam is the focal point but it’s still cutting above and below - just not as narrowly. The further into the material you place the point the wider the top of the cut gets.