Newbie laser question

[Millwab]

I’m new to laser engraving and could use some help understanding. I bought an Ortur 15w diode engraver a little while ago. Brought it out last week to engrave some blanks to cut at a demonstration later this year. My idea is to engrave an image on the blanks and then cut them into small puzzles while I’m demonstrating scrolling. After tweaking the settings to get the burn how I wanted I started engraving. Most of them came out fine, but every once in awhile I would get dropout on the bottom of the image. The only thing I can think of is a variation in the wood (using BB ply) affecting the focus. Is that possible? Any idea how sensitive the focus is? Any other suggestions on what might cause this?

[meflick]

I have an Ortur diode 15 watt butt haven’t used it much lately. You do want to make sure your piece is level and well focused. If it is not level, it will change the focus in that area. Also, if here is variation in the wood density, fibers can make a difference in the burn. I usually have seen that more in certain woods. One thing you can do is look before you take it off the laser bed and do a second burn if necessary. Others sometimes use a baking soda and water mixture or borax and water mixture (there is no specific ratio) to spray on and let dry. It will intensify the burn. I have used the baking soda water mixture and had it do well. Some don’t like it, discolors the wood somewhat. I didn’t find it an issue in my use.