Hello all,
I got an iphone cover from a friend who wants a logo lasered onto the veneer panel on the back of it. The veneer on the back is probably 3/64" to 1/16" thick. Has anyone dealt with Koa before? Since I only have one shot at this I thought I would ask the brain trust here!
Thanks
This is a tricky thing because you probably don’t know how it is finished.
If it were me I’d look up the hardness of koa compared to other woods, then search the forum for settings for them.
The settings you choose for an engrave are pretty variable and depend a lot on what you’re trying to do. I’ll assume you want dark and shallow? If so, I’d be trying to work out settings that I think will work, then back off and see what I get.
Got a pic of the case? is it wood through to the back/interior? You might be able to do a very small engrave mark inside the case on the corners (somewhere you don’t plan to touch from the outside), and try to dial them in.
In the end… if it were really up to me and you really need it to work and have the time, I’d tell the friend to buy you a backup case to test on first then go for the main event. you don’t have a ton of margin for error here.
Agree in the finish comment, but I expect walnut settings will be just fine. Can you engrave a small icon on the inside as a test cut?
@evansd2 is totally right if you’re interested in the well reasoned, conservative approach.
In this case I’m more of the “it’s just a phone case, they’re cheap” kind of guy. Most phone cases with veneer are glued to a plastic case anyway so the case will still be good even if you go through the veneer. In short though, it’s just a phone case, not an irreplaceable heirloom.
With wood veneer I’d let her rip with fasted speed, and probably 50-60 power for an engrave. Keep your LPI in the lower range (195-225) and don’t even think about scoring anything. Make a couple passes if needed.
This all depends on your image and how much risk you want to take.
You might also want to consider masking so you don’t have to try sanding and scorch marks on the finished surface. You don’t know how this wood veneer is going to react. 
One more thing, so that you can position your design just so. Make a jig out of cardboard. Make your first cut to hold the case in place and ignore your design/logo bits. Then insert your case and do your engraving after setting up your job again. Get the right height in for the case. Don’t forget to turn off the cut. Use pegs or magnets to hold your jig in place.
Good luck with whatever you decide 
I’d caution about max speed because higher speeds tend to yield lighter colors and lose out on finer details.
Ideal settings will depend on the koa and your design intent.
But yes it’s just a phone case.
Thank you all for the advice, just what I was looking for. I knew this was the place to come to ask. I’ll let everyone know how it turns out.