That’s true of aluminum (the GPD laptop one I posted has a definite curve towards the sides - the engrave looks as good on the edges as on the main body where I focused).
I’ve noticed from de-focusing the laser for other materials, that the differences it makes are very very small.
We’re talking about a laser beam that’s been collimated to the width of a human hair, so moving the focal point up or down a small fraction of an inch makes differences in the thousandths of inches.
Different materials can resolve different levels of detail, and maybe leather or wood won’t show the difference as readily as acrylic or anodized aluminum for examples.
Was there any concern about the type of leather? If it wasn’t vegetable tanned, then I thought the laser interaction can cause some dangerous gasses to be produced…
Or you could do something like this:
Also, I know some people have done glass and the microscopic results indicate the shattering effect it has. It appears, from this, defocusing could help smooth that out:
This engraving looks so good, Dave! How did you clean out the soot? We’re experimenting with our new glowforge and so far it turns the leather black every time; even a power as low as 10. Would love to know how to get the tone-on-tone look like yours instead of sooty black :}
Another question: What Lines Per Inch setting did you use for your celtic knot? We have tried 225 LPI; we left the speed at 600 and depth at 0.4in for consistency.
I’m pretty sure LPI was the default (225). As far as cleaning it, I just used a dry shop paper towel. I think some others had better ideas, but I haven’t tried those yet.
Do you know how that red leather was tanned? No real leather knowledge here, but I know that different tanning processes have a huge effect on laserability.
Gotcha, thanks for replying so quickly!
Ah of course! Definitely something to consider. We have other types around, I’ll try the same settings on different leathers…