I made two NC files, one for the text and one for the circles.
I set the feedrates to 50.
I used another stronger engraving tool.
This did the text OK ( at 0.1mm deep ).
I did the text again, another 0.1mm deeper.
Again feedrates at 50. Depth of cut about 0.52mm ( 6 cuts down to 3.1mm deep )
On feeding down, it broke the tool.
I reprogrammed it with feedrates at 10 and bought a new cutter from my dad.
This worked better, but it was too slow to stand and watch. I changed the horizontal feedrate to 25, leaving the vertical feedrate at 10. Later I upped the horizontal feedrate to 40 and it was still OK. Even so, with 6 depths of cut for each profile, it took at least an hour to cut, with me standing there pouring coolant from a jug.
It hadn't cut all the way through, instead it had pushed the steel down into the wood in a bulge. I had to cut through this with a knife.
I filed the sharp edges and sanded it with "Wet and Dry".
The profile operation, in HeeksCNC, is not remembering the previously entered feedrates.