Every so often, oh about every other job!, I swear off metal. I decide that's it. No more. I'll just be a no-metal man! But then I can't that. One of my favorite items is the knife. Of course there is a wide range of metals in knives but they're all hard and quite predictable.
I keep asking myself why I keep taking things metal....other than knives and other known, harder metals.
I my head is not totally in the process, I may bury the bur deep into the first stroke on a piece of mushy pewter or aluminum and the game is over right there. Might be able to fix it but often not. Throw in the alloys that may have who-knows-what in the brew that makes for lousy lettering at my best on unknown metals.
This Christmas ornament turned out well. Before I touched the front side shown here, I turned it over and with the bur I planned to use, I merely engraved the year to see how the metal reacted to the selected bur.
It was NOT a new bur, but one somewhat experienced. I turned the ornament over again, drew a couple of guidelines with a non-permanent marker, and did the engraving.
Some permanent markers like Sharpies are dangerous on some metals. If the ink is too permanent....and there ARE different degrees of permanence...the lines won't come off. Use a Flair or ultra soft pencil; I keep a round of 6B pencils in my drawer for guidelines on such items. Just a bit harder than lipstick but will wash right off with a drop of alcohol.
After the test on the back of the first one, everything was peachy. I knew the bur to use. I knew the pressure required, and I knew to use the soft pencil for guidelines.
As for the tungsten carbide...only a diamond bur will cut it. A carbide bur on tungsten carbide is like a ball point pen on a sheet of glass.
Good luck with metal. The secret to getting it right is to test it on the back before you commit to the front.
Glass and crystal are so predictable