engraving an aluminum sundial.

[knight_toolworks]

this was a bit of a challenge. the customer is a engineer and he really wants to check things out. we were having trouble on the sample one I had to play with getting a good cut with a single flute engraving bit. so I tried a 1/31" ballnose bit and it worked great.
so I machined a holder for this sucker it weighs about 20 pounds it is forged aluminum. the customer machined the face so it is dead on.
I first cut the ring around it to see the depth and broke a bit in the first 1" I was only cutting .5 ips on both speeds with 12k rpms and only cutting less then .01 deep. on my test cuts this was fine. got all the way around it and I could see that the cut varied in depth. this was the wear and tear on the machine showing. so I gave up till he could come back in and check it. even though the line varied it was only about .005 deeper on the one side. he and reground the engraving bit and we cut it with that. it worked great on this one I only cut .3 ips and 12k.
he will fill the grooves in with poder coat and bake them.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/55CB7AA5-orig.jpg
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/E7985D96-orig.jpg

[lrheimpel]

Really nice job Steve.

Can you talk more about the bit and how it is held? I searched the internet a bit for small bits, the small bits seem to have small shanks and the problem would be how to place them in the router.

[knight_toolworks]

the bit Had a 3/16" shaft. but it was ground pretty steeply maybe 25 degrees.