Need advice-new to engraving

[bherr]

I'm running a BP series II interact 4 which will top out at 3750 rpm's. I'm engraving detailed graphics in T-6061 aluminum. I've been using a .124 ball mill running at 80 IPM, but the finished work isn't up to my standards. I need to go to a V shaped cutting tool. Bit & Bits suggested going to their 1/8" 50 t0 80 deg angle bits and then making multiple passes. I've been milling down to .0625 depth and Paul at bits thought that was pretty deep for engraving, My concern is if I go less on depth that when I have the pieces chromed I lose some of the graphic. Anyone have experience in this???

Ben

[Ciaran]

Hi Ben,
If you are going to use pointed engraving bits you will need higher rpm and loads of passes taking tiny cuts.The problem is the size of the program will probably need to be drip fed and it will take ages to machine and when it is finished you may find the tip gone off the engraving cutter and all that time wasted.
The ball nose cutter will work ok but your max rpm 3750 at 80 inch/min seems very fast to give you a good surface finish.I would suggest for a two flute cutter 20inches/min would be safer and a depth of cut of around 0.2 or 0.3mm (sorry 0.007 inches)at a time until you reach your end depth.
If you are going to be doing alot of engraving try get a loan of a spindle speeder that will give you 20,000 revs as this will help keep you machine times down.Some aluminiums can be difficult to cut so add more concentrate to your coolant.
Hope this helps.
Ciaran