You can also just get a direct r8 set screw holder. I use a 1/2" one just for aggressive roughing with long hi helix end mills. Chatter or not, it's not pulling out. I can walk away in peace :-)
I have never done 2” but have done a bit of 1.5” alu (clean up at 0.001) with a 3 flute Mari tool with 2.3” stick out and get a nice surface finish and never had the machine grown at me with that cut, would need to look at sprutcam for the speeds and feeds. The pull out is the major concern and agree with the others as the main area of investigation. The only time I have managed to pull out tools is when I have forgotten to clean the set screw holder and inside of the r8 collet, with alcohol and cut deep. (As I have to inhibit all tools after use, due rust problems on the coast) so they need to be cleaned prior to use.
But I also have the 770 so am lacking in the grunt side of things but find I stall before tool pull out.
Cheers,
Adrian
I recently made some big parts and had to finish 3" deep. I used a 1/2" meri-tool reduced shank end mill. The flutest are .625" deep and tool stickout is 4" from the holder. I left .0 03" after roughing and finished using a helical boring cycle at 70 IPM 6000 rpm. Finish came out real nice