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Problem Drilling Cast 304 Stainless on CNC Mill

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Hello all!

I am the machine operator for my manufacturing company, operating a Hurco VM1 installed with an Ultimax controller. I program solely in G-Code.

Having major issues drilling a through hole 1.42" depth, 13/16" diameter in cast 304 stainless. It also has a smaller hole at the bottom that is 13/32" in diameter. I make a pilot hole, then drill the 13/32" all the way through, then use a 51/64" to make the large hole, then ream it with a 13/16" reamer.

I don't have much issue with the 13/32" or the reamer, but am having massive problems with the 51/64". I use a 118 degree S&D HSS Drill. I have tried different feeds and speeds, have tried 135 degree split point drills, and have even tried a solid carbide drill instead of HSS. Still have problems with high spindle load and bits even getting stuck causing a fault. Attached are images of the cast part before drilling and after drilling. Sometimes a single bit lasts 100 parts. Other times it only lasts 1 to 5. Am 90% sure this is a problem with drill flexing when it breaks through the side of the hole near the bottom.

Current Feeds and Speeds for the 51/64 S&D HSS Drill:

F: 2.0
S: 251

Any help would greatly appreciated!

Attached are images.
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