5/16" VARIABLE FLUTE CARBIDE ROUGHING ENDMILL

I purchased several roughing end Mills recommend by John at NYCNC, that's a YouTube channel. We make lots of parts from 1/4 inch HR steel and I want to cut them out in one pass with a 1/4 inch end mill. Over the years I've had very limited success with this but wanted to try it again. If I can conquer this I can do these parts in house instead of sending them out for laser cutting. The tool path is about 12" long and a slot about half way. I set the feed rate at about 8 IPM at 4000 RPM and 0.25 DOC thinking this would be easy on the end mill. Much to my dismay the end mill broke on the 3rd part. I called Lakeshore Carbide and see if they could offer some suggestions on what I might be doing wrong. I got a hold of Carl and explained my situation. It turns out that Carl is a very patient and understanding man and an expert when it comes to carbide tooling. After a very complete easy to understand explanation my eyes were opend and I realized I was cutting way to slow. Carl recommended starting at 17 IPM at 4000 RPM and leave the DOC at 0.25. If everything was working fine increase to 24 IPM. Even though it seemed to fast I reprogrammed my Milltronics VMC accordingly. On the first part I increased from 17 to 24 IPM because it was cutting super good. I continued to cut 47 more parts and finished the job without a single problem and the end mill looks plenty good to do a lot more. Now these parts will be staying in house and my guys are thrilled! The bottom line is I will be purchasing my carbide tools from Lakeshore carbide exclusively. They have won my business for sure and I highly recommend them to all. There's nothing better than high quality American-made tools at a fair price with great customer service. That combination cannot be beat! Thanks Carl for all your help. I learned a very important lesson here and really appreciate it! Kerry Harrison - Harrison Specialties LLC