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Had a cutter grab and snap on a deep pocket yesterday
I was about 4 hours into a run of aluminum brackets at the shop on a new Haas VF-2. Everything was going smooth, feeds were dialed, coolant was flowing nice. Then on a deep pocket pass, I heard this screech that just sounded wrong. Before I could even hit the feed hold, the 1/2 inch carbide end mill grabbed and snapped right off. The part lifted off the vise and got thrown across the enclosure. I spent the next hour picking out the broken pieces and re-tramming the head because I was worried I knocked it out. Turns out my stepover was too aggressive for the depth, I was taking 40% on a full slot cut. My programmer buddy said I should have been at 20% max for that depth. Any of you guys run into chatter issues on deep aluminum pockets and find a go-to fix?
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johnson.river11h ago
My buddy who flies RC planes noticed the same thing happens with propellers if you push the pitch too fast at low speed. It's the Same exact concept with cutters - too much load too fast and something gives. @iris_schmidt nailed it with that variable helix suggestion, I've seen those handles chatter way better than standard end mills in deep cuts. I run my stepover at 20% or less on anything deeper than 2x diameter now and it's saved me from that pain.
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iris_schmidt13h ago
40% stepover on a deep full slot cut" yikes that'll do it. Ran into the same thing on a part once where I was doing a 3/4" deep slot in 6061 and it started making that death screech. Switched to a 3 flute variable helix and dropped to 15% stepover, never had another issue.
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