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Tried a 1-inch rougher end mill on aluminum instead of my usual 3/4 and got a nasty chatter pattern I didn't expect
I ran a 1-inch rougher at 3500 rpm and 15 ipm on some 6061 last week, and it vibrated so bad it left visible lines on the part. Turns out the extra tool length was causing harmonic resonance with the machine's spindle speed. Has anyone else had chatter issues after switching to a bigger rougher for aluminum work?
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blake7921mo ago
Honestly, the thing most people miss here is that router bits and end mills are a whole different animal even if they look the same. You might be getting into a situation where the tool holder or the drawbar tension is too light for that bigger rougher's mass, so it's actually flexing at the collet before the cut even starts. Try torquing your holder nut a little more or switching to a heavy-duty collet that can handle the extra side load. Also check your spindle bearings if you've pushed them hard before because a little bit of wear there gets real loud with a bigger cutter.
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dixon.james1mo ago
That bigger rougher really changes the whole dynamic of the cut. The extra diameter means more surface contact and the flute geometry is different, so the harmonics shift on you. I found with a 1-inch rougher on a Haas I used to run, dropping the RPM to around 2800 and bumping the feed to 20 ipm helped settle it down by changing the vibration frequency. Sometimes you can also try a different stepover like 60% instead of 50% to break up the resonant pattern. It's a pain to dial in, but once you find the sweet spot those big roughers really fly through aluminum.
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