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Chatter in X axis milling going X+ to X-.


Sep 2, 2017
Syracuse, NY
Hey all, so I'm machining some 4340 using a 5/8" endmill 5 fl variable pitch taking 1.500" doc and have tried rdoc of .03-.125" and multiple combinations of different feeds and speeds all with the same results. It is running around the entire part and machining two 1.25" slots through the part as well all using an apative tool path. It cuts like butter everywhere except when cutting the back of the part moving in the X axis it sounds like someone is murdering a small child. I've checked the backlash which is as close to 0 as it's going to be in all directions. I'm using a milling chuck and not trying to run at any crazy feeds or speeds so something is telling me there is something loose in my machine. If anyone has and things to check it'd be greatly appreciated!
What speeds and feeds are you running it at now?
I assume it's PHT material?
If it were me, I'd go 1.5" deep, .0312 width of cut, 803sfpm and .0114" ipt.
The chatter could be due to backlash or maybe a worn ballscrew.
Do you typically machine a lot of parts in that area of the table? Maybe move the setup a foot to the left or right?
Running from X to -X on the back side of the part sounds like you're conventional cutting. You could try reversing direction and climb cut.

As an aside... You might try a better description of the sound your tools make so people can relate. I'm sure hoping there aren't any people around here that know what "murdering a small child" sounds like. I'm hard pressed to even imagine it. (Not that I'd want to anyway.) If you think of something better and care to edit it, I'd be happy to remove this aside.
This may not be helpful, unless it has to do with the machine speeds and feeds or mechanical parts, sometimes very rarely I have noticed that the coolant no being applied the same going in the opposite direction has had a impact on chatter