aluminum chatter

[rolfcam]

Hello I am new to this forum and new to cnc as well so forgive my wording so.  I am cutting parts out of aluminum I previously cut out a template for my parts with no issue, then came back to it days later to start cutting out parts started cutting out the radius of one part and i did not like the sound of the chatter so i Changed the F&S it worked but not without chatter. F&S is 1/8 endmill 2f,12 passes, pass depth .06, stepover .05, speed 9000 feed 10 Ipm plunge 5,. i tried it again with a piece of wood matching the aluminum with the same F&S and although it was better i still noticed the chatter.
i went over everything i could but nothing has changed does anybody have any suggestions

[dadealeus]

I've done some milling in aluminum without issues using the numbers from GWizard.

I plugged in the values you listed and it's suggesting nearly doubling your RPMs from 9000 to 17000.

I've noticed that softer metals will still require a fairly high RPM value and a value of 9000 is probably just taking too large of bites from the stock - causing deflection and chatter in the tool.

That would be my guess, at least.

[rolfcam]

Thanx you I will try that so when you say you plugged in the numbers how do you come up with the right numbers

[dadealeus]

I used my machine for a couple of years before I looked for something to help me figure out feeds and speeds and it made a HUGE difference.

Maybe feeds and speeds come more naturally to other people or those with more experience, but my AR 8 Pro was my first CNC mill and I didn't know I was off by as much as I was until I tried a program called GWizard.

Basically, you plug in your material, your tool, and your cut details (how many flutes, cut depth, stepover you want to use, etc.) and it will spit out a good figure for you to start with in terms of RPMs and IPM for both plunges and linear movement.

It made a HUGE difference in my cut speed and efficiencies. I'm not affiliated with them in any way, but I'm very happy with the program. It has a 1-month free trial you can use to check it out if you're interested:

www.cnccookbook.com/g-wizard-cnc-speeds-and-feeds-calculator

I highly recommend either that one or something else like it.