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End mill chatter like crazy!!

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  • #31
    lol - yeah kinda like that guy lol

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    • #32
      I wonder if the shank on the endmill is a tad too small in diameter, and maybe not being held over its full length in the collet-
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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      • #33
        Originally posted by A.K. Boomer View Post
        Yes I know but 1550's all I got --- even works for 1/8" with caution and again it has to work because it's all I got...
        If that's all you've got, then that's all you've got. But, if that's all the RPM you've got, why run carbide? HSS is cheaper, will last longer, and can be run closer to the speed it was designed to run at. If you're machining aluminum, there's almost no upside to running carbide on a hobby machine. (Even on a Bridgeport, there's not that many situations where running carbide on aluminum is advantageous.)

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        • #34
          Originally posted by darryl View Post
          I wonder if the shank on the endmill is a tad too small in diameter, and maybe not being held over its full length in the collet-
          I'm also wondering the same thing.
          Undersized or slightly tapered shank, collet , etc. We still didn't get the mfg. of the end mill.

          JL................

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          • #35
            Originally posted by nickel-city-fab View Post
            X2 try turning the revs down to a prime number that won't be divided by two... say 737 RPM for example.
            You might want to sit down with a beer and think about this a little longer...

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            • #36
              Okay - I actually goofed. Flute length is 3/4", but I have 1.25" stickout because the flutes are ground so high up, I wanted the collet to grab onto a continuous solid shank.

              This is the end mill: https://www.shars.com/products/cutti...rbide-end-mill

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              • #37
                Originally posted by tomato coupe View Post
                If that's all you've got, then that's all you've got. But, if that's all the RPM you've got, why run carbide? HSS is cheaper, will last longer, and can be run closer to the speed it was designed to run at. If you're machining aluminum, there's almost no upside to running carbide on a hobby machine. (Even on a Bridgeport, there's not that many situations where running carbide on aluminum is advantageous.)
                I've heard this logic before and purchased some nice HSS tools because of it. They worked fine but eventually dulled. Meanwhile, I've been using the same carbide lathe inserts and end mills for years in aluminum and steel, and they remain sharp. That said, carbide is FAR less tolerant to chatter and flexibility because it's so brittle. One tiny wrong move and they shatter. With a good setup though I prefer uncoated carbide to HSS for everything but drills and parting tools.

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                • #38
                  Originally posted by tomato coupe View Post
                  If that's all you've got, then that's all you've got. But, if that's all the RPM you've got, why run carbide? HSS is cheaper, will last longer, and can be run closer to the speed it was designed to run at. If you're machining aluminum, there's almost no upside to running carbide on a hobby machine. (Even on a Bridgeport, there's not that many situations where running carbide on aluminum is advantageous.)
                  It's just that I machine a fair amount of hardened material and stuff so just handy to do a one end mill fits all - I really don't have too much trouble machining aluminum with anything --- only time iv really got into trouble is not enough mist and then the friction stir happening...

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                  • #39
                    Originally posted by tomato coupe View Post

                    You might want to sit down with a beer and think about this a little longer...
                    Nah, diet coke is fine. His machine maxes out far lower than anywhere near ideal. So my comment was all about what has worked for me in the past, in the same situation. I probably should have said that you'll have to slow the feed all the way down.
                    25 miles north of Buffalo NY, USA

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                    • #40
                      Originally posted by nickel-city-fab View Post

                      Nah, diet coke is fine. His machine maxes out far lower than anywhere near ideal. So my comment was all about what has worked for me in the past, in the same situation. I probably should have said that you'll have to slow the feed all the way down.
                      I want to hear the theory about RPMs being prime numbers.

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                      • #41
                        I think darryl and JoeLee might very well be on to something. Maybe it's a 6 mm end mill. Time to get out the mic.
                        Location: Saskatoon, Saskatchewan, Canada

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                        • #42
                          The prime number thing doesn't make sense, but getting out of a harmonic does. The tool has a natural frequency related to the stiffness, mass, and is excited based on cutting parameters.

                          I'm just baffled by why I've never experienced this before. I've had tools chirp usually when running too slow but this is straight up squealing.

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                          • #43
                            Originally posted by kuksul08 View Post
                            I recently got a shiny new carbide end mill - 1/4" diameter, 1" flute length and 1" stickout, 2 flutes, standard helix, ER20 collet, and the darn thing chatters like crazy. I have never experienced this before with any of my tools to this degree. Usually a small tweak in feed/speed will cure it, but this is so bad I'm getting a rough nail-file like diagonal finish on my 6061 aluminum parts.

                            I'm running it anywhere from full slot to .010" WOC, 1/8" DOC, 4000RPM, 16IPM.

                            I've read some threads about how I need to load up the tool (0.020" chip load 😨) to get it to quiet down and smooth out, or slow it down to the 1000RPM range and keep my .005" chipload to get out of any harmonics that are occurring.

                            I'm thinking of staying with 3-flutes forever after this experience.
                            the likely reason people told you to up the chip load is because of whats called chipped thinning. In my shop we have fancy cnc’s and cam programs and can run really fast feed rates and not worry about breaking a tool in corners. With your endmill I would try to start and use the full flute length of .75” if needed, if it didnt work well I would drop it down to .375”doc, and if it was a new endmill to me I would probably start with a little bit bigger width of cut, usually in the range of 10%-15% the diameter of the endmill, so .025”-.0375”. I have a machinist calculator on my phone and the chip thinning calculator says to get a .005” chip load, at that width of cut, you use .0083” for the chip load to ipm conversion which at 4000rpm would be 65.9ipm. This style of machining works really well if your using cam that supports high efficiency tool paths, if not youre probably going to break endmills and have chatter. Note, some endmills are just noisy and we rarely use two flutes these days in aluminum, pretty much all three flutes and a four flute when we have too. . Yeah higher rpm’s would be nicer

                            good stuff on chip thinning on harveys website. Take a look at their other tech articles, even if youre not using their tooling.
                            https://www.harveyperformance.com/in...chip-thinning/
                            Last edited by mochinist; 02-03-2021, 06:25 PM.

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                            • #44
                              Originally posted by mochinist View Post
                              the likely reason people told you to up the chip load is because of whats called chipped thinning. In my shop we have fancy cnc’s and cam programs and can run really fast feed rates and not worry about breaking a tool in corners. With your endmill I would try to start and use the full flute length of .75” if needed, if it didnt work well I would drop it down to .375”doc, and if it was a new endmill to me I would probably start with a little bit bigger width of cut, usually in the range of 10%-15% the diameter of the endmill, so .025”-.0375”. I have a machinist calculator on my phone and the chip thinning calculator says to get a .005” chip load, at that width of cut, you use .0083” for the chip load to ipm conversion which at 4000rpm would be 65.9ipm. This style of machining works really well if your using cam that supports high efficiency tool paths, if not youre probably going to break endmills and have chatter. Note, some endmills are just noisy and we rarely use two flutes these days in aluminum, pretty much all three flutes and a four flute when we have too. . Yeah higher rpm’s would be nicer

                              good stuff on chip thinning on harveys website. Take a look at their other tech articles, even if youre not using their tooling.
                              https://www.harveyperformance.com/in...chip-thinning/
                              That begs the next question for the OP: Is he doing climb or conventional milling?

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                              • #45
                                Originally posted by tomato coupe View Post

                                That begs the next question for the OP: Is he doing climb or conventional milling?
                                Climb always

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