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End mill chatter like crazy!!

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  • #16
    Originally posted by tomato coupe View Post

    The speed is too low, regardless of what type of coolant is used. 4000 RPM only gets him to about 250 fpm, and he needs to be in the 800-2000 range.
    I hear it all the time here about carbide and rpm. I dont get it. Again I am not production just trying to produce.

    On my two small mills I use carbide exclusively for aluminum, at between 2500-4000rpm. The 1/4" though is a lil small for that speed I have noticed.

    With those I try to keep the stick out as small as possible due to more of a "rubbing" effect vs cutting with the slow spindle, vibration. That helps as well as a tight carriage and gibs.

    So I tend to not push the feeds, carbide can handle the extra heat due to "rubbing" if it is sharp.

    Because you seem to already have a handle on your machine I would suspect the cutter/ JR
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

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    • #17
      Originally posted by JRouche View Post

      I hear it all the time here about carbide and rpm. I dont get it. Again I am not production just trying to produce.

      On my two small mills I use carbide exclusively for aluminum, at between 2500-4000rpm. The 1/4" though is a lil small for that speed I have noticed.

      With those I try to keep the stick out as small as possible due to more of a "rubbing" effect vs cutting with the slow spindle, vibration. That helps as well as a tight carriage and gibs.

      So I tend to not push the feeds, carbide can handle the extra heat due to "rubbing" if it is sharp.

      Because you seem to already have a handle on your machine I would suspect the cutter/ JR
      Do I understand this correctly? You're advocating running carbide at low speeds to induce rubbing rather than cutting?

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      • #18
        In this case, I think there may be some effect of running slow.... the chatter might really be the effect of the two teeth slamming into the work at a higher chipload, combined with something being loose. That can make the machine jump around as if it were chattering, and make nasty surface finishes, especially if the looseness has a resonance near the "flute frequency". It might as well BE chatter, because it acts pretty much the same.

        Running faster might get the pounding of the two edges to a higher frequency and reduce the problem. Finding whatever is loose would also help, assuming that there is something loose.

        People love to talk about carbide as if it just does not work at all if run slower than their 10 HP industrial machine can do flat out. It ain't so. I run carbide slower because I cannot run it faster, and it works fine. I do that if I am cutting harder material such as 4140 PH, which will tear up HSS. I don't think you need to waste the money on carbide unless you need it, OR can use it to the potential, but that's your thing, nothing to me.

        I have a couple carbide end mills, and they work pretty much the same as any others. I can guarantee to you that I am not running them at the "optimum" speed.
        2730

        Keep eye on ball.
        Hashim Khan


        It's just a box of rain, I don't know who put it there.

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        • #19
          Originally posted by tomato coupe View Post

          The speed is too low, regardless of what type of coolant is used. 4000 RPM only gets him to about 250 fpm, and he needs to be in the 800-2000 range.
          https://www.youtube.com/watch?v=hQUN6_bI-io

          I've been machining for years running well below recommended SFM with no issues. Granted, I've never used an end mill quite like this so I'm confused why it's so sloppy.

          For coolant I am using some soluble oil Kool Rite 2290 in flood.

          I will admit I didn't look closely at the flute length and it's longer than I would like. I generally prefer stub length end mills for their rigidity and I rarely do any kind of pocketing.

          I'm going to take a closer look at the runout and try some test runs on a chunk of AL to see if I can find a speed and feed that doesn't chatter. Will report back,

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          • #20
            Originally posted by tomato coupe View Post

            Do I understand this correctly? You're advocating running carbide at low speeds to induce rubbing rather than cutting?
            Close. I am saying running them to the potential of the machine you have. And yes, with high quality end mills I can keep from chipping them and keep from shattering them with a slower feed rate. I am not a machinist, I am Grute. JR
            My old yahoo group. Bridgeport Mill Group

            https://groups.yahoo.com/neo/groups/...port_mill/info

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            • #21
              Running FASTER is more likely to induce rubbing than running slow.

              Why?

              Because you need an insane feed to keep a decent chipload on the cutter if you are running extra high SFM. Go slower on feed, and you are rubbing!

              Going slower, but keeping the chipload at the recommended level is not going to rub. It's CHIPLOAD that controls rubbing, NOT SFM.
              2730

              Keep eye on ball.
              Hashim Khan


              It's just a box of rain, I don't know who put it there.

              Comment


              • #22
                Originally posted by J Tiers View Post
                Running FASTER is more likely to induce rubbing than running slow.

                Why?

                Because you need an insane feed to keep a decent chipload on the cutter if you are running extra high SFM. Go slower on feed, and you are rubbing!

                Going slower, but keeping the chipload at the recommended level is not going to rub. It's CHIPLOAD that controls rubbing, NOT SFM.
                What he said. I said rubbing when I meant cutting at a very slow rate. I am Groot. JR
                My old yahoo group. Bridgeport Mill Group

                https://groups.yahoo.com/neo/groups/...port_mill/info

                Comment


                • #23
                  Originally posted by tomato coupe View Post
                  Why are you running carbide that slow?
                  Because I don't have to run it fast. Good sharp carbide will shave it right off. There is usually some type of pattern left, usually vertical lines, sometimes they are slightly angled but that depends on the end mill. like 2 flute or 4 flute. Some end mills leave a smoother finish than others but the cutter needs to be sharp.
                  I've never got rough ragged surfaces side milling any material. WD or coolant will help prevent chips from sticking to teh cutting edge which is usually the reason for a rough and ratty looking finish.


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

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                  • #24
                    kuks, is that the firs/only carbide endmill you have? is it from "decent provenience" or an ebay tool?

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                    • #25
                      With a light milling machine like you have,
                      and having success with 3 and 4 flute end mills
                      maybe you have found a harmonic resonance
                      in using the 2 flute. It might be worth trying
                      faster and slower RPMs just to see if that helps.

                      -D
                      DZER

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                      • #26
                        Is it coated or uncoated? Who is the manufacturer?

                        FWIW, carbide - as a material - does NOT need to be run fast. However, because carbide can be run fast, tool geometry is generally optimized for high SFMs. Consequently, some tools (especially coated ones that tend to have a honed edge) will chatter at low speeds in smaller machines because the tool may have a negative rake cutting edge. (Note that coated tools with honed edges may have an overall positive rake but the honing creates a small negative rake edge that isn't really noticeable unless you're looking through a loupe or microscope.

                        As a concrete example of carbide being run slow, a typical 1/4" carbide reamer being used in aluminum has a recommended RPM of about 3800 (recommended SFM of 250-300), e.g. https://www.hannibalcarbide.com/tech...and-speeds.php

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                        • #27
                          Originally posted by Doozer View Post
                          With a light milling machine like you have,
                          and having success with 3 and 4 flute end mills
                          maybe you have found a harmonic resonance
                          in using the 2 flute. It might be worth trying
                          faster and slower RPMs just to see if that helps.

                          -D
                          X2 try turning the revs down to a prime number that won't be divided by two... say 737 RPM for example.
                          25 miles north of Buffalo NY, USA

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                          • #28
                            I should have mentioned in my previous post that you might want to try climb cutting. I often find that leaves a smoother finish. Not sure if anyone mentioned this.

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

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                            • #29
                              Originally posted by tomato coupe View Post

                              If you're running 1/4" carbide end mills at 1500 RPM, you're actually shortening their life.
                              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...

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                              • #30
                                Originally posted by A.K. Boomer View Post

                                it has to work because it's all I got...


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