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End mill chatter like crazy!!

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  • #46
    Originally posted by A.K. Boomer View Post

    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...
    If you're only going to own one end mill in each size then, sure, go with carbide. I wouldn't, but that's me. (Actually, I can't imagine having only one type of end mill.)

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    • #47
      carbide end mills on hobby mills are useful for a couple of reasons, even when used slower than manufacturers specify: 1) machining hard materials 2) extended reach

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      • #48
        Originally posted by Arcane View Post
        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.
        6mm is about .236. I doubt a 1/4" would close up on it.
        At least not an R8.

        I've bought a lot of metric end mills but they always came with standard size shanks.

        JL.....


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        • #49
          Originally posted by tomato coupe View Post

          If you're only going to own one end mill in each size then, sure, go with carbide.
          cool yeah that's what I was thinking
          I wouldn't, but that's me.
          wait a minute thought you just agreed???
          (Actually, I can't imagine having only one type of end mill.)
          Actually you can - and you did in your first statement... are you usually this confused about stuff? endmills are simple - buy em and use them to put out work... no need to freak out about stuff that other people seem to be having success with...

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          • #50
            Originally posted by A.K. Boomer View Post
            cool yeah that's what I was thinking wait a minute thought you just agreed??? Actually you can - and you did in your first statement... are you usually this confused about stuff? endmills are simple - buy em and use them to put out work... no need to freak out about stuff that other people seem to be having success with...
            If you're only going to own one end mill in each size then, sure, go with carbide. I wouldn't, but that's me.
            You means you. If that's what you want to do, go for it.

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            • #51
              Originally posted by tomato coupe View Post
              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 use carbide when using a ball endmill on aluminum because I seem to get better life out of them.

              I only use OSG, Garr, Niagara and SGS because they are good and I got them dirt cheap on ebay. I have enough to last me my days, I hope

              But even those can cause me issues with chipping due to the sharp corners. Sometimes I will know the corner down a lil to prevent it from chipping off. JR

              Click image for larger version

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              My old yahoo group. Bridgeport Mill Group

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

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              • #52
                Originally posted by tomato coupe

                A carbide ball nose in aluminum on a low RPM machine – now you're just being mean.
                Contact patch on the ballmill is very small. JR
                My old yahoo group. Bridgeport Mill Group

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

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                • #53
                  A carbide ball nose in aluminum on a low RPM machine – now you're just being mean.

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                  • #54
                    Originally posted by JRouche View Post
                    Contact patch on the ballmill is very small. JR
                    And the smaller effective diameter means it needs an even higher spindle speed than a square end mill of the same diameter.

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                    • #55
                      Originally posted by tomato coupe View Post
                      And the smaller effective diameter means it needs an even higher spindle speed than a square end mill of the same diameter.
                      This is true, actually ball end mills are a perfect teaching tool to see what you can get away with as they are a total variable set of rules right in front of you, in theory you can't spin one fast enough for total dead center results to be perfect, unlike conventional as it's the outer swath thats mowing everything down in the first place...

                      it's not unusual to see a little bad finish dead center with a ball end mill ---- if it's extending out from dead center even a little then it's just begging for more RPM's

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                      • #56
                        Originally posted by tomato coupe View Post
                        A carbide ball nose in aluminum on a low RPM machine – now you're just being mean.
                        Ooops. Sorry. I didnt mean to imply I use my center cutting ballmills for center cutting, if I did.

                        I only use the radius of the ballmill, the 90 degree section. I dont center cut with them, till the very last sliver at the bottom of the inside contour. I hog the pocket out with square endmills and leave a channel for the ballmill to finish up.

                        The smaller contact per rev I was thinking of was the 90 degree section of the mill I use, and a shave of the vertical portion when making pockets.

                        When doing outside contouring I use even less of the cutting edge of the mill. So I can shave away as slow as I need to get the job done.

                        I get it, might be the wrong way to do things. The problem is it works for me

                        I do appreciate the education. Thank you Sir... Always willing to learn. JR
                        My old yahoo group. Bridgeport Mill Group

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

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                        • #57
                          Following up on this one.

                          I was running my mill and one of my larger tools started developing the same chatter issue, which is very strange. I stopped everything and started at the basics. As it turns out, I had some pretty noticeable runout as a result of damaged/worn R8 collet. Upwards of .004" at 3 inches from the spindle face. It should be less than .001"

                          I've since bought replacement parts and hopefully this cures the issue.

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                          • #58
                            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.)
                            Solid carbide seem to be actually cheaper than decent HSS in small sizes. Chinese solid carbide end mills have proven serviceable but I have had very little luck with cheap HSS.
                            12mm coated solid carbide end mills are only about 15 usd per piece. I haven’t been able to find comparable HSS end mill for less than 20 usd.

                            6mm coated carbides were only 3 usd per piece and cheapest usable HSS is closer to 15usd.
                            Location: Helsinki, Finland, Europe

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                            • #59
                              but $15 doesnt get you micrograin .

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                              • #60
                                Originally posted by dian View Post
                                but $15 doesnt get you micrograin .
                                Thats what the aliexpress tool shops sell me.. hard to say if it is micrograin for real or not. Toughness and sharpness would lead me to believe these are micrograin carbide for real. Fracture surface looks also like micrograin, not like some older lathe inserts that appear to be made from sintered sand grains.

                                what I haven’t been able to find for 15 bucks is variable-helix solid carbide. These seem to be available only in western brands and typically like 60usd for 12mm.
                                Location: Helsinki, Finland, Europe

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