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End mill chatter like crazy!!

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  • #76
    Phooey on "magic numbers"....... The rpm is an unknown, varying with load, so no amount of magic numbers will ensure not hitting a resonance, unless it is away from rpm by more than the slip at FLA.

    The "hunting tooth" as I understand it is usually to make sure that the gears do not continually mate the same teeth together. If there is any error, then it is distributed, not fixed in relation to the spindle. And perhaps there is a decent chance of any errors gradually being eliminated by averaging out of the wear.
    2801 3147 6749 8779 4900 4900 4900

    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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    • #77
      the notion of having to use prime numbers migh be comming from a confusion of prime and irrational. when od/id grinding and wheel speed/workpiece speed is an integer, imbalance and concentricity imperfections of the wheel will translate into waviness issues. the same holds if the relation is something like 10.5. only if its an irrational nuber will the waviness equalize out.
      Last edited by dian; 03-22-2021, 01:57 PM.

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      • #78
        You know, with all the hullabaloo about magic numbers, im still waiting to hear how carbide doesnt work below a certain surface speed

        Cause, uhh, nobody tell my end mills that. Hopefully theyre just too dumb to know that they arent supposed to work and if nobody tells them, theyll keep working just fine

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        • #79
          Simple... if its chattering ..slow it down till it stops.

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          • #80
            Originally posted by epicfail48 View Post
            You know, with all the hullabaloo about magic numbers, im still waiting to hear how carbide doesnt work below a certain surface speed
            A few years ago, I cut a 1/2" -13 thread on a 304 ss rod with carbide at 9rpm on my Large and Shapely lathe, seemed to work OK.

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            • #81
              Originally posted by Fasturn View Post
              Simple... if its chattering ..slow it down till it stops.
              That ended up being my workaround. I ran it at 2500RPM with a corresponding feed rate and it returned the best finishes I've ever seen on my machine. Reflective with no vertical marks.

              Will report back after fixing the runout to see if it helped.

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              • #82
                Originally posted by epicfail48 View Post
                You know, with all the hullabaloo about magic numbers, im still waiting to hear how carbide doesnt work below a certain surface speed

                Cause, uhh, nobody tell my end mills that. Hopefully theyre just too dumb to know that they arent supposed to work and if nobody tells them, theyll keep working just fine
                True, Carbide works just fine at slower speeds. But if I'm gonna run slow then why not just save $$$ and use HSS? In my case the only reason to have carbide is if I'm turning something hardened. I run carbide most of the time just for convenience, not out of any actual need. And certainly my lathe was never designed to work in the range of carbide speeds.
                25 miles north of Buffalo NY, USA

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                • #83
                  Originally posted by nickel-city-fab View Post

                  But if I'm gonna run slow then why not just save $$$ and use HSS? .
                  Well, cause i can actually find halfway decent carbide end mills easier than HSS, the carbide lasts longer, and i dont have to slow down if im working with steel instead

                  Frankly, its harder for me to come up with a reason i should use HSS instead. Sure, im not pushing it to its absolute limits and getting all the benefits, but it still works great

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                  • #84
                    Originally posted by Michael Edwards View Post

                    A few years ago, I cut a 1/2" -13 thread on a 304 ss rod with carbide at 9rpm on my Large and Shapely lathe, seemed to work OK.
                    I have done slower even on a 4000 rpm spindle!
                    14 micrometer diameter steel rod.
                    Location: Helsinki, Finland, Europe

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                    • #85
                      NC spindles can run a 1/4 x 3/4 EM @ 5 to 7k with the CAT 40 holders efficiently. Lighter duty spindles may not. One size DOES NOT fit all with speeds and feeds. The new carbide endmills have much better edges than 30 years ago. The 3 flutes are Aluminum killers. High speed works well, but NC shops use carbide for tool life. Carbide edges can crack off with non rigid spindles ( Bridgeport ) - tougher materials like tool steel. In other words, carbide does not like to bounce around on steel !

                      We had a 20,000 rpm machine that was breaking .014 drills in 303 st. I ended up drilling them on a jig bore @ 3000 rpm.
                      Go figure ?
                      Last edited by Fasturn; 03-23-2021, 01:01 PM.

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                      • #86
                        End result?

                        Replaced my collet with a new one. Improved runout from .0040" to .0005". No more chatter. Buttery smooth and perfect surface finish!

                        I will get a little bit of chatter when slotting with the 2flute that can be solved with lower RPM, but everything else is fixed!!

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                        • #87
                          Originally posted by kuksul08 View Post
                          End result?

                          Replaced my collet with a new one. Improved runout from .0040" to .0005". No more chatter. Buttery smooth and perfect surface finish!
                          *GROAN* last thing I would have thought of.... well, glad you got it fixed!
                          Maybe I trust collets too much?
                          25 miles north of Buffalo NY, USA

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                          • #88
                            I have to admit, I have only tested the runout of about 10% of my collets.

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                            • #89
                              Originally posted by MattiJ View Post

                              14 micrometer diameter steel rod.
                              Now that is small work, .0005"/.014 mm stock (-:

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                              • #90
                                Originally posted by Fasturn View Post
                                We had a 20,000 rpm machine that was breaking .014 drills in 303 st. I ended up drilling them on a jig bore @ 3000 rpm.
                                Go figure ?
                                Yup, Jig Bore says it all.

                                Everyone wants one. We just fit them in our garages. Hauser... Lust, if I find one Ill drag it home. JR

                                P.S> I have been looking at jig bores for 20 years. Tons of Moore out there. Problem with the moore besides size? The associated tooling. Arms and legs start flying off to buy some. JR
                                Last edited by JRouche; 04-03-2021, 10:03 PM.
                                My old yahoo group. Bridgeport Mill Group

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

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