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  • speed on horizontal mill

    i have a little 30-taper horizontal. the original speeds are 87 - 1000 rpm. why is there not a lower speed?

    for a 80 mm saw/cutter the speed is 72 ft/min, for 100 mm its 88 ft/min. so im limited to 80 mm and a 22 mm depth of cut with hss. and even 72 ft/min is too fast for my liking, i ruined two cutters on some inclusions in hot rolled. so i either use the mill for aluminum or with carbide cutters (i have just a few). i dont remember what the power is, but i can run a 125 carbide saw with no problems.

    what were they thinking? what are the speeds on you mill?
    Last edited by dian; 06-27-2020, 01:24 PM.

  • #2
    At least you have 87 RPM. My Nichols' lowest speed is 100 RPM. I do have a VFD, but with only 1HP on tap, you can't drop the speed much before you really start losing power. Thankfully I do mostly turn aluminum, and it's worked out well.

    As to why, I don't know what specific machine you have, but generally speaking, most small horizontals, like the Burke, Nichols, old Pratt & Whitney, many Browne & Sharpes, etc. were intended for factory work, not necessarily general machining. Meaning you had a row of them all set up, and each would only make one cut per blank. The blank would progress through dozens of machines, each with a different fixture and cutter, emerging as a finished part at the other end.

    That's how we did things in those dim, dark pre-CNC days.

    As such, many of those machines would not necessarily be set up to take slitting-saw type cutters- they'd have standard endmills or similar tools, where the smaller OD would somewhat mitigate spindle speed issues.

    They were also generally set up with flood coolant in one manner or another, which would let you turn a cutter a little faster.

    Doc.
    Doc's Machine. (Probably not what you expect.)

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    • #3
      mine is 40 taper and goes down to 31. Aside from larger cutters, its nice having the slow speed, as you often want to slow things so a set up can handle a certain cut with out making dust.

      otoh, 72 or 88 is not too fast for mild steel, and many others for that matter. There might also be something to the dia/number of teeth. (I know temp at the edge is mostly a function a cutting speed so as I type this it seems slightly dubious)....unlike lathe work or an endmill the duty cycle for each tooth is much less. That might mean the tooth coming into cut is starting at a much low temp at the end than say an endmill, because its been soaked in coolant and doing no work for 80% of the revolution. Definitely use flood, cutters will last longer before sharpening, finish is improved, work doesn't grow and so on.

      you could always add a vfd (there's already tons of torque at the low speed) or change a pulley/belt
      Last edited by Mcgyver; 06-27-2020, 06:26 AM.
      in Toronto Ontario - where are you?

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      • #4
        My horizontal mill goes from 25 to 1400 rpm. It has 7hp.
        Location: The Black Forest in Germany

        How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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        • #5
          My small mill has minimum speed of 30 rpm or so. You are correct that slower is good for cutters in the larger sizes, and for tool steels, etc.

          But most small mills are set up to be little screamers, with 100 to 200 rpm minimums. You typically find them for sale with a 1/8" slotting saw on them, smack dab in the middle of a long unsupported arbor.

          Folks do not take small mills seriously.
          1601

          Keep eye on ball.
          Hashim Khan

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          • #6
            Small mills like the Ajax on a tubal Cain video that seems to be the one that comes up when I look around youtube are only meant for 2 - 3 in cutters with a low tooth count and don't have the room for the bigger pulleys to make it slower. Also if derived from line shaft design the move to integral motor didn't allow for the faster input speed. So often see smallish mills on ebay with a few 6 in cutters thrown in 'cos the owner thought swinging a big one would improve his manhood. Same is applying to modern small lathes with no back gear - just have to use small slitting saws.

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            • #7
              How old do you think the mill is ? Before carbide machines were made for HSS, before that for carbon Steel cutters ( think that is the name)
              the last type would lowest speeds.

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              • #8
                if it is 30 taper, it is "relatively new", since those standard tapers did not come in until "recently", as in the last 80 or 90 years, which would be well into the HSS and even carbide time period.

                I have a small "kit" mill from the late 40s. The original did not have back gear, and would have had about 150 rpm minimum, direct belt drive. But a common modification done by builders of the machines is back gears. I can run 4" cutters at a suitable speed for tool steel, and I can run slabbing type cutters as well.

                1601

                Keep eye on ball.
                Hashim Khan

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                • #9
                  no idea how old and no trace of the (italian) manufacturer.

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                  • #10
                    Originally posted by dian View Post
                    no idea how old and no trace of the (italian) manufacturer.
                    Does it have outboard support for the arbor you are using ?

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                    • #11
                      Originally posted by Black Forest View Post
                      My horizontal mill goes from 25 to 1400 rpm. It has 7hp.
                      Swing it, brother !

                      -D
                      DZER

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                      • #12
                        Originally posted by 754 View Post

                        Does it have outboard support for the arbor you are using ?
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                        • #13
                          Man that us a sweet little machine..

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                          • #14
                            That's a nice looking mill. Based on wrenches and the cord, it seems rather diminutive? Whats size is the arbor? its to be expected the small they are, the smaller the max anticipated cutter diameter will be. At 87 rpm you're fine at a 4" cutter...and all the provisions for coolant are built in. I'd just set it up an use it...or as suggested you could change pulley or use a VFD

                            whats the make?
                            in Toronto Ontario - where are you?

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                            • #15
                              Could it be a Pederson mill? (Danish)

                              -Doozer
                              DZER

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