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Thread: Large End Mill for Bridgeport

  1. #91
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    3,614

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    Quote Originally Posted by donf View Post
    It could be. It machines fine at low speeds but has a very ugly torn finish. Speeding up the rpm cures that, but kills the HSS edges.
    This is pretty typical for soft mild steel. Build-up edge causes torn finish.
    https://www.youtube.com/watch?v=uwh3ouvzSLk

    Few workarounds:
    -really sharp tool and light pass. Might still tear but tear marks are 100x smaller and not issue anymore
    -either increase or decrease the speed considerably to get out of the "BUE zone"
    (slow speed is usually awfully slow and you dont want to go there unless its last option. upper speed range often means carbide)
    -heavy feed and DOC if using normal "not uber sharp" inserts

    Kinda opposite solutions to same problem but as long as you move enough far from "friction welding" conditions things should improve.

  2. #92
    Join Date
    Apr 2017
    Location
    Kelowna BC
    Posts
    2,570

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    Try another piece of cold roll If that is mystery metal.

  3. #93
    Join Date
    Apr 2012
    Location
    Medford Oregon USA
    Posts
    155

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    Just an update. I got the Morse AL5 Carbide bits in the mail a few days ago. I just stuck one unaltered in the fly cutter and cranked it up to 600 rpm. There is an noticeable difference in the finish and the way it cuts. Its not quite a mirror, but very nice. No real groves at all. I resharpened the original hss bit but without a radius on the tip just the edges knocked off on the stone. It was back to the ugly finish but at 120 rpm it was not pushing the edge. I will retry the tests on another piece of steel when I get it. For the fly cutter in the mill, I am really liking the brazed bits, no question its a better result and much faster. Thank you all for the input.

  4. #94
    Join Date
    Apr 2017
    Location
    Kelowna BC
    Posts
    2,570

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    I have 2 flycutting tools thAt fit my 2.5? Inch r8 flycutter.
    Both have around 1/8 rad on tip. One is HSS with high rake, about 45 degrees. The other carbide with almost neutral rake.
    Those 2 get me though all flycutting.

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