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Turning Al Trick

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  • Turning Al Trick

    Just a little tidbit I’d thought I share. Was turning down some Al this weekend, really don’t do a lot of AL here in the shop but had to make some fixtures. Turning Al was driving me crazy, long stringy chips, balling up, slinging all over the place. Tried changing speeds/feeds/DOC , carbide, HSS, chip breakers, no chip breakers, coolant..no coolant… all with the same results. Long stringy ..dangerous ..chips.

    Finally decided to try one of those cheap brazed on carbide 60 deg bits, the type used for threading. Beautiful ½ inch little chip curls, and super nice finish. Speed/feed /DOC didn’t seem to matter, just cute little curls all magically falling off at about the ½ inch mark.

    This may be old news to many of you..but for me, it's new.

    Mike
    Mike Hunter

    www.mikehunterrestorations.com

  • #2
    What alloy were you turning and at what speed?
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      Evan

      Don't know the alloy just some bar Al I have laying around for GP.

      I tried speeds ranging from 85 up to about 1800 rpm, and most in between, didnt seem to matter, just long stringy chips.

      With the brazed threading tool, I was doing about 900-1000 rpm, fairly good feed and .030 - .040 DOC. Again speed & feed didn't seem to matter, just nice little 1/2 in curled chips.
      Mike Hunter

      www.mikehunterrestorations.com

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      • #4
        I would guess that what you were turning was one of the low or no alloy grades of aluminum. I have found that when turning really soft aluminum that completely contrary to popular wisdom and even my own previous advice it is possible to obtain good results using a negative rake tool. The trick is that it must be coated or of a particular grade of carbide or better yet a ceramic or diamond tool and run at the highest speed available. The grades of carbide that work best are the low hardness grades such as C1 that I use for most roughing.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          I've had similar experience with "unknown alloy" Aluminum also. 6061-T6 seems to work better for me for my hobby work and is not terribly expensive (its strong too).

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