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  1. #1
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    Default Turning aluminium

    I need to remove a LOT of material from the centre of an ali billet (disk), so I tried to use an 86mm hole saw that I happened to have, mounted in the tail stock, but the chatter was horrendous so I canned that idea.
    Any suggestions for reasonably quick removal?

    The lathe is 40 years old, Chinese, with only 3 speeds, and is VERY under powered, so I can only take light cuts otherwise it stalls, so machining out the centre would take many hours.

    The material that needs to be removed is basically a 100mm diameter disk, 37mm thick, from rest of the disk which is 200mm diameter.

    Cheers. )

  2. #2
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    Default

    Make up a face grooving tool, then use it to cut in to almost half way from each side then knock the guts out with a hammer or press.

    Steve

  3. #3
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    Default

    What type of holesaw are you using, lubricant, and at what speed?
    Have you thought about drilling a series of holes just inside the diameter required, either overlaping slightly or next to one another, then cutting through the pieces that hold together?
    That's probably the quickest way I can think of.
    To grow old is mandatory, growing up is optional.

  4. #4
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    Default

    Hi Phill,

    Fairly low RPM say 50 to 75 and plenty of lube. I use diesel but WD40 works as well. You can't push hole saws into aluminium too hard they will pick up and jam.

    HTH.
    Best Regards:
    Baron J.

  5. #5
    BobL is offline Member: Blue and white apron brigade
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    Default

    Chatter suggests the speed is too fast.

    Sometimes you have to face facts that you don't have the equipment to go the job as quick as you would like and you have to go slowly.

    I would use a narrower (not thinner) parting tool and make a series of stepped depth cuts around the 40-48 mm radius mark, then flip it over and cut from the other side, then use a boring bar to take out the rest.

    Meths is my choice of lube for Al -you can use heaps and it leaves zero mess but you will need ventilation or you will poison yourself.

  6. #6
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    Default

    Maybe try a carbide tipped hole saw as well, they have fewer teeth and much better chip evacuation than the HSS ones.

  7. #7
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    Default

    I thought the chatter might be speed related, but the lowest speed is the lowest speed, which is probably around 200rpm.
    I might try that step method, should work, otherwise a smaller hole saw, at least it will get rid of some material.
    Thanks for all the ideas. )

  8. #8
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    Default

    If the lathe is under powered as you say it may struggle with the hole saw, it would probably struggle with the face groove/trepaining method, by the time you try the methods suggested you might of been better off just boring it out.

  9. #9
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    Quote Originally Posted by ptrott View Post
    I thought the chatter might be speed related, but the lowest speed is the lowest speed, which is probably around 200rpm.
    I might try that step method, should work, otherwise a smaller hole saw, at least it will get rid of some material.
    Thanks for all the ideas. )
    Can you use back gear ? That should get you down into the 50 - 100 rpm range.
    Best Regards:
    Baron J.

  10. #10
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    Default

    A saw blade, fitted to a filing machine, could be put into a small hole drilled into the Al block?

  11. #11
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    Default

    Thanks, but no filing machine, and no gears, just a rudimentary 3 size pulleys on motor and lathe.

  12. #12
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    Default

    Where there is a will........
    Adaptor plate hole sawing..jpg

    Adaptor plate front side almost finished.jpg

    Despite the drill press having a similar low speed to the lathe, for some reason the hole saw worked ok in the press.
    All in all it has save me a LOT of machining.
    Cheers.

  13. #13
    BobL is offline Member: Blue and white apron brigade
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    Good work!

    TIP, when using a hole saw in thick metal (or wood ) drill several 1/2" holes all the way through on the waste side just touching the hole edge. This helps clear the swarf so you don'y have to keep backing out all the time.

  14. #14
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    I haven’t personally tried this but I’ve read on this or the wood forum that a Forstner bit will drill Al.
    Use kero for lube.
    H.
    Jimcracks for the rich and/or wealthy. (aka GKB '88)

  15. #15
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    Quote Originally Posted by BobL View Post
    Good work!

    TIP, when using a hole saw in thick metal (or wood ) drill several 1/2" holes all the way through on the waste side just touching the hole edge. This helps clear the swarf so you don'y have to keep backing out all the time.
    Bugga, I could have used that info this morning as clearing swarf was over half the job.
    I'll do that next time for sure, Cheers )

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