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  1. #1
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    Default Bit of direction needed

    IMG_20200309_164957.jpg

    Firstly,...the sum total of my milling experience is what you are looking at.
    Secondly, the only way I can mill at the moment is with the lathe, and on that tool post.
    Thirdly, the only milling tools I have is a small set of cheap end mills.

    In hindsight I probably should have run the first cut with the 10mm, and the second cut with a 12mm, leaving me with a very thin web,....maybe the next time.

    What is left is about 2.8mm thick. I might be able to break it out, or grind a hacksaw blade down enough to fit in there and cut it out, but I was hoping there was a better way?

  2. #2
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    Quote Originally Posted by ptrott View Post
    I might be able to break it out, or grind a hacksaw blade down enough to fit in there and cut it out, but I was hoping there was a better way?
    Maybe I'm missing something, but why not just run an endmill through it? Use the 12mm one. Phil.

  3. #3
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    Quote Originally Posted by SP_Flip View Post
    Maybe I'm missing something, but why not just run an endmill through it? Use the 12mm one. Phil.
    My thoughts were that it would be far too flimsy to take that. I had visions of it vibrating horrendously and bits breaking off, or it bending & mangling, but really I don't know.
    Willing to try anything that doesn't end in a mess

  4. #4
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    If you want that middle web out just do what you have been doing and mill it out on the lathe.

    If it breaks off it will save milling so much, then just clean up what's left as it won't break below the surface.
    Using Tapatalk

  5. #5
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    Quote Originally Posted by ptrott View Post
    My thoughts were that it would be far too flimsy to take that. I had visions of it vibrating horrendously and bits breaking off, or it bending & mangling, but really I don't know.
    Willing to try anything that doesn't end in a mess
    It should be fine. I can see a lot of chatter marks in the existing cuts. How many passes did you take for each of those two cuts?

    Based on the width of previous cuts I'm guess that they are about 20mm deep, and that web is about 5mm? (EDIT: sorry, you said it's about 2.8mm). Also assuming cold rolled mild steel?

    If so, take it in 4 passes x 5mm deep each maximum and it should be fine - that's conservative as that setup doesn't look very rigid ... it's always hard to get a good setup when milling on a lathe. Anything you can do to buttress the part will help with the vibration. Ideally, an angle plate behind it with the part held to that with strap clamps. The shallower each cut, the less scary the cut will be.

    Phil

  6. #6
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    Quote Originally Posted by SP_Flip View Post
    It should be fine. I can see a lot of chatter marks in the existing cuts. How many passes did you take for each of those two cuts?

    Based on the width of previous cuts I'm guess that they are about 20mm deep, and that web is about 5mm? (EDIT: sorry, you said it's about 2.8mm). Also assuming cold rolled mild steel?

    If so, take it in 4 passes x 5mm deep each maximum and it should be fine - that's conservative as that setup doesn't look very rigid ... it's always hard to get a good setup when milling on a lathe. Anything you can do to buttress the part will help with the vibration. Ideally, an angle plate behind it with the part held to that with strap clamps. The shallower each cut, the less scary the cut will be.

    Phil
    Ok, I'll give it a shot tomorrow.
    They are 20mm deep, and I started at 0.5mm per pass for a couple of mm, then upped it to 1mm per pass. Any more than that and things get very noisy and don't look good. At those depths I get a decent feed rate going,....75mm in 20 seconds or so. (At 1230rpm)

  7. #7
    Join Date
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    Perth
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    Phil,
    Just to add another perspective seeing as the milling is done on the lathe, rigidity of setup is important, this is probably something that's not present, therefore I would suggest cutting the center piece with a thinned hacksaw blade or one of those round blades to about a 3-4mm stub and then mill the remainder. A cold chisel from both ends would also be a possibility and break off the remainder. Good luck with it. Alan.

  8. #8
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Hi Phill, Guys,

    You are a much braver man than I ! For me, milling on the lathe was a frightening experience.

    OK I know that your lathe is bigger than mine, but from what little milling I've done on mine, rigidity is king. Anything you can do to make the workpiece more rigid will help.

    As everyone has said, you have milled two slots, milling that bit in the middle should be a doddle.
    Best Regards:
    Baron J.

  9. #9
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    Quote Originally Posted by ptrott View Post
    ... (At 1230rpm)
    For a 10mm end mill I would not be going faster than 900rpm. For a 12mm mill, 750rpm. If you are going at 1230 you are likely to overheat the cutter and blunt it.

    Michael

  10. #10
    Join Date
    Dec 2007
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    Sydney
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    Those round things are abrafiles.
    Handy for holes in sheet metal if you have an original holder.(I have my dads).
    If not there are adapters for a normal hacksaw.
    H.
    Jimcracks for the rich and/or wealthy. (aka GKB '88)

  11. #11
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    Revesby - Sydney Australia
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    Quote Originally Posted by clear out View Post
    Those round things are abrafiles
    or, Remington "Grip Edge"s...

    IMG_0542.jpg


    Note that both of these types were standard hacksaw length?

  12. #12
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    Quote Originally Posted by Michael G View Post
    For a 10mm end mill I would not be going faster than 900rpm. For a 12mm mill, 750rpm. If you are going at 1230 you are likely to overheat the cutter and blunt it.

    Michael
    Thanks Michael, I'll slow it down & see how it goes.

  13. #13
    Join Date
    Nov 2018
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    Tasmania
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    Quote Originally Posted by Michael G View Post
    For a 10mm end mill I would not be going faster than 900rpm. For a 12mm mill, 750rpm. If you are going at 1230 you are likely to overheat the cutter and blunt it.

    Michael
    I agree with this speed
    A rule of thumb I use for max RPM is 9000 / D
    Where D is the endmill diameter or workpiece if turning

    This applies for HSS cutter on mild steel. If running carbide I try to triple it

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