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  1. #1
    Join Date
    Apr 2008
    Location
    Perth
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    269

    Default Machining a Cast Iron back plate

    Hi Blokes

    At long last I have managed to buy a D1-5 backplate from H&F to suit my lathe. The dia of the backplate is 250mm, I need to machine it down to 200mm to fit a new 4 jaw chuck. My lathe has 9 speeds, which speed would I need to use to do this, already had a bit of a go, damn stuff is a shocker to work with. Speeds on the lathe are as follows 60, 95, 145, 225, 335, 535, 835, 1320, 2000.

    All my tipped tools are neutral, would I need a negative rake tool to do this job.

    Regards

    DD

  2. #2
    Join Date
    May 2010
    Location
    Lower Lakes SA
    Age
    58
    Posts
    2,607

    Default

    What did they slug you for that? I need D1-5 too, and it's hard to find.
    Speed chart attached. Edit: To see it properly, click the thumbnail below, then when it opens click it again. You should then be able to zoom in.
    PS: It only goes up to 100mm dia, but just halve that speed for 200mm, or divide by 2.5 for 250mm.

    cut.speed.chart.col.jpg

  3. #3
    Join Date
    Mar 2010
    Location
    Nth Qld
    Posts
    687

    Default

    I bought a couple if D1-5's from an Ebay seller in South Australia. I haven't seen any lately, I think he still has them but gave up listing them.
    They are cnc machined steel though and soft, like free machining steel. Will go look and find out his name again, they sold for $39.95 plus freight.

    Edit: It was Ozmestore ozmestore1 items - Get great deals on Machine Tool Accessories, Metal Cutting Tools items on eBay Stores!

  4. #4
    Join Date
    May 2010
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    Lower Lakes SA
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    58
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    Default

    Yikes, that's cheaper than I could find. Thanks Mark I'll chase him up.

  5. #5
    Join Date
    Mar 2010
    Location
    Nth Qld
    Posts
    687

    Default

    While I remember, He combines purchased items into the one box but does not combine freight charges, this was only a problem when I bought a 10" 4 jaw and a dial indicator at the same time.

  6. #6
    Join Date
    Apr 2010
    Location
    ringwood vic
    Posts
    251

    Default

    G'Day DD,
    When I fitted my 6 1/2" 3 jaw chuck to an 8" backplate I left the extra material as I find it a convenient hand hold for turning the chuck by hand, and yes turning cast iron is a bitch, an old towel over the bed and a high power button magnet under the tool holder makes the clean up much easier.
    Regards,
    Martin

  7. #7
    Join Date
    Jun 2012
    Location
    SA
    Posts
    1,649

    Default

    Yeah cast iron is real messy.

    The dust is also carcenagenic so wear a dust mask.

    It's not very abrasive so it's not as bad as grinder dust, but certainly is a bastard to clean up.

    Rob

  8. #8
    Join Date
    Apr 2008
    Location
    Perth
    Posts
    269

    Default

    Thanks Toolman, neat idea with the magnet, have a few of them rare earth ones. Thought about leaving the meat on the backplate, cant though, the over size gets in the way off the guard, which I have removed to machine down to size. I like all the safety bits on the lathe.

    Thanks Bryan for the speed chart, will do as you advised in regards to halving the speed for the area being machined.

    DD

  9. #9
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    Use your lowest speed or your next up,have your feed set at no more than the nose radious of your tool.
    If there is a scale get under it in one pass.

  10. #10
    Join Date
    Jun 2012
    Location
    SA
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    Default

    Quote Originally Posted by pipeclay View Post
    Use your lowest speed or your next up,have your feed set at no more than the nose radious of your tool.
    If there is a scale get under it in one pass.
    It's interesting that most people say machine cast at a slow speed, and yes it does a good job, but I've machined quite a bit of cast iron, and even at 200 RPM (for a 50 - 100 mm OD pulley) it's no problem.

    I always cut it dry, as the book says, but speed wise I can't see any difference in results.

    It cuts like butter and apart from the black mess, is pretty easy stuff to work from my experience.

    Rob

  11. #11
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
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    Default

    Does the book ever talk about using coolant.

  12. #12
    Join Date
    Jun 2012
    Location
    SA
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    Default

    You can use coolant for some jobs (eg, facing), but most articles and machinists say to cut it dry on a bench lathe.

    Cast iron has a high graphite content, which is the main reason you cut it dry.

    The other metal you machine dry is brass. I hate machining that stuff - the fine splinters are bad news, so damn easy to get them in your skin and hard to find them to remove.

    I find the best way to clean up after machining cast iron is a good vacuum and them wipe everything down with toilet paper. The paper fibers catch/pick up the particles extremely well, and then you just toss the lot in the bin.

    Rob

  13. #13
    Join Date
    Apr 2012
    Location
    Melbourne
    Age
    57
    Posts
    122

    Default

    Quote Originally Posted by nearnexus View Post

    The dust is also carcenagenic so wear a dust mask.

    Rob
    Nothing I found says it's carcinogenic. Still, enough of it isn't good for your lungs.

  14. #14
    Join Date
    Jun 2012
    Location
    SA
    Posts
    1,649

    Default

    Quote Originally Posted by Clubman7 View Post
    Nothing I found says it's carcinogenic. Still, enough of it isn't good for your lungs.
    Looks like your right. I was told by a machinist that it was a cancer hazard, but it appears not to be a carcogen.

    This sheet lists it medical risk factor.

    http://www.lethiron.com/downloads/pd...AST%20IRON.pdf

    Still, better safe than sorry.

    I usually wear a dust mask with it as it certainly gets up your nose without one.

    Rob

  15. #15
    Join Date
    Apr 2010
    Location
    ringwood vic
    Posts
    251

    Default

    Yep, big black boogers

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