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machining cast iron

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  • machining cast iron

    I am building a small gas engine and am going to use cast iron for the flywheel. It is 3.750 diameter. Any thing to watch for when working with cast iron? This is a first for me as I have not machined any cast iron. I did find that HHS dulled real fast when cutting it. It is class 40 hot rolled.

  • #2
    should machine beautifully and not dull tools - how fast were you going? take enough DOC to get past the scale, machine with tool geometry as you would steel except machine dry and a little slower, 70-80 sfm...good quality cast iron is one my favorites to machine
    .

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    • #3
      Its messy, cover up your ways/lathe if you can and clean up as much as you can afterwards.
      Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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      • #4
        I always like machining it, but hate cleaning up afterward. It's really messy. It comes off in little dusty chips that get everywhere. The dust can be quite abrasive, so make sure to clean your lathe really well after the fact.
        Stuart de Haro

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        • #5
          The current HSM magazine has an article of a motorcycle cylinder being built from cast iron. Between the cylinder fins and the bore that had to be one messy cuss to turn. Anyway, it might be worth a read for anyone thinking about turning iron.

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          • #6
            Class 40 hot-rolled is grey cast iron. Beautiful to machine. The graphite dust is a mess, like others have said. I keep a Shop Vac nearby while I'm machining. If you try to wipe it up, it gets all over you, and you'll have racoon eyes around your safety glasses.
            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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            • #7
              As the others have said, beautiful to machine, messy to clean up afterward.
              I usually direct the nozzle of a running shop vac at the area being cut, saves a lot of time cleaning up.
              Last edited by Willy; 05-10-2010, 01:11 AM.
              Home, down in the valley behind the Red Angus
              Bad Decisions Make Good Stories​

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              • #8
                After machining, use a paper handkerchief to clean your nose.


                Nick

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                • #9
                  Take a good first cut to get under the skin of the casting. The surface layer tends to be hard and contain bits of sand from the mould, so if you take a light first cut and let the tool rub, it will dull HSS pretty quickly. Other than that, keep the speed down, maybe as low as 50RPM for your size, especially for the first cut, then speed up a bit for the finishing cut. I like cast iron, and work it a lot. OK its messy, maybe wear disposable domestic gloves while you are turning it, otherwise the graphite gets engrained into your skin and is a pig to wash off. Also, if you wash your hands in the house bathroom or kitchen sink, the dust off your hands tends to leave nasty rusty marks in the basin, which will not make you popular!

                  Richard

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                  • #10
                    maybe wear disposable domestic gloves while you are turning it,
                    You should never wear gloves on the lathe (mill, drillpress, ...).

                    I do have the impression, that the US-people wear gloves for everything, even in the most in-appropriate places or situations. I woundn't wonder when they change gloves while they fart.


                    Nick

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                    • #11
                      I can't see how wearing a pair of disposable nitrile gloves would be a safety concern here. They tear if you look at them the wrong way.

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                      • #12
                        An old speaker magnet in a ziplock bag is allegedly good for catching cast iron dust, when finished turn the bag inside out and you've a bag of dust.

                        I think I may have read this tip on here before but cannot remeber who by so regrettably can't give credit.

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                        • #13
                          Originally posted by hornluv
                          The dust can be quite abrasive, so make sure to clean your lathe really well after the fact.
                          A sand casting can have abrasive bits in the outer layer, and the skin on cast iron bar stock could be abrasive, but i'd guess no more so than the skin on hot rolled....once you're through that why would it be abrasive?

                          Not sure what i'm doing different but I just don't find it that messy, and i end up with a pile chips and minimal dust. because machining is done dry and the chips are all broken, cleanup is the easiest of all, just a shop vac.....now grinding, for that i wear a mask
                          .

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                          • #14
                            Dont use a liquid coolant when cutting cast iron.
                            MBB

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                            • #15
                              At the risk of sounding like a complete idiot, do the previous recommendations apply to durabar? I've got a stick of it and was thinking about making some 123 blocks out of it. True, they won't be hardened but if I'm carefull with them, they should work out fine.
                              John B

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