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  • cutting speed for cast iron

    Is 150 ft per second too fast to cut cast iron? (not a misprint)

    Let me rephrase this- I'm cutting through a thickness of about 5/8 inch, and the piece is too awkward to mount on the bandsaw. It's too heavy to hold and feed by hand, plus the angles are all wrong. There are no flat or square sides to orient against the bandsaw table, and to jigsaw this would take so long that my arm would drop off.

    So- I came down to the ---- the -- the table saw. The one flat side can sit on the table and the piece can be wedged to remain oriented for the cut. I have a carbide blade mounted, and -- well, I tried it. I'm partway through now and no problems except it's slow and I have to stop about every 30 seconds to let the cast cool. It takes awhile to cool, but that's ok. I'm getting about an inch every five minutes, so it's going to take about a half hour of actual cutting time to get through this. Several hours probably will be wasted waiting for the thing to cool. I can do other things during this time, of course.

    The blade doesn't seem to mind so far.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    Originally posted by darryl
    Is 150 ft per second too fast to cut cast iron? (not a misprint)

    Let me rephrase this- I'm cutting through a thickness of about 5/8 inch, and the piece is too awkward to mount on the bandsaw. It's too heavy to hold and feed by hand, plus the angles are all wrong. There are no flat or square sides to orient against the bandsaw table, and to jigsaw this would take so long that my arm would drop off.

    So- I came down to the ---- the -- the table saw. The one flat side can sit on the table and the piece can be wedged to remain oriented for the cut. I have a carbide blade mounted, and -- well, I tried it. I'm partway through now and no problems except it's slow and I have to stop about every 30 seconds to let the cast cool. It takes awhile to cool, but that's ok. I'm getting about an inch every five minutes, so it's going to take about a half hour of actual cutting time to get through this. Several hours probably will be wasted waiting for the thing to cool. I can do other things during this time, of course.

    The blade doesn't seem to mind so far.
    3000 rpm? 12" blade?

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    • #3
      Possible?

      Me too Derek.

      I suspect that darryl means 150 ft/min which is 150/pi = 150/3.14 ~48 RPM

      But 150 ft/sec X 60 = 9,000 ft/min

      But I am presuming that he is using a cold-saw as here where most run at 40>80 RPM:
      http://www.machineryhouse.com.au/Coldsaws

      - except for the Brobo saws which run at in excess of 3,000 RPM:
      http://www.machineryhouse.com.au/Pro...stockCode=S117

      I guess that anything is possible.

      Comment


      • #4
        Whend I do have to cut a big odd piece of cast iron I use the cutting torch .

        By feeding a 1/4 " steel round bar in front of the puddle ,clean with a grinder to take of the hard spot before machining

        Bazz

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        • #5
          90 SFM for high speed steel, 40 SFM for carbon steel

          90 SFM for high speed steel, 40 SFM for carbon steel

          This is for annealed gray cast iron

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          • #6
            Originally posted by oldtiffie
            Me too Derek.

            I suspect that darryl means 150 ft/min which is 150/pi = 150/3.14 ~48 RPM

            But 150 ft/sec X 60 = 9,000 ft/min

            But I am presuming that he is using a cold-saw as here where most run at 40>80 RPM:
            http://www.machineryhouse.com.au/Coldsaws

            - except for the Brobo saws which run at in excess of 3,000 RPM:
            http://www.machineryhouse.com.au/Pro...stockCode=S117

            I guess that anything is possible.
            150 sfm is doable for carbide

            Comment


            • #7
              Doing the math, - sorry I made a mistake, it's an 8 inch blade not a 10 inch- now I'm getting 120 ft per second. Per second- 8 inch blade, circumference is 25 inches, speed is 3450 I'm guessing, so 86250 inches per minute, so 1437inches or 120 ft per second. A bit less as I load it down of course.

              It's a regular table saw for wood, carbide blade, and I'm pushing cast iron through it. It's a very slow go because the cast is heating up. The blade is staying cold, or barely warm. I'm being very careful, taking about 10-15 seconds to go about .05 inch or so, and I'm adjusting the blade up and down so as to have about 3 teeth in the work and no more. If I don't adjust the blade, I get about 5 teeth in the work, and it goes too slow.

              I'm definitely not recommending anyone do this because it's not right, but it is working. Cut for about 30 seconds, take five. As I said, it's going to take about 30 minutes of actual cutting time to get through this, and a day or more to cater to this duty cycle.

              It has occured to me just a few minutes ago that I could have adapted a cut-off wheel to the table saw arbor and ground my way through this piece. There's a picture- a blast of sparks driving into a pile of sawdust hidden inside the stand- so far with the carbide blade I'm only getting the odd white spark, and I figure that must be sand or hard spots in the metal.

              I'm amazed that the blade is staying together. It's not loud, and so far no teeth have chipped and they all feel sharp still. I can't wait to shove a piece of wood through the blade after this cut is done.

              Again, this is not a recommended practice, it's just a nutcase trying it out to see if it could work (and get the job done somehow).
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

              Comment


              • #8
                Wearing (chewing??) it through

                OK - done on a wood-work saw - that explains it.

                In days gone by we used to use a 9" "Makita" hand power saw to cut roofing sheet. Just get an old non- TC tipped blade, put in backward and go like hell. It just wore its way through and it made one hell of a noise!!! This was before abrasive cut-off blades or saws were common. Anything beat cutting with snips/shears!!!

                But back to that cast iron. That thickness is well in the zone of many plasma cutters which do a quick accurate job (on any conductive metal) with minimal heating and distortion.

                Comment


                • #9
                  sounds like a train wreck waiting to happen.

                  why not use an (well several) abrasive masonry wheel in a hand held circular saw ?

                  Comment


                  • #10
                    I was planning to go with an abrasive disc, but the only ones I have are too large to fit the saw. At the same time I thought about all the sparks that would be coming out and igniting the sawdust under the table saw. I was fully prepared to deal with the loss of the carbide blade, since it's old and probably doesn't have more than one sharpening left anyway, but it lives on amazingly.

                    A train wreck waiting to happen, yeah that's what I thought at first. I'll repeat myself again- this is not something I'd recommend to anybody to try, so don't take this as a possible way to cut some cast iron- it was an experiment I tried, and happily enough it's getting this job done, so it is what it is, as they say, whoever they are.

                    I wonder if the cut surfaces are going to be hardened by this cutting action- won't matter anyway since so far the cut looks pretty clean and it's not a reference surface either. All it will need when I'm done is a de-burring.

                    Projects like this make me wish I'd made up my own bandsaw using a 33 ft long blade (3 blades from a 100 ft length of stock). The plan for this was to have two wheels in the base and another two wheels up near the ceiling, taking advantage of existing ceiling joists to carry the upper wheels. The building itself would have become the structure of the bandsaw. I still may do this at some time.
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                    Comment


                    • #11
                      Originally posted by darryl
                      Projects like this make me wish I'd made up my own bandsaw using a 33 ft long blade (3 blades from a 100 ft length of stock). The plan for this was to have two wheels in the base and another two wheels up near the ceiling, taking advantage of existing ceiling joists to carry the upper wheels. The building itself would have become the structure of the bandsaw. I still may do this at some time.
                      no one can accuse you of not thinking outside the box

                      take lots of pics if you do......if its for metal one thing that would dissuade me is that once one tooth gets broken, those around it quickly go...be shame to to toss a 100' blade too early in the game
                      .

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                      • #12
                        I did consider the cost of replacing a 30 odd foot long blade due to a mishap or whatever- I don't know how much more expensive it would be than a normal blade length, 64 inches in this case. Shouldn't be more than about 2-3 bucks a foot in bulk, would it? I haven't priced it yet. I'm paying the equivalent of 3-4 bucks a foot for the made-up blades already.

                        One thing I don't like with the 4x6 bandsaw is that the blade is approaching the elastic limit to be able to curve around the wheels. If I don't wreck the teeth, the blade will die anyway because it's over-stressed just to stay on the machine. I used a thinner blade once and I liked it, but I can't find them now- plus the thicker blade is more stable in the cut so it's a trade-off. At any rate, if I decide to build this thing I'll use larger wheels.

                        The piece of cast I'm cutting on the table saw is coming along. I've only got about ten minutes of actual time on the cut so far- I keep forgetting to run over to the saw and give it another 30 seconds of cutting, but I've been busy doing other things anyway. Maybe I'll get to finish it off tonite.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                        Comment


                        • #13
                          good point on the wheel dia...on breaking a tooth, i wasn't think the blade stock cost, more I was thinking that breaking that first tooth the starts the inevitable march toward a new blade was a bit of a random walk....it hits a hard spot in some welding tubing or whatever. If that's incorrect, if breaking a tooth was just a function of wear and is predictable, then i guess it wouldn't matter. Or you could argue that with a 30' blade it'd be more than worthwhile to weld in a patch, or have enough movement in the adjustment mechanism that you just take out the offending section and keep going with a 29 1/2 foot blade
                          .

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                          • #14
                            Precisely what I was thinking- have two wheels movable to accommodate a shorter blade. I can see how to do that easily enough. The only real problem I see is that tension on the blade will be pulling the ceiling towards the floor. Anchoring into the floor is probably not a big deal- having several hundreds of pounds pulling down on the joists is something to consider. I don't even know how many pounds of tension is on a properly adjusted blade. Guess I'll have to look it up.

                            Got another half inch through the casting last night-
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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