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Cutting circles

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  • steve schaeffer
    replied
    program a canned drill cycle to circumscribe the hole with a lot of little holes, then knock the slug out with a hammer and true up on the lathe (if you are using the circle)or finish mill out the lole (if you are using that)hahahahahahahahahah

    you left out some info, do you need a lot of these? are they a job, or just something you need? i agree you can farm that out if its a job, plasma cut or laser cut machines are everywhere. if not how you did it is good, also you could torch it then true it up on the lathe, or if you are good and have the right set up you can torch it and run it as is. you can make a circle cutting attachment for your torch very easy, even something crude for a one off job. the setup is important, if you are cutting a1/4" plate you would want a very small tip size. oxygen pressure should be high on cut to keep kerf clean of plate. it should look like a sheared edge when you are done. i used to sell automated welding and cutting systems, before, and also worked in a steel mill for several years. you would be amazed at how clean and straight a torch cut can be if done properly. we could cut a 9 inch slab and it looked like a machined edge. as far as you go, you are no machine, so cut the parts before you have your morning coffee. a steady hand is needed to make a steady cut.
    good luck.

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  • ShavingMaker
    replied
    Joel, I would do it exactly like you did it. All of the other ways may work too, but none of them are easy and you will probably have to true up the edges in the end anyway.

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  • yf
    replied
    I cut out a blank for a chuck backplate from HR steel with a trepanning cutter in the horizontal mill. Like a heavy duty circle cutter with a lathe bit for the cutter. You can make one.

    With the plate stationary, circles can be cut from any area on the plate, and no center hole either, if not wanted. Can also be done on the lathe, use an angle to hold the plate on the cross slide.


    If you're spinning the plate in the lathe... good luck.

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  • wierdscience
    replied
    Find a local fab shop that has a cnc driven plasma arc, I have found that if I am not in to big a hurry I can get what I want for a contibution to the beer fund.

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  • Dave Opincarne
    replied
    Make a hole saw. Press and weld a shank into a piece of 1/4" plate (you might even have some laying around )Turn the plate just smaller than the diameter you need with the shank held in the chuck. Tack weld a bimetal saw blade to the circumfrence. Use a hose clamp to hold it in place while you adjust the blade to run true.

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  • darryl
    replied
    set up a rotary table with a clock drive, use an EDM to vaporize out the circle. Book a holiday for 2 weeks, and have someone check your house for fire while you;re gone. Ok, I couldn't resist, somebody had to suggest a completely useless means of doing that. Maybe it was something I ate for lunch. Hm. Anyway, that has been a stumbling area for me, as well. I often wish to cut something out of sheet stock, and frequently don't do the project because of the hassle of extracting a piece the req'd size and shape from the blank. I can do circles in plastic well enough with a glorified circle cutter, but aluminium is harder, and steel is a no-no, with my jig. I guess it's time I went down to the dollar store and picked up a laser cutting table.

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  • Guest's Avatar
    Guest replied
    Use tripanning tool on lathe. You can hand grind the tool bit yourself.

    Albert

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  • SGW
    replied
    Holesaw!

    But if that's out...mount the plate on a rotary table, with spacers under it, and mill out the circle, mebbe?

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  • SJorgensen
    replied
    I don't do production work and I don't know the quantity that you are looking for or the quality. One thought I had for you was getting some 5 3/4" steel bar stock and a metal cutting bandsaw. Nice thing about these is you can set it cutting and let it go on it's own. They aren't very expensive machines either. I have not cut this size stock with one though either. On my lathe I might try parting off 1/4" slices. How about setting up lots of 6" squares on a threaded rod and turning it all down to the circles you need in one operation? Another method would be to shear them out of sheet stock with a hydraulic press. This you could farm out. I've seen lots of circles cut with CNC controlled plasma cutters. If you ask me that is the slickest way to do it. I'm trying to get my first CNC tool project built and then I'll be able to tell you how easy it is.
    Spence

    [This message has been edited by SJorgensen (edited 03-24-2003).]

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  • Joel
    replied
    Thanks, but I can't justify the expense of a 5 3/4" holesaw. I was hoping there was a safer/easier way of doing this, hopefully on the lathe.

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  • Dr. Rob
    replied
    Holesaw.

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  • Joel
    started a topic Cutting circles

    Cutting circles

    What is the easiest way to cut circles out of plate? I had to cut some 5 3/4" circles out of a piece of 6" square, 1/4" thick plate. I chucked it in a mandrel by a center hole, cut a ditch most of the way through, then trimmed off corners and turned the periphery smooth. Surely not the best way. I have no bandsaw, and I don't want to use the torch or a jigsaw. Experts, show me your brilliance!
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