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Burr when machining the edge of a brass plate.

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  • Burr when machining the edge of a brass plate.

    I'm trying to square the edges of a brass plate.. it's about .200 thick. I'm getting a fairly substantial burr along the edge.
    I've tried faster and slower spindle speeds, faster and slower feeds, 2 flute and 4 flute mills, results seem to be about the same.
    Seems to happen whether I'm cutting with the side of the mill or the end.

    I've been taking cuts of about .025 or so.

    Is this just to be expected or is there something I haven't tried that I'm just missing?

    TIA for any advise or words of encouragement.

  • #2
    If removing the burr is not satisfactory, try clamping a sacrificial piece along the area to be machined. This will leave a much more sharp edge on the work piece and transfer the burr to the added piece.
    Jim

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    • #3
      Thanks Jim,

      Filing it off is no problem, just curious if I was doing something wrong. Thanks for the tip about backing it up with another piece.
      I've been working on my first "real" machining project (A little wobbler engine)... up till now it's mostly been making little bushings, washers and lots of chips.

      I'm quickly learning just how much I don't know

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      • #4
        Common problem with Brass,
        Using Jim's method is the usual approach, Climb milling can help if your mill can handle it.
        I would go with a finish pass of about .005.
        Rich

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        • #5
          When you say Burr,how much of a Burr? .002" fuzz or 1/8" razor blades? If it's fuzz,it's just part of the job,some fine files and some small sanding blocks and your good.
          I just need one more tool,just one!

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          • #6
            What's the recommended cutting lube for brass? Might make some difference- also brass is probably sensitive to the sharpness of the tooling, and there's probably an optimum set of relief angles.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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            • #7
              If you have used the cutter on steel forget about using it on brass it will not cut well and throw up burrs


              I reserve my new cutters for brass when they have lost their keen edge then they get demoted to steel , Never the other way round

              Stuart

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              • #8
                Like others, I like climb milling for a good finish, especially on brass and aluminum.Bob.

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                • #9
                  Thanks everyone... taking a lighter cut reduced the burr a bit. I can knock what's left down with a file easily enough.

                  I'm about done with the plate.

                  Tonight's project is making a bearing/bushing for the flywheel and axle to turn in. I came across a piece of Oilite bronze in a box of brass stock I'd picked up at an estate sale. Seems like miserable stuff to turn.. chips are almost dust and getting a decent finish is a challenge, but it should make a pretty good bearing.

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                  • #10
                    No lube for Brass, and the cutting tools should genreally have zero, or even negative rake - totally different than steel.
                    "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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                    • #11
                      Originally posted by mickeyf View Post
                      No lube for Brass, and the cutting tools should genreally have zero, or even negative rake - totally different than steel.
                      The brass I've been turning so far has come out fairly nice. I did the flywheel for my little wobbler last weekend. Got just a little bit of chatter near the outside rim. I'm thinking it was mostly down to a lack of rigidity in my setup. I turned the center of the flywheel about .200 thinner to create a rim around the edge. I wasn't able to get it in my chuck in a way that felt secure to me, so I put it on a 3/8" arbor and turned it that way.

                      The bronze has been a bit more challenging... it's pretty crumbly and brittle. I had one small piece just snap when I tried to part it off. So far about 1/3 of the parts I've made have ended up as scrap and had to be remade, but I'm having a blast and learning a lot.

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