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Feedrate specs for milling? Any help?

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  • Feedrate specs for milling? Any help?

    Anyone know of a good book on feedrates for my bridgeport 2hp series one milling machine? My machinery handbook is off about 500 percent. I have snapped enough taps, cheaper to buy another book.. (or am I just reading it wrong?)
    A formula"? mill-teeth * rpm * metal type? * phase of the moon? ANy help?
    Some mills sure don't cut like other ones, any good brands to buy?

  • #2
    Here's a good one:

    It also explains what can affect the rate. Like how the work is clamped, etc.


    • #3


      • #4
        Have a page for tables and math goodies that should help. I had an exact link to it in a previous post.

        Some of the carbide companies have slide rules for cutting data - these are free give aways. Contact them and ask for one.


        • #5
          Using High speed steel most common tool steels are 50 SFM(surface feet per minute)
          CRS is 90 SFM and aluminum is about 200 SFM
          double the above for carbide.
          now for the disclaimer. this is a guide and so is your machinery hand book. they are never right and never will be. so if you are looking for an exact guide good luck there is no such animal.
          there are to many things involved to give even a close feed rate or rpm. How ridgide is your fixture how long is the end mill. whats the condition of the machine?

          What I'm trying to say is that it's more a matter of feel then anything. look at the color of the chips. How fast does the oil start to smoke when you apply it to the tool?
          how hard is the motor working?

          My rule is take as much as you can as fast as you can.
          If I used the rules I was shown in trade school I'd still be working on my first part.
          and those where the specs right out of the hand book. It a good place to start if you're not sure but feel free to make changes as your job suits
          Rule #1 be 10% smarter then what you\'re working on.
          Rule #2 see Rule #1


          • #6
            Color of the chips? ie: ya mean not blue? I am running my mill about 1/20th of the machinery handbook specs. 2 ipm on a 1/16th mill @ .10 cut in aluminum @ max spindle speed, any faster slide speed and the mill is broke. I am needing to clock my mill table rate also to confirm speed.
            Also the plunge rate on brass, it is critical I have found out. It seems to grab the cutter and snap a corner.
            At $20 per 1/4" double ended mill, I can't afford to experiment too much.


            • #7
              For one on a 1/16" end mill .100" is way to deep of depth of cut you need to take about .025" at the most this will allow you to speed the feed up to a point but still if you push it to fast the endmill will deflect or snap.
              And running small endmills on low rpm machines is a pain. you should be running about 20,000 rpm or higher with a high speed head.
              Right now were doing some engravings at work and if your feed is not ultra smooth and the speed ultra high you get lots of busted cutters and were using as small as .005" endmils not engraving cutters.
              Rule #1 be 10% smarter then what you\'re working on.
              Rule #2 see Rule #1


              • #8
                You need to shop around more. $20. hoe a 1/4" double ended end mill sounds kinda high!

                to figure you depth of cut, don't go any deeper then your Dia per pass. Thier are always exceptions, but it is a good general rule.