Drill speeds and feed rates

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  • Carlos
    Veteran Member
    • Jan 2004
    • 1893
    • Phoenix, AZ, USA.

    Drill speeds and feed rates

    It's very hard to find previous discussions on this using the search, but it seems like something that would have come up. I'm looking at a variety of speed charts all over the web, and they disagree with each other. Sometimes by 2x or more. I made a spreadsheet using Irwin's SFM formula and SFM charts, which comes up with wildly different numbers compared to several pre-calculated charts I could find. Do you have a chart you really like? Link?

    Any reason to disbelieve the Irwin formula and SFM recommendations here? http://www.irwin.com/uploads/documen...ents_Guide.pdf
  • LCHIEN
    Internet Fact Checker
    • Dec 2002
    • 20920
    • Katy, TX, USA.
    • BT3000 vintage 1999

    #2
    I just go with the widely circulated Wood magazine chart. Works well enough for me.
    May not be perfectly optimal but I think there's a lot of leeway.

    This chart includes recommended operating speeds (in RPMs) for many different types of drill bits and accessories.


    WOOD DrillPressSpeedChart.pdf
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

    Comment

    • capncarl
      Veteran Member
      • Jan 2007
      • 3564
      • Leesburg Georgia USA
      • SawStop CTS

      #3
      It's so hard to change the speed on my drill press/milling machine that I usually use whatever it was left on the last use, and adjust my pressure accordingly. When I have to change it I use the speed recommended in my machinist manual.

      Comment

      • poolhound
        Veteran Member
        • Mar 2006
        • 3195
        • Phoenix, AZ
        • BT3100

        #4
        Good discussion. I tend to just go faster for smaller twist a bp bits and slower for forstners. I am sure I am often
        going faster than I should. It doesn't help that the digital readout on my DP has been broken for quite a while.
        Jon

        Phoenix AZ - It's a dry heat
        ________________________________

        We all make mistakes and I should know I've made enough of them
        techzibits.com

        Comment

        • leehljp
          Just me
          • Dec 2002
          • 8429
          • Tunica, MS
          • BT3000/3100

          #5
          Below is a photo originally posted by Loring quite some time ago. That speaks volumes on the correct speed, or at least being fast enough. Most of the time we try to keep from going too fast, but going fast enough is just as important.

          Click image for larger version

Name:	Drill bit speed.jpg
Views:	52
Size:	104.6 KB
ID:	829541
          Hank Lee

          Experience is what you get when you don't get what you wanted!

          Comment

          • Carlos
            Veteran Member
            • Jan 2004
            • 1893
            • Phoenix, AZ, USA.

            #6
            It is clear from my research that almost all of us amateurs run the RPM too slow, and the feed pressure slightly fast. The ratio of feed rate to RPM is an interesting one, which I tried to reflect in the spreadsheet I made. This uses approximately middle ground numbers for the SFM and IPM ratios. Most of the speeds end up being slightly higher than the pre-made charts. And for the small sizes, my custom chart shows 3k RPM, because that's the max for my press. Most of those should actually be MUCH faster.




            Comment

            • LCHIEN
              Internet Fact Checker
              • Dec 2002
              • 20920
              • Katy, TX, USA.
              • BT3000 vintage 1999

              #7
              Originally posted by leehljp
              Below is a photo originally posted by Loring quite some time ago. That speaks volumes on the correct speed, or at least being fast enough. Most of the time we try to keep from going too fast, but going fast enough is just as important.
              Click image for larger version  Name:	Drill bit speed.jpg Views:	1 Size:	104.6 KB ID:	829541
              That's from when I only had a 5-speed DP, an improvement from the old 3-speed I originally got.

              Now I have 12 speeds. But I do change frequently. It's not that hard; it has three pulleys, two belts. Chart is in the cover. Takes less than a minute if I don't have crap piled on top of the DP.
              Last edited by LCHIEN; 03-12-2017, 11:43 PM.
              Loring in Katy, TX USA
              If your only tool is a hammer, you tend to treat all problems as if they were nails.
              BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

              Comment

              • tfischer
                Veteran Member
                • Jul 2003
                • 2343
                • Plymouth (Minneapolis), MN, USA.
                • BT3100

                #8
                I have a 16-speed DP but tend to use only 2 speeds... the second slowest (for forstner bits) and the second fastest (for twist bits). In the rare case that I drill metal I might put something in-between.

                (why second slowest/fastest? Habit... and I just happened to use those because it's an easy belt configuration to set up without looking at the chart)

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