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  • Small Hole Drilling

    I have to drill .022 holes (#74 bit) in .250 in. dia. 303 stainless steel rod to a depth of .500 to .625.

    I have available a micro drill press of possible the Sherline Mill (CNC) to do the job.

    Even though I have drilled small dia. holes before I have never done any in stainless steel.

    Suggestions Please.
    Last edited by StephenK; 05-12-2006, 06:27 PM.

  • #2
    That is equivalent to drilling a 1/2" hole a foot deep. Not going to work in SS. That is a job for either an electron beam or a laser.
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    • #3
      Perhaps you could find someone to fast hole drill them (EDM).

      Peter

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      • #4
        .022

        You CAN drill it, because I've done it. You probably know about peck drilling? The slightest chip will break the drill and it's a PITA. Use the highest quality bit, high rpm's and keep it clean, Real clean. Hope you are not planning running production, though. It'll be all right.

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        • #5
          Why does it need to be that diameter, that deep ?
          can you get away with opening the hole up for say 1/2" then just finish the last bit at the smaller size ?

          .
          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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          • #6
            Originally posted by Evan
            That is equivalent to drilling a 1/2" hole a foot deep. Not going to work in SS. That is a job for either an electron beam or a laser.
            Cmon Evan dont spout off if you dont know what your talking about, I do it all the time in SS, copper, and aluminum, up to an inch deep.

            I use a cnc mill to do it, it can be done on a manual machie though with a sensitive drill chuck, but it is gonna suck. Since you have a sherline cnc mill use that.

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            • #7
              Small Hole Drilling

              The part that I'm making is 1.00 length x .250 Diameter with a luer taper whick is approx. 3deg. This is for the front .500 in. It has to be stainless and that is why I chose 303 for the machining.

              One end is threaded, 10-24 x .250 length. The .022 hole is for a hypodermic needle cannula. This is for an assembly fixture.

              I gave it a try by the peck method, hand operation on the sherline lathe and was able to drill in just shy of .500 on the first try.

              Back in the 70's when I worked for a J&J Company I remember them drilling small holes in stainless steel using a set up that was made in their shop, air operated and doing peck type drilling.

              Although I haven't done that type of drilling on the Sherline CNC Mill I'll spend some time to find out how to set up that program and give it a try.

              Thanks guys.

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              • #8
                I do it too but the first time it work hardens in the SS that is the end of drilling the hole. Hopefully it won't matter too much if a few drill bits break off. The first time I drilled holes like that was in the 1960s when I was about 14. I made a flying spot scanner.
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  You might consider 416 stainless. It is a free machining stainless, used for gun barrels. Machinability is .91, compared to .68 for 303.

                  It is slightly magnetic and not as corrosion resistant as other stainless grades.
                  Jim H.

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                  • #10
                    Originally posted by Evan
                    I do it too but the first time it work hardens in the SS that is the end of drilling the hole. Hopefully it won't matter too much if a few drill bits break off. The first time I drilled holes like that was in the 1960s when I was about 14. I made a flying spot scanner.
                    Wow stroke yourself much

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                    • #11
                      duplicate, sorry
                      Last edited by Mcgyver; 05-12-2006, 11:12 PM.
                      .

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                      • #12
                        JC, isn't the 303 free cutting as well... 304 she's whore, 303, she's for me. I'd guess that partially or mostly makes the work hardening concern go away? it would seem next impossible with conventional machining if it wasn't free cutting as how would ever 'get under' the worked hardened area with such a small chip?
                        .

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                        • #13
                          303 & 416 both have sulfur added for free cutting. 416 is more free cutting than 303, and is heat treatable.

                          The .91 and .68 machinability figures are compared to C1212, which is free cutting low carbon steel as 1.
                          Jim H.

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                          • #14
                            All the austenitic stainless steels work harden, including 303. In fact, the addition of sulphur makes it less ductile as well. The free machining rating does not take into account work hardening.

                            For best results in drilling the bit must be sharp. Since it isn't practical to resharpen such small bits spares should be on hand. Unfortunately, the indication that it is becoming dull will be that the hole cannot be drilled. When that happens a new bit will not help either.
                            Free software for calculating bolt circles and similar: Click Here

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                            • #15
                              Shd

                              I don't know why some people complain about this forum. Just reading the results about my question on small hole drilling I'm getting quite an education on stainless steel.

                              Thanks guys.

                              No problems only opportunities.

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