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How to use a REALLLLY small #68 drill bit .0310"

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  • How to use a REALLLLY small #68 drill bit .0310"

    Hi Group,

    I've never seen such a small drill bit until this week when I ordered a tiny set. What I need to do is drill a hole through 260 brass that is .065" wall thickness. I have a 1/8" pilot or guide hole before the brass. As in the picture.
    This is for (not the one in the picture) a brake master cylinder I have relined and need to drill the balancing port back in for the reservoir. I have a milling machine, a sears 1/2" drill press and a (temporarily broken see my other post about it) Southbend 9A lathe, and various hand tools. I don't have one of those sensitive drill presses. 😁

    So what tooling or setup can I make to do this job.

    Click image for larger version  Name:	Master Cylinder sample.jpg Views:	0 Size:	4.92 MB ID:	1996310

    TX
    Mr fixit for the family
    Chris
    Last edited by Mr Fixit; 04-10-2022, 03:36 PM. Reason: Size of hole is .0310" picture is wrong.

  • #2
    There are a few youtube videos showing how to drill .3mm holes for 3d printer nozzles. The techniques should apply.

    Comment


    • #3
      I would make a small 1/8 by Machining Bronze bushing to keep it centered when drilling. You will need an extension to reach that deep. A small pencil looking drill chuck will work. They also make # drills mounted in brass hex for gas orifice drilling. How will you deburr the inside of the sleeve? Gently pecking with drill press should work.

      Comment


      • #4
        I have some small carbide drills with 1/8 shanks that work surprisingly well in a Dremel tool by hand. Sets range in price depending on the size and quantity of bits. I think my set with ten assorted was under 10 dollars.

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        • #5
          You dont need a sensitive drill press. A sensitive drill chuck would work also. See link.
          https://www.ebay.com/itm/Albrecht-Ke...-127632-2357-0
          I know that they are expensive there are others about half the price of the Albright keyless .
          You could do it with a hand drill if your steady?? But you still would need a chuck that will hold a tiny drill bit and it needs to spin FAST. Maybe make a collet for a dremel tool? There are many dremel tool collet sets available on Ebay from China for only a few dollars if you can wait.

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          • #6
            Do not use power, do it by hand with a Pin Vise
            https://www.mcmaster.com/pin-vises/
            You can make a side guide for the pin vise to keep it centered
            Concentric work is required with those small drills
            Rich
            Green Bay, WI

            Comment


            • #7
              You will need an extension. Can you get your broken lathe to drill a hole?

              Anyway.

              A 6-8 inch length of .250 brass rod, drill a center hole in one end using the drill bit size required. Soft solder the drill bit to the extension.
              For drilling brass take a fine triangular stone and dub off the cutting flute. DEAD SHARP, but square! This is to avoid catching on breakthrough that is sure to break the drill bit.

              Use your mill. Crank up "by the numbers". Don't use the drilling quill. (again. break out in brass can be a problem. Using the mill this way offers complete control.

              A brake cylinder hone will take care of any burr that would cut the piston seal.

              Comment


              • #8
                Do it on your mill at its highest speed. Make a rod extension for the drill to get the reach you need. You can use the Machining Bronze to drill into 1/4” rod and then loctite into the rod. A high quality pin vice can be used as mentioned. Breakthrough will be an issue so peck your way through.

                Comment


                • #9
                  I've had pretty good luck with 1/32 drills in the past. And that's only 1.5 thou bigger than your # 64 But it does require a fine touch and an accurate chuck so the drill is running very centered. And I also like to use pretty high RPM. I'm pretty lucky and my mid size bench top drill press has a good feel through the quill handle. Plus I've got a second MT2 arbor with a chuck on it that goes down almost to zero.

                  You'll be doing a peck style drilling with it. That's about a 1/4 to 1/3 second of drilling under pressure then clear the hole. You'll need to use a light touch so it doesn't dig in on the re-entry.

                  You do want to have some feel at the drill through the quill handle. Without that you would not know when the end contacts in the hole and could easily end up driving it in and causing it to bind and snap. As mentioned my own drill press has pretty good feel in that way. My mill does not. YMMV but you want it to be very easily felt. A good measure of this is how well your own shop options do when drilling 1/16 size holes. If you can't feel the action of the drill through the hand wheel and find that you snap those occasionally then it'll be easily 4 times worse risk with a 64 drill

                  Those Albrecht adapters for use in a drill press are a pretty princely price. But if your machines don't give you a good quality sensitive feel then you might look at some YT videos of how they work and consider making one to add to your tool kit. They aren't all that tough to make. A good way to start would be one of the soft ended machinable morse taper blanks LIKE THIS ONE.
                  Last edited by BCRider; 04-11-2022, 02:44 AM.
                  Chilliwack BC, Canada

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                  • #10
                    OK, what is with the odd links. I see links in blue to "Machining Bronze" in some threads and thought they were pointing to another thread... which is where the link takes me. But I posted # 64 a couple of times in my reply without the space and the final post had "Machining Bronze" instead of the drill size. And it looks like the rest of you got tagged the same way. It's a forum software oddity obviously. But how does a # and number after it cause a link to a past thread?
                    Chilliwack BC, Canada

                    Comment


                    • #11
                      Oh come on guys, 0.031" is only a few tenths smaller than a 1/32" bit. I have been using them since I was a teenager and no one gave me any instructions back then. I just used them in a pin vise and had zero problems. 0.031" is NOT in the break if you look at it category. Not by a long shot.

                      Now 0.0031" would be another case. But still doable.

                      Get a pin vise. The General brand is good and usually available in most hardware stores. I don't know current prices, but would probably be between $5 and $10. It may even take care of your extension problems as they are not very large in diameter.

                      If you want to go the power route, a Dremel tool and Dremel drill press would be the ticket.
                      Paul A.
                      SE Texas

                      And if you look REAL close at an analog signal,
                      You will find that it has discrete steps.

                      Comment


                      • #12
                        Oh, I thought it was a question, I thought wrong again..

                        ""How to use a REALLLLY small Machining Bronze drill bit .0310""

                        Because my answer would have been, and still is,

                        I do not know. I was jolikng by the way. JR

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                        • #13
                          Drexel?, fairly fast, as said stick it in an extension rod,
                          mark
                          no spellchecker DREMEL

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                          • #14
                            If you haven't torn down your lathe you could make a tiny spade drill from a bit of drill rod. This would be a very short drill with a 1/8" guide included. Something like the one I made here:
                            https://gadgetbuilder.com/GearlessCl...l#Escape_Wheel

                            If you look closely you can see my tiny spotting drill. It need not be hardened for drilling 1 hole in brass. You could make it smaller diameter as I did or make it the full 0.031 diameter.
                            No need for high speed on brass with these small holes, I drilled 60 0.029" holes in the wheel shown using the mill-drill.
                            Location: Newtown, CT USA

                            Comment


                            • #15
                              Originally posted by GadgetBuilder View Post
                              If you haven't torn down your lathe you could make a tiny spade drill from a bit of drill rod. This would be a very short drill with a 1/8" guide included. Something like the one I made here:
                              https://gadgetbuilder.com/GearlessCl...l#Escape_Wheel

                              If you look closely you can see my tiny spotting drill. It need not be hardened for drilling 1 hole in brass. You could make it smaller diameter as I did or make it the full 0.031 diameter.
                              No need for high speed on brass with these small holes, I drilled 60 0.029" holes in the wheel shown using the mill-drill.
                              I've done that a few times now just using hobby grade K & S music wire using files and/or sharpening stones. They obviously do pretty well in softer metals and plastics. But I was surprised that if used at a slightly slower speed and with a little cutting oil they can do OK in mild steel if the drilled hole is not very deep. I was able to manage about 1/16 inch. It was clearly getting dull at the end of that but it did the job for that one hole. Lots of pecking due to zero chip clearing of course. But very doable.... It's certainly time for good clear high magnification head gear though.... And even a microscope for final inspection would not be amiss on the smaller sizes. So heartily supported and highly recommended if this sort of performance would suit the job.

                              The use of a pin vise would not be all that bad either. It might seem like you're getting nowhere. But in the end it's surprising how far one can safely drill in something like 3 to 5 minutes in pretty good safety with a pin vise and small drill of this size. Just be careful of side flexing and side loading.
                              Last edited by BCRider; 04-11-2022, 04:39 PM.
                              Chilliwack BC, Canada

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