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  • unusual stub drills

    I just bought 25 solid carbide stub drills, new, for £13 and the seller was really nice by adding another 5 because I have bought from her before. They are uncoated and have a 170 degree tip. This is almost slot drill angle, and I wonder what they are intended for. The shanks are all 1/8" and the sizes range from 3mm to 4.7mm. I think there are more available, and am tempted to grab some more. Any thoughts?
    You may only view thumbnails in this gallery. This gallery has 3 photos.

  • #2
    so how do they drill? i wound be tempted to say masonry.

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    • #3
      Most likely for doing PCB drilling and similar hardness and styles of materials like phenolic or micarta. I've got a few of those myself that were in a bulk bin and where too dull for drilling the originally intended material or which were used for a while and then changed out by reason of run time. But still plenty sharp enough for home use. And they have the very flat nose angle to them
      Chilliwack BC, Canada

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      • #4
        Those seem very small for masonry bits, they look more like circuit board drills to me. Usually carbide twist drills are more for abrasive materials like fiberglass, micarta, carbon fiber, plastics, etc. The straight flute and spade drill ones usually hold up better for hardened steel applications.
        Kansas City area

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        • #5
          Since there are lots, and they were cheap, I would not be too worried about sacrificing them on something like drilling holes in hardened chuck jaws and the like. I have a box full of goodies to take to the museum when it re opens in the middle of May, my favourite is a 16mm solid carbide boring bar,(Teknik made in Turkey) picked up on ebay for £33 including postage.

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          • #6
            Circuit board drills.

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            • #7
              Obvious pcb/circuit board drills. They have quite unforgiving geometry but I have drilled holes to hardened file with those.
              Location: Helsinki, Finland, Europe

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              • #8
                Probably handy for fiberglass work.
                I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                • #9
                  The very large tip angle is so the whole point is drilling before the point breaks out the other side of thin material. This is important if you want smooth round holes. In circuit boards!

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                  • #10
                    They are Curcuit Board drills. They are carbide and they are short. Perfect for drilling without a center drill. They can be as accurate as a jig bore reamer in a true spindle. For Aluminum, they are first drill I reach for. Generally used for small delicate work. I had the pleasure of using .010 diameter PCB on Macor. Fun!

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                    • #11
                      Get the PCB drill idea. Problem is they are not drills.

                      I have many varieties of 1/8" shank tools. Thats not a drill. Too flat on the face? JR
                      My old yahoo group. Bridgeport Mill Group

                      https://groups.yahoo.com/neo/groups/...port_mill/info

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                      • #12
                        Originally posted by JRouche View Post
                        Get the PCB drill idea. Problem is they are not drills.

                        I have many varieties of 1/8" shank tools. Thats not a drill. Too flat on the face? JR
                        JR.. they are drills. Used them to drill holes for last 30 years.
                        Not some hack machine shop, Northrop Grumman Aero Space. They were designed for circuit board drilling, but works for a lot more. Sometimes I would hand grind the the ends to 118°. My first job was re- grinding the 4 facit tip on them. The web is thin, so they drill very well. Drilled alot of A-40 aluminum with these. Has glass in it so very abrasive. Copper also drills well with these.

                        Because they are stubby, I have been known to mill slots with them in a pinch.
                        Last edited by Fasturn; 04-02-2021, 02:25 AM.

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                        • #13
                          Since they were so cheap, I bought another batch. Now I have 60 of them for £22.58 including postage, all new. When I get the chance, I will try them out on various materials, everything except circuit boards and masonary.
                          Last edited by old mart; 04-02-2021, 10:14 AM.

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                          • #14
                            Originally posted by Fasturn View Post

                            JR.. they are drills. Used them to drill holes for last 30 years.
                            Not some hack machine shop, Northrop Grumman Aero Space. They were designed for circuit board drilling, but works for a lot more. Sometimes I would hand grind the the ends to 118°. My first job was re- grinding the 4 facit tip on them. The web is thin, so they drill very well. Drilled alot of A-40 aluminum with these. Has glass in it so very abrasive. Copper also drills well with these.

                            Because they are stubby, I have been known to mill slots with them in a pinch.
                            First of all, shh! Loose lips sink ships.

                            "Northrop Grumman Aero Space" Ohh, fancy I worked for some Lockheed folks that drilled composites also a metal and fiber structure. Never saw a blunt drill for that material. Everything was water jet, even the very small holes.

                            Dont talk about the materials you have worked on unless your old boss said its ok. Just because its in the media doesn't give you clearance, Clearance to talk about it. Is what they told me lol..

                            Thanks for the info (Schooling) . I bet you worked on some very nice stuff. Post some photos??? JR

                            My old yahoo group. Bridgeport Mill Group

                            https://groups.yahoo.com/neo/groups/...port_mill/info

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                            • #15
                              Guess I hit a nerve lol. Just wanted Old Mart to know he scored on some nice drills. Everyone works different so what works at one shop can change at another. As for nice stuff, look up James Webb telescope. Last thing I work on before retirement. Never worked on a ship ?

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