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OT: Wood - No Tear Countersink

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  • OT: Wood - No Tear Countersink

    I often make wood projects using the old reliable "glue and screw" assembly technique. And, being thrifty, I often use inexpensive woods, like pine, which are not the best for working with. Drilling holes in soft wood with standard, twist drills will almost always produce produce tear-out on the edges of the holes. A countersink cutter will leave a somewhat better edge, but tear-out is still a problem and this will ruin the appearance of a project.

    Some time ago I purchases an excellent set of brad point drills from Lee Valley and supplemented it with some individual sizes from Grizzly. These are great for drilling holes in wood, even soft wood, without any tear-out on the edges. They are so well sharpened that there really is no problem.

    But what about a countersink? Here is what I worked out for making countersinks in woods with perfect edges - no tear-out.

    1. Drill a small pilot hole, usually 1/16". There is no brad point drill that small in the set so I either use a size or two larger or just use a standard, twist drill bit. The tear-out will be small enough to ignore.

    2. Then I choose a brad point bit that is the size of my screw head or slightly larger and just kiss the surface of the wood with it to score a circle. This prevents the tear-out.

    3. I use a standard bit (resharpened to 90 degrees if the wood is hard) to hollow out the countersink. I find that the depth stop on one of my drill presses is good for doing this to a uniform depth. In the photo I was using a dry wall style screw which has a rather flat underside so I just used a standard bit with a 118 degree tip.

    4. The final step is to drill the body sized hole, again with a brad point bit. When possible, this can be started from the bottom side of the piece to prevent tear-out even there.

    The result is a perfect, countersunk hole in the wood.

    Click image for larger versionName:	P10 R800x^00.JPGViews:	0Size:	102.5 KBID:	1850683

    This photo was taken immediately after drilling the countersinks. No sanding or other cleanup work was done.
    Last edited by Paul Alciatore; 01-23-2020, 03:35 AM.
    Paul A.
    SE Texas

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

  • #2
    You drill a hole four times for each screw?

    Have you tried Forstner bits?

    I use something like this https://imged.com/aircraft-tools-mic...-13556235.html (similar, but not exactly like this - mine is old enough I can't even find anything like it)

    I also use mostly hardwood. I generally do not countersink pine. I find that the screw just "sinks" on its own, when I tighten it. It is my experience that folks aren't looking for perfection, when they are looking at pine as a construction material. On the other hand, they expect nice looking fasteners (when exposed) with walnut or other hardwoods - so I generally use brass screws.

    Comment


    • #3
      Use finishing washers if you're offended by the ragged hole edges.

      Maybe it's just the picture or lighting, but frankly the disparity in sizes of the countersink hole and the screw head look worse to me than a less-than-pristine countersink hole
      Last edited by lynnl; 01-23-2020, 09:33 AM.
      Lynn (Huntsville, AL)

      Comment


      • #4
        Did you feel the rain Paul? Personally, if it takes drilling four times to get the look you're after, so be it. Sheesh!
        “I know lots of people who are educated far beyond their intelligence”

        Lewis Grizzard

        Comment


        • #5
          On occasion for chamfering larger holes I've used my metal shop countersinks that have the hole through them that forms the cutting edge. When the depth is such that it is the upper/outer portion that slopes inward to the center does the actual cutting the edge is notably smoother than straight flute countersinks.

          It makes me wonder if shop made countersinks for the wood shop that have negative spiral flutes might not work well for wood countersinks. Such a countersink would be pretty easy to make too. Just cut a cone on the lathe then file away to form the teeth with a square file. Or for larger sizes mill them away. I would not even use anything other than "eyeball indexing" for this so the angles between the teeth are random. That would aid with avoiding harmonic chatter.

          The neat thing is that for use in wood starting with a mild steel prototype proof of concept would work just fine for a few cuts. If it works then make a set from drill rod and harden and temper it. Or from a machinable tool steel which is hard enough to take and hold a good edge for some time.
          Chilliwack BC, Canada

          Comment


          • #6
            Forstner bits????? I have two sets of Forstner bits and both start at 1/4" and go UP from there. The hole illustrated in my post was for a screw that needed a body drill of 3/16". Please let me know about your source for Forstner bits smaller than 1/4". As for using four operations for each hole, it is only when I want a nice, CLEAN hole that will show in a project that will be on display. We often do similar things for holes in metal when circumstances dictate. And it is not excessive when you are drilling a bunch of holes. I did 11 of the holes in my illustration so I could do a bunch of them and then change tools.

            I guess I could have used a Forstner bit for scoring the surface of the wood for the countersink, but I already had the set of brad point drills at the drill presses so why waste time fetching another set.

            As for the brass screws, this is a semi-nice project. It will go in my office and I will be the principal one who sees it. I want it nice, but I am not going to get overly picky about it. And these screws will be mostly hidden. I also have brass screws for use when I want them. The same idea works for them. Oh, by the way, good luck forcing a #8 or #10 BRASS screw into making it's own countersink in walnut or other hard woods. What you are going to wind up with at least half the time is a buggered up screw head on a partially seated screw that will be most difficult to back out so you can replace it. Just making the proper countersink with the proper cutting tools is a lot easier and faster. Been there. Done that. Sorry, no tee shirts available for it.



            Originally posted by 6270 Productions View Post
            You drill a hole four times for each screw?

            Have you tried Forstner bits?

            I use something like this https://imged.com/aircraft-tools-mic...-13556235.html (similar, but not exactly like this - mine is old enough I can't even find anything like it)

            I also use mostly hardwood. I generally do not countersink pine. I find that the screw just "sinks" on its own, when I tighten it. It is my experience that folks aren't looking for perfection, when they are looking at pine as a construction material. On the other hand, they expect nice looking fasteners (when exposed) with walnut or other hardwoods - so I generally use brass screws.
            Last edited by Paul Alciatore; 01-23-2020, 06:32 PM.
            Paul A.
            SE Texas

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

            Comment


            • #7
              Those are called O Flute countersinks and I have several sets. I love them. They are great for metal and I have used them for wood. But I feel that this technique is better. It almost always leaves a completely clean hole while I have had some problems with the O flute countersinks in wood, especially soft woods. Oak, walnut, and other hard woods do produce less problems.



              Originally posted by BCRider View Post
              On occasion for chamfering larger holes I've used my metal shop countersinks that have the hole through them that forms the cutting edge. When the depth is such that it is the upper/outer portion that slopes inward to the center does the actual cutting the edge is notably smoother than straight flute countersinks.

              It makes me wonder if shop made countersinks for the wood shop that have negative spiral flutes might not work well for wood countersinks. Such a countersink would be pretty easy to make too. Just cut a cone on the lathe then file away to form the teeth with a square file. Or for larger sizes mill them away. I would not even use anything other than "eyeball indexing" for this so the angles between the teeth are random. That would aid with avoiding harmonic chatter.

              The neat thing is that for use in wood starting with a mild steel prototype proof of concept would work just fine for a few cuts. If it works then make a set from drill rod and harden and temper it. Or from a machinable tool steel which is hard enough to take and hold a good edge for some time.
              Paul A.
              SE Texas

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

              Comment


              • #8
                Originally posted by Paul Alciatore View Post
                Forstner bits????? I have two sets of Forstner bits and both start at 1/4" and go UP from there. The hole illustrated in my post was for a screw that needed a body drill of 3/16". Please let me know about your source for Forstner bits smaller than 1/4". As for using four operations for each hole, it is only when I want a nice, CLEAN hole that will show in a project that will be on display. We often do similar things for holes in metal when circumstances dictate. And it is not excessive when you are drilling a bunch of holes. I did 11 of the holes in my illustration so I could do a bunch of them and then change tools.

                I guess I could have used a Forstner bit for scoring the surface of the wood for the countersink, but I already had the set of brad point drills at the drill presses so why waste time fetching another set.

                As for the brass screws, this is a semi-nice project. It will go in my office and I will be the principal one who sees it. I want it nice, but I am not going to get overly picky about it. And these screws will be mostly hidden. I also have brass screws for use when I want them. The same idea works for them. Oh, by the way, good luck forcing a #8 or #10 BRASS screw into making it's own countersink in walnut or other hard woods. What you are going to wind up with at least half the time is a buggered up screw head on a partially seated screw that will be most difficult to back out so you can replace it. Just making the proper countersink with the proper cutting tools is a lot easier and faster. Been there. Done that. Sorry, no tee shirts available for it.




                I guess that is what I get when I enter a woodworking post on a metalworking forum.

                I will go back to the woodworking forums for woodworking related discussions.

                I will stay here and learn about metalworking and metal workers.

                Comment


                • #9
                  Not a wood guy, so I'm learnin'. I was wondering about sharpen up the end of a pipe, use it like a gasket punch to pre-cut the edges of the countersink.
                  25 miles north of Buffalo NY, USA

                  Comment


                  • #10
                    How about a 3-in-one tool? I'm picturing a rig a little like those bits for pre-drilling hinges that have a spring loaded 118 deg collar around the drill. But in this case the drill is a piloted countersink and the collar is a spring loaded thin wall toothed tube a little like a forstner with a larger stop collar around it. The drill hits first, then the tube hits, cuts and bottoms on it's outer collar, then the countersink does it's thing. Only issue is some light sanding to get rid of scuff marks from the spinning outer stop collar.
                    Location: Jersey City NJ USA

                    Comment


                    • #11
                      I am sure that would work. But it is probably easier to get all the right sizes of brad point drill bits than a similar collection of pipe or tube sizes. Anyway I already have the drill bits. I probably have at least a dozen sets of drills, but the brad point drill set is one that I only broke down and purchased about a year ago and I have been finding uses for them ever since. I really love them for wood work.

                      6270, this was not any kind of trap and I did prefix the title with "OT" and "wood". I was just trying to share an idea that I found useful. I am sure it is not the only way to do it. Perhaps there are better ones. And I do not claim to have invented something new. I would bet a lot of wood workers probably have used it or something similar for years. I was just trying to share.



                      Originally posted by nickel-city-fab View Post
                      Not a wood guy, so I'm learnin'. I was wondering about sharpen up the end of a pipe, use it like a gasket punch to pre-cut the edges of the countersink.
                      Paul A.
                      SE Texas

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

                      Comment


                      • #12
                        Originally posted by Paul Alciatore View Post
                        I am sure that would work. But it is probably easier to get all the right sizes of brad point drill bits than a similar collection of pipe or tube sizes. Anyway I already have the drill bits. I probably have at least a dozen sets of drills, but the brad point drill set is one that I only broke down and purchased about a year ago and I have been finding uses for them ever since. I really love them for wood work.
                        I imagine its a lot easier to find the center with them compared to a regular bit on wood. I actually get more "wander" on wood than I do on steel, it frustrates me more. Fortunately I don't have to do much fancy work.

                        25 miles north of Buffalo NY, USA

                        Comment


                        • #13
                          Originally posted by Paul Alciatore View Post
                          Those are called O Flute countersinks and I have several sets. I love them. They are great for metal and I have used them for wood. But I feel that this technique is better. It almost always leaves a completely clean hole while I have had some problems with the O flute countersinks in wood, especially soft woods. Oak, walnut, and other hard woods do produce less problems.
                          In the original post the pictures certainly show a very nice clean screw install. I'd say that while it's a bit more work that the results are worth it for particular projects. And for some cases I'd use your suggestion without a further thought.

                          I'm still keen on the idea of reverse spiral fluted countersinks for more general use.

                          Chilliwack BC, Canada

                          Comment


                          • #14
                            Originally posted by Paul Alciatore View Post

                            snip . . .
                            I was just trying to share.
                            . . . snip
                            I have been working wood for a very long time. I also was just trying to share.







                            Comment


                            • #15
                              Wow! Nice work there 6270!
                              Too bad you got those shelves a little crooked. Misplace your ruler did you...? Also the sides are awfully crooked. Keep working on it though ...you'll soon get it right.
                              Lynn (Huntsville, AL)

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