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I've never been happy using standard tip jobber drill bits for drilling holes when making ferrules or when drilling reel seat hardware, and I don't have the ability to make my own flat bottom drill bits. Ran across ICS Cutting Tools that offers helical flat bottom point drill bits. Just received an order yesterday and wow! do they cut nice flat bottom holes and drill extremely accurate holes "from scratch". With my Sherline lathe, I have always had to drill stepwise upwards (to 27/64") when drilling for butt caps, then bore the rest of the way. The flat bottom 27/54" drill bit drilled the hole in one step. Like cutting through butter.  (Jaz)

Rule

A question for you machining experts:  My lathe is starting to drill oversize. A 13/64 hole ends up .005 oversize.  The same drill does fine in the drill press.  Both holes were center drilled first.  (Dennis Bertram)

    Check the run out in your chuck and also check to make sure that the tail stock is exactly centered with the chuck. The tail stock being off, will do that.  (Dave LeClair)

    Check the alignment of the tailstock to the headstock.  A slight misalignment of the tailstock will result in oversize holes.  (Howard Bryan)

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I drill 792 and 752 rod on the lathe with .093 and .082 drills.  I am drilling in about 3/8" deep.  Its not a real big deal except it is very repetitive work as I'm tired of continually having to retract and clear chips half way in.  I have tried various off-the-shelf drill bits and always use a couple drops of "Cool Tool II" for lubrication. 

Have tried different speeds and doesn't help.  It does help to have a very new drill bit -- works better for a while, but soon becomes "colored" with fine coating of nickel silver or whatever.  Have also tried half round drills to no avail (does work in larger drill sizes).  (Ted Godfrey)

    Lower your speed, use a lot of lubricating oil and keep the drill from getting really hot.

    Patience.  (Danny Heus)

Rule

In searching for a solution to my reamer problem, I came across a description for solid carbide drills. It stated "Create more accurate holes with a better hole finish at higher machine speeds and feed rates. These bits maximize productivity while reducing machining time and post-operational costs. Provides greater stability and drill point cooling and improves surface finishes so reaming is rarely needed.

The "reaming is rarely needed" bit caught my attention, so I decided to get one and try it out. The cost of one solid carbide drill is about the same as a quality high speed steel drill and a high speed steel reamer put together, but if it saves me the step of having to ream the ferrule, it might be worth it.

Drilling without reaming with the solid carbide drill works. I usually polish the inside of my ferrules with a Q-Tip and polishing compound, so I did so after just drilling with the carbide bit, and the hole is as straight and accurate as when I used a reamer. The ferrule goes together nicely and comes apart with a nice pop.

The carbide drill drills nickel silver and Duronze both quickly and with less heat build up than the HSS drill I have been using. They are a little pricey, but worth it.  (Darryl Hayashida)

    The only reason to use a reamer is to insure concentricity of the hole you are drilling or finishing. I drill to about 1/64 under my final dimension and then ream to final size.  Drills do not drill perfectly round holes so reamers are used to finish them up to size.  (Mark Babiy)

    Don't know if you saw my article in the last Power Fibers, but I found a neat trick for getting flat bottoms on the inside of the ferrules at the water plug.  Get yourself one of those brad point style drills, grind off the point, and leave a very slight indent where the brad point was.  Regrind the cutting edges of the drill bit so that they almost meet in the middle.  More or less makes a non-center cutting end mill out of a drill bit.  I've been experimenting with these modified drill bits on a few ferrules now, and they work really nice. 

    All it leaves is a very small dimple in the bottom of the ferrule, and now I can get the entire barrel to seat without bottoming out, with a much thinner water plug.  And way cheaper than buying a bunch of small diameter end mills to do the same thing.

    So, with the carbide drill, no problems going from NS to Duronze?  (Mark Wendt)

      Where did I see someone using an end mill to drill a flat bottomed hole?  more specifically they were using an end mill for drilling out the cap for a cap and ring reel seat.  (Tim Wilhelm)

        I'm not sure about that.  The suggestion to use a non center cutting end mill to flatten the bottom of the hole was one of the many that I got from a metal working list, before I got the suggestion to try the brad point drill bit regrind trick.  Even a boring tool was suggested, until I happened to mention the size of the holes we work with in ferrule making...  (Mark Wendt)

      So far the solid carbide drills have drilled everything I've tried to drill with no problems, aluminum, brass, NS, and Duronze. I just wish I had tried them before I bought all the reamers I have.

      Flat bottomed holes - I can see where there are a few advantages  to that, but to gain the advantage of not having to use a reamer I will stick to the carbide drills.  (Darryl Hayashida)

        I think the biggest advantage to the flat bottom holes is you get more cane into the ferrule to glue, event though it may be a small amount.  More gluing surface is better.  (Mark Wendt)

          If you dome the end of your blank that little bit of rod will still go into the ferrule.  (Darryl Hayashida)

            Yeah, but then you'd have to do the same to the end of the male ferrule.  (Mark Wendt)

              I would think that if the small dome / cone at the water plug / inside the ferrule is centered, then coning the end of the blank you force the point into the cone eliminating "wobble" of a slightly larger ferrule over the blank making a straighter union. Also would give you a slightly larger surface area right at the end.   (Pete Van Schaack)

                Probably true, but on the other hand, at least for the male end inserting  into the female barrel, you're not going to get the full depth, unless you make the female barrel longer.  Then, you've just changed the parameters further away from the percentage dimensions used to create the Super Z style ferrule.  I'm not sure if that's a really big deal or not, or if it would really affect the moments over the ferrule by changing the length of the ferrule, but it's something to keep in mind when making the ferrule.  You've added more metal to the equation, making the moisture caps on both the male and the female thicker.  (Mark Wendt)

                  If you look at the design for the Super Z ferrule there is a built in air gap of 0.06 inches between the end of the male ferrule and the bottom of the hole in the female side - which nicely accommodates the point of the drill.  (Darryl Hayashida)

                    True, but...  On an 11/64 drill bit, with a 118 degree grind, the depth of the cone will be .086".  With a 12/64 ferrule, the depth goes up to .094".  Even if you go to a drill bit with a 135 degree grind, the depth of the cone on a 12/64 ferrule will be .094".  (Mark Wendt)

        Ran across a cutting speed chart in an old South Bend Lathe book that may be of help/interest. The chart is based on peripheral speed, Feet Per Minute, of the work. Cutting speed for Tungsten-Carbide Tools in Red.  As can be seen in the chart, HSS Tools work at a lower speed, lathe RPM, than Carbide. Also, The smaller the diameter the work the more RPMs required for both. There wasn't any numbers in the chart for Aluminum & Bronze for carbide tools. Looking at the chart and as a guess on my part for carbide tools, Aluminum would require a slightly higher rpm than Brass, Bronze would require about the same rpm as  Machine Steel.

        Hope this helps. (Don Schneider)

        For High Speed Steel cutter tools.
        All numbers are in peripheral FPM, Feet Per Minute Lathe Speed

              RPM= FPM x 12 3.1416 x dia of work

        Material
        Heavy Cut
        Finish Cut
        Screw Threads
         
        Cast Iron
        60 +200 to 500%
        80 +200 to 500%
        25 +200 to 500%
        Machine Steel
        90 +100 to 200%
        100 +100 to 200%
        35 +100 to 200%
        Tool Steel (Annealed)
        50 +75 to 100%
        75 +75 to 100%
        20 +75 to 100%
        Brass
        150 +400 to 800%
        200 +400 to 800%
        50 +400 to 800%
        Aluminum
        200
        300
        50
        Bronze
        90
        100
        25

          I have no way of measuring rpm on my lathe, but I did notice that I get a smoother inside wall if I up the speed with the carbide drills.  (Darryl Hayashida)

    In my search for carbide drills I saw descriptions of coated carbide drills. The coatings were titanium nitride (TiN) and titanium aluminum nitride (TiAlN). I had heard that the coatings were a big improvement over the uncoated drills, so I bought one of each to try out. The coated drills are only a few dollars more than the uncoated ones.

    The coated drills seem to be just a touch duller than the uncoated, I think due to the coating over the cutting edges, but the coated drills can take a faster lathe speed and a heavier cut. Due to the faster lathe speed, the inside finish is smoother. Since I polish the inside of the female slide area this isn't that much of an advantage. There may be an advantage in the longevity of the drill bit, since they claim the drills will last 50 to 100 percent longer. Only time and use will tell if that is true.  (Darryl Hayashida)

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