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Deep hole drilling on lathe - tips?

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  • #16
    Following on from my previous post, it is quite possible to make a good (but cheap, easy and effective) drilling jig/fixture to do this drilling on a pedestal drill instead or on a mill or a lathe.

    It would certainly be easier and quicker to do it using any of these several ways other than on a lathe.

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    • #17
      A lot of machine shops have a way to pull the tailstock with the carriage for drilling. The latch looks like a large heavy duty screen door latch.
      Bob Scott

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      • #18
        Both of those materials like a very sharp drill. The stainless will reqire a lot of drill shapening. I like a a slow spindle speed when drilling stainless and a little more agressive with the feed. Lots and lots of coolant is required.
        On most lathes you can put the tailstock in front of the carrage and power feed the drill. I don't reccoment it myself because you run the risk of loading the drill and breaking it.
        Always use a center drill when drilling in the lathe.
        For accuracy's sake sometimes you just have to suck it up and crank the handle back and forth.

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        • #19
          Originally posted by Rustybolt View Post
          Both of those materials like a very sharp drill. The stainless will reqire a lot of drill shapening. I like a a slow spindle speed when drilling stainless and a little more agressive with the feed. Lots and lots of coolant is required.
          On most lathes you can put the tailstock in front of the carrage and power feed the drill. I don't reccoment it myself because you run the risk of loading the drill and breaking it.
          Always use a center drill when drilling in the lathe.
          For accuracy's sake sometimes you just have to suck it up and crank the handle back and forth.
          Not if you use a quality, coated, high performance drill. Decide what is of value to you more; either you spend for a good drill, or you spend a lot of time resharpening a cheap one.

          And center drills suck. Use them only when you need a center for turning on centers.

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          • #20
            Originally posted by PixMan View Post
            Not if you use a quality, coated, high performance drill. Decide what is of value to you more; either you spend for a good drill, or you spend a lot of time resharpening a cheap one.

            And center drills suck. Use them only when you need a center for turning on centers.
            My experience differs from yours.

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            • #21
              If it's center drills you refer to:

              Of course I've used center drills for over 35 years in machining for a living. They have their place.

              That said, once you get accustomed to using spot drills and never again have to deal with the broken tip of a center drill mashed into a workpiece and see the more accurate location of holes you find why industry chooses spot drills over center drills. And even within spot drills, some work better than others. Here's a comparison of Guhring and Titex, both in ط1/4" size. The TiN-coated Guhring has a thicker web, I prefer the thinner, easier cutting action of the Titex. Those are available in TiN coating as well, but I got those off eBay for just a few bucks.



              As for deep hole drilling in austenitic (300 series) stainless steels, I've done work recently making axles for motorcycles out of 316SS. I had to drill ط12mm (.4724") though a 221mm (8.7") long and ط20mm (.7874") though 262mm (10.315") long stock, in my lathe. With the spot drills giving me a good start, the holes were straight and true, less than .004" of wander from end to end on either one. And using coolant of course, the drills lived to work another day and don't need reconditioning.



              That bottom photo is the ط20mm drilled hole after turning the O.D. down to size. I do that after drilling so the bore and O.D. get even closer to concentric.
              Last edited by PixMan; 05-04-2015, 07:49 AM.

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              • #22
                I specialized in drilling deep holes for screw machine work in all kinds of materials.
                Occaisonally, in order to get the drill to follow center, I actually had to use a center drill.
                For tens of thousands of parts.

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                • #23
                  Well, given that 16 of my 35+ years in this business was setup, program and run up to six single and sub-spindle equipped CNC screw machines I have similar experience. Once I snapped off a few tips of #0 and #00 center drills I went to spotting with just the first tip angle 0.003" to 0.025" deep, depending upon size. Then I found 120؛ and 90؛ spotting drills are CHEAPER and work better, especially with solid carbide coolant fed drills.

                  Hundreds of thousands of parts, millions more with no holes to spot.

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                  • #24
                    Like I said. Our experiences differ.

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