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  • Knurling, I Know Nothing About Knurling.

    Mild steel, diameter is 1.850. If it matters, the knurls are 3/4" diameter with 46 cuts. My internet research is pretty conflicting. Before I resort to my machinist's handbook, I thought I would go the lazy mans route and ask is there a certain feed per revolution I should be using.


  • #2
    For something that long I'd feed it automatically too. You want to feed it about the same as a fairly coarse cut. I normally feel mine manually so I can listen to the "grunt" it makes and alter the feed. It should make some sound but if fed too fast it alters tone and I know I'm going too fast.

    Sorry I can't be more specific but there's no way to describe it other than in that way. Perhaps try some scrap knurling first and manually feed it starting fairly slow and speed up until it starts to sound odd.

    With the scissors style tools like you have I like to come in and set the knurls so they make contact at about 11:15 and 6:45 o'clock on the work. Or in your case perhaps more towards the 12 and 6 at 11:30 and 6:30. Then instead of reefing on the nut on the back of the scissors just feed in with the cross slide to get your bite. It's a lot less stress on the tool that way. And it's still low stress on the head stock bearings since most of the pressure is angled between the knurls.

    The other trick I use is to start at the end and only engage half the knurls at first. Push in and get the knurls forming. Shut off and check that one of the wheels isn't double cutting. If all is well start up again and start feeding along with flooding a generous supply of oil to the work. And this time it doesn't need to be cutting oil since it's not cutting. Just regular oil is fine. Might even be better in fact. Not sure on that.

    If you do get one or both double cutting start up and drive in a little harder and shut off. if it has not shifted to single forming then it's one of the magic mystery diameters. Skim a few thou off and clean up the failed knurl and try again.

    Following this I typically get nice knurls 9 out of 10 times on the first go. That tenth time is one of the mystery diameters that simply needs to be dressed down a little.

    If the knurl is forming correctly but is rough looking then you have too much pressure. Ease off by .006 to .010 and carry on. Likely things will crisp up and look sharper and shinier at the same time.

    That's the sum total of what I know about knurling. Hope it helps.
    Chilliwack BC, Canada

    Comment


    • #3
      BC has most of it covered, not much to add. Some people are convinced that you need to start with an exact diameter to let a specific knurl cut whole numbers of teeth, like a gear, but John Stevenson once published a nice photo of a long tapered workpiece being knurled, completely disproving this - so your diameter is fine, whatever it is.

      In principle, knurling just moves metal around. In reality, I find that it also produces a very fine "swarf", a sort of a metal slurry. Dribbling machine oil onto the knurls keeps them lubricated, and nicely washes the slurry away. Just keep the RPM's fairly low.

      Ian
      All of the gear, no idea...

      Comment


      • #4
        I don't know. People worry about diameters and feeds, but I never knew knurling was difficult until people told me it was, after I'd been happily knurling successfully for many years.
        I use scissors knurls, opened just short of 'going over the top', about 100 rpm, cutting oil, start at the end and traverse along. Just make sure you are happy with the depth, going over it twice is a recipe for a mess.
        'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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        • #5
          The Ol Dredged Knurl. Hated as much as the lil Cut off blade, or parting tool; for you tight wads.

          Yes, to knurl is pretty nice.

          Thanks for the reminder./ JR

          Comment


          • #6
            Originally posted by junkaddict View Post
            Mild steel, diameter is 1.850. If it matters, the knurls are 3/4" diameter with 46 cuts. My internet research is pretty conflicting. Before I resort to my machinist's handbook, I thought I would go the lazy mans route and ask is there a certain feed per revolution I should be using.
            ]
            Conflicting info....lolo....knurling seems one of the machining contentious recyclables, along with notable contenders such as leveling a lathe, tramming a mill and should I buy new Chinese or 50 year old iron.

            I've knurled by pressure, cut and scissor methods and have never worried about calculating diameters - a major theme of the contentiousness. Especially irrelevant for pressure and scissor knurls as the starting OD the teeth track on is not the final pitch dia. Anyone remember John Stevenson going on about that?

            I do like to keep the work slathered in oil. Run maybe 1/3-1/2 as fast as if cutting. With a sturdy lathe and scissor knurls, you should be able to go to depth and knurl in one pass.

            That's what I have to offer
            in Toronto Ontario - where are you?

            Comment


            • #7
              Originally posted by BCRider View Post
              For something that long I'd feed it automatically too. You want to feed it about the same as a fairly coarse cut. I normally feel mine manually so I can listen to the "grunt" it makes and alter the feed. It should make some sound but if fed too fast it alters tone and I know I'm going too fast.

              Sorry I can't be more specific but there's no way to describe it other than in that way. Perhaps try some scrap knurling first and manually feed it starting fairly slow and speed up until it starts to sound odd.

              With the scissors style tools like you have I like to come in and set the knurls so they make contact at about 11:15 and 6:45 o'clock on the work. Or in your case perhaps more towards the 12 and 6 at 11:30 and 6:30. Then instead of reefing on the nut on the back of the scissors just feed in with the cross slide to get your bite. It's a lot less stress on the tool that way. And it's still low stress on the head stock bearings since most of the pressure is angled between the knurls.

              The other trick I use is to start at the end and only engage half the knurls at first. Push in and get the knurls forming. Shut off and check that one of the wheels isn't double cutting. If all is well start up again and start feeding along with flooding a generous supply of oil to the work. And this time it doesn't need to be cutting oil since it's not cutting. Just regular oil is fine. Might even be better in fact. Not sure on that.

              If you do get one or both double cutting start up and drive in a little harder and shut off. if it has not shifted to single forming then it's one of the magic mystery diameters. Skim a few thou off and clean up the failed knurl and try again.

              Following this I typically get nice knurls 9 out of 10 times on the first go. That tenth time is one of the mystery diameters that simply needs to be dressed down a little.

              If the knurl is forming correctly but is rough looking then you have too much pressure. Ease off by .006 to .010 and carry on. Likely things will crisp up and look sharper and shinier at the same time.

              That's the sum total of what I know about knurling. Hope it helps.
              I've found knurling to sometimes be hit and miss. What has worked best for me with my Aloris BXA knurl is to make sure each knurl is contacting the top and bottom of the part equally over TDC of the part. Then I tighten it down slightly rocking the chuck back and forth to get a good impression, the initial bite makes all the difference. Turn the chuck by hand in the direction of rotation a full turn to make sure the pattern doesn't start to over ride itself or climb ahead. If the pattern meets after one revolution it's good to go and I do it under power.
              Once the pattern is established I can go over it back and forth until I get my desired depth / pattern. It does produce some (flakes) or knurling swarf but that doesn't seem to hurt anything. Occasionally I'll stop and brush it off.
              I never take the full depth in one pass, it's just too much of a load for my machine. Maybe OK with convex knurls but I only have one set of that style.
              Convex knurls seem to work easier rather than plowing through with a square edge knurl. With the flat or square knurls I'll put a slight angle on the tool post to give the knurl a leading edge.

              JL................
              Last edited by JoeLee; 02-15-2021, 08:20 AM.

              Comment


              • #8
                Yah, don't open the Machinery handbook. Don't want to do that.
                It's so 20th century.

                -D
                DZER

                Comment


                • #9
                  Originally posted by Mcgyver View Post

                  Conflicting info....lolo....knurling seems one of the machining contentious recyclables, along with notable contenders such as leveling a lathe, tramming a mill and should I buy new Chinese or 50 year old iron.

                  I've knurled by pressure, cut and scissor methods and have never worried about calculating diameters - a major theme of the contentiousness. Especially irrelevant for pressure and scissor knurls as the starting OD the teeth track on is not the final pitch dia. Anyone remember John Stevenson going on about that?

                  I do like to keep the work slathered in oil. Run maybe 1/3-1/2 as fast as if cutting. With a sturdy lathe and scissor knurls, you should be able to go to depth and knurl in one pass.

                  That's what I have to offer
                  Same way that I do it ( think). Scissors knurls, flooded with any cheap oil. Low gear slow (improves the finish on some materials). If I use power feed on a long piece, I knurl a stripe to full depth on the end, then start the power feed on the slowest setting I have -- .0015 inch per rev. It takes forever, but works good. Crisp, sharp knurls.
                  25 miles north of Buffalo NY, USA

                  Comment


                  • #10
                    A while ago, I scored a cut-knurling tool on ebay.
                    It was Quick brand, made in Austria if I remember.
                    The forces are pretty low and it generates chips
                    because it is not an impression knurl, but a cut
                    knurl. It has a dial that you set to the workpiece
                    diameter, that changes the angle of the wheels
                    slightly. Very intelligent setup for sure.

                    -D
                    DZER

                    Comment


                    • #11
                      Doozer, could you post a pic of that super knurling tool you have?

                      Comment


                      • #12

                        Aaand.... If you really want to improve your success rate, dump the steel and use aluminum or brass! No, seriously. Knurling is generally for looks and/or a knob that will be turned by hand or gripped manually, and you may be able to make that part using a softer material. Or shrink/press the softer part onto the necessarily hard part.
                        "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

                        Comment


                        • #13
                          On using the simple push style Aloris style knurls. I'm pretty sure that the best way to use that tool is to back off the height adjuster so it sits a touch low and not lock the wedge or piston. Or that the center on it be set VERY carefully. There's a reason every other knurling tool in creation has the ability to float up and down at least a little.
                          Chilliwack BC, Canada

                          Comment


                          • #14
                            The biggest problem with Aloris style knurls id getting both knurls to engage the work evenly. I fiddle with the height adjustment. Sometimes I back off the height adjuster and leave the wedge unclamped. I am sometimes tempted to pull the Aloris tool post and use the lantern toolpost and a swivel head knurling tool.

                            Comment


                            • #15
                              These are the recommendations from Eagle Rock that I pulled out of the box the scissor tool came in.

                              These settings are a good place to start, I normally push it a bit faster due to time constraints and have seized knurls to the pin in doing so (-:
                              Also use as much flood coolant as possible, one nozzle per wheel if you can.

                              CNC Lathe

                              Manual Lathe

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