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Do you like your bump knurling tool?

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  • #16
    Originally posted by J Tiers View Post
    The force is very large if you "just jam it in". If you tried to press that pattern into the metal it would take a great deal of pressure. Since it is rotating, the pressure is spread out over time, but the material work-hardens during the knurling, and presumably gets harder toward the final forming.
    Accu Trak says you should aim to get a deep impression in the first revolution. That allows it to track for future revolutions. They call it the "secret to success". Obviously machine and work are going to limit how hard you can push it.


    Originally posted by TGTool View Post
    I use a scissors knurling tool and it always works - without any calculation for diameter. Putting a lot of pressure on the clamp seems like the key to getting it to register. I'll engage it, tighten the nut, turn the lathe on and off to get a few revolutions and see what the pattern looks like, If it's not a clear pattern (mismatch of knurl pitch and work diameter) it just needs more cranking on the nut. Oil it up, crank it down and she'll be good...
    So you are effectively changing the diameter. Instead of calculating it and starting with the right diameter, you are adjusting the wheels until they are set at the right diameter to track correctly. JT beat me to it
    Last edited by pinstripe; 01-17-2017, 12:31 PM.

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    • #17
      I have a SB9A and I use a bump knurling tool and get good results by taking light cuts and repeat multiple times which seems to not put as much pressure on the machine.
      Paul, do you have a design for the sissor tool you show . I have a project that I'm trying to knurling 3/16" brass and it keeps bending with the bump tool, as I've read here this is what I need.

      PS. Mcgyver what does your tool look like, possible to see a picture?


      TX
      Mr fixit for the family
      Chris.
      Last edited by Mr Fixit; 01-17-2017, 12:49 PM.

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      • #18
        If I was so concerned about wear on my lathe that I was afraid to use a bump knurling tool I probably wouldn't want to use any other tooling either. I have only used bump knurling tools for the last 40 years and haven't had any problems.

        Brian
        OPEN EYES, OPEN EARS, OPEN MIND

        THINK HARDER

        BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

        MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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        • #19
          Originally posted by Mr Fixit View Post
          PS. Mcgyver what does your tool look like, possible to see a picture?
          I did it as a build piece in HSM so made it nice and shiney



          in Toronto Ontario - where are you?

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          • #20
            Cut knurling = sharp knurling in crumbly materials and neat knurling where less than full depth cuts and flat surfaces are required.
            I use cut or clamp, push went in the bin years ago except from a few old speciality cutters that are no longer available,

            - Nick
            If you benefit from the Dunning-Kruger Effect you may not even know it ;-)

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            • #21
              Scissor knurl tools for me. For the manual lathes a generic, cheap, no-brand-name tool. For the CNC where tooling space is a premium I have a B&S unit modified to mount using a 5/8" round shank.

              Setup is the same for both tools. No concern is given to work diameter. Adjust them over the workpiece to get in correct range then back off and close a bit. Form knurl. Verify depth of form is right or adjust as needed. Never a bad part or miss-tracking of the knurls.

              On the CNC I run dry with a quick spurt of coolant onto the knurl axles for lubrication prior to engaging the work.

              On the CNC where there's precise control of speeds and feeds I program the knurl to approach the work center fast, dwell on the work for a couple revolutions of the part and rapid off.

              On rare occasions a drawing will have a close diameter tolerance on a knurled area. In that case we make the knurl slightly oversize and take a skim cut over the knurl just trimming the crests to bring it to size.

              I do have a cut knurling tool. Way too much hassle in setup.

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              • #22
                I started off with a bump knurl tool, and thought it worked well for me. Then I bought a generic scissor knurl tool (~$40 from Wholesale Tool IIRC) and have never touched the bump knurl again, I've found no reason to ever go back to that.

                On a lot of steels I'm able to get a good knurl in one pass with the scissor tool, instead of running back and forth with the bump tool. I use the lathe's power feed to drive it.

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                • #23
                  I agree about bump knurling, in that the amount of extra wear on things probably isn't a realistic issue for most home shop folks, at least if it's done the right way. That being said, I don't find it to be an enjoyable process at all. Until I happened into a cut knurling tool, bump knurling is all I had done, and once I had some practice, full depth knurls were rarely a problem. Cut knurling, though, is wonderful. Ease of setup I think depends entirely on the tool you're using, but mine is very easy to setup. It's a Brown & Sharpe tool, meant to be used in a small turret. For batches of stuff of course I use it in the turret, but for one off stuff I use an adapter that goes from my tailstock taper to the straight 5/8" shank on the cut knurling tool. The fact that it's tailstock (or turret) mounted I think really helps with ease of setup.

                  EDIT: In one of the vids on my youtube channel, the video about making the Dixi mill clamp, I use the turret cut knurler held in the tailstock for one of the parts, if anyone cares to see what that arrangement looks like.
                  Last edited by mars-red; 01-17-2017, 01:30 PM.
                  Max
                  http://joyofprecision.com/

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                  • #24
                    Mcgyver, that is a piece of art!!
                    Do you know what issue your project was in. I would like to build myself a new tool after seeing that wonderful sculpture of steel.

                    TX
                    Mr fixit for the family
                    Chris.

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                    • #25
                      Not really any point in commenting at this point with all the replies but .....I never liked my bump knurling tool. It puts way too much strain on the cross slide screw and nut. I went to the compression type and get much better results with very minimal load on the cs screw.
                      It still puts quit a drag on the carriage as you can feel it when you try to turn the hand wheel.

                      JL.................

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                      • #26
                        It's never too late to throw your two cents in

                        With regards to the carriage drag, are your knurls bevelled? That should help. Accu Track also makes convex knurls which they claim are much better for axial feeding.

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                        • #27
                          Originally posted by Mr Fixit View Post
                          I have a SB9A and I use a bump knurling tool and get good results by taking light cuts and repeat multiple times which seems to not put as much pressure on the machine.
                          Paul, do you have a design for the sissor tool you show . I have a project that I'm trying to knurling 3/16" brass and it keeps bending with the bump tool, as I've read here this is what I need.
                          Sorry Chris no drawings I'm afraid, I made mine from stock I had on hand roughly following the design of the Hemingway Knurler Kit and including some of the ideas David Haythornthwaite carried out to his kit, the finished item is very rigid and produces very good results on all sizes up to 4" or so.

                          Paul

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                          • #28
                            Originally posted by bborr01 View Post
                            If I was so concerned about wear on my lathe that I was afraid to use a bump knurling tool I probably wouldn't want to use any other tooling either. I have only used bump knurling tools for the last 40 years and haven't had any problems.

                            Brian
                            Ah, beans.

                            Some things just seem like "forcing" beyond what is reasonable, others do not. Some people have no "mechanical feel" whatsoever, no sensitivity at all to what "feels like too much" , so they are happy cranking-in even when the machine is obviously "complaining", and they are looking around for a cheater bar. If it works for them, then fine.

                            I find, with a 10" Logan, that running the bump knurler in to where it actually gives a good knurl just feels too much like cranking down a milling vise for a tough cut. It's beyond what seems reasonable, so I avoid it, and try to sneak in sideways in order to have less force required.

                            If I had a narrower knurl tool, it would probably be fine.

                            Suppose you first, before crowing about how little trouble it is, tell us what machine you are doing that on. And how wide the knurl wheel is/are, and if it is a single or double wheel tool.
                            Last edited by J Tiers; 01-17-2017, 02:34 PM.
                            CNC machines only go through the motions

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                            • #29
                              Originally posted by pinstripe View Post
                              It's never too late to throw your two cents in

                              With regards to the carriage drag, are your knurls bevelled? That should help. Accu Track also makes convex knurls which they claim are much better for axial feeding.
                              No, they are not the convex style knurl. I've had a lot of people recommend them. I'm not sure if they cut down one the drag on the carriage though. It seems like they would.


                              JL..............

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                              • #30
                                Originally posted by J Tiers View Post
                                Ah, beans.

                                Some things just seem like "forcing" beyond what is reasonable, others do not. Some people have no "mechanical feel" whatsoever, no sensitivity at all to what "feels like too much" , so they are happy cranking-in even when the machine is obviously "complaining", and they are looking around for a cheater bar. If it works for them, then fine.

                                I find, with a 10" Logan, that running the bump knurler in to where it actually gives a good knurl just feels too much like cranking down a milling vise for a tough cut. It's beyond what seems reasonable, so I avoid it, and try to sneak in sideways in order to have less force required.

                                If I had a narrower knurl tool, it would probably be fine.

                                Suppose you first, before crowing about how little trouble it is, tell us what machine you are doing that on. And how wide the knurl wheel is/are, and if it is a single or double wheel tool.
                                Forcing beyond what is reasonable depends on the size of the lathe. Figure out the amount of force it takes to make a good impression. If for example you need 500 Lbs of force to make a good impression and you have a 13" lathe then it should send up a red flag.............. like I'm not putting that much force on my cross slide screw.
                                Usually the amount of force needed to knurl is at least a hundred times more than you would need to take the heaviest cut you would evere push your lathe to do.

                                JL...............
                                Last edited by JoeLee; 01-17-2017, 06:44 PM.

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