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How do you knurl with a QCTP

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  • How do you knurl with a QCTP



    I've never needed to do hash knurl; it was always just straight lines. I noticed that these knurling holders aren't adjustable, so how do you produce strongly defined hash patterns?

  • #2
    You have to center it, meaning that the center line of your work has to exactly centered betwen the two knurls.

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

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    • #3
      Hi,

      You push really hard.

      The general consensus is this style of knurl tool is hard on the lathe cross slide and compound because of the pressure needed to impress the pattern on the material. With smaller home shop lathes I do agree. But with bigger commercial machines, I'm not so sure. In any case, knurling isn't all that common of a operation for most machinists. So it might be a less concern than we sometimes make of it.

      I personally use squeeze type knurlers.

      dalee
      If you think you understand what is going on, you haven't been paying attention.

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      • #4
        I have one that came with my QCTP and a smaller squeeze type one. The squeeze one is definitely a bit easier to use and requires a lot less feed force to make a good knurl.

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        • #5
          I just made a special BIG tool holder to hold my old style lantern tool post knurlers.
          Andy

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          • #6
            Originally posted by JoeLee View Post
            You have to center it, meaning that the center line of your work has to exactly centered betwen the two knurls.

            JL................
            Yes but the knurl spacing must be a multiple of the circumferance, so ..?

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            • #7
              Originally posted by Elninio View Post
              Yes but the knurl spacing must be a multiple of the circumferance, so ..?
              Ideally, knurl pitch should match the circumference. Don't worry about spacing.

              Everything else aside, this is the worst type of knurler, IMO, but it's worth trying if you have nothing better.
              Last edited by MichaelP; 05-28-2013, 01:17 AM.

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              • #8
                Look at it this way.

                A 30 pitch knurl has a lead of .033". In 200 pitches (≈ 2" diameter), each tooth would have to gain (or loose) only ≈.000075" to make up a difference of .016" on the circumference.

                Dave

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                • #9
                  Originally posted by Elninio View Post
                  Yes but the knurl spacing must be a multiple of the circumferance, so ..?
                  Yes, true but with diametreal pitch knurls, and I think that is what they are called........... as long as your OD is an even dimension, example, 1", 5/8" 11/16" etc. they will work just fine.

                  But as mentined, it takes a lot of force to displace the surface of the work, something you don't want to do on a small lathe.
                  However, some of that force can be over come by slightly angleing the knurl so the edge of the wheel bites in vs the whole surface.

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

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                  • #10
                    Originally posted by Elninio View Post
                    Yes but the knurl spacing must be a multiple of the circumferance, so ..?
                    Exactly !

                    Two things
                    First ,the style of holder shown above should be started with only a partial knurl , say a width of .060 , and then the knurler fed to the left slowly
                    to minimize the load on the Cross-feed screw/nut. Also this style requires the use of a tailstock center.

                    Second, the diameter needs to be adjusted to match the knurl pitch. Most machinists plunge in, until the knurl matches the pattern
                    needed on the part. When the knurl pattern approaches a close point, the knurl form roller can slip a small amount to keep the pattern in sync.
                    You may note that sometimes you have a nice pattern, but not sharp points. Trying to go deeper means having either slip in the rollers, or a screwed up pattern.

                    Here is a photo of an operating valve I made.
                    The valve body is 1/4 inch in diameter, the flared copper pipes are .060 ( 1.5 mm) in diameter and the flare nuts are scale.
                    The knurled cap ( .160") was made with a .100 pitch knurler. A standard knurler on an Aloris holder.
                    Note the pitch on the knurl produced is about .020 , which is a 5 start knurl before repeating.
                    By reducing the diameter .002 at a time, I was able to find the magic point that produced the scale knurl using a course knurling tool.
                    For newbies, The knurl roller came around the part and missed the original mark, and made a new mark about .020. this repeated about 4 times and then it entered the original mark
                    Because the diameter was controlled a distinctive knurl was created. This cannot be done by plunging in -you must start a small area and when the pattern develops, then feed to the left
                    So multi-starting a knurl can work to your advantage !
                    Rich



                    Last edited by Rich Carlstedt; 05-28-2013, 02:29 PM.

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                    • #11
                      Originally posted by Elninio View Post
                      Yes but the knurl spacing must be a multiple of the circumferance, so ..?
                      This has been disproved many time over. All that is required is
                      increase the pressure while turning till the knurls track. I've
                      done it with scissor tools using diamond knurls lots of times on
                      any diameter materials. Most often it was aluminum but on
                      occasion steel.
                      ...lew...

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                      • #12
                        Both of the pieces shown are 303SS, and were done using a scissor type knurling tool. They are not the same diameter. BTW, nobody has mentioned it, but do this with coolant if you want the best results, you do get some flakes that need to need to be flushed.
                        The parts are the knob and a "minute" dial for a TA adjuster.



                        To answer the OP's original question. I have had to use one those knurling tools shown on a 16" Monarch lathe. It wasn't easy, nor was it fun. Do yourself a favor and get a scissor type knurler. One of the problems with the bump type tool, unless the knurl is centered on the toolpost clamp screw, the toolpost will want to rotate. It's happened to me acouple of times, not often, but I do make sure the clamping screw is extra tight.
                        Harry
                        Last edited by beckley23; 05-28-2013, 06:48 PM.

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                        • #13
                          As much as it's logical to be careful to match the diameter of the part and the pitch of the knurl, I still don't find myself doing that. I'll admit that most of my work is fairly loose when it comes tolerances. In fact, I guess I have a high tolerance for low tolerance, as long as I get the job done. (Too much woodworking in my past, I'm sure.)

                          With that preamble, I've only ever knurled one thing where the final diameter was critical - a coarse diamond knurl on 1/4" steel. Except for that one job, I've always relied on the "magic" to get the job done. I set the knurl to center, plunge in until I get a good pattern, and call it done. Look at my work with a loupe and you'll might see some unpleasant stuff, but to the naked eyeball, it looks pretty good to me. Here's an example, with a single knurling roller - I did not calculate anything - I just pushed it in until things looked right:



                          And, I do squirt a stream of cutting oil to flush the chips.

                          By the way, it's easy to set the nonadjustable double knurl to center. Just bring it in to the work, turn the spindle by hand and tighten the tool post as you feel how the rollers are making contact with your finger, then when you start up you can see the pattern starting and you can raise or lower the tool to get an even pattern with each roller.

                          I really don't quite get the business about "bump" or pressure knurling being hard on the lathe. I assume that simple turning often puts a pretty heavy load on the bearings and cross slide, and really, how much time to you actually spend knurling anyway?

                          Now, for knurling small diameter or long pieces, that kind of tool can easily bend the work, so I'm a big fan of scissor knurls for that reason as well.

                          Here's my best tip on knurling: Take a stroll around your shop and look carefully at the knurled items you'll find there - knobs, nuts, tool grips, etc. If your stuff is anything like mine, you'll find any number of high quality tools with slightly (or not so slightly) uneven, incomplete, or otherwise less-than-perfect knurling that you hadn't noticed before. Once you notice the variances in quality from producers like South Bend, Starrett, etc., you may find it less difficult to please yourself, and you can just "go for it" and get on to the next project.

                          OK, maybe this isn't he place for "lowered expectations," but I do think that striving for perfection can be overdone.
                          Last edited by Frank Ford; 05-28-2013, 03:48 PM.
                          Cheers,

                          Frank Ford
                          HomeShopTech

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                          • #14
                            Very good post Frank, and so true!!

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                            • #15
                              It seems that diamond, or skew, knurling will conform to the size of the part nicely.

                              Straight knurling I have had trouble with if I didn't get it pretty close to an ideal size... that sort of knurl hasn't as many ways to slide to fit, it pretty much looks like a gear. I expect that small errors get washed out even with straight knurls, though, so within limits any knurl will make itself fit.

                              Originally posted by Frank Ford View Post
                              I really don't quite get the business about "bump" or pressure knurling being hard on the lathe. I assume that simple turning often puts a pretty heavy load on the bearings and cross slide, and really, how much time to you actually spend knurling anyway?
                              Well, maybe you don't, but I do.... I find that using that sort of knurl takes more force than turning does.... Since when does turning ever take real "C-clamp type" force exerted by the crosslide screw? If it ever does, that would mean your tool quit cutting, and you didn't notice.

                              Getting a deep well-formed knurl on steel sometimes seems to take a lot of force, far more than I would ever exert with a cutting tool. As for the downward force, I think that also is less, but I have no screw to turn against it, so I cannot be certain.

                              Remember, you are work-hardening the steel as you knurl.
                              Last edited by J Tiers; 05-28-2013, 10:52 PM.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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