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HSS Basic Lathe Turning Tool

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  • HSS Basic Lathe Turning Tool

    Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

    Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

    Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

    Thanks for any thoughts or comments on this very basic question.

    Gary
    S E Michigan

  • #2
    Clearance, clearance, cleararance.. if you have none it won't cut.

    Comment


    • #3
      Originally posted by OaklandGB View Post
      Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

      Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

      Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

      Thanks for any thoughts or comments on this very basic question.

      Gary
      In MY experience and MY lathe the angled tool is less prone to chatter with heavy cuts. Even better if I put some negative back rake on the tool. Radial cutting forces are bigger if you use tool like this and it cuts "oversize" but at least on my lathe its less prone to chatter.
      Maybe depends what parts of the lathe are loose and made of noodles.
      Location: Helsinki, Finland, Europe

      Comment


      • #4
        Originally posted by OaklandGB View Post
        ....

        Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.


        Gary
        To get a 90 degree shoulder you'd simply rotate the compound tool rest to present that leading tool edge at a perpendicular angle to the lathe axis.
        Lynn (Huntsville, AL)

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        • #5
          If you give it a few degrees ckearance toward rfw back the it always works put it in a holder and go.. if cutting edge is parallel then you have to always angle it, or risk not machining the face square to the work.

          Comment


          • #6
            Side cutting angle can be made independent of lead angle or they might be the same. I like to set my QCTP square with a parting tool and leave it there until I have to adjust the compound for some reason, then set it square again, so my side cutting angle tends equal my lead angle. The same is true with most insert tooling.

            I linked to some info about lead angle below, but mainly it's been discussed. A bit of positive lead angle thins the chip, protects the nose radius, and tends to chatter less, but can't cut a shoulder or face. It's very handy for quick jobs to be able to turn and face with the same tool in the same position.

            I think 754 is describing a negative lead angle whereas the OP was talking about positive. A negative lead tool, such as an MCLN toolholder for 80 deg diamond inserts is very handy as a universal turning and facing tool. In fact this type of tool is my primary tool and I have 2 loaded with different inserts for different materials and go to first unless I really need to do some roughing.

            If I'm using HSS I tend to grind with 0 deg side cutting angle and primarily side rake (seen this referred to as knife tool). I then set the blank in the QCTP holder to give just a little negative lead so I can face/turn to shoulder. This could also simply be accomplished by turning the toolpost. Both of which are easier than grinding in a negative lead into a tool blank.

            The one issue with this type of grind is it's trickier to maintain that edge by hand grinding, so you'll often end up with an angle one way or the other, but it really doesn't matter. In reality you don't ever want/need to set the tool to dead zero lead. You either want a couple degrees negative for facing or several degrees positive for heavy turning.


            http://www.mitsubishicarbide.com/en/...g_cutting_edge
            Last edited by JCByrd24; 11-15-2018, 02:03 PM.

            Comment


            • #7
              Actually, a dead zero lead, or as close as possible to it, has uses. If you want to turn part of a part to a very small diameter, leaving the rest larger, you really have an issue doing this with standard tools. Something like a countern=bore nose, that mas a thin stem that holds it, but a fat nose to fit the hole that is to be counterbored.

              The standard tool has a good deal of radial force, due to the angle and the nose radius. This will mean tiny cuts as you approach the final size, to avoid bending the thin stem portion of the part.

              If you use a near zero nose radius, and a dead radial edge with a good deal of rake to the right, you can take the entire diameter reduction in one step, assuming your lathe will handle it. That means the thin stem is always supported by the thick stock, up until it is reduced to final size. Bending and failure is essentially eliminated.

              The only other way to make such a part that is fairly risk-free is to make in two parts, shrinking or loctiting the stem and nose parts together.
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                I think I see. Leaving no side cutting angle puts added stress on the tool and rigidity of my machine. The Mitsubishi site helps illustrate it. Perhaps that is where the chatter came from before I reground the tool with a small side cut angle. Way more smooth with the angle there. More to learn and experiment with. With each new understanding comes 3 or 4 additional areas to explore. Maybe that is what makes this hobby, even in its most basic form, so intriguing.

                The folks on this site are so helpful...and patient.... Really provides a new hobby machinist with the inspiration to take the next steps no matter how small they are.

                Thanks!!!

                Gary
                S E Michigan

                Comment


                • #9
                  Yes I shouldn't have used the word ever, rarely is that a good idea. Point being if you need to set to zero lead it can be done even if you goof the factory edge of your tool blank so you have a little side cutting angle one way or the other. I think I've seen one of the youtube machinist demonstrate just as you say and make a very long thin part by taking it in one bite with a zero lead tool with a lot of side rake.

                  Comment


                  • #10
                    Originally posted by OaklandGB View Post
                    Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

                    Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

                    Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

                    Thanks for any thoughts or comments on this very basic question.

                    Gary
                    Also if you're not a big fan of grinding your own HSS, look into getting some insert holders and some carbide inserts.

                    Comment


                    • #11
                      JCByrd24,

                      From the humorous, beginner's perspective, I tried taking the "one bite"...but it was an accident, not intentional. However, I still learned from it...namely about stalling the lathe!!

                      Onward I go!
                      S E Michigan

                      Comment


                      • #12
                        .....If you use a near zero nose radius, and a dead radial edge with a good deal of rake to the right, you can take the entire diameter reduction in one step, assuming your lathe will handle it. That means the thin stem is always supported by the thick stock, up until it is reduced to final size. Bending and failure is essentially eliminated......
                        This part in quotes from JTiers' post works extremely well. I've used it on a few occasions now to produce very small pins on larger stock.

                        Oakland, what you're seeing in the differences are the preferences that have been around for years from the days even before HSS where the cutters were done with regular high carbon tool steel and care was needed to avoid heat and tempering of the edges. Some of it has distinct advantages such as a dragged back angle for heavy cuts and others are about angling the cutter to allow getting very close to the chuck jaws without fouling the old style lantern tool posts and holders against the chuck and without a lot of overhang. Or as mentioned there's some good reason for raked back cutters used for hogging away a lot of waste. And for others it may be related to wanting a square edge but without the need to shift the base of their tool post around.

                        I've even gone with a slightly different option. About 15 years back I made a tool post somewhat similar to a four way. But the slot which was to be used for my standard turning tool was done with an angle to it. This angle was cut so I could use a basic shim or no shim and adjust the height of the cutter by the amount of protrusion. The piece of 1/2" square HSS is then sharpened back with all the rakes and clearances sort of like a pencil so I never need to do anything more than a light touch up of the three faces and add a slight nose radius with three small touches then a lick from a small sharpening stone.

                        I am looking at a new idea now for a new block which will both angle and twist the main cutter so the top would never need any grinding at all. Just the end and front for rake and clearance angles. Then adjust the protrusion after each sharpening to restore the tip to the center height.
                        Chilliwack BC, Canada

                        Comment


                        • #13
                          Practical example:

                          Making the test cut to check size before doing the actual cut




                          The cut completed. You can see the wide chips on the tool




                          The part that I wanted to make, a soldering tool. It had to fit the soldering iron to be used, which is why the thin stem.

                          Last edited by J Tiers; 11-15-2018, 03:44 PM.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            Is that copper plated steel? Usually soldering tools are iron-clad copper. Is the difference in color caused by lighting?
                            http://pauleschoen.com/pix/PM08_P76_P54.png
                            Paul , P S Technology, Inc. and MrTibbs
                            USA Maryland 21030

                            Comment


                            • #15
                              It is clear to me now that no side angle introduced unacceptable chatter in my small lathe. I'm sticking with HSS as I find it interesting to experiment and see what happens. Next up is likely a chamfer tool. We'll see what works for just general edge relief. Thanks for all the comments, all are very helpful.
                              Gary
                              S E Michigan

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