Announcement

Collapse
No announcement yet.

Why Does This Insert Gall ?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Why Does This Insert Gall ?

    I made this radius tool a while back to finish form the groove in my U-bolt rolling dies. I made the inserts, they are both 01 hardened to the max. The larger one is .317 in dia. and the smaller one is .254. After roughing out the groove in the die I use this tool to finish the groove.

    I've used the 5/16" on several times and it works perfectly. I have to turn my lathe spindle by hand to avoid chatter but the insert shaves to a nice finish and final dimension.

    So, today I had to make a roll die for 1/4" rod. I couldn't get that 1/4" insert to cut clean no matter what I did. It would snag, drag a burr and gall.

    It's the exact same geometry as the 5/16" insert, just smaller in dia. no difference. I tried various positions below the center line and it still galled.
    It's dead sharp and I can shave my finger nail with it but I just can't figure out why it doesn't cut clean like the larger one does. I'm using the same material too.

    Is there something about the dia. of that style insert where it won't cut clean? I'm at a loss.



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

  • #2
    Probably lack of clearance, it will do it every time..try tilting the tool.

    Comment


    • #3
      Originally posted by 754 View Post
      Probably lack of clearance, it will do it every time..try tilting the tool.
      Thats what I thought? Sounds like you are getting a lil tight.

      Make the 1/4" R at the tip, say 90degrees worth of good cutting edge, and under grind the rest of it so its just the perfect geometry for 90 degrees and everything else is gone. at .25"r and it will eat. I think JR

      P.S. You are not cutting per say. Mostly chasing or profiling. Doesnt take much of a back support unless you go hog wild. JR
      Last edited by JRouche; 05-17-2020, 10:29 PM.

      Comment


      • #4
        how deep do you go with the inserts? full radius?

        Comment


        • #5
          Solly. I didnt look at the pic till just now. Yeah, yer phuked

          I think now after looking at the cutter 747 showed he might have the correct plan.

          You might want to tilt it in a lil. That will give you the clearance Clarence.

          What? JR

          Comment


          • #6
            Originally posted by JRouche View Post

            Thats what I thought? Sounds like you are getting a lil tight.

            Make the 1/4" R at the tip, say 90degrees worth of good cutting edge, and under grind the rest of it so its just the perfect geometry for 90 degrees and everything else is gone. at .25"r and it will eat. I think JR

            P.S. You are not cutting per say. Mostly chasing or profiling. Doesnt take much of a back support unless you go hog wild. JR
            Yes, that's a good way to describe it, chasing and or finish profiling. I can't cut the entire groove with it. I go in with a thin parting tool on the center of the groove and then use a hand ground 1/4" radius tool bit to get a pretty close profile. When I'm about .010 or so from my finish depth I use the the profile insert which is about .005 over size for clearance. I have to turn the spindle slowly by hand to finish. The 5/16" one works fine, the 1/4" galls as soon as I touch it. It's the same geometry as the 5/16" one, that's what I don't understand. Isn't dropping below center line the same as tilting the insert?? Only the dead sharp cutting edge is contacting the work. The insert doesn't have a tapered sided so I have to keep it below the center line. I made it purposely that way so I could sharpen it without changing the dia.

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

            Comment


            • #7
              Originally posted by dian View Post
              how deep do you go with the inserts? full radius?
              The groove depth on all my roll dies is about half the dia of the rod that I'm rolling. I only do two sizes. 5/16" and 1/4", so my rule of thumb is a little less than half the dia. I get better and more consistent results with a deeper groove.





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

              Comment


              • #8
                Dropping below the center line gives clearance at the center of your tool but clearance is reduced as you move toward the side of the groove, zero clearance at 90 degrees. You might try making an insert with a bit of clearance and see how that works; it won't be re-sharpenable, of course. An alternate approach might be a grinding wheel with a 1/4" radius.
                Location: Newtown, CT USA

                Comment


                • #9
                  Originally posted by GadgetBuilder View Post
                  Dropping below the center line gives clearance at the center of your tool but clearance is reduced as you move toward the side of the groove, zero clearance at 90 degrees. You might try making an insert with a bit of clearance and see how that works; it won't be re-sharpenable, of course. An alternate approach might be a grinding wheel with a 1/4" radius.
                  OK, I can see that now........ but why don't I have this problem with the 5/16" dia. insert ? as I said both inserts are the exact same geometry. Only difference is the dia.

                  So if I were to slightly tip the tool holder, basically giving it a negative rake, by how much?? .003 - .005 should be sufficient, correct?? That's about what the relief angle is on most inserts.


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

                  Comment


                  • #10
                    Are the chips jamming up against a the hold down screw John b.
                    John b. SW Chicago burbs.

                    Comment


                    • #11
                      Originally posted by JoeLee View Post
                      OK, I can see that now........ but why don't I have this problem with the 5/16" dia. insert ? as I said both inserts are the exact same geometry. Only difference is the dia.

                      So if I were to slightly tip the tool holder, basically giving it a negative rake, by how much?? .003 - .005 should be sufficient, correct?? That's about what the relief angle is on most inserts.


                      JL............
                      Don't know why the 5/16" doesn't have the same problem. And I'm not certain relief will cure the problem but it is likely an issue and is reasonably easy to try the fix.

                      Tipping the tool holder won't provide clearance on the sides of the tool. Your tool is effectively a cylinder with a sharp upper edge. You need to taper the cylinder slightly so the bottom edge is smaller than the top to provide clearance at the sides. Leave 10 thou or so under the top edge un-tapered so you're certain the upper diameter is not affected.
                      Location: Newtown, CT USA

                      Comment


                      • #12
                        as gadget said, you have no clearance on the sides. maybe the decrease in size is just enough to make it a problem. and what exactly do you mean by galling? does it happen on the tip also? when i do pulleys i use a straight grinder with a lollipop cutter in the toolpost.

                        Comment


                        • #13
                          Originally posted by john b View Post
                          Are the chips jamming up against a the hold down screw John b.
                          No, not at all. They seem to stick at random places to the cutting edge and drag a deep scratch around the groove. This insert doesn't really make chips, more like fine grit, like salt from your salt shaker and even smaller. Depending on feed and DOC the chips may look like the old lead tinsel you used to hang on your Christmas tree.


                          JL............
                          Last edited by JoeLee; 05-18-2020, 12:56 PM.

                          Comment


                          • #14
                            Originally posted by dian View Post
                            as gadget said, you have no clearance on the sides. maybe the decrease in size is just enough to make it a problem. and what exactly do you mean by galling? does it happen on the tip also? when i do pulleys i use a straight grinder with a lollipop cutter in the toolpost.
                            Yes, this is the only thing I could think of since both inserts are geometrically identical, only difference being the dia. Originally I had asked if there was a point in the dia. of this style insert where they just don't cut clean.

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

                            Comment


                            • #15
                              IHow many degrees clearance on insert, they may not be the same. To me in the small one look tilted to the holder, the big one looks almost straight up.
                              also rough it out first reduce the load. Best Becket with cutting oil as you near full depth, and peck.. run it in observe your number, then back out quickly. . In and out fast.. when near full profile.
                              if your lathe us light or wiggly it's a real challenge.
                              Last edited by 754; 05-18-2020, 03:05 PM.

                              Comment

                              Working...
                              X