Announcement

Collapse
No announcement yet.

Ductile Iron for solid tool post?

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

  • #31
    Originally posted by George Bulliss View Post

    Feeling a little pissy today? This kind of **** is why most newcomers don't stick around long. If you don't have anything to say, then don't say anything.
    J Tiers has said all that's needed to be said on the subject and our newbie has chosen to totally ignore his knowledge and common sense. If they aren't going to listen to good advice, there's not much reason for them to be asking questions in the first place. I can guarantee if someone gave him two identical tool posts, one cast iron and the other steel, painted so he wouldn't know which was which and he used each, he wouldn't be able to identify which was which by the results he got or by any observations made while doing the turning.
    Location: Saskatoon, Saskatchewan, Canada

    Comment


    • #32
      Originally posted by Arcane View Post

      J Tiers has said all that's needed to be said on the subject and our newbie has chosen to totally ignore his knowledge and common sense. If they aren't going to listen to good advice, there's not much reason for them to be asking questions in the first place. I can guarantee if someone gave him two identical tool posts, one cast iron and the other steel, painted so he wouldn't know which was which and he used each, he wouldn't be able to identify which was which by the results he got or by any observations made while doing the turning.
      And it upset you enough that you felt he deserved a couple of snarky comments? What do you care what he does in his shop? Steel would work just fine, as will the cast iron he is considering. That's not my point, however. My point is that you made the kind of snarky, dismissive comment that drives away newcomers. It's not helpful to anyone, Village Press included.
      George
      Traverse City, MI

      Comment


      • #33
        I'm not upset at all. I just made a comment like hundreds of others have made over the years.
        Location: Saskatoon, Saskatchewan, Canada

        Comment


        • #34
          Originally posted by J Tiers View Post
          How is vibration absorbed?

          It is absorbed by material deforming under the forces, and when it deforms, the material properties convert the mechanical energy to heat, due to frictional effects.

          OK. So how much does a block of CI deform under cutting forces? You can check the force, and the modulus of the material to see. I am not going to bother, because I can tell you something you know already.... the CI does not deform in any meaningful amount under cutting forces.
          Interesting. So what you're saying, baically, is that even though the toolpost is in compression (via the bolt from the nut to the compound t-nut), it is not in compression along the axis where the cutting forces are being appliied. Correct? If the cutting forces were coming from the nut aop the tool post, the vibration would be absorbed, but because they are coming from the side (and presumably going out the other side) they are not.

          Comment


          • #35
            Almost.

            What I am saying is that there is so much CI involved compared to the forces (and that is deliberate, a part of the plan), that the CI is just too stiff to deflect compared to all the other stuff in series mechanically, so the CI is not acting in a manner that will do any significant absorbing.

            The "structure" is just not set up in a way that could take advantage of any absorbing property that the CI may have.

            The "benefit" of a big lump of CI in this case, is pretty much equal to what a similar lump of steel, or even Zamak, could do, as it is essentially based on the mass of the lump, compared to the springiness of the rest of the structure.

            The CI is not being used as it might be in the case of a lathe bed, etc. And even there, the effect of pure mass is significant.
            CNC machines only go through the motions

            Comment


            • #36
              Originally posted by J Tiers View Post
              Almost. ...................The "structure" is just not set up in a way that could take advantage of any absorbing property that the CI may have
              ..................... as it is essentially based on the mass of the lump, .............................
              Sorry Jerry, but you are wrong . You have not considered the material factors

              First, you do not recognize that Cast Iron "Dampens Vibration " when you say "may have"
              read the physics of the metal------- http://www.atlasfdry.com/grayiron-damping.htm
              In my field of engineering, it is well known to have 10 times the dampening effect of steel
              When designing a tool , of any nature, selection of material can make a major difference in success . It is important , but access and the amount of work to make it also count.

              Second, if you will please feel your parting tool the next time you part off, you will feel some of the vibration that tool posts are exposed to in normal machining work
              and yes, mass helps, but so does the ability to dampen such forces ( Did you know that CI face Plates are superior to Steel Face plates when RPM is not a factor ?)

              Third, chastising the poster for the selection of material is not a what he posted for, he wanted a source AND he said he wanted an easy to machine material and selected CI

              Civility is part of our obligation on this board

              Rich

              PS You know a Dead Blow Hammer and a Ball Peen hammer may have the same weight/Mass, but
              the effect on the work piece is totally different .. it is in effect----the dampening effect that makes it so.
              Peace brother
              Last edited by Rich Carlstedt; 07-15-2021, 02:00 AM.
              Green Bay, WI

              Comment


              • #37
                Originally posted by George Bulliss View Post
                My point is that you made the kind of snarky, dismissive comment that drives away newcomers. It's not helpful to anyone, Village Press included.
                Damm Puppy!

                Thats the point.

                I try to encourage new folks, even long term folks.

                I get it, many Machinist type folks are Helpful to extrema. I dig that.

                It might be some sorts of overload to a new Lady, or Guy wanting to join our base? Just saying. JR

                Comment


                • #38
                  Originally posted by Rich Carlstedt View Post

                  Sorry Jerry, but you are wrong . You have not considered the material factors

                  First, you do not recognize that Cast Iron "Dampens Vibration " when you say "may have"
                  read the physics of the metal------- http://www.atlasfdry.com/grayiron-damping.htm
                  In my field of engineering, it is well known to have 10 times the dampening effect of steel
                  When designing a tool , of any nature, selection of material can make a major difference in success . It is important , but access and the amount of work to make it also count.

                  Second, if you will please feel your parting tool the next time you part off, you will feel some of the vibration that tool posts are exposed to in normal machining work
                  and yes, mass helps, but so does the ability to dampen such forces ( Did you know that CI face Plates are superior to Steel Face plates when RPM is not a factor ?)

                  Third, chastising the poster for the selection of material is not a what he posted for, he wanted a source AND he said he wanted an easy to machine material and selected CI

                  Civility is part of our obligation on this board

                  Rich

                  PS You know a Dead Blow Hammer and a Ball Peen hammer may have the same weight/Mass, but
                  the effect on the work piece is totally different .. it is in effect----the dampening effect that makes it so.
                  Peace brother
                  Rich, you paid no attention to the points I made.' I deny the truth of your contention. You are not considering the system. Go on and do whatever you like, it does not hurt me.

                  Yes, CI AS A STRUCTURE has damping characteristics.

                  Bolting a piece of CI into an otherwise rather floppy construction does NOT utilize those characteristics. IT WILL NOT BE VERY EFFECTIVE, IF AT ALL, aside from its mass, which steel can also supply at much lower cost

                  The OP might ask how to use firecrackers to make a rocket to ride. One then can give suggestions, or advise against the project.... I suggest the latter. This is only more expensive than needed, so the only disadvantage is to the OP's pocketbook.

                  Edit:

                  Just to be clear..... it is not that CI has no such property. It is that the system here does not USE that property effectively. The stiff block of CI bolted on top of n oil-filled sliding connection (crosslide to carriage) to a carriage that also has an oil-filled sliding connection to the bed, is not making use of the characteristics of CI in the proposed block attached to the crosslide. Nearly ANY material with similar mass and stiffness would be as good.

                  Why? As stated before, the big CI block is too stiff to have any significant deflection under the loads applied. The other joints will "give" first. Without significant deflection (which does not need to be a lot), there is no significant internal friction, and thus no damping*.

                  The BED does have the benefits of the damping characteristic, regardless of what is sliding on top of it. But that is the same with CI, steel, or tissue paper used to support the toolholder. And it comes from how the CI is used.... in the part of the structure that has significant deflection, with internal friction as a result. It is a major structural element. The block here is not

                  This is an important point... For any material to have it's properties used to maximum effect, it must be located and stressed in such a way that the properties are in fact used.

                  Springs are springy because of their shape. A cube of spring steel would not be very effective as a spring, but the same mass of material in a different shape would be orders of magnitude more effective.

                  It is NOT effective to "bolt on" a piece in a way that does not allow making use of its properties. That is "sprinkling pixie dust", rather than designing, and the properties can not be effective..

                  * What is damping? It is the absorption of energy, generally by converting it to heat, typically energy of vibration in this sort of situation. To dissipate energy in a material, it must exist within the material. Not just as an overall movement of the "lump", but differentially, where different parts of the material are moving relative to one another in order to create that friction.

                  Rich, the irony here is that your own example proves the point!

                  The dead-blow hammer is designed to have that differential movement inside it. The particulate filling (it's in there, shake one and listen) moves with a good deal of friction during the impact, and dissipates much of the energy that would otherwise cause a rebound.

                  If your contention about CI were true, then a dead blow hammer could be made of CI. I do not see any such, so one may draw the conclusion that the design actually used is more effective than a lump of CI. One can make a bell of CI. It rings, but not as clearly nor as long as one made of bell metal. That is damping at work, due to vibration. A bell of lead rings far worse than a CI bell, it's internal damping is even higher than CI.

                  Are you not a mechanical engineer? If you are, then you already know these facts.
                  Last edited by J Tiers; 07-15-2021, 01:00 PM. Reason: Clarification, correct fat finger typing
                  CNC machines only go through the motions

                  Comment


                  • #39
                    In my field of engineering, it is well known to have 10 times the dampening effect of steel
                    If its oscillations not moisture content we're talking about, its damping, not dampening.
                    in Toronto Ontario - where are you?

                    Comment


                    • #40
                      I am finding this discussion interesting because one of my back-burner projects is a new toolpost for the clapper on the shaper. I have been going back and forth over cast iron or steel (I have a suitable piece of each), but the vibration-damping properties of cast iron had not occurred to me (and, likely would not matter much). My understanding is that cast iron has a greater dimensional stability compared to rolled steel, but is also more brittle: the long grains of the rolled steel make it ductile.

                      What I have not come to a conclusion on is whether the brittleness of cast iron would be a problem (the springiness of the steel would be) given the relatively light forces involved (it's an Ammco shaper, after all).

                      J Tiers' point above is further food for thought: the clapper and the entire slide are of steel, and this would nullify any possible gain from the cast iron. The cutting force on a shaper pushes down through the base of the toolpost directly onto the clapper block and then the slide. A square inch or less of cast iron is not going to make any difference considering the steel of the tool/toolholder, the clapper, and the slide.

                      If this proceeds any futher I am in great danger of deciding on steel for the project, and then having to go and actually start making it.
                      Last edited by thin-woodsman; 07-19-2021, 11:25 PM.

                      Comment


                      • #41
                        Steel is less "springy" than cast iron, in so far as modulus of elasticity is concerned.
                        21" Royersford Excelsior CamelBack Drillpress Restoration
                        1943 Sidney 16x54 Lathe Restoration

                        Comment


                        • #42
                          Originally posted by thin-woodsman View Post
                          .................................

                          J Tiers' point above is further food for thought: the clapper and the entire slide are of steel, and this would nullify any possible gain from the cast iron. The cutting forbe on a shaper pushes down through the pase of the toolpost directly onto the clapper block and then the slide. A square inch or less of cast iron is not going to make any difference considering the steel of the tool/toolholder, the clapper, and the slide.

                          If this proceeds any futher I am in great danger of deciding on steel for the project, and then having to go and actually start making it.
                          Go for it.... In your case, the bulk of the machine is cast iron. That structure is active and has the properties of cast iron. A bit of steel on it won't matter, and using cast iron probably would not help much.




                          Last edited by J Tiers; 07-19-2021, 07:51 PM.
                          CNC machines only go through the motions

                          Comment

                          Working...
                          X