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chatter on new enco 13x40 lathe

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  • chatter on new enco 13x40 lathe

    I bought a new enco 13x40 lathe in dec 2001, the question I have is concerning chatter when cutting threads, It's pretty bad. I have checked the center height of the tool bit, tried carbide and hss, made sure the bit was sharp, used different cutting fluids, tightened everything down tight, used centers and steadyrest. Nothing seems to help, do I need to change the headstock bearings? Any help would be greatly appreciated. Thanks, Bill

  • #2
    Is the chatter about the same when threading different materials? I'm relatively new to
    machining, but I've found that some materials just didn't want to be threaded nice and smoothly, while others would cut smooth as silk. Tho I see in your profile that you do gunsmithing.. you probably already knew that.
    Where's Dandridge, TN? I'm in N. Ala (Huntsville).
    Lynn (Huntsville, AL)

    Comment


    • #3
      At the risk of stating the obvious, I offer my 2 cents worth (it's Canadian 2cents so it's not worth a whole lot).

      I hope you're not trying to cut the thread in a single pass. Dont' feed the tool straight in. Instead set your compound rest at 29 degrees and use the compound feed to advance the cut until you get the depth that you need.

      Also, with all new machines, check the gibs on the saddle and the cross slide, and make sure they are snug and moving smoothly with no play.

      Bofore you go entertaining such wonderful ideas as replacing the headstock bearings check with a dial indicator for all run outs.

      There are many other possible reasons for the chatter but you can methodically rule out each possibilities. Good luck.

      Albert


      [This message has been edited by Rotate (edited 03-06-2002).]

      Comment


      • #4
        To the first reply, Dandridge is 40 miles east of Knoxville. To the second reply, Multiple passes, ending with several at .001, Tightened all gibs, adjusted belt tention,etc. I've got a call in to enco, but they haven't responded yet.(thought I'd check with the experts first) I've been an avid machinist and gunsmith for 22 years, and this has got me stumped.

        Comment


        • #5
          I don't have anything to contribute on the threading problem.

          I am interested in which model Enco lathe you bought. Does it have the foot brake or is it the bench model?

          What is your opinion of the machine besides the threading problem?

          Thanks.

          Greg

          ------------------

          Comment


          • #6
            Hi greg; It's the model 110-1351. The problems i've found are minor. Toolholder : not at the correct height for either 3/8 or 1/2 inch toolbits(?), I just milled the bottom of the 1/2 inch toolbits to the correct center height. The chatter!! Other than that it's a good lathe for the money, heavy, good range of speeds/feeds, good hole through the spindle 1.5"

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            • #7
              I have been trying to decide between the one you got and the next level up (111-3310; 13x40 with foot brake and wider bed).

              Did you make a similiar decision on the Enco lathes?

              Thanks.

              Greg

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              • #8
                Greg; Not much of a decision on my part , it was the one I could afford.

                Comment


                • #9
                  Bill,

                  Please do let us know when you've found the source of the chatter.

                  Albert

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                  • #10
                    Bill

                    Have you kept your slides and carrage well lubricated with way lubricant? This can have a big effect - the oil dampens vibration somewhat and can eliminate chatter sometimes.

                    Make sure the tool is exactly on center - very important!

                    Set the top slide over 29*. Then insure the 60* cutting tool is perpindicular to the work piece. The top slide infeed is then used to advance the tool - not the cross slide! This will cut only on one side of the tool and and "wipe" the other side smooth. If you are directly plunging in and trying to cut a "V" chip - this is the problem.

                    Change RPMs.

                    Double check cutting edge - carbide cuts rough when you have a fractured edge, cratering, plastic deformation, or BUE.

                    Set your cutting tools as close to the toolholder to reduce overhang - if the bits stick out too far it flexes more under load and vibrates (chatter).

                    Some materials are a bitch to thread or have a poor surface finish because of physical properties - good cutting fluid helps and should always be used. If you use coolant, use more - more is better - flood the cut especially with carbide. Carbide can experience thermal shock loads from inadequate coolant - you have to flood the cut properly or dry machine - it is all or nothing here. Make sure the coolant is mixed properly.



                    [This message has been edited by Thrud (edited 03-07-2002).]

                    Comment


                    • #11
                      Does this lathe have a feed rod separate from the lead screw, used for longitudinal feed for normal machining? If so that might suggest an explanation for a difference in machining quality between threading and normal cutting in automatic mode. What I'm suggesting is there may be some vibration being introduced thru the halfnuts or the leadscrew/gearing itself.
                      (...just a W.A.G.)
                      Lynn
                      Lynn (Huntsville, AL)

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                      • #12
                        Is this one of those funky 4 way tool posts with a indexer detent made into compound. Or is it in tee nut bar, whatever, they won't index right if compound set at 29 or 29 1/2 degrees from cross slide. Maybe what I should say is that detent letting toolpost sit down right if its not on top of it's regular detenting spot.

                        Tool post needs to be sitting down good and proper, good and tight.

                        To put your finger on the problem, literally maybe. Get this in a long vibrating cut, and start putting finger at anywhere 2 parts mate together, the fingertip might just find the problem. Something sounds loose, maybe a chip between the compound and cross slide.

                        I wouldn't start tearing apart the headstock yet. I'd at least get out the indicator first.

                        Chuck mounted proper?

                        Does the center taper match up with tailstock hole good, machined right?

                        Compound bolt getting tight but not actually tightening, as in threads not cut far enough, too long of bolt?

                        Lots of possibilities. These Asian made machines just need a little going over, attention to little details, final inspections are sometimes lacking.

                        [This message has been edited by halfnut (edited 03-07-2002).]

                        Comment


                        • #13
                          Gents,
                          First time poster on your board but have been going to class here for about a month. Excellent Board!
                          I also have a New Enco Lathe model 110-2086 (bought 1 آ½ year ago) - 12z36 Gear Head Gap Bed in which I am experiencing the same phenomenon per the chattering threads. I have threaded about every kind of metal I can get my hands on and it still chatters. I have done all of the things you gentlemen have suggested and so far the one thing that helped (but did not fix) the problem is leveling the lathe with a Starrett Precision Level. I also changed the toolpost to the Aloris type, tried HSS and Carbide threading tools and have even threaded from 50 rpm to 800 rpm. The 800 rpm thread did look pretty good. I read one thread on another board that said if you pass a sheet of paper between the drive gears and it cuts the paper then the gears are too close together and will cause chatter – spaced the gears but that didn’t help. I have threaded several rifle barrels, bolts, assorted brass & stainless nuts and bolts and all seem to screw together perfectly but I can still see the “chatterâ€‌ look on the threads. Most laymen that look at the threads do not see it but I do and it bothers me. I have a friend (he talked me into buying this model) whom has the exact lathe and his threads perfect and I CAN’T STAND IT! I have had several machinists look at my lathe and no one has found the problem. I hope one of you intelligent guys can tell Bill and I how to fix our problem before I pull the rest of my hair out.

                          Comment


                          • #14
                            Like gater I've tried everything that I know, that's why I thought I might need to change the headstock bearings. I've tried threading drill rod, cold roll, stainless, aluminum, and a salvaged hydraulic ram. Nothing threads smooth. All the threaded parts work well, but I'm not used to the poor appearence of the threads. BTW, the chatter is apparent even when turning to dia., the finer the feed, the finer the chatter, but it's still there. HELP!

                            Comment


                            • #15
                              Do you also get the same chatter when facing with the crossfeed in auto? ie. same frequency? Is this belt driven from the motor? Could there possibly be some slippage there? (maybe you'd already mentioned cheking that.. if so, sorry)
                              Lynn (Huntsville, AL)

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