Announcement

Collapse
No announcement yet.

Another Boring Day

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

  • Another Boring Day

    Was trying to Bore (ive done so many successfuly YET) a 4 inch deep 1.375 diameter hole today. Couldnt get boring bar to work right?? I have tried so many and it seems to usually give me lots of grief. I think i need some new tips on Hole Boring. I find doing the Longer Bores causes me loads of trouble Any tips guys thanx Mike

  • #2
    Make sure the tool is on the center line .

    Use the biggest bar you got that will fit the hole

    Take light cuts if using a small bar

    I usually hog as much material out of the hole that I can with a drill , then use a bar .
    NRA member

    Gun control is using both hands

    Comment


    • #3
      Deep Bores

      I seem to run into troubles in my home shop due to using a old bridgeport and substandard chinese boring bars. Also when bore depths get into 4 inch plus region chatter and tip breakage seems always a problem I run the mill at the slowest spindle speed and tried fasrter slower and so on,. Nothing works squeals and so on. Tips Please?? Thanx

      Comment


      • #4
        I take from you 2nd post your using a mill, not a lathe. I prefer to bore on the lathe and Js's tips are right on. Usually, a ratio of 3:1 or 4:1 depth:diameter should be adhered to so a 1" boring bar(HSS) would fit this for 4" depth.
        What dia. are you using?
        Also, watch your clearance angles.
        What material are you trying to bore?
        I bury my work

        Comment


        • #5
          Use hss toolbit with lots of top rake, reduces the load on the bar. Of course you will have to slow down. 200 for mild steel less for alloy steel. I have had 0 luck with china carbide boring bars. bought one set and they are for decoration only. I have no trouble with hss. Peter
          The difficult done right away. the impossible takes a little time.

          Comment


          • #6
            Chinese

            CRAP_ Boring Bars. i even tried re silver soldering tips onto the ends. No Luck Later Pissed off Mike

            Comment


            • #7
              One trick someone showed me was that if the stock started to ring and cause chatter to wrap the stock tightly on the outside with a rubber strap like maybe a bicycle inner tube opened up and cut to width. Never seen that mentioned here but it works well for me when i'm boring out a piece of 3" AL. When I get within 1/2" from the outer diameter it starts ringing like a bell and the cut goes to hell. Wrap it and all is good.
              Ernie (VE7ERN)

              May the wind be always at your back

              Comment


              • #8
                You should be doing that in a lathe, not a mill. Is that a through hole or blind hole?
                It's only ink and paper

                Comment


                • #9
                  Originally posted by Carld
                  You should be doing that in a lathe, not a mill. Is that a through hole or blind hole?
                  Carl was that directed at my post??? If so that was on a lathe and blind holes
                  Ernie (VE7ERN)

                  May the wind be always at your back

                  Comment


                  • #10
                    Rule #1 when boring. Rigidity, rigidity, rigidity. Rule #2, see rule #1. as noted as big a bar as you can fit in the hole with the minimum amount of length possible.
                    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

                    Comment


                    • #11
                      I made a boring bar holder for my mill, starting with a chunk of steel larger in diameter than the spindle. Into that I turned a recess so that chunk would be a snug fit over the spindle. A drawbar holds it in place, and a pin keeps it from rotating on the spindle. The rest of the chunk is machined like a boring tool, and uses 3/8 shank boring bars. I've had no problem going the full depth into aluminum, and it works in steel also, but I haven't gone the full 3 inches deep in steel.

                      This setup is more rigid than the other boring tool I made which mounts inside the spindle, like all the other accessories such as end-mill holders, fly cutters, etc. I recently made another boring tool, for larger diameter holes up to about 6 inches, using the same method. I've been equally impressed with how smoothly a cut can be made. Let me coin a phrase, if it hasn't already been done- 'flex makes wrecks'. Ok, so that's cheesy, but it says the same thing- rigidity is good.

                      Another thing which helps and has already been stated is that damping is good. I actually haven't tried damping the workpiece, but several times I've put damping material on a boring bar and improved things a lot. I used to use a lot of window sealing strip in a previous job, the black tarry type stuff, and that's what I use for damping. Playing with its location on the boring bar will be worth the effort.

                      Some of my projects involve either turning or grinding on a small diameter workpiece, which is often several diameters out of the chuck. Many times I'll use a finger on it to dampen, and that works well- however I can show you one or two fingers without any fingerprints left - not funny really, getting burnt or making zillions of tiny slices in the skin from the rough surface of the workpiece, but it does show instantly what damping can do to improve things.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                      Comment


                      • #12
                        D:
                        Can you post a pic of your device?

                        Thanks, Paul
                        I bury my work

                        Comment


                        • #13
                          Rapping string or better yet heavy solder ot lead wire around the bar or work will dampen vibration quite well.
                          The shortest distance between two points is a circle of infinite diameter.

                          Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                          Southwestern Ontario. Canada

                          Comment


                          • #14
                            No one else said it.

                            If your mill is a bit worn, or perhaps not made in USA or Canada you may find it far better to bore by raising the knee rather than lowering the quill. Some quills dont fit very well and most arent adjustable for fit. Its harder work, unless you have power to raise the knee. Regards David Powell.

                            Comment


                            • #15
                              dockrat, no, I was refering to madman's problem. You did your boring job right. Doing a job he and you described is best done on a lathe with a positive carriage stop. One still has to be carefull at the bottom of a bore on a blind hole.

                              Even if his is a through hole that long of a bore is a problem on a mill. Not that it can't be done on a mill, it's just harder because you have to use a smaller boring bar with the boring head.
                              It's only ink and paper

                              Comment

                              Working...
                              X