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Boring a hole on my milling machine - cheap boring head woes

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  • Boring a hole on my milling machine - cheap boring head woes

    I had to bore a couple 22mm holes in 1/4" aluminum for a ball bearing. I was able to make the first one a pretty good press fit, but the second one went a few thousandths oversize - probably due to looseness in the boring head. Here's how it "went down":



    Looks like I need a better boring head, or maybe I can rework what I have? Here are some that seem OK without breaking the bank:

    http://www.lathemaster.com/BORINGHEADSETMTSHANK.htm

    http://www.ebay.com/itm/2-Boring-Head-002-Precision-Milling-Lathe-Tool-Workholding-Boring-Head-/281310398221

    http://www.littlemachineshop.com/pro...ProductID=4764

    http://www.littlemachineshop.com/pro...ProductID=1266

    http://www.littlemachineshop.com/pro...ProductID=1630
    http://pauleschoen.com/pix/PM08_P76_P54.png
    Paul , P S Technology, Inc. and MrTibbs
    USA Maryland 21030

  • #2
    You can use an end mill to do this instead of that boring bar. I've been pretty happy with the results I get.

    Comment


    • #3
      Seemed ok until the end there. Lots of possibilities with a lower quality boring head. Gib could be scraped for better fit to dovetails. Dovetails could be checked for parallelism. Set screws could be swapped out for "real" set screws from McMaster and a redo of adjustment screw to something you know is accurate and good matching thread to that in the boring head. If the boring head is indeed the issue (which it most probably is), it should be fixable, like many other "kits of parts" sold as a usable tool, from price-point sensitive suppliers.
      Cheers,
      Gary

      Comment


      • #4
        I had a similar expirience, bought a cheap set, used it on a small mill/drill, results noise chatter and an oversized hole, consigned it to the bottom draw where things go to die, bought a tidy cincinnati mill, ok made in france but you know what i mean, needed a boring head so resurected it from the graveyard, refitted a 40 taper arbour to it and gave it a go, it wasent perfect but a whole lot better which i founf odd, possibly the mill drill column was deflecting as well as the cutter?, since then i tend to use the biggest cutter that will go in the hole as i found they spring an awful lot when boring, especially in a boring head, you can grab the cutter and flex it 20 thou with your fingers, try it!
        With a little head lots and lots of realy light cuts to sneak up on the aim size is my new way, good quality boring and facing heads are certainly expensive, dont think i have seen one for less than £400.
        Apart from that thanks for taking the time to record and post the vidio, it was good
        Regards
        Mark

        Comment


        • #5
          Use the biggest cutter that you can mount there. Also, do not trust that advancement screw, measure the needed offset with a dial indicator to be sure it moves exactly what you want and stays there when you lock it down.

          Also when boring, you usually just bore through and not peck the hole.

          Also replace the set screws used for locking with proper cap head screws.
          Amount of experience is in direct proportion to the value of broken equipment.

          Comment


          • #6
            Originally posted by boslab View Post
            i found they spring an awful lot when boring, especially in a boring head, you can grab the cutter and flex it 20 thou with your fingers, try it!
            With a little head lots and lots of realy light cuts to sneak up on the aim size is my new way, good quality boring and facing heads are certainly expensive, dont think i have seen one for less than £400.
            Mark
            That exactly it. Your mill is a wet noodle. Especially with a boring head and a long boring bar in it.
            You should sneak up to the end dimension so that your only taking a thou or two off per pass.
            Once you get up to the final dimension you need to take several passes, dead slow feed (high rpm), without changing any settings before measuring for how much to move the boring head. You will see it taking off little hairs of material with each additional pass. (At least, in aluminum, Some materials do not enjoy very light passes)

            You can also use an indicator clamped to the table, onto the boring head to get a better indication of how much it moved when you adjust it, without worrying about backlash/inaccuracy in the screw. Also good for checking it didn't move when you tightened the gibs.
            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

            Comment


            • #7
              If that material is aluminium, I would be squirting wd40 in there at the same time, I've found ally likes to grab the tip and pull it in or build up and push it off without it.

              I always use power feed and auto stop when boring on the mill, always straight through in each pass, unless I want a shoulder of course
              If it does'nt fit, hit it.
              https://ddmetalproducts.co.uk
              http://www.davekearley.co.uk

              Comment


              • #8
                You are not using it correctly. You set the 2 outside setscrews for a light drag on the slide, make your adjustment and tighten the center one. When that size is done, loosen the middle setscrew and make the next adjustment and re tighten. In your case, it looks like the slide on the boring head is working it's way out due to centrifugal forces and vibration.

                Never try to move the adjustment screw with the setscrews tight or you will strip out the adjusting threads. That will happen on even the best quality boring heads.
                Kansas City area

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                • #9
                  Do you really think the stuff from LMS which is made in china is any better than the rest of the chinee stuff being sold on Fleabay or by Victor, 800Watt, Shars, ToolsforCheap or any other seller? Minor differences in fir and finish, but by and large the same stuff. The chinee boring heads are probably as good as those Horror Freight setscrews or their bandsaw blades. You buy cheap, you get cheap. If you want an import head, buy a Yuasa.

                  Comment


                  • #10
                    I've got a LatheMaster boring head (Chinese) that works pretty well for what I do. I don't work the boring head very hard. I take a lot of light passes--probably 0.050" off the diameter max. Most of the time it's much less than that. I feed it real slow (no auto-feed on my mill). If I'm making a big hole I'll remove most of the material with something else--drill, hole saw, endmill and rotary table, whatever--and then clean up with the boring head. I have found the markings on the adjustment to be quite accurate. Just be aware that the boring bar is going to flex a lot on a heavy cut, so you do have to "sneak up" up on your final dimension or you'll just be guessing when you switch from a heavy cut to a light cut.

                    When I first got the boring head I would loose the setscrews on the slides before an adjustment and then tighten after. Now I just let them drag a little and don't bother with loosening and tightening again for every adjustment. That's been working for me.

                    I had the opportunity to use a Criterion boring head when I was taking that class last year. Aside from the fact that the markings on the adjustment screw were much easier to see than the ones on my LatheMaster, I didn't really notice any difference in operation. After having replaced the cheesy setscrews in mine, I have been well pleased with it.

                    Jim

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                    • #11
                      Reading these posts make me realize how lucky I was to get a Bridgeport boring head with the tooling when I bought my mill. Every time I have used it has been a good expirience.

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                      • #12
                        Thanks for the replies. So I took a closer look at the boring head, and found several issues. The button head screw below the adjustment screw was cross-threaded and thus did not hold the adjustment plate properly, causing some play in the position of the head. I was able to screw it out and back in correctly, and the screw threads seem OK, but obviously the threads in the head are buggered. I took it apart:





                        As you can see, the adjustment plate is very roughly formed, and the socket head screws are rather buggered up. The Allen wrenched that came with the set have become badly rounded, but a proper 2.5 mm wrench still works OK. However, I think I will need to replace the screws so I can use this tool with better results. Meanwhile I can look for a better boring head if one comes along at a bargain price.
                        http://pauleschoen.com/pix/PM08_P76_P54.png
                        Paul , P S Technology, Inc. and MrTibbs
                        USA Maryland 21030

                        Comment


                        • #13
                          Originally posted by PStechPaul View Post
                          Thanks for the replies. So I took a closer look at the boring head, and found several issues. The button head screw below the adjustment screw was cross-threaded and thus did not hold the adjustment plate properly, causing some play in the position of the head. I was able to screw it out and back in correctly, and the screw threads seem OK, but obviously the threads in the head are buggered. I took it apart:

                          As you can see, the adjustment plate is very roughly formed, and the socket head screws are rather buggered up. The Allen wrenched that came with the set have become badly rounded, but a proper 2.5 mm wrench still works OK. However, I think I will need to replace the screws so I can use this tool with better results. Meanwhile I can look for a better boring head if one comes along at a bargain price.
                          Glad I bought a used Yuasa for $75. Is that rust (and pitting) on the shank and the head?

                          Comment


                          • #14
                            There appears to be no gib, and thus no way to adjust for wear or lock the thing.

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                            • #15
                              There is a split on one side of the boring head that allows it to clamp the slide.
                              Kansas City area

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